Sample records for regions slope failures

  1. Mapping basin-wide subaquatic slope failure susceptibility as a tool to assess regional seismic and tsunami hazards (United States)

    Strasser, Michael; Hilbe, Michael; Anselmetti, Flavio S.


    With increasing awareness of oceanic geohazards, submarine landslides are gaining wide attention because of their catastrophic impacts on both offshore infrastructures (e.g. pipelines, cables and platforms) and coastal areas (e.g. landslide-induced tsunamis). They also are of great interest because they can be directly related to primary trigger mechanisms including earthquakes, rapid sedimentation, gas release, glacial and tidal loading, wave action, or clathrate dissociation, many of which represent potential geohazards themselves. In active tectonic environments, for instance, subaquatic landslide deposits can be used to make inferences regarding the hazard derived from seismic activity. Enormous scientific and economic efforts are thus being undertaken to better determine and quantify causes and effects of natural hazards related to subaquatic landslides. In order to achieve this fundamental goal, the detailed study of past events, the assessment of their recurrence intervals and the quantitative reconstruction of magnitudes and intensities of both causal and subsequent processes and impacts are key requirements. Here we present data and results from a study using fjord-type Lake Lucerne in central Switzerland as a "model ocean" to test a new concept for the assessment of regional seismic and tsunami hazard by basin-wide mapping of critical slope stability conditions for subaquatic landslide initiation. Previously acquired high-resolution bathymetry and reflection seismic data as well as sedimentological and in situ geotechnical data, provide a comprehensive data base to investigate subaquatic landslides and related geohazards. Available data are implemented into a basin-wide slope model. In a Geographic Information System (GIS)-framework, a pseudo-static limit equilibrium infinite slope stability equation is solved for each model point representing reconstructed slope conditions at different times in the past, during which earthquake-triggered landslides

  2. Storm-Induced Slope Failure Susceptibility Mapping (United States)


    A pilot study was conducted to characterize and map the areas susceptible to slope failure using state-wide available data. The objective was to determine whether it would be possible to provide slope-failure susceptibility mapping that could be used...

  3. Slope failure investigation management system. (United States)


    Highway slopes are exposed to a variety of environmental and climatic conditions, such as deforestation, cycles of : freezing and thawing weather, and heavy storms. Over time, these climatic conditions, in combination with other : factors such as geo...

  4. Development of a GIS-based failure investigation system for highway soil slopes (United States)

    Ramanathan, Raghav; Aydilek, Ahmet H.; Tanyu, Burak F.


    A framework for preparation of an early warning system was developed for Maryland, using a GIS database and a collective overlay of maps that highlight highway slopes susceptible to soil slides or slope failures in advance through spatial and statistical analysis. Data for existing soil slope failures was collected from geotechnical reports and field visits. A total of 48 slope failures were recorded and analyzed. Six factors, including event precipitation, geological formation, land cover, slope history, slope angle, and elevation were considered to affect highway soil slope stability. The observed trends indicate that precipitation and poor surface or subsurface drainage conditions are principal factors causing slope failures. 96% of the failed slopes have an open drainage section. A majority of the failed slopes lie in regions with relatively high event precipitation ( P>200 mm). 90% of the existing failures are surficial erosion type failures, and only 1 out of the 42 slope failures is deep rotational type failure. More than half of the analyzed slope failures have occurred in regions having low density land cover. 46% of failures are on slopes with slope angles between 20° and 30°. Influx of more data relating to failed slopes should give rise to more trends, and thus the developed slope management system will aid the state highway engineers in prudential budget allocation and prioritizing different remediation projects based on the literature reviewed on the principles, concepts, techniques, and methodology for slope instability evaluation (Leshchinsky et al., 2015).

  5. Centrifuge model test of rock slope failure caused by seismic excitation. Plane failure of dip slope

    International Nuclear Information System (INIS)

    Ishimaru, Makoto; Kawai, Tadashi


    Recently, it is necessary to assess quantitatively seismic safety of critical facilities against the earthquake induced rock slope failure from the viewpoint of seismic PSA. Under these circumstances, it is essential to evaluate more accurately the possibilities of rock slope failure and the potential failure boundary, which are triggered by earthquake ground motions. The purpose of this study is to analyze dynamic failure characteristics of rock slopes by centrifuge model tests for verification and improvement of the analytical methods. We conducted a centrifuge model test using a dip slope model with discontinuities limitated by Teflon sheets. The centrifugal acceleration was 50G, and the acceleration amplitude of input sin waves increased gradually at every step. The test results were compared with safety factors of the stability analysis based on the limit equilibrium concept. Resultant conclusions are mainly as follows: (1) The slope model collapsed when it was excited by the sine wave of 400gal, which was converted to real field scale, (2) Artificial discontinuities were considerably concerned in the collapse, and the type of collapse was plane failure, (3) From response acceleration records observed at the slope model, we can say that tension cracks were generated near the top of the slope model during excitation, and that might be cause of the collapse, (4) By considering generation of the tension cracks in the stability analysis, correspondence of the analytical results and the experimental results improved. From the obtained results, we need to consider progressive failure in evaluating earthquake induced rock slope failure. (author)

  6. Slope failure susceptibility zonation using integrated remote sensing ...

    Indian Academy of Sciences (India)


    In view of the above, hazard assessment was necessary to identify area with ... Singrauli coalfield and surrounding regions comprise of two distinct .... highwall slope failure susceptibility zonation was done using multi-layered ... iii) generation of false colour composites (band combinations and ratioing) iv) generation of.

  7. Laboratory and 3-D-distinct element analysis of failure mechanism of slope under external surcharge (United States)

    Li, N.; Cheng, Y. M.


    Landslide is a major disaster resulting in considerable loss of human lives and property damages in hilly terrain in Hong Kong, China and many other countries. The factor of safety and the critical slip surface for slope stabilization are the main considerations for slope stability analysis in the past, while the detailed post-failure conditions of the slopes have not been considered in sufficient details. There are however increasing interest on the consequences after the initiation of failure which includes the development and propagation of the failure surfaces, the amount of failed mass and runoff and the affected region. To assess the development of slope failure in more details and to consider the potential danger of slopes after failure has initiated, the slope stability problem under external surcharge is analyzed by the distinct element method (DEM) and laboratory model test in the present research. A more refined study about the development of failure, microcosmic failure mechanism and the post-failure mechanism of slope will be carried out. The numerical modeling method and the various findings from the present work can provide an alternate method of analysis of slope failure which can give additional information not available from the classical methods of analysis.

  8. Dip-slope and Dip-slope Failures in Taiwan - a Review (United States)

    Lee, C.


    Taiwan is famous for dip-slope and dip-slope slides. Dip-slopes exist at many places in the fold-and-thrust belt of Taiwan. Under active cutting of stream channels and man-made excavations, a dip-slope may become unstable and susceptible for mass sliding. Daylight of a bedding parallel clay seam is the most dangerous type for dip-slope sliding. Buckling or shear-off features may also happen at toe of a long dip-slope. Besides, a dip-slope is also dangerous for shallow debris slides, if the slope angle is between 25 to 45 degrees and the debris (colluvium or slope wash) is thick (>1m). These unstable slopes may slide during a triggering event, earthquake or typhoon storm; or even slide without a triggering event, like the 2010 Tapu case. Initial buckling feature had been found in the dip-slope of the Feitsui arch dam abutment after detailed explorations. Shear-off feature have also been found in dip-slope located in right bank of the Nahua reservoir after field investigation and drilling. The Chiufengerhshan slide may also be shear-off type. On the other hand, the Tapu, the Tsaoling slides and others are of direct slide type. The Neihoo Bishan slide is a shallow debris slide on dip-slope. All these cases demonstrate the four different types of dip-slope slide. The hazard of a dip-slope should be investigated to cover these possible types of failure. The existence of bedding parallel clay seams is critical for the stability of a dip-slope, either for direct slide or buckling or shear-off type of failure, and is a hot point during investigation. Because, the stability of a dip-slope is changing with time, therefore, detailed explorations to including weathering and erosion rates are also very necessary to ensure the long-term stability of a dip-slope.

  9. Deformation and failure mechanism of slope in three dimensions

    Directory of Open Access Journals (Sweden)

    Yingfa Lu


    Full Text Available Understanding three-dimensional (3D slope deformation and failure mechanism and corresponding stability analyses are crucially important issues in geotechnical engineering. In this paper, the mechanisms of progressive failure with thrust-type and pull-type landslides are described in detail. It is considered that the post-failure stress state and the pre-peak stress state may occur at different regions of a landslide body with deformation development, and a critical stress state element (or the soil slice block exists between the post-failure stress state and the pre-peak stress state regions. In this regard, two sorts of failure modes are suggested for the thrust-type and three sorts for pull-type landslides, based on the characteristics of shear stress and strain (or tensile stress and strain. Accordingly, a new joint constitutive model (JCM is proposed based on the current stability analytical theories, and it can be used to describe the mechanical behaviors of geo-materials with softening properties. Five methods, i.e. CSRM (comprehensive sliding resistance method, MTM (main thrust method, CDM (comprehensive displacement method, SDM (surplus displacement method, and MPM (main pull method, for slope stability calculation are proposed. The S-shaped curve of monitored displacement vs. time is presented for different points on the sliding surface during progressive failure process of landslide, and the relationship between the displacement of different points on the sliding surface and height of landslide body is regarded as the parabolic curve. The comparisons between the predicted and observed load–displacement and displacement–time relations of the points on the sliding surface are conducted. The classification of stable/unstable displacement–time curves is proposed. The definition of the main sliding direction of a landslide is also suggested in such a way that the failure body of landslide (simplified as “collapse body” is only

  10. Slope failure investigation management system : [research summary]. (United States)


    Highway slopes are exposed to a variety of environmental and climatic conditions, : such as deforestation, cycles of freezing and thawing weather, and heavy storms. : Over time, these climatic conditions, in combination with other factors such as : g...

  11. Submarine slope failures along the convergent continental margin of the Middle America Trench (United States)

    Harders, Rieka; Ranero, CéSar R.; Weinrebe, Wilhelm; Behrmann, Jan H.


    We present the first comprehensive study of mass wasting processes in the continental slope of a convergent margin of a subduction zone where tectonic processes are dominated by subduction erosion. We have used multibeam bathymetry along ˜1300 km of the Middle America Trench of the Central America Subduction Zone and deep-towed side-scan sonar data. We found abundant evidence of large-scale slope failures that were mostly previously unmapped. The features are classified into a variety of slope failure types, creating an inventory of 147 slope failure structures. Their type distribution and abundance define a segmentation of the continental slope in six sectors. The segmentation in slope stability processes does not appear to be related to slope preconditioning due to changes in physical properties of sediment, presence/absence of gas hydrates, or apparent changes in the hydrogeological system. The segmentation appears to be better explained by changes in slope preconditioning due to variations in tectonic processes. The region is an optimal setting to study how tectonic processes related to variations in intensity of subduction erosion and changes in relief of the underthrusting plate affect mass wasting processes of the continental slope. The largest slope failures occur offshore Costa Rica. There, subducting ridges and seamounts produce failures with up to hundreds of meters high headwalls, with detachment planes that penetrate deep into the continental margin, in some cases reaching the plate boundary. Offshore northern Costa Rica a smooth oceanic seafloor underthrusts the least disturbed continental slope. Offshore Nicaragua, the ocean plate is ornamented with smaller seamounts and horst and graben topography of variable intensity. Here mass wasting structures are numerous and comparatively smaller, but when combined, they affect a large part of the margin segment. Farther north, offshore El Salvador and Guatemala the downgoing plate has no large seamounts but

  12. Application of distinct element method of toppling failure of slope

    International Nuclear Information System (INIS)

    Ishida, Tsuyoshi; Hibino, Satoshi; Kitahara, Yoshihiro; Ito, Hiroshi


    The authors have pointed out, in the latest report, that DEM (Distinct Element Method) seems to be a very helpful numerical method to examine the stability of fissured rock slopes, in which toppling failure would occur during earthquakes. In this report, the applicability of DEM for such rock slopes is examined through the following comparisons between theoretical results and DEM results, referring Voegele's works (1982): (1) Stability of one block on a slope. (2) Failure of a rock block column composed of 10 same size rectangular blocks. (3) Cable force required to make a slope stable. Through above 3 comparisons, it seems that DEM give the reasonable results. Considering that these problems may not be treated by the other numerical methods such as FEM and so on, so DEM seems to be a very useful method for fissured rock slope analysis. (author)

  13. Application of distinct element method to toppling failure of slopes

    International Nuclear Information System (INIS)

    Ishida, Tsuyoshi; Hibino, Satoshi; Kitahara, Yoshihiro; Asai, Yoshiyuki.


    Recently, the stability of slopes during earthquakes has become to be an important engineering problem, especially in case of the earthquake-proof design of nuclear power plants. But, for fissured rock slopes, some problems are remained unresolved, because they can not be treated as continua. The authors have been investigating toppling failure of slopes, from a point of view which regards a fissured rock mass as an assemblage of rigid blocks. DEM (Distinct Element Method) proposed by Cundall (1974) seems to be very helpful to such a investigation. So, in this paper, the applicability of DEM to toppling failure of slopes is examined through the comparison between DEM results and theoretical or experimental results using 3 simple models. (author)

  14. Determination of slope failure using 2-D resistivity method (United States)

    Muztaza, Nordiana Mohd; Saad, Rosli; Ismail, Nur Azwin; Bery, Andy Anderson


    Landslides and slope failure may give negative economic effects including the cost to repair structures, loss of property value and medical costs in the event of injury. To avoid landslide, slope failure and disturbance of the ecosystem, good and detailed planning must be done when developing hilly area. Slope failure classification and various factors contributing to the instability using 2-D resistivity survey conducted in Selangor, Malaysia are described. The study on landslide and slope failure was conducted at Site A and Site B, Selangor using 2-D resistivity method. The implications of the anticipated ground conditions as well as the field observation of the actual conditions are discussed. Nine 2-D resistivity survey lines were conducted in Site A and six 2-D resistivity survey lines with 5 m minimum electrode spacing using Pole-dipole array were performed in Site B. The data were processed using Res2Dinv and Surfer10 software to evaluate the subsurface characteristics. 2-D resistivity results from both locations show that the study areas consist of two main zones. The first zone is alluvium or highly weathered with the resistivity of 100-1000 Ωm at 20-70 m depth. This zone consists of saturated area (1-100 Ωm) and boulders with resistivity value of 1200-3000 Ωm. The second zone with resistivity values of > 3000 Ωm was interpreted as granitic bedrock. The study area was characterized by saturated zones, highly weathered zone, highly contain of sand and boulders that will trigger slope failure in the survey area. Based on the results obtained from the study findings, it can be concluded that 2-D resistivity method is useful method in determination of slope failure.

  15. Slope failure of chalk channel margins

    DEFF Research Database (Denmark)

    Gale, A.; Anderskouv, Kresten; Surlyk, Finn


    provide evidence for recurring margin collapse of a long-lived Campanian channel. Compressionally deformed and thrust chalk hardgrounds are correlated to thicker, non-cemented chalk beds that form a broad, gentle anticline. These chalks represent a slump complex with a roll-over anticline of expanded, non......-cemented chalk in the head region and a culmination of condensed hardgrounds in the toe region. Observations strongly suggest that the slumping represents collapse of a channel margin. Farther northwards, the contemporaneous succession shows evidence of small-scale penecontemporaneous normal faulting towards...

  16. Submarine slope failures due to pipe structure formation. (United States)

    Elger, Judith; Berndt, Christian; Rüpke, Lars; Krastel, Sebastian; Gross, Felix; Geissler, Wolfram H


    There is a strong spatial correlation between submarine slope failures and the occurrence of gas hydrates. This has been attributed to the dynamic nature of gas hydrate systems and the potential reduction of slope stability due to bottom water warming or sea level drop. However, 30 years of research into this process found no solid supporting evidence. Here we present new reflection seismic data from the Arctic Ocean and numerical modelling results supporting a different link between hydrates and slope stability. Hydrates reduce sediment permeability and cause build-up of overpressure at the base of the gas hydrate stability zone. Resulting hydro-fracturing forms pipe structures as pathways for overpressured fluids to migrate upward. Where these pipe structures reach shallow permeable beds, this overpressure transfers laterally and destabilises the slope. This process reconciles the spatial correlation of submarine landslides and gas hydrate, and it is independent of environmental change and water depth.

  17. Laboratory and 3-D distinct element analysis of the failure mechanism of a slope under external surcharge (United States)

    Li, N.; Cheng, Y. M.


    Landslide is a major disaster resulting in considerable loss of human lives and property damages in hilly terrain in Hong Kong, China and many other countries. The factor of safety and the critical slip surface for slope stabilization are the main considerations for slope stability analysis in the past, while the detailed post-failure conditions of the slopes have not been considered in sufficient detail. There is however increasing interest in the consequences after the initiation of failure that includes the development and propagation of the failure surfaces, the amount of failed mass and runoff and the affected region. To assess the development of slope failure in more detail and to consider the potential danger of slopes after failure has initiated, the slope stability problem under external surcharge is analyzed by the distinct element method (DEM) and a laboratory model test in the present research. A more refined study about the development of failure, microcosmic failure mechanisms and the post-failure mechanisms of slopes will be carried out. The numerical modeling method and the various findings from the present work can provide an alternate method of analysis of slope failure, which can give additional information not available from the classical methods of analysis.

  18. Recent slope failures in the Dolomites (Northeastern Italian Alps) in a context of climate change (United States)

    Chiarle, Marta; Paranunzio, Roberta; Laio, Francesco; Nigrelli, Guido; Guzzetti, Fausto


    Climate change in the Greater Alpine Region is seriously affecting permafrost distribution, with relevant consequences on slope stability. In the Italian Alps, the number of failures from rockwalls at high elevation markedly increased in the last 20-30 years: the consistent temperature increase, which warmed twice than the global average, may have seriously influenced slope stability, in terms of glaciers retreat and permafrost degradation. Moreover, the growing number of tourists and activities in alpine regions (in particular in the Dolomites) made these areas particularly critical in relation to natural hazards. In this light, an integrated short-term geomorphological and climatic analysis was performed, in order to better comprehend the impact of main climate elements (especially temperature and precipitation) on slope failures in high mountain areas. In this contribution, we focus on three recent slope failures occurred at high elevation sites in the Dolomites (Northeastern Italian Alps), declared a UNESCO World Heritage Site in August 2009. We describe here three important rock falls occurred in the autumn 2013: 1) the Sorapiss rock fall, on 30 September 2013; 2) the Monte Civetta rock fall, on 16 November 2013; 3) the Monte Antelao rock fall, on 22 November 2013. The Monte Civetta rock fall damaged some climbing routes, while the other two landslides did not cause any damage or injury. Despite the limited volume involved, these three events represent an important warning sign in the context of ongoing climate change. Geomorphological information about the rock fall sites were combined with the climatic data acquired from the meteorological stations surrounding the slope failure areas. A short-term climatic analysis was performed, with the aim of understanding the role of the main climatic elements in the triggering of natural instability events in this area and in the Alps in general.

  19. Slope failures and timing of turbidity flows north of Puerto Rico (United States)

    ten Brink, Uri S.; Chaytor, Jason D.


    The submerged carbonate platform north of Puerto Rico terminates in a high (3,000–4,000 m) and in places steep (>45°) slope characterized by numerous landslide scarps including two 30–50 km-wide amphitheater-shaped features. The origin of the steep platform edge and the amphitheaters has been attributed to: (1) catastrophic failure, or (2) localized failures and progressive erosion. Determining which of the two mechanisms has shaped the platform edge is critically important in understanding landslide-generated tsunami hazards in the region. Multibeam bathymetry, seismic reflection profiles, and a suite sediment cores from the Puerto Rico Trench and the slope between the trench and the platform edge were used to test these two hypotheses. Deposits within trench axis and at the base of the slope are predominantly composed of sandy carbonate turbidites and pelagic sediment with inter-fingering of chaotic debris units. Regionally-correlated turbidites within the upper 10 m of the trench sediments were dated between ∼25 and 22 kyrs and ∼18–19 kyrs for the penultimate and most recent events, respectively. Deposits on the slope are laterally discontinuous and vary from thin layers of fragmented carbonate platform material to thick pelagic layers. Large debris blocks or lobes are absent within the near-surface deposits at the trench axis and the base of slope basins. Progressive small-scale scalloping and self-erosion of the carbonate platform and underlying stratigraphy appears to be the most likely mechanism for recent development of the amphitheaters. These smaller scale failures may lead to the generation of tsunamis with local, rather than regional, impact.

  20. A modified risk evaluation method of slope failure in a heavy rain. For application to slopes in widespread area

    International Nuclear Information System (INIS)

    Suenaga, Hiroshi; Tanaka, Shiro; Kobayakawa, Hiroaki


    A risk evaluation method of slope failure has developed to combine gas-liquid two phase flow analysis as a rainfall infiltration analysis and elastic-plastic finite element analysis as a slope stability analysis and has applied to a slope field. This method, however, had a difficulty to apply to many slopes since it needed many parameters to calculate the risk of the slope failure. The method was simplified to lessen input parameters which included an inclination and length of a slope, a depth of bedrock and a rainfall pattern assuming that hydraulic properties and mechanical properties were similar for the same geological unit. The method was also modified to represent a water collection structure, a surface runoff, an existence of a forest road and a water level variation of a downward river / pond which could affect infiltration phenomena. Results of the simplification and the modification made it possible to enhance a prediction precision of the method and create a hazard map of slopes in widespread area. (author)

  1. A model for predicting embankment slope failures in clay-rich soils; A Louisiana example (United States)

    Burns, S. F.


    A model for predicting embankment slope failures in clay-rich soils; A Louisiana example It is well known that smectite-rich soils significantly reduce the stability of slopes. The question is how much smectite in the soil causes slope failures. A study of over 100 sites in north and south Louisiana, USA, compared slopes that failed during a major El Nino winter (heavy rainfall) in 1982-1983 to similar slopes that did not fail. Soils in the slopes were tested for per cent clay, liquid limits, plasticity indices and semi-quantitative clay mineralogy. Slopes with the High Risk for failure (85-90% chance of failure in 8-15 years after construction) contained soils with a liquid limit > 54%, a plasticity index over 29%, and clay contents > 47%. Slopes with an Intermediate Risk (55-50% chance of failure in 8-15 years) contained soils with a liquid limit between 36-54%, plasticity index between 16-19%, and clay content between 32-47%. Slopes with a Low Risk chance of failure (soils with a liquid limit plasticity index soil characteristics before construction. If the soils fall into the Low Risk classification, construct the embankment normally. If the soils fall into the High Risk classification, one will need to use lime stabilization or heat treatments to prevent failures. Soils in the Intermediate Risk class will have to be evaluated on a case by case basis.

  2. Human-induced geomorphology: Modeling slope failure in Dominical, Costa Rica using Landsat imagery (United States)

    Miller, Andrew J.

    Unchecked human development has ravaged the region between Dominical and Uvita, Costa Rica. Much of the development transition has been driven by tourism and further foreign direct investment in residential, service and commercial enterprises. The resulting land-use/land-cover change has removed traditional forest cover in exchange for impervious surfaces, physical structures, and bare ground which is no longer mechanically supported by woody vegetation. Combined with a tropical climate, deeply weathered soils and lithography which are prone to erosion, land cover change has led to an increase in slope failure occurrences. Given the remoteness of the Dominical-Uvita region, its rate of growth and the lack of monitoring, new techniques for monitoring land use and slope failure susceptibility are needed. Two new indices are presented here that employ a Digital Elevation Model (DEM) and widely available Landsat imagery to assist in this endeavor. The first index, or Vegetation Influenced Landslide Index (VILI), incorporates slope derived from a DEM and Lu et al.'s (2007) Surface Cover Index to quantify vegetative cover as a means of mechanical stabilization in landslide prone areas. The second index, or Slope Multiplier Index (SMI), uses individual Landsat data bands and basic Landsat band ratios as environmental proxies to replicate soil, vegetative and hydrologic properties. Both models achieve accuracy over 70% and rival results from more complicated published literature. The accuracy of the indices was assessed with the creation of a landslide inventory developed from field observations occurring in December 2007 and November 2008. The creation of these indices represents an efficient and accurate way of determining landslide susceptibility zonation in data poor areas where environmental protection practitioners may be overextended, under-trained or both.

  3. Physical and theoretical modeling of rock slopes against block-flexure toppling failure

    Directory of Open Access Journals (Sweden)

    Mehdi Amini


    Full Text Available Block-flexure is the most common mode of toppling failure in natural and excavated rock slopes. In such failure, some rock blocks break due to tensile stresses and some overturn under their own weights and then all of them topple together. In this paper, first, a brief review of previous studies on toppling failures is presented. Then, the physical and mechanical properties of experimental modeling materials are summarized. Next, the physical modeling results of rock slopes with the potential of block-flexural toppling failures are explained and a new analytical solution is proposed for the stability analysis of such slopes. The results of this method are compared with the outcomes of the experiments. The comparative studies show that the proposed analytical approach is appropriate for the stability analysis of rock slopes against block-flexure toppling failure. Finally, a real case study is used for the practical verification of the suggested method.

  4. Assessing rockfall susceptibility in steep and overhanging slopes using three-dimensional analysis of failure mechanisms (United States)

    Matasci, Battista; Stock, Greg M.; Jaboyedoff, Michael; Carrea, Dario; Collins, Brian D.; Guérin, Antoine; Matasci, G.; Ravanel, L.


    Rockfalls strongly influence the evolution of steep rocky landscapes and represent a significant hazard in mountainous areas. Defining the most probable future rockfall source areas is of primary importance for both geomorphological investigations and hazard assessment. Thus, a need exists to understand which areas of a steep cliff are more likely to be affected by a rockfall. An important analytical gap exists between regional rockfall susceptibility studies and block-specific geomechanical calculations. Here we present methods for quantifying rockfall susceptibility at the cliff scale, which is suitable for sub-regional hazard assessment (hundreds to thousands of square meters). Our methods use three-dimensional point clouds acquired by terrestrial laser scanning to quantify the fracture patterns and compute failure mechanisms for planar, wedge, and toppling failures on vertical and overhanging rock walls. As a part of this work, we developed a rockfall susceptibility index for each type of failure mechanism according to the interaction between the discontinuities and the local cliff orientation. The susceptibility for slope parallel exfoliation-type failures, which are generally hard to identify, is partly captured by planar and toppling susceptibility indexes. We tested the methods for detecting the most susceptible rockfall source areas on two famously steep landscapes, Yosemite Valley (California, USA) and the Drus in the Mont-Blanc massif (France). Our rockfall susceptibility models show good correspondence with active rockfall sources. The methods offer new tools for investigating rockfall hazard and improving our understanding of rockfall processes.

  5. Dynamic stability and failure modes of slopes in discontinuous rock mass

    International Nuclear Information System (INIS)

    Shimizu, Yasuhiro; Aydan, O.; Ichikawa, Yasuaki; Kawamoto, Toshikazu.


    The stability of rock slopes during earthquakes are of great concern in rock engineering works such as highway, dam, and nuclear power station constructions. As rock mass in nature is usually discontinuous, the stability of rock slopes will be geverned by the spatial distribution of discontinuities in relation with the geometry of slope and their mechanical properties rather than the rock element. The authors have carried out some model tests on discontinuous rock slopes using three different model tests techniques in order to investigate the dynamic behaviour and failure modes of the slopes in discontinuous rock mass. This paper describes the findings and observations made on model rock slopes with various discontinuity patterns and slope geometry. In addition some stability criterions are developed and the calculated results are compared with those of experiments. (author)

  6. Submarine slope failures in the Beaufort Sea; Influence of gas hydrate decomposition (United States)

    Grozic, J. L.; Dallimore, S.


    The continental shelf of the Beaufort Sea is composed of complex of marine and non-marine sequences of clay, silt, and sand. In many areas of the shelf these sediments contain occurrences of ice-bonded permafrost and associated pressure and temperature conditions that are conducive to the occurrence of methane gas hydrates. This complex environment is undergoing dramatic warming, where changes in sea level, ocean bottom temperatures, and geothermal regimes are inducing permafrost thawing and gas hydrate decomposition. Decomposition is inferred to be occurring at the base and top of the gas hydrate stability zone, which will cause sediment weakening and the generation of excess water and free gas. In such settings, the overlying permafrost cap may act as a permeability barrier, which could result in significant excess pore pressures and reduction in sediment stability. The shelf to slope transition is thought to be an area of extensive regional instability with acoustic records indicating there is upwards of 500 km of slumps and glides extending over the entire Beaufort margin. Some of these slide regions are coincident with up-dip limit of the permafrost gas hydrate stability zone. In this paper, a two dimensional model of the Beaufort shelf was constructed to examine the influence of gas hydrate decomposition on slope stability. The model relies on available data on the Beaufort sediments generated from offshore hydrocarbon exploration in the 1980s and 90s, as well as knowledge available from multidisciplinary marine research programs conducted in the outer shelf area. The slope stability model investigates the influence of marine transgression and ocean bottom warming by coupling soil deformation with hydrate dissociation during undrained conditions. By combining mechanical and thermal loading of the sediment, a more accurate indication of slope stability was obtained. The stability analysis results indicate a relatively low factor of safety for the Beaufort

  7. NEESROCK: A Physical and Numerical Modeling Investigation of Seismically Induced Rock-Slope Failure (United States)

    Applegate, K. N.; Wartman, J.; Keefer, D. K.; Maclaughlin, M.; Adams, S.; Arnold, L.; Gibson, M.; Smith, S.


    Worldwide, seismically induced rock-slope failures have been responsible for approximately 30% of the most significant landslide catastrophes of the past century. They are among the most common, dangerous, and still today, least understood of all seismic hazards. Seismically Induced Rock-Slope Failure: Mechanisms and Prediction (NEESROCK) is a major research initiative that fully integrates physical modeling (geotechnical centrifuge) and advanced numerical simulations (discrete element modeling) to investigate the fundamental mechanisms governing the stability of rock slopes during earthquakes. The research is part of the National Science Foundation-supported Network for Earthquake Engineering Simulation Research (NEES) program. With its focus on fractures and rock materials, the project represents a significant departure from the traditional use of the geotechnical centrifuge for studying soil, and pushes the boundaries of physical modeling in new directions. In addition to advancing the fundamental understanding of the rock-slope failure process under seismic conditions, the project is developing improved rock-slope failure assessment guidelines, analysis procedures, and predictive tools. Here, we provide an overview of the project, present experimental and numerical modeling results, discuss special considerations for the use of synthetic rock materials in physical modeling, and address the suitability of discrete element modeling for simulating the dynamic rock-slope failure process.

  8. Slope failures in surface mines, methods of studying landslides

    Energy Technology Data Exchange (ETDEWEB)

    Flisiak, J; Korman, S; Mazurek, J


    This paper presents a review of methods of measuring landslide fissures, displacement of ground surface points in the landslide area and of points inside the landslide. An analysis of the landslide process is given, stressing various stages and phases of a landslide. Studies carried out by the Institute of Mining Geomechanics of the Technical University of Mining and Metallurgy in Cracow are evaluated. The studies concentrated on the final state of slopes in brown coal surface mines after a landslide occurs. The necessity of developing an apparatus for continuous recording of displacements of points on a landslide surface is stressed. An apparatus developed by the Institute and used for continuous measuring and recording of displacements is described. The apparatus is used to measure displacements of points during the initial phase of a landslide and during the phase of the largest displacements. The principle of the system consists in locating a number of observation points on the ground and a slope. The points are connected among themselves by flexible connectors. The connectors are equipped with potentiometric transmitters which transform the relative displacements into electric pulses. These pulses are recorded by a conventional recording apparatus. (55 refs.) (In Polish)

  9. Efficient Meshfree Large Deformation Simulation of Rainfall Induced Soil Slope Failure (United States)

    Wang, Dongdong; Li, Ling


    An efficient Lagrangian Galerkin meshfree framework is presented for large deformation simulation of rainfall-induced soil slope failure. Detailed coupled soil-rainfall seepage equations are given for the proposed formulation. This nonlinear meshfree formulation is featured by the Lagrangian stabilized conforming nodal integration method where the low cost nature of nodal integration approach is kept and at the same time the numerical stability is maintained. The initiation and evolution of progressive failure in the soil slope is modeled by the coupled constitutive equations of isotropic damage and Drucker-Prager pressure-dependent plasticity. The gradient smoothing in the stabilized conforming integration also serves as a non-local regularization of material instability and consequently the present method is capable of effectively capture the shear band failure. The efficacy of the present method is demonstrated by simulating the rainfall-induced failure of two typical soil slopes.

  10. Slope Stability Analysis of Mountainous/Hilly regions of Nepal: A case study of Bhotekoshi Hydropower site (United States)

    Acharya, A.; Gautam, S.; Kafle, K. R.


    Nepal is a mountainous, developing country that straddles the boundary between the Indian and Himalayan tectonic plates. In Nepal, landslides represent a major constraint on development, causing high levels of economic loss and substantial number of fatalities each year. There is a general consensus that the impacts of landslides in mountainous countries such as Nepal are increasing with time due to unstable slopes. The present study deals with the field investigation of slope stability in mountainous/hilly region of Nepal. Among the natural hazards that occur in regularly in Nepal, flood and landslides due to unstable slopes are by far the serious ones. They claim many human lives every year and cause other damages such as destruction and blockage of highway, destruction of hydropower, losses of livestock, crops and agricultural land. Slope Mass Rating system and stereographic projection has been carried out for analysis of slope stability using standard formats and parameters. It has been found that there are few major discontinuities that play the role for the rock/soil slides around the area. The major discontinuities are 235°/67°. These joint sets play the main role to the plane as well as wedge failures around the area. The rock mass rating of the slope has been found to be 27 and the slope mass rating has been found to be 37.8. The obtained slope mass rating value lies on IV class (Bad) that represents unstable slope having planner or big wedge failure and needs to be corrective measures in the slope. From stereographic projection, wedge failure of the slope has been seen according to the conditions of slope failure.

  11. Detection of resistance mutations and CD4 slopes in individuals experiencing sustained virological failure

    DEFF Research Database (Denmark)

    Schultze, Anna; Paredes, Roger; Sabin, Caroline


    during the episode were included. Mutations were identified using the IAS-US (2013) list, and were presumed to be present from detection until the end of an episode. Multivariable linear mixed models with a random intercept and slope adjusted for age, baseline CD4 count, hepatitis C, drug type, RNA (log...... mutations on CD4 slopes in patients undergoing episodes of viral failure. MATERIALS AND METHODS: Patients from the EuroSIDA and UK CHIC cohorts undergoing at least one episode of virological failure (>3 consecutive RNA measurements >500 on ART) with at least three CD4 measurements and a resistance test......-scale), risk group and subtype were used to estimate CD4 slopes. Individual mutations with a population prevalence of >10% were tested for their effect on the CD4 slope. RESULTS: A total of 2731 patients experiencing a median of 1 (range 1-4) episodes were included in this analysis. The prevalence of any...

  12. The Effect of Rainfall Patterns on the Mechanisms of Shallow Slope Failure

    Directory of Open Access Journals (Sweden)

    Muhammad Suradi


    Full Text Available This paper examines how rainfall patterns affect the mechanisms of shallow slope failure. Numerical modelling, utilising the commercial software SVFlux and SVSlope, was carried out for a coupled analysis of rainfall-induced slope seepage and instability, with reference to a shallow landslide took place in Jabiru, Northern Territory (NT Australia in 2007. Rainfall events were varied in terms of pattern in this analysis. The results revealed that slopes are sensitive to rainfall pattern when the rainfall intensity has a high degree of fluctuation at around the same value as that of saturated hydraulic conductivity. Average rainfall intensity at the beginning of a rainfall period plays a primary role in determining the rate of decrease in initial factor of safety (Fi towards minimum factor of safety (Fmin. The effect of rainfall events on the slope instability is attributed to the amount of rainwater infiltration into slope associated with rainfall pattern.

  13. Forecasting slope failures from space-based synthetic aperture radar (SAR) measurements (United States)

    Wasowski, J.; Bovenga, F.; Nutricato, R.; Nitti, D. O.; Chiaradia, M. T.; Tijani, K.; Morea, A.


    New space-borne radar sensors enable multi-scale monitoring of potentially unstable slopes thanks to wide-area coverage (tens of thousands km2), regular long-term image acquisition schedule with increasing re-visit frequency (weekly to daily), and high measurement precision (mm). In particular, the recent radar satellite missions e.g., COSMO-SkyMed (CSK), Sentinel-1 (S-1) and improved multi-temporal interferometry (MTI) processing techniques allow timely delivery of information on slow ground surface displacements. Here we use two case study examples to show that it is possible to capture pre-failure slope strains through long-term MTI-based monitoring. The first case is a retrospective investigation of a huge 500ML m3 landslide, which occurred in Sept. 2016 in a large, active open-cast coal mine in central Europe. We processed over 100 S-1 images acquired since Fall 2014. The MTI results showed that the slope that failed had been unstable at least since 2014. Importantly, we detected consistent displacement trends and trend changes, which can be used for slope failure forecasting. Specifically, we documented significant acceleration in slope surface displacement in the two months preceding the catastrophic failure. The second case of retrospectively captured pre-failure slope strains regards our earlier study of a small 50 m long landslide, which occurred on Jan. 2014 and caused the derailment of a train on the railway line connecting NW Italy to France. We processed 56 CSK images acquired from Fall 2008 to Spring 2014. The MTI results revealed pre-failure displacements of the engineering structures on the slope subsequently affected by the 2014 slide. The analysis of the MTI time series further showed that the displacements had been occurring since 2009. This information could have been used to forewarn the railway authority about the slope instability hazard. The above examples indicate that more frequent and consistent image acquisitions by the new radar

  14. An Analytical Solution for Block Toppling Failure of Rock Slopes during an Earthquake

    Directory of Open Access Journals (Sweden)

    Songfeng Guo


    Full Text Available Toppling failure is one of the most common failure types in the field. It always occurs in rock masses containing a group of dominant discontinuities dipping into the slope. Post-earthquake investigation has shown that many toppling rock slope failures have occurred during earthquakes. In this study, an analytical solution is presented on the basis of limit equilibrium analysis. The acceleration of seismic load as well as joint persistence within the block base, were considered in the analysis. The method was then applied into a shake table test of an anti-dip layered slope model. As predicted from the analytical method, blocks topple or slide from slope crest to toe progressively and the factor of safety decreases as the inputting acceleration increases. The results perfectly duplicate the deformation features and stability condition of the physical model under the shake table test. It is shown that the presented method is more universal than the original one and can be adopted to evaluate the stability of the slope with potential toppling failure under seismic loads.

  15. Porosity determination from 2-D resistivity method in studying the slope failures (United States)

    Maslinda, Umi; Nordiana, M. M.; Bery, A. A.


    Slope failures have become the main focus for infrastructures development on hilly areas in Malaysia especially the development of tourism and residential. Lack of understanding and information of the subsoil conditions and geotechnical issues are the main cause of the slope failures. The failures happened are due to a combination of few factors such as topography, climate, geology and land use. 2-D resistivity method was conducted at the collapsed area in Selangor. The 2-D resistivity was done to study the instability of the area. The collapsed occurred because of the subsurface materials was unstable. Pole-dipole array was used with 5 m minimum electrode spacing for the 2-D resistivity method. The data was processed using Res2Dinv software and the porosity was calculated using Archie's law equation. The results show that the saturated zone (1-100 Ωm), alluvium or highly weathered rock (100-1000 Ωm), boulders (1600-7000 Ωm) and granitic bedrock (>7000 Ωm). Generally, the slope failures or landslides occur during the wet season or after rainfall. It is because of the water infiltrate to the slope and cause the saturation of the slope which can lead to landslides. Then, the porosity of saturated zone is usually high because of the water content. The area of alluvium or highly weathered rock and saturated zone have high porosity (>20%) and the high porosity also dominated at almost all the collapsed area which means that the materials with porosity >20% is potential to be saturated, unstable and might trigger slope failures.

  16. Significance of the actual nonlinear slope geometry for catastrophic failure in submarine landslides. (United States)

    Puzrin, Alexander M; Gray, Thomas E; Hill, Andrew J


    A simple approach to slope stability analysis of naturally occurring, mild nonlinear slopes is proposed through extension of shear band propagation (SBP) theory. An initial weak zone appears in the steepest part of the slope where the combined action of gravity and seismic loads overcomes the degraded peak shear resistance of the soil. If the length of this steepest part is larger than the critical length, the shear band will propagate into the quasi-stable parts of the slope, where the gravitational and seismically induced shear stresses are smaller than the peak but larger than the residual shear strength of the soil. Growth of a shear band is strongly dependent on the shape of the slope, seismic parameters and the strength of soil and less dependent on the slope inclination and the sensitivity of clay. For the slope surface with faster changing inclination, the criterion is more sensitive to the changes of the parameters. Accounting for the actual nonlinear slope geometry eliminates the main challenge of the SBP approach-determination of the length of the initial weak zone, because the slope geometry can be readily obtained from submarine site investigations. It also helps to identify conditions for the early arrest of the shear band, before failure in the sliding layer or a change in loading or excess pore water pressures occurs. The difference in the size of a landslide predicted by limiting equilibrium and SBP approaches can reach orders of magnitude, potentially providing an explanation for the immense dimensions of many observed submarine landslides that may be caused by local factors acting over a limited portion of the slope.

  17. Slope failure at Bukit Antarabangsa, Ampang, Selangor and its relationship to physical soil properties

    International Nuclear Information System (INIS)

    Muhammad Barzani Gasim; Sahibin Abd Rahim; Mohd Ekhwan Toriman; Diyana Ishnin


    Slope failure which occurred on 6 December 2008 at Bukit Antarabangsa, Ampang Selangor has caused mortalities and loss of properties whereas more than 20 houses were flattened. Prior to slope failure, it was heavily down poured for a few hours that increased the soil saturation and plasticity properties. A total of 10 soil samples were randomly taken from stable and unstable slopes to determine physical soil properties, infiltration rate and their relationship to rainfall pattern. Soils were analyzed in terms of their physical properties; five years (2005-2009) of daily rainfalls were analyzed to determine their relationship to infiltration rate at each sampling station. Infiltration rate is determined by using infiltrometer double ring. Analysis of physical soils properties shows that soil texture was dominated by sandy soil with relatively high percentage of sand. Values of clay dispersion coefficient were relatively stable to very stable from 0.013 % to 11.85 % and organic content from 1.38 % to 2.74 %. Range of porosity was from 50.12 % to 62.31 %, while the average levels of hydraulic conductivity was from level 2 to 5 or relatively slow to fast. Percentage of soil aggregate stability was from 5.12 % to 48.42 % and this value indicates that relative strength of soil mechanical pressure is inversely proportional to the percentage of water content. Soil plasticity value was high to very high but characterized by inactive colloids. Distribution of monthly rainfall was from 38 mm to 427 mm. The infiltration rate during sampling time was from 3.0 cm/ hr to 7.0 cm/ hr; but it was expected from 10.94 cm/ hr to 915.05 cm/ hr during slope failures. Overall, it was interpreted that physical soil properties was closely interrelated with slope stability, structure of sandy soil will enhanced soil porosity stage and enhance the infiltration process during heavy rainfall, and finally triggering of slope failure. (author)

  18. Geological Aspect of Slope Failure and Mitigation Approach in Bireun - Takengon Main Road, Aceh Province, Indonesia

    Directory of Open Access Journals (Sweden)

    Ibnu Rusydy


    Full Text Available A soil and rock slope assessment survey was conducted along Bireun – Takengon main road in Aceh Province, Indonesia. The slope assessment survey was carried out to determine the geological condition, verify and identify the potential areas of slope failure and to study what type of slope stability and protection method could be applied to the road. Several research methodologies were conducted in the field such as rock and soil identification, and slope assessment. The survey was conducted in four selected areas along Bireun – Takengon main road. In study area I, soil creep occurred because of a presence of montmorillonite clay. The mitigation methods to reduce soil creeping in this area are building a retaining wall and pile. The shotcrete, wire mesh, net rock bolting, and rock removal method is suitable to apply in study area II. The shotcrete and soil nails were used because the type of rocks in those areas is sedimentary rock such as shale, sandstone, siltstone, and a boulder of a volcanic rock. The same approach shall be applied in study area IV. study area III was the best spot to learn about the mitigation approach for slope stability and provides many lessons learned. Aceh Province experience active tectonic movement, high intensity of rain, geological structures, a high degree of weathering, and high intensity of earthquake,as primary factors which trigger landslides. The techonology of slope stabilizing and protection methods can be applied to mitigate landslides.

  19. Editorial: Introduction to the Special Issue ;Slope Tectonics: Inherited Structures, Morphology of Deformation and Catastrophic Failure; (United States)

    Hermanns, R. L.; Oppikofer, T.; Jaboyedoff, M.; Clague, J. J.; Scarascia-Mugnozza, G.


    The "Conference on Slope Tectonics" has become an international scientific meeting point to present and discuss a variety of topics related to slope deformation and the deposits of related failures. The first conference took place on February 15-16, 2008 at University of Lausanne (Switzerland). It was followed by a second conference on September 6-10, 2011, in Austria (organized by the Geological Survey of Austria) and a third on September 8-12, 2014, in Norway (organized by the Geological Survey of Norway). The two later events included field trips. It has become a tradition that selected papers from these conference are published - papers from the first conference were published by the Geological Society as Special Publication 351 (Jaboyedoff, 2011), and those from the second conference were published in a special issue of Tectonophysics (Baron and Jaboyedoff, 2013). This special issue of Geomorphology is a collection of papers presented at the Norwegian Conference on Slope Tectonics. This collection of papers focuses on the role of tectonics in gravitationally induced rock-slope instabilities. The slopes either deform over long periods as deep-seated gravitational slope deformation (DSGSD) or more rapidly as rockslides or rock avalanches. The reconstruction of slope deformation is an integral part of the studies captured in this special issue.

  20. Capturing pre-failure signs of slope instability using multi-temporal interferometry and Sentinel-1 data (United States)

    Wasowski, Janusz; Bovenga, Fabio; Nitti, Davide Oscar; Tijani, Khalid; Morea, Alberto; Nutricato, Raffaele; Chiaradia, Maria Teresa


    The shorter repeat cycle (6 days since October 2016) and regularity of acquisitions of Sentinel-1A/B with respect to earlier European Space Agency (ESA) satellites with C-band sensors (ERS1/2, ENVISAT) represent the key advantages for the research-oriented and practical applications of multi-temporal interferometry (MTI). The applicability of the Interferometric Wide Swath acquisition mode of Sentinel-1 (images covering a 250 km swath on the ground) to regional scale slope instability detection through MTI has already been demonstrated, e.g., via studies of landslide-prone areas in Italy. Here we focus on the potential of Sentinel-1 data for local (site-specific), MTI-based monitoring and capturing pre-failure signs of slope instability, by exploiting the Persistent and Distributed Scatterers processing capability of the SPINUA algorithm. In particular, we present an example of a retrospective study of a large (over 2 km long) landslide, which took place in 2016 in an active open-cast coal mine in central Europe. This seemingly sudden failure caused destruction of the mining equipment, blocked the mining operations thereby resulting in significant economic losses. For the study, we exploited over 60 Sentinel-1A/B images acquired since November 2014. The MTI results furnished a valuable overview of the ground instability/stability conditions within and around the active mine, even though considerable spatial gaps in information were encountered due to surface disturbance by mining operations. Significantly, the ground surface displacement time series revealed that the 2016 slope failure was preceded by very slow (generally 1-3 cm/yr) creep-like deformations, already present in 2014. The MTI results also indicated that the slope experienced a phase of accelerated movement several weeks prior to the landslide event. Furthermore, the spatio-temporal analysis of interferometric coherence changes in the unstable area (mapped on Sentinel-2 Bottom Of Atmosphere reflectance

  1. Slope failures evaluation and landslides investigation using 2-D resistivity method

    Directory of Open Access Journals (Sweden)

    M.M. Nordiana


    Full Text Available Slope failure is a complex phenomenon that may caused to landslides. Buildings and infrastructure such as transportation facilities and pipelines located within the boundaries of a landslide can be damaged or destroyed. Slope failure classification and various factors contributing to the instability using 2-D resistivity survey conducted in Selangor, Malaysia are described. Six 2-D resistivity survey lines with 5 m minimum electrode spacing using Pole-dipole array were performed. The data were processed using Res2Dinv and surfer10 software to evaluate the subsurface characteristics. The 2-D resistivity results show that the subsurface consist of two main zones. The first zone was alluvium or highly weathered with resistivity value of 100–1000 Ω m and depth of >30 m. This zone consists of saturated area with resistivity value of 1–100 Ω m and boulders with resistivity value of 1200–7000 Ω m. The second zone with resistivity value of >7000 Ω m was interpreted as granitic bedrock. The study area was characterized by saturated zones, highly weathered zone, highly contain of sand and boulders that will trigger slope failure in the survey area. This will cause to low strength of soil, debris flow and movement of earth. On the basis of the case examples described, 2-D resistivity method is categorized into desirable and useful method in determination of slope failure and future assessments. Keywords: Slope failure, Landslides, 2-D resistivity, Saturated, Boulders

  2. Natural disasters in the Shikoku district. 2. ; Slope failures and rockfalls. Shikoku ni okeru shizen saigai. 2. ; Dosha saigai

    Energy Technology Data Exchange (ETDEWEB)

    Yamagami, T [Tokushima Univ., Tokushima (Japan). Faculty of Engineering


    Although landslide, slope failure, debris flow, rock fall, etc. are included in disasters caused by earth and sand, this report focuses only on slope failures. It is very difficult to discuss various soil engineering problems concerning earth and sand disasters in the Shikoku district from dynamic aspect. Therefore, this report is made focusing on perfunctory classification. As regards slope failures, there are natural and embankment (artificial) slope failures, but only natural slope failures are discussed in this report. The numbers of annually investigated areas in 4 prefectures in the Shikoku district and frequencies of failures for each geological group are tabulated for explanation. Transverse shape figure, longitudinal section, slope of ground level, land form where surface water and ground water tend to concentrate, etc. can be considered as factors for the occurrence of landslides. The relationship between those topographical factors and the frequency of failure occurrence is investigated. Failure of cut slope and the relation between rainfall and slope failure are outlined. Examples of rock fall disasters are introduced to point out the difficulty in predicting the occurrence of rock falls. 12 refs., 2 figs., 7 tabs.

  3. Centrifuge model tests of rainfall-induced slope failures for the investigation of the initiation conditions (United States)

    Matziaris, Vasileios; Marshall, Alec; Yu, Hai-Sui


    Rainfall-induced landslides are very common natural disasters which cause damage to properties and infrastructure and may result in the loss of human lives. These phenomena often take place in unsaturated soil slopes and are triggered by the saturation of the soil profile, due to rain infiltration, which leads to a loss of shear strength. The aim of this study is to determine rainfall thresholds for the initiation of landslides under different initial conditions. Model tests of rainfall-induced landslides are conducted in the Nottingham Centre for Geomechanics 50g-T geotechnical centrifuge. Initially unsaturated plane-strain slope models made with fine silica sand are prepared at varying densities at 1g and accommodated within a climatic chamber which provides controlled environmental conditions. During the centrifuge flight at 60g, rainfall events of varying intensity and duration are applied to the slope models causing the initiation of slope failure. The impact of soil state properties and rainfall characteristics on the landslide initiation process are discussed. The variation of pore water pressures within the slope before, during and after simulated rainfall events is recorded using miniature pore pressure transducers buried in the soil model. Slope deformation is determined by using a high-speed camera and digital image analysis techniques.

  4. Gravity-driven groundwater flow and slope failure potential: 1. Elastic effective-stress model (United States)

    Iverson, Richard M.; Reid, Mark E.


    Hilly or mountainous topography influences gravity-driven groundwater flow and the consequent distribution of effective stress in shallow subsurface environments. Effective stress, in turn, influences the potential for slope failure. To evaluate these influences, we formulate a two-dimensional, steady state, poroelastic model. The governing equations incorporate groundwater effects as body forces, and they demonstrate that spatially uniform pore pressure changes do not influence effective stresses. We implement the model using two finite element codes. As an illustrative case, we calculate the groundwater flow field, total body force field, and effective stress field in a straight, homogeneous hillslope. The total body force and effective stress fields show that groundwater flow can influence shear stresses as well as effective normal stresses. In most parts of the hillslope, groundwater flow significantly increases the Coulomb failure potential Φ, which we define as the ratio of maximum shear stress to mean effective normal stress. Groundwater flow also shifts the locus of greatest failure potential toward the slope toe. However, the effects of groundwater flow on failure potential are less pronounced than might be anticipated on the basis of a simpler, one-dimensional, limit equilibrium analysis. This is a consequence of continuity, compatibility, and boundary constraints on the two-dimensional flow and stress fields, and it points to important differences between our elastic continuum model and limit equilibrium models commonly used to assess slope stability.

  5. Distributed specific sediment yield estimations in Japan attributed to extreme-rainfall-induced slope failures under a changing climate

    Directory of Open Access Journals (Sweden)

    K. Ono


    Full Text Available The objective of this study was to estimate the potential sediment yield distribution in Japan attributed to extreme-rainfall-induced slope failures in the future. For this purpose, a regression relationship between the slope failure probability and the subsequent sediment yield was developed by using sediment yield observations from 59 dams throughout Japan. The slope failure probability accounts for the effects of topography (as relief energy, geology and hydro-climate variations (hydraulic gradient changes due to extreme rainfall variations and determines the potential slope failure occurrence with a 1-km resolution. The applicability of the developed relationship was then validated by comparing the simulated and observed sediment yields in another 43 dams. To incorporate the effects of a changing climate, extreme rainfall variations were estimated by using two climate change scenarios (the MRI-RCM20 Ver.2 model A2 scenario and the MIROC A1B scenario for the future and by accounting for the slope failure probability through the effect of extreme rainfall on the hydraulic gradient. Finally, the developed slope failure hazard-sediment yield relationship was employed to estimate the potential sediment yield distribution under a changing climate in Japan.

    Time series analyses of annual sediment yields covering 15–20 years in 59 dams reveal that extreme sedimentation events have a high probability of occurring on average every 5–7 years. Therefore, the extreme-rainfall-induced slope failure probability with a five-year return period has a statistically robust relationship with specific sediment yield observations (with r2 = 0.65. The verification demonstrated that the model is effective for use in simulating specific sediment yields with r2 = 0.74. The results of the GCM scenarios suggest that the sediment yield issue will be critical in Japan in the future. When the spatially averaged sediment

  6. Stability charts for uniform slopes in soils with nonlinear failure envelopes


    Eid, Hisham T.


    Based on the results of an extensive parametric study, charts were developed for assessment of the stability of uniform slopes in soils with nonlinear shear strength failure envelopes. The study was conducted using envelopes formed to represent the realistic shapes of soil nonlinear drained strength envelopes and the associated different degrees of nonlinearity. The introduction of a simple methodology to describe the nonlinear envelopes and a stability parameter, the value of which depends o...

  7. A hazard and risk classification system for catastrophic rock slope failures in Norway (United States)

    Hermanns, R.; Oppikofer, T.; Anda, E.; Blikra, L. H.; Böhme, M.; Bunkholt, H.; Dahle, H.; Devoli, G.; Eikenæs, O.; Fischer, L.; Harbitz, C. B.; Jaboyedoff, M.; Loew, S.; Yugsi Molina, F. X.


    The Geological Survey of Norway carries out systematic geologic mapping of potentially unstable rock slopes in Norway that can cause a catastrophic failure. As catastrophic failure we describe failures that involve substantial fragmentation of the rock mass during run-out and that impact an area larger than that of a rock fall (shadow angle of ca. 28-32° for rock falls). This includes therefore rock slope failures that lead to secondary effects, such as a displacement wave when impacting a water body or damming of a narrow valley. Our systematic mapping revealed more than 280 rock slopes with significant postglacial deformation, which might represent localities of large future rock slope failures. This large number necessitates prioritization of follow-up activities, such as more detailed investigations, periodic monitoring and permanent monitoring and early-warning. In the past hazard and risk were assessed qualitatively for some sites, however, in order to compare sites so that political and financial decisions can be taken, it was necessary to develop a quantitative hazard and risk classification system. A preliminary classification system was presented and discussed with an expert group of Norwegian and international experts and afterwards adapted following their recommendations. This contribution presents the concept of this final hazard and risk classification that should be used in Norway in the upcoming years. Historical experience and possible future rockslide scenarios in Norway indicate that hazard assessment of large rock slope failures must be scenario-based, because intensity of deformation and present displacement rates, as well as the geological structures activated by the sliding rock mass can vary significantly on a given slope. In addition, for each scenario the run-out of the rock mass has to be evaluated. This includes the secondary effects such as generation of displacement waves or landslide damming of valleys with the potential of later

  8. Slope Failure Prediction and Early Warning Awareness Education for Reducing Landslides Casualty in Malaysia (United States)

    Koay, S. P.; Tay, L. T.; Fukuoka, H.; Koyama, T.; Sakai, N.; Jamaludin, S. B.; Lateh, H.


    Northeast monsoon causes heavy rain in east coast of Peninsular Malaysia from November to March, every year. During this monsoon period, besides the happening of flood along east coast, landslides also causes millions of Malaysian Ringgit economical losses. Hence, it is essential to study the prediction of slope failure to prevent the casualty of landslides happening. In our study, we introduce prediction method of the accumulated rainfall affecting the stability of the slope. If the curve, in the graph, which is presented by rainfall intensity versus accumulated rainfall, crosses over the critical line, the condition of the slope is considered in high risk where the data are calculated and sent from rain gauge in the site via internet. If the possibility of slope failure is going high, the alert message will be sent out to the authorities for decision making on road block or setting the warning light at the road side. Besides road block and warning light, we propose to disseminate short message, to pre-registered mobile phone user, to notify the public for easing the traffic jam and avoiding unnecessary public panic. Prediction is not enough to prevent the casualty. Early warning awareness of the public is very important to reduce the casualty of landslides happening. IT technology does not only play a main role in disseminating information, early warning awareness education, by using IT technology, should be conducted, in schools, to give early warning awareness on natural hazard since childhood. Knowing the pass history on landslides occurrence will gain experience on the landslides happening. Landslides historical events with coordinate information are stored in database. The public can browse these historical events via internet. By referring to such historical landslides events, the public may know where did landslides happen before and the possibility of slope failure occurrence again is considered high. Simulation of rainfall induced slope failure mechanism

  9. A method to assess collision hazard of falling rock due to slope collapse application of DEM on modeling of earthquake triggered slope failure for nuclear power plants

    International Nuclear Information System (INIS)

    Nakase, Hitoshi; Cao, Guoqiang; Tabei, Kazuto; Tochigi, Hitoshi; Matsushima, Takashi


    Risk evaluation of slope failure against nuclear power plants, which is induced by unexpectedly large earthquakes, has been urgent need for disaster prevention measures. Specially, for risk evaluation of slope failure, understanding of information such as traveling distances, collision velocities, and collision energies is very important. Discrete Element Method (DEM) such as particle simulation method contributes important role on predicting the detailed behavior of slope failure physics. In this study, instead of accurately predicting the complicated behavior of sliding and falling for each rock, we introduce the DEM modeling to evaluate the average traveling distance of collapsed rocks and its statistical variability. First, we conduct the validation test of the proposed DEM model on the basis of reconstruction of experiment results. Next, we conducted the parametric studies to examine sensitivities of important parameters. Finally, validity of the proposed method is evaluated and its applicability and technical assignments are also discussed. (author)

  10. Shoreline Erosion and Slope Failure Detection over Southwest Lakeshore Michigan using Temporal Radar and Digital Elevation Model (United States)

    Sataer, G.; Sultan, M.; Yellich, J. A.; Becker, R.; Emil, M. K.; Palaseanu, M.


    Throughout the 20th century and into the 21st century, significant losses of residential, commercial and governmental property were reported along the shores of the Great Lakes region due to one or more of the following factors: high lake levels, wave actions, groundwater discharge. A collaborative effort (Western Michigan University, University of Toledo, Michigan Geological Survey [MGS], United States Geological Survey [USGS], National Oceanographic and Atmospheric Administration [NOAA]) is underway to examine the temporal topographic variations along the shoreline and the adjacent bluff extending from the City of South Haven in the south to the City of Saugatuck in the north within the Allegan County. Our objectives include two main tasks: (1) identification of the timing of, and the areas, witnessing slope failure and shoreline erosion, and (2) investigating the factors causing the observed failures and erosion. This is being accomplished over the study area by: (1) detecting and measuring slope subsidence rates (velocities along line of site) and failures using radar interferometric persistent scatter (PS) techniques applied to ESA's European Remote Sensing (ERS) satellites, ERS-1 and -2 (spatial resolution: 25 m) that were acquired in 1995 to 2007, (2) extracting temporal high resolution (20 cm) digital elevation models (DEM) for the study area from temporal imagery acquired by Unmanned Aerial Vehicles (UAVs), and applying change detection techniques to the extracted DEMs, (3) detecting change in elevation and slope profiles extracted from two LIDAR Coastal National Elevation Database (CoNED) DEMs (spatial resolution: 0.5m), acquired on 2008 and 2012, and (4) spatial and temporal correlation of the detected changes in elevation with relevant data sets (e.g., lake levels, precipitation, groundwater levels) in search of causal effects.

  11. Can we use ice calving on glacier fronts as a proxy for rock slope failures? (United States)

    Abellan, Antonio; Penna, Ivanna; Daicz, Sergio; Carrea, Dario; Derron, Marc-Henri; Jaboyedoff, Michel; Riquelme, Adrian; Tomas, Roberto


    Ice failures on glacier terminus show very similar fingerprints to rock-slope failure (RSF) processes, nevertheless, the investigation of gravity-driven instabilities that shape rock cliffs and glacier's fronts are currently dissociated research topics. Since both materials (ice and rocks) have very different rheological properties, the development of a progressive failure on mountain cliffs occurs at a much slower rate than that observed on glacier fronts, which leads the latter a good proxy for investigating RSF. We utilized a terrestrial Laser Scanner (Ilris-LR system from Optech) for acquiring successive 3D point clouds of one of the most impressive calving glacier fronts, the Perito Moreno glacier located in the Southern Patagonian Ice Fields (Argentina). We scanned the glacier terminus during five days (from 10th to 14th of March 2014) with very high accuracy (0.7cm standard deviation of the error at 100m) and a high density of information (200 points per square meter). Each data series was acquired at a mean interval of 20 minutes. The maximum attainable range for the utilized wavelength of the Ilris-LR system (1064 nm) was around 500 meters over massive ice (showing no-significant loss of information), being this distance considerably reduced on crystalline or wet ice short after the occurrence of calving events. As for the data treatment, we have adapted our innovative algorithms originally developed for the investigation of both precursory deformation and rockfalls to study calving events. By comparing successive three-dimensional datasets, we have investigated not only the magnitude and frequency of several ice failures at the glacier's terminus (ranging from one to thousands of cubic meters), but also the characteristic geometrical features of each failure. In addition, we were able to quantify a growing strain rate on several areas of the glacier's terminus shortly after their final collapse. For instance, we investigated the spatial extent of the

  12. Development of evaluation methods for impact of earthquake-induced slope failure on nearby critical structures. Analysis of behavior of collapsed rock masses using 3-D distinct element method

    International Nuclear Information System (INIS)

    Ishimaru, Makoto; Tochigi, Hitoshi; Nakajima, Masato; Shirai, Koji


    Recently, importance of evaluation for impact of earthquake-induced slope failure on nearby critical structures is increasing in order to evaluate seismic stability of the slope, in addition to evaluating the possibilities of slope failure. In this study, we presented an examination flow chart to evaluate the impact on structures after slope failure. In the examination flow chart, we assumed the following four considerations; (1) evaluation of the collapse region of the slope, (2) evaluation of behavior of the collapsed rock masses, (3) evaluation of the impact on the structures, (4) examination of the countermeasures. And, for the purpose of using three dimensional distinct element method (DEM) for evaluation of behavior of the collapsed rock masses, we firstly confirmed applicability of DEM to behavior of a mass hurtling down the slope by means of comparing with the model test results. Moreover, we clarified influence of initial position or restitution coefficient of rock masses on final traveling distance of collapsed rock masses. (author)

  13. Polycyclic aromatic hydrocarbon concentrations across the Florida Panhandle continental shelf and slope after the BP MC 252 well failure

    International Nuclear Information System (INIS)

    Snyder, Richard A.; Ederington-Hagy, Melissa; Hileman, Fredrick; Moss, Joseph A.; Amick, Lauren; Carruth, Rebecca; Head, Marie; Marks, Joel; Tominack, Sarah; Jeffrey, Wade H.


    Graphical abstract: The R/V Bellows, Florida Institute of Oceanography (FIO), with faculty and students from the University of West Florida (UWF), sampling mats of oil floating over the continental shelf south of Pensacola Florida during the BP MC 252 well failure. PAH concentrations in sediments on the shelf declined over time after the well was capped with a half life of ∼200 days. - Highlights: • PAHs concentrations were highest in slope sediments near the failed well site. • PAH concentrations in the shelf sediments were highest during the oil spill. • PAHs concentrations declined over time since the spill. - Abstract: The Florida Panhandle continental shelf environment was exposed to oil from the BP oil well failure in the Gulf of Mexico during 2010. Floating mats of oil were documented by satellite, but the distribution of dissolved components of the oil in this region was unknown. Shipek® grab samples of sediments were taken during repeated cruises between June 2010 and June 2012 to test for selected polycyclic aromatic hydrocarbons (PAHs) as indicators of this contamination. Sediments were collected as composite samples, extracted using standard techniques, and PAHs were quantified by GC/MS-SIM. PAHs in samples from the continental slope in May 2011 were highest near to the failed well site and were reduced in samples taken one year later. PAHs from continental shelf sediments during the spill (June 2010) ranged from 10 to 165 ng g −1 . Subsequent cruises yielded variable and reduced amounts of PAHs across the shelf. The data suggest that PAHs were distributed widely across the shelf, and their subsequent loss to background levels suggests these compounds were of oil spill origin. PAH half-life estimates by regression were 70–122 days for slope and 201 days for shelf stations

  14. Detailed analysis of the Valdes slide: a landward facing slope failure off Chile (United States)

    Anasetti, Andrea; Krastel, Sebastian; Weinrebe, Willy; Klaucke, Ingo; Bialas, Jorge


    The Chilean continental margin is a very active area interested by important tectonic movements and characterized by a fast morphological evolution. Geophysical data acquired during cruise JC 23, aboard RV JAMES COOK in March/April 2008 and previous cruises cover most of the active Chilean continental margin between 33° and 37° S. Integrated interpretation of multi-beam bathymetric, sub-bottom profiles, side-scan sonar and seismic data allowed the identification of a number of slope failures. The main topic of this project is the morphological and sedimentological analysis of the Valdes slide, a medium-sized submarine landslide offshore the city of Talcahuano (300 km south of Santiago). In contrast to most other slides along continental margins, the Valdes slide is located on the landward facing eastern slope of a submarine ridge. This setting has important implications for the associated tsunami wave field (first arrival of positive amplitude). We measured geometrical parameters of the failure and adjacent slope. The slide affected an area of 19 km2 between ~1060 m and >1700 m water depths. Its is ~ 6 km long, up to 3 km wide and involved a total sedimentary volume of about 0,8 km3. The failure process was characterized by a multiple-event and we assume its tsunami potential to be high. Using the high resolution bathymetric data and the seismic profiles along the slide deposit it was possible to reconstruct the original morphology of the area in order to understand the relation between the slide event and the structural evolution of the ridge. Through the analysis of the data and bibliographic information about the Chilean margin, we analyzed potential trigger mechanisms for the landslide. The Valdes slide is situated on a steep ridge flank. The ridge follows an elongated fault zone running app. parallel to the margin. This fault zone has a dextral component which in combination with the faults elongation results in a compressional regime that is superimposed on

  15. Tsunamis caused by submarine slope failures along western Great Bahama Bank. (United States)

    Schnyder, Jara S D; Eberli, Gregor P; Kirby, James T; Shi, Fengyan; Tehranirad, Babak; Mulder, Thierry; Ducassou, Emmanuelle; Hebbeln, Dierk; Wintersteller, Paul


    Submarine slope failures are a likely cause for tsunami generation along the East Coast of the United States. Among potential source areas for such tsunamis are submarine landslides and margin collapses of Bahamian platforms. Numerical models of past events, which have been identified using high-resolution multibeam bathymetric data, reveal possible tsunami impact on Bimini, the Florida Keys, and northern Cuba. Tsunamis caused by slope failures with terminal landslide velocity of 20 ms -1 will either dissipate while traveling through the Straits of Florida, or generate a maximum wave of 1.5 m at the Florida coast. Modeling a worst-case scenario with a calculated terminal landslide velocity generates a wave of 4.5 m height. The modeled margin collapse in southwestern Great Bahama Bank potentially has a high impact on northern Cuba, with wave heights between 3.3 to 9.5 m depending on the collapse velocity. The short distance and travel time from the source areas to densely populated coastal areas would make the Florida Keys and Miami vulnerable to such low-probability but high-impact events.

  16. Using street view imagery for 3-D survey of rock slope failures

    Directory of Open Access Journals (Sweden)

    J. Voumard


    Full Text Available We discuss here different challenges and limitations of surveying rock slope failures using 3-D reconstruction from image sets acquired from street view imagery (SVI. We show how rock slope surveying can be performed using two or more image sets using online imagery with photographs from the same site but acquired at different instances. Three sites in the French alps were selected as pilot study areas: (1 a cliff beside a road where a protective wall collapsed, consisting of two image sets (60 and 50 images in each set captured within a 6-year time frame; (2 a large-scale active landslide located on a slope at 250 m from the road, using seven image sets (50 to 80 images per set from five different time periods with three image sets for one period; (3 a cliff over a tunnel which has collapsed, using two image sets captured in a 4-year time frame. The analysis include the use of different structure from motion (SfM programs and a comparison between the extracted photogrammetric point clouds and a lidar-derived mesh that was used as a ground truth. Results show that both landslide deformation and estimation of fallen volumes were clearly identified in the different point clouds. Results are site- and software-dependent, as a function of the image set and number of images, with model accuracies ranging between 0.2 and 3.8 m in the best and worst scenario, respectively. Although some limitations derived from the generation of 3-D models from SVI were observed, this approach allowed us to obtain preliminary 3-D models of an area without on-field images, allowing extraction of the pre-failure topography that would not be available otherwise.

  17. Time shift in slope failure prediction between unimodal and bimodal modeling approaches (United States)

    Ciervo, Fabio; Casini, Francesca; Nicolina Papa, Maria; Medina, Vicente


    within the Bishop stress theory framework (Ciervo et al., 2015). The proposed work tends to emphasize how a more accurate slope stability analysis that accounts dual-structure could be useful to reach a more accurate definition of the stability conditions. The effects in practical analysis may be significant. The highlighted discrepancies between the different approaches in describing the timing processes and strength contribution due to capillary forces may entail no negligible differences in slope stability predictions, especially in those cases where the possibility of a failure in unsaturated terrains is contemplated.

  18. Berm design to reduce risks of catastrophic slope failures at solid waste disposal sites. (United States)

    De Stefano, Matteo; Gharabaghi, Bahram; Clemmer, Ryan; Jahanfar, M Ali


    Existing waste disposal sites are being strained by exceeding their volumetric capacities because of exponentially increasing rates of municipal solid waste generation worldwide, especially in densely populated metropolises. Over the past 40 years, six well-documented and analyzed disposal sites experienced catastrophic failure. This research presents a novel analysis and design method for implementation of a series of in-situ earth berms to slow down the movement of waste material flow following a catastrophic failure. This is the first study of its kind that employs a dynamic landslide analysis model, DAN-W, and the Voellmy rheological model to approximate solid waste avalanche flow. A variety of single and multiple berm configuration scenarios were developed and tested to find an optimum configuration of the various earth berm geometries and number of berms to achieve desired energy dissipation and reduction in total waste material runout length. The case study application of the novel mitigation measure shows that by constructing a series of six relatively inexpensive 3 m high earth berms at an optimum distance of 250 m from the slope toe, the total runout length of 1000 m and associated fatalities of the Leuwigajah dumpsite catastrophic failure in Bandung, Indonesia, could have been reduced by half. © The Author(s) 2016.

  19. Tracing the source of emerging seepage water at failure slope downstream, Kampung Bharu Bukit Tinggi, Bentong, Pahang

    International Nuclear Information System (INIS)

    Lakam Mejus; Wan Zakaria Wan Mohd Tahir; Md Shahid Ayub; Jeremy Andy; Johari Latif


    This paper discusses method and monitoring result of the source of seepage water emerging (mud flow) at downstream toe of the failure slope at Kampung Bharu Bukit Tinggi, Bentong Pahang. In this investigation, a saline-tracer experiment was conducted by injecting its solution into a drain at an upstream section (old road to Janda Baik town) where a pipeline was found leaking in the vicinity of the roadside and flowing towards hill slopes. Some parts of flowing water was left undetected and seeped through the soil on its way to downstream area. Seepage water downstream was monitored by using a conductivity sensor hooked up to a CR10X data logger and optical back scattering conductivity probes. From the result, it is believed that the source of seepage water is related to the water from the leaking pipeline upstream. The travelling time for the leaking water to reach downstream slope failure was within 16-17 hours. Based on this preliminary investigation, one can conclude that seepage water is one of the main contributing factors that cause slope failure in the vicinity of the investigated hill slopes. Further investigation to understand the failure mechanism at this place by conducting multi-experimental approaches in different seasons, particularly during continuous rain storms. (Author)

  20. Probabilistic Approach to Provide Scenarios of Earthquake-Induced Slope Failures (PARSIFAL Applied to the Alcoy Basin (South Spain

    Directory of Open Access Journals (Sweden)

    Salvatore Martino


    Full Text Available The PARSIFAL (Probabilistic Approach to pRovide Scenarios of earthquake-Induced slope FAiLures approach was applied in the basin of Alcoy (Alicante, South Spain, to provide a comprehensive scenario of earthquake-induced landslides. The basin of Alcoy is well known for several historical landslides, mainly represented by earth-slides, that involve urban settlement as well as infrastructures (i.e., roads, bridges. The PARSIFAL overcomes several limits existing in other approaches, allowing the concomitant analyses of: (i first-time landslides (due to both rock-slope failures and shallow earth-slides and reactivations of existing landslides; (ii slope stability analyses of different failure mechanisms; (iii comprehensive mapping of earthquake-induced landslide scenarios in terms of exceedance probability of critical threshold values of co-seismic displacements. Geotechnical data were used to constrain the slope stability analysis, while specific field surveys were carried out to measure jointing and strength conditions of rock masses and to inventory already existing landslides. GIS-based susceptibility analyses were performed to assess the proneness to shallow earth-slides as well as to verify kinematic compatibility to planar or wedge rock-slides and to topples. The experienced application of PARSIFAL to the Alcoy basin: (i confirms the suitability of the approach at a municipality scale, (ii outputs the main role of saturation in conditioning slope instabilities in this case study, (iii demonstrates the reliability of the obtained results respect to the historical data.

  1. Key indicator tools for shallow slope failure assessment using soil chemical property signatures and soil colour variables. (United States)

    Othman, Rashidi; Hasni, Shah Irani; Baharuddin, Zainul Mukrim; Hashim, Khairusy Syakirin Has-Yun; Mahamod, Lukman Hakim


    Slope failure has become a major concern in Malaysia due to the rapid development and urbanisation in the country. It poses severe threats to any highway construction industry, residential areas, natural resources and tourism activities. The extent of damages that resulted from this catastrophe can be lessened if a long-term early warning system to predict landslide prone areas is implemented. Thus, this study aims to characterise the relationship between Oxisols properties and soil colour variables to be manipulated as key indicators to forecast shallow slope failure. The concentration of each soil property in slope soil was evaluated from two different localities that consist of 120 soil samples from stable and unstable slopes located along the North-South Highway (PLUS) and East-West Highway (LPT). Analysis of variance established highly significant difference (P shallow slope failure were high value of L*(62), low values of c* (20) and h* (66), low concentration of iron (53 mg kg -1 ) and aluminium oxide (37 mg kg -1 ), low soil TOC (0.5%), low CEC (3.6 cmol/kg), slightly acidic soil pH (4.9), high amount of sand fraction (68%) and low amount of clay fraction (20%).

  2. Large bedrock slope failures in a British Columbia, Canada fjord: first documented submarine sackungen (United States)

    Conway, Kim W.; Vaughn Barrie, J.


    Very large (>60×106 m3) sackungen or deep-seated gravitational slope deformations occur below sea level along a steep fjord wall in central Douglas Channel, British Columbia. The massive bedrock blocks were mobile between 13 and 11.5 thousand radiocarbon years BP (15,800 and 13,400 BP) immediately following deglaciation. Deformation of fjord sediments is apparent in sedimentary units overlying and adjacent to the blocks. Faults bound the edges of each block, cutting the glacial section but not the Holocene sediments. Retrogressive slides, small inset landslides as well as incipient and older slides are found on and around the large failure blocks. Lineations, fractures and faults parallel the coastline of Douglas Channel along the shoreline of the study area. Topographic data onshore indicate that faults and joints demarcate discrete rhomboid-shaped blocks which controlled the form, size and location of the sackungen. The described submarine sackungen share characteristic geomorphic features with many montane occurrences, such as uphill-facing scarps, foliated bedrock composition, largely vertical dislocation and a deglacial timing of development.

  3. Damage-Based Time-Dependent Modeling of Paraglacial to Postglacial Progressive Failure of Large Rock Slopes (United States)

    Riva, Federico; Agliardi, Federico; Amitrano, David; Crosta, Giovanni B.


    Large alpine rock slopes undergo long-term evolution in paraglacial to postglacial environments. Rock mass weakening and increased permeability associated with the progressive failure of deglaciated slopes promote the development of potentially catastrophic rockslides. We captured the entire life cycle of alpine slopes in one damage-based, time-dependent 2-D model of brittle creep, including deglaciation, damage-dependent fluid occurrence, and rock mass property upscaling. We applied the model to the Spriana rock slope (Central Alps), affected by long-term instability after Last Glacial Maximum and representing an active threat. We simulated the evolution of the slope from glaciated conditions to present day and calibrated the model using site investigation data and available temporal constraints. The model tracks the entire progressive failure path of the slope from deglaciation to rockslide development, without a priori assumptions on shear zone geometry and hydraulic conditions. Complete rockslide differentiation occurs through the transition from dilatant damage to a compacting basal shear zone, accounting for observed hydraulic barrier effects and perched aquifer formation. Our model investigates the mechanical role of deglaciation and damage-controlled fluid distribution in the development of alpine rockslides. The absolute simulated timing of rock slope instability development supports a very long "paraglacial" period of subcritical rock mass damage. After initial damage localization during the Lateglacial, rockslide nucleation initiates soon after the onset of Holocene, whereas full mechanical and hydraulic rockslide differentiation occurs during Mid-Holocene, supporting a key role of long-term damage in the reported occurrence of widespread rockslide clusters of these ages.

  4. Coastal cliffs, rock-slope failures and Late Quaternary transgressions of the Black Sea along southern Crimea (United States)

    Pánek, Tomáš; Lenart, Jan; Hradecký, Jan; Hercman, Helena; Braucher, Règis; Šilhán, Karel; Škarpich, Václav


    Rock-slope failures represent a significant hazard along global coastlines, but their chronology remains poorly documented. Here, we focus on the geomorphology and chronology of giant rockslides affecting the Crimean Mountains along the Black Sea coast. Geomorphic evidence suggests that high (>100 m) limestone cliffs flanking the southern slopes of the Crimean Mountains are scarps of rockslides nested within larger deep-seated gravitational slope deformations (DSGSDs). Such pervasive slope failures originated due to lateral spreading of intensively faulted Late Jurassic carbonate blocks moving atop weak/plastic Late Triassic flysch and tuff layers. By introducing a dating strategy relying on the combination of the uranium-thorium dating (U-Th) of exposed calcareous speleothems covering the landslide scarps with the 36Cl exposure dating of rock walls, we are able to approximate the time interval between the origin of incipient crevices and the final collapse of limestone blocks that exposed the cliff faces. For the three representative large-scale rockslides between the towns of Foros and Yalta, the initiation of the DSGSDs as evidenced by the widening of crevices and the onset of speleothem accumulation was >300 ka BP, but the recent cliff morphology along the coast is the result of Late Pleistocene/Holocene failures spanning ∼20-0.5 ka BP. The exposures of rockslide scarps occurred mostly at ∼20-15, ∼8, ∼5-4 and ∼2-0.5 ka, which substantially coincide with the last major Black Sea transgressions and/or more humid Holocene intervals. Our study suggests that before ultimate fast and/or catastrophic slope failures, the relaxation of rock massifs correlative with karstification, cracks opening, and incipient sliding lasted on the order of 104-105 years. Rapid Late Glacial/Holocene transgressions of the Black Sea likely represented the last impulse for the collapse of limestone blocks and the origin of giant rockslides, simultaneously affecting the majority

  5. True Volumes of Slope Failure Estimated From a Quaternary Mass-Transport Deposit in the Northern South China Sea (United States)

    Sun, Qiliang; Alves, Tiago M.; Lu, Xiangyang; Chen, Chuanxu; Xie, Xinong


    Submarine slope failure can mobilize large amounts of seafloor sediment, as shown in varied offshore locations around the world. Submarine landslide volumes are usually estimated by mapping their tops and bases on seismic data. However, two essential components of the total volume of failed sediments are overlooked in most estimates: (a) the volume of subseismic turbidites generated during slope failure and (b) the volume of shear compaction occurring during the emplacement of failed sediment. In this study, the true volume of a large submarine landslide in the northern South China Sea is estimated using seismic, multibeam bathymetry and Ocean Drilling Program/Integrated Ocean Drilling Program well data. The submarine landslide was evacuated on the continental slope and deposited in an ocean basin connected to the slope through a narrow moat. This particular character of the sea floor provides an opportunity to estimate the amount of strata remobilized by slope instability. The imaged volume of the studied landslide is 1035 ± 64 km3, 406 ± 28 km3 on the slope and 629 ± 36 km3 in the ocean basin. The volume of subseismic turbidites is 86 km3 (median value), and the volume of shear compaction is 100 km3, which are 8.6% and 9.7% of the landslide volume imaged on seismic data, respectively. This study highlights that the original volume of the failed sediments is significantly larger than that estimated using seismic and bathymetric data. Volume loss related to the generation of landslide-related turbidites and shear compaction must be considered when estimating the total volume of failed strata in the submarine realm.

  6. Wintertime slope winds and its turbulent characteristics in the Yeongdong region of Korea (United States)

    Jeon, H. R.; Eun, S. H.; Kim, B. G.; Lee, Y. H.


    The Yeongdong region has various meteorological phenomenons by virtue of complicated geographical characteristics with high Taebaek Mountains running from the north to the south and an adjacent East Sea to the east. There are few studies on the slope winds and its turbulent characteristics over the complex terrain, which are critical information in mountain climbing, hiking, paragliding, even winter sports such as alpine skiing and ski jump etc. For the understanding of diverse mountain winds in the complex terrain in Yeongdong, hot-wire anemometers (Campbell Scientific) have been installed at a couple of sites since October 2014 and several automatic weather stations at several sites around the mountainous region in Yeongdong since November 2012.WRF model simulations have been also done with an ultra-fine horizontal resolution of 300 m for 10 years. Generally, model and observation show that the dominant wind is westerly, approximately more than 75%. It is quite consistent that wind fields from both model and observation agree with each other in the valley region and at the top of the mountain, but there is a significant disagreement in wind direction specifically in the slide slope. Probably this implies model's performance with even an ultra-fine resolution is still not enough for the slide slope domain of complex terrains. Despite that, the observation clearly showed up- and down slope winds for the weak synoptic conditions carefully selected such as strong insolation and a synoptic wind less than 5m/s in the 850 hPa. The up- and down slope flows are also demonstrated in the snow-covered condition as well as grass ground. Further, planar fit transformation algorithm against the coordinate tilt has been applied to raw wind data (10Hz) of the slope site for the analysis of turbulence properties. Turbulence also increases with synoptic wind strength. Detailed analysis of mechanical turbulence and buoyance will be discussed for different surface properties (grass

  7. Influence of scale-dependent fracture intensity on block size distribution and rock slope failure mechanisms in a DFN framework (United States)

    Agliardi, Federico; Galletti, Laura; Riva, Federico; Zanchi, Andrea; Crosta, Giovanni B.


    An accurate characterization of the geometry and intensity of discontinuities in a rock mass is key to assess block size distribution and degree of freedom. These are the main controls on the magnitude and mechanisms of rock slope instabilities (structurally-controlled, step-path or mass failures) and rock mass strength and deformability. Nevertheless, the use of over-simplified discontinuity characterization approaches, unable to capture the stochastic nature of discontinuity features, often hampers a correct identification of dominant rock mass behaviour. Discrete Fracture Network (DFN) modelling tools have provided new opportunities to overcome these caveats. Nevertheless, their ability to provide a representative picture of reality strongly depends on the quality and scale of field data collection. Here we used DFN modelling with FracmanTM to investigate the influence of fracture intensity, characterized on different scales and with different techniques, on the geometry and size distribution of generated blocks, in a rock slope stability perspective. We focused on a test site near Lecco (Southern Alps, Italy), where 600 m high cliffs in thickly-bedded limestones folded at the slope scale impend on the Lake Como. We characterized the 3D slope geometry by Structure-from-Motion photogrammetry (range: 150-1500m; point cloud density > 50 pts/m2). Since the nature and attributes of discontinuities are controlled by brittle failure processes associated to large-scale folding, we performed a field characterization of meso-structural features (faults and related kinematics, vein and joint associations) in different fold domains. We characterized the discontinuity populations identified by structural geology on different spatial scales ranging from outcrops (field surveys and photo-mapping) to large slope sectors (point cloud and photo-mapping). For each sampling domain, we characterized discontinuity orientation statistics and performed fracture mapping and circular

  8. Tsunami-hazard assessment based on subaquatic slope-failure susceptibility and tsunami-inundation modeling (United States)

    Anselmetti, Flavio; Hilbe, Michael; Strupler, Michael; Baumgartner, Christoph; Bolz, Markus; Braschler, Urs; Eberli, Josef; Liniger, Markus; Scheiwiller, Peter; Strasser, Michael


    Due to their smaller dimensions and confined bathymetry, lakes act as model oceans that may be used as analogues for the much larger oceans and their margins. Numerous studies in the perialpine lakes of Central Europe have shown that their shores were repeatedly struck by several-meters-high tsunami waves, which were caused by subaquatic slides usually triggered by earthquake shaking. A profound knowledge of these hazards, their intensities and recurrence rates is needed in order to perform thorough tsunami-hazard assessment for the usually densely populated lake shores. In this context, we present results of a study combining i) basinwide slope-stability analysis of subaquatic sediment-charged slopes with ii) identification of scenarios for subaquatic slides triggered by seismic shaking, iii) forward modeling of resulting tsunami waves and iv) mapping of intensity of onshore inundation in populated areas. Sedimentological, stratigraphical and geotechnical knowledge of the potentially unstable sediment drape on the slopes is required for slope-stability assessment. Together with critical ground accelerations calculated from already failed slopes and paleoseismic recurrence rates, scenarios for subaquatic sediment slides are established. Following a previously used approach, the slides are modeled as a Bingham plastic on a 2D grid. The effect on the water column and wave propagation are simulated using the shallow-water equations (GeoClaw code), which also provide data for tsunami inundation, including flow depth, flow velocity and momentum as key variables. Combining these parameters leads to so called «intensity maps» for flooding that provide a link to the established hazard mapping framework, which so far does not include these phenomena. The current versions of these maps consider a 'worst case' deterministic earthquake scenario, however, similar maps can be calculated using probabilistic earthquake recurrence rates, which are expressed in variable amounts of

  9. Rumblings and Rainfall, Rebels, Remittances and Roads- The complex landscape of slope failure in Nepal (United States)

    McAdoo, Brian G.; Sudmeier, Karen; Devkota, Sanjaya


    During the first monsoon season following the deadly 2015 Gorkha earthquake, 27 people were killed during two events in Nepal's Western Region due to debris flows triggered by a 24-hour, 315 mm cloudburst (Devkota et al. 2015). Both events were linked with roads: the first was caused by an accumulation of water on a newly constructed road above a steep, deforested slope, the second wiped out a major road and destroyed 10 houses. These deadly landslides were not triggered solely by extreme rainfall, but rather a complex combination of earthquakes, intensified rainfall associated with climate change and an explosion of unplanned rural road construction fueled by an increase in foreign investment, remittances and decentralisation of budgets and power from the central government to local villages. This complexity is explored through a trend data analysis on the number of landslides, landslide fatalities, rainfall intensity, and the road network in Nepal between 1980-2014 (McAdoo et al, submitted). Of most concern are the poorly constructed roads in Nepal's Middle Hill districts ( 1000-3000 m above sea level, humid, subtropical) as they are proliferating at an unprecedented pace without proper alignment, drainage, grading or maintenance. They are occurring in areas which frequently receive up to 4,000-5,000 mm of precipitation per year, causing considerable loss in lives, livelihoods and investment. Landslide fatalities increased from 88 on average for the period 1982-1995 to 130 deaths per year for the period 2007-2014 (Desinventar, 2016). Contrary to numerous studies which show a strong link between rainfall and landslides, our trend analysis demonstrates a decoupling of climate and the geomorphic drivers, pointing to other factors, namely the exponential road construction trend to explain the increase in landslide fatalities. Nepal has some of the oldest manuals and well-trained cadres in low-cost green engineering practices, yet these are rarely applied. To reverse

  10. Integration of two-phase solid fluid equations in a catchment model for flashfloods, debris flows and shallow slope failures

    KAUST Repository

    Bout, B.


    An integrated, modeling method for shallow landslides, debris flows and catchment hydrology is developed and presented in this paper. Existing two-phase debris flow equations and an adaptation on the infinite slope method are coupled with a full hydrological catchment model. We test the approach on the 4 km2 Scaletta catchment, North-Eastern Sicily, where the 1-10-2009 convective storm caused debris flooding after 395 shallow landslides. Validation is done based on the landslide inventory and photographic evidence from the days after the event. Results show that the model can recreate the impact of both shallow landslides, debris flow runout, and debris floods with acceptable accuracy (91 percent inventory overlap with a 0.22 Cohens Kappa). General patterns in slope failure and runout are well-predicted, leading to a fully physically based prediction of rainfall induced debris flood behavior in the downstream areas, such as the creation of a debris fan at the coastal outlet.

  11. Locating Critical Circular and Unconstrained Failure Surface in Slope Stability Analysis with Tailored Genetic Algorithm (United States)

    Pasik, Tomasz; van der Meij, Raymond


    This article presents an efficient search method for representative circular and unconstrained slip surfaces with the use of the tailored genetic algorithm. Searches for unconstrained slip planes with rigid equilibrium methods are yet uncommon in engineering practice, and little publications regarding truly free slip planes exist. The proposed method presents an effective procedure being the result of the right combination of initial population type, selection, crossover and mutation method. The procedure needs little computational effort to find the optimum, unconstrained slip plane. The methodology described in this paper is implemented using Mathematica. The implementation, along with further explanations, is fully presented so the results can be reproduced. Sample slope stability calculations are performed for four cases, along with a detailed result interpretation. Two cases are compared with analyses described in earlier publications. The remaining two are practical cases of slope stability analyses of dikes in Netherlands. These four cases show the benefits of analyzing slope stability with a rigid equilibrium method combined with a genetic algorithm. The paper concludes by describing possibilities and limitations of using the genetic algorithm in the context of the slope stability problem.

  12. Influences of Holocene sea level, regional tectonics, and fluvial, gravity and slope currents induced sedimentation on the regional geomorphology of the continental slope off northwestern India

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O.S.; Almeida, F.

    the Holocene sea level. The Bombay high area has slope breaks between 400 and 600 m, whereas off Saurashtra steep breaks in the slope occur between 560 and 960 m depth. Further southwards, at the slope, elevations and depressions are present. Variations...

  13. Remote Sensing for Characterisation and Kinematic Analysis of Large Slope Failures: Debre Sina Landslide, Main Ethiopian Rift Escarpment

    Directory of Open Access Journals (Sweden)

    Jan Kropáček


    Full Text Available Frequently occurring landslides in Ethiopia endanger rapidly expanding settlements and infrastructure. We investigated a large landslide on the western escarpment of the Main Ethiopian Rift close to Debre Sina. To understand the extent and amplitude of the movements, we derived vectors of horizontal displacements by feature matching of very high resolution satellite images (VHR. The major movements occurred in two phases, after the rainy seasons in 2005 and 2006 reaching magnitudes of 48 ± 10.1 m and 114 ± 7.2 m, respectively. The results for the first phase were supported by amplitude tracking using two Envisat/ASAR scenes from the 31 July 2004 and the 29 October 2005. Surface changes in vertical direction were analyzed by subtraction of a pre-event digital elevation model (DEM from aerial photographs and post-event DEM from ALOS/PRISM triplet data. Furthermore, we derived elevation changes using satellite laser altimetry measurement acquired by the ICESat satellite. These analyses allowed us to delineate the main landslide, which covers an area of 6.5 km2, shallow landslides surrounding the main landslide body that increased the area to 8.5 km2, and the stable area in the lower part of the slope. We assume that the main triggering factor for such a large landslide was precipitation cumulated over several months and we suspect that the slope failure will progress towards the foot of the slope.

  14. Observations of seasonal exchange in the Celtic Sea slope region from underwater gilders (United States)

    Porter, Marie; Inall, Mark; Smeed, David; Palmer, Matthew; Dumont, Estelle; Aleynik, Dmitry


    Between June 2012 and January 2013, four underwater gliders, profiling to a maximum depth of 1000m, occupied a transect between 47.6°N, 10.3°W and 48.4°N, 9.3°W, perpendicular to the Celtic Sea continental slope. Due to the significant and well-documented internal tide activity in this region and the relatively slow through-water speed of gliders it is first demonstrated that the chosen sampling methodology minimised aliasing of the internal tide. Gliders were flown along a repeat transect and care was taken to ensure that each location was sampled at a different phase of the tide on repeat occupations. Through monthly averaging of the transect data, the effects of the internal tide are minimised and the lower frequency processes made visible. In this presentation we highlight the importance of the lower frequency variability in contributing to cross-slope exchange. Analysis of monthly averaged glider transect data suggests two distinct regimes; 1) Summer, June - October, when the surface water was temperature stratified and, 2) Winter, from October to January, when the seasonal thermocline was mixed down to below the depth of the shelf break (200 m). During the stratified summer months a well-defined shelf break salinity front limits the exchange of water between the ocean and the shelf, preventing the spread of the more saline, sub-surface ocean water (centred at ~150m) onto the shelf. Nevertheless, some cross-slope flow is identified during these months: an intermediate depth salinity minimum (centred at ~600m) is observed to upwell (from 600m to 200-300m) up the slope, sometimes continuing onto the shelf. As the stratification is eroded during the winter months, subsurface upwelling switches to downwelling, and the intermediate depth salinity minimum (~600m) retreats away from the slope region removing it as a potential source of oceanic water on the shelf. Downwelling near to the slope does however allow for an intrusion of the shallower high salinity

  15. Centrifuge model test of rock slope failure caused by seismic excitation. Applicability to the stability evaluation method of safety factors against sliding

    International Nuclear Information System (INIS)

    Ishimaru, Makoto; Kawai, Tadashi


    The purposes of this study are to analyze dynamic failure characteristics of slopes in discontinuous rock mass with brittle fracture by centrifuge model tests and to study applicability to the equivalent linear analysis against dynamic sliding failure of rock slopes. We conducted centrifuge model test using a dip slope model with discontinuities imitated by Teflon sheets. The centrifugal acceleration was 30G, and the acceleration amplitudes of input sin waves were increased gradually at every step. The test results were compared with safety factors of the sliding surface based on the equivalent linear analysis. The following results were obtained: (1) The slope model collapsed when it was excited by the sine wave of 350gal, which was converted to real field scale. (2) Artificial discontinuities considerably affected the collapse, and the type of collapse was plane failure. (3) From response displacement records measured at the slope model, the failure around toe of the slope model probably caused the collapse. (4) The evaluation of safety factors against sliding based on the equivalent linear analysis were conservative compared with the experimental results. (author)

  16. Large-scale slope failure and active erosion occurring in the southwest Ryukyu fore-arc area

    Directory of Open Access Journals (Sweden)

    T. Matsumoto


    Full Text Available The southwestern Ryukyu area east of Taiwan Island is an arcuate boundary between Philippine Sea Plate and Eurasian Plate. The topographic features in the area are characterised by (1 a large-scale amphitheatre off Ishigaki Island, just on the estimated epicentre of the tsunamigenic earthquake in 1771, (2 lots of deep sea canyons located north of the amphitheatre, (3 15–20 km wide fore-arc basin, (4 15–20 km wide flat plane in the axial area of the trench, (5 E-W trending half grabens located on the fore-arc area, etc., which were revealed by several recent topographic survey expeditions. The diving survey by SHINKAI6500 in the fore-arc area on a spur located 120 km south of Ishigaki Island was carried out in 1992. The site is characterised dominantly by rough topography consisting of a series of steep slopes and escarpments. A part of the surface is eroded due to the weight of the sediment itself and consequently the basement layer is exposed. The site was covered with suspended particles during the diving, due to the present surface sliding and erosion. The same site was resurveyed in 1997 by ROV KAIKO, which confirmed the continuous slope failure taking place in the site. Another example that was observed by KAIKO expedition in 1997 is a largescale mud block on the southward dipping slope 80 km south of Ishigaki Island. This is apparently derived from the shallower part of the steep slope on the southern edge of the fan deposit south of Ishigaki Island. The topographic features suggest N-S or NE-SW tensional stress over the whole study area. In this sense, the relative motion between the two plates in this area is oblique to the plate boundary. So, the seaward migration of the plate boundary may occur due to the gravitational instability at the boundary of the two different lithospheric structures. This is evidenced by a lack of accretionary sediment on the fore-arc and the mechanism of a recent earthquake which occurred on 3 May 1998 in

  17. Imaging derived cortical thickness reduction in high-functioning autism: key regions and temporal slope. (United States)

    Scheel, Christian; Rotarska-Jagiela, Anna; Schilbach, Leonhard; Lehnhardt, Fritz G; Krug, Barbara; Vogeley, Kai; Tepest, Ralf


    Cortical thickness (CT) changes possibly contribute to the complex symptomatology of autism. The aberrant developmental trajectories underlying such differences in certain brain regions and their continuation in adulthood are a matter of intense debate. We studied 28 adults with high-functioning autism (HFA) and 28 control subjects matched for age, gender, IQ and handedness. A surface-based whole brain analysis utilizing FreeSurfer was employed to detect CT differences between the two diagnostic groups and to investigate the time course of age-related changes. Direct comparison with control subjects revealed thinner cortex in HFA in the posterior superior temporal sulcus (pSTS) of the left hemisphere. Considering the time course of CT development we found clusters around the pSTS and cuneus in the left and the paracentral lobule in the right hemisphere to be thinner in HFA with comparable age-related slopes in patients and controls. Conversely, we found clusters around the supramarginal gyrus and inferior parietal lobule (IPL) in the left and the precentral and postcentral gyrus in the right hemisphere to be thinner in HFA, but with different age-related slopes in patients and controls. In the latter regions CT showed a steady decrease in controls but no analogous thinning in HFA. CT analyses contribute in characterizing neuroanatomical correlates of HFA. Reduced CT is present in brain regions involved in social cognition. Furthermore, our results demonstrate that aberrant brain development leading to such differences is proceeding throughout adulthood. Discrepancies in prior morphometric studies may be induced by the complex time course of cortical changes. Copyright © 2011 Elsevier Inc. All rights reserved.

  18. Identifying hydrological pre-conditions and rainfall triggers of slope failures for 2014 storm events in the Ialomita Subcarpathians, Romania (United States)

    Chitu, Zenaida; Bogaard, Thom; Busuioc, Aristita; Burcea, Sorin; Adler, Mary-Jeanne; Sandric, Ionut


    Like in many parts of the world, in Romania, landslides represent recurrent phenomena that produce numerous damages to infrastructure every few years. Various studies on landslide occurrence in the Curvature Subcarpathians reveal that rainfall represents the most important triggering factor for landslides. Depending on rainfall characteristics and environmental factors different types of landslides were recorded in the Ialomita Subcarpathians: slumps, earthflows and complex landslides. This area, located in the western part of Curvature Subcarpathians, is characterized by a very complex geology whose main features are represented by the nappes system, the post tectonic covers, the diapirism phenomena and vertical faults. This work aims to investigate hydrological pre-conditions and rainfall characteristics which triggered slope failures in 2014 in the Ialomita Subcarpathians, Romania. Hydrological pre-conditions were investigated by means of water balance analysis and low flow techniques, while spatial and temporal patterns of rainfalls were estimated using radar data and six rain gauges. Additionally, six soil moisture stations that are fitted with volumetric soil moisture sensors and temperature soil sensors were used to estimate the antecedent soil moisture conditions.

  19. A study of soil erosion on a steep cultivated slope in the Mt. Gongga region near Luding, Sichuan, China, using the 137Cs technique

    International Nuclear Information System (INIS)

    Zhang, X.B.; Wen, A.B.; Quine, T.A.; Walling, D.E.


    This paper reports the results of an investigation of soil erosion on a steep cultivated slope in the Mt Gongga region of the Upper Yangtze River Basin, Southwest China, using the 137 Cs technique. The effective 137 Cs reference inventory for the study field, estimated from the bottom layer of a 137 Cs depth profile at the deposition zones, is 2373.9 Bq/m2, accounting for 65.8% the local 137 Cs reference inventory of 3607.7 Bq/m2. It strongly indicates that a considerable amount of 137 Cs input was lost prior to incorporation into the ploughing layer from the study field during the nuclear weapons testing period because of 137 Cs surface enrichment. The average erosion rate is estimated to be 4914 t/km 2 yr for a typical cultivated steep slope with an angle of 34 deg at the subtropical zone in the Mt Gongga region. It can reach to 22856 t/km 2 yr for a failure slope under cultivation. (author)

  20. A development of an evaluation flow chart for seismic stability of rock slopes based on relations between safety factor and sliding failure

    International Nuclear Information System (INIS)

    Kawai, Tadashi; Ishimaru, Makoto


    Recently, it is necessary to assess quantitatively seismic safety of critical facilities against the earthquake- induced rock slope failure from the viewpoint of seismic PSA. Under these circumstances, it is needed to evaluate the seismic stability of surrounding slopes against extremely strong ground motions. In order to evaluate the seismic stability of surrounding slopes, the most conventional method is to compare safety factors on an expected sliding surface, which is calculated from the stability analysis based on the limit equilibrium concept, to a critical value which judges stability or instability. The method is very effective to examine whether or not the sliding surface is safe. However, it does not mean that the sliding surface falls whenever the safety factor becomes smaller than the critical value during an earthquake. Therefore the authors develop a new evaluation flow chart for the seismic stability of rock slopes based on relations between safety factor and sliding failure. Furthermore, the developed flow chart was validated by comparing two kinds of safety factors calculated from a centrifuge test result concerned with a rock slope. (author)

  1. [Vulnerability of eco-economy in northern slope region of Tianshan Mountains]. (United States)

    Wu, Jian-zhai; Li, Bo; Zhang, Xin-shi; Zhao, Wen-wu; Jiang, Guang-hui


    Based on the theoretical meaning of vulnerability, a vulnerability assessment of eco-econom in fifteen counties in the northern slope region of Tianshan Mountains was conducted. The ecosystem services change to land use was regarded as the impact, and based on the fourteen indices from resource holding, society development, and economy development statistic data, the adaptive ability was evaluated by using the methods of analytic hierarchy process (AHP) and fuzzy synthetic evaluation. On the basis of assessment results of impact and adaptive capacity, the fifteen counties were divided into five classes under the assessment principles, and the district with higher-class number was of more vulnerability. The first class included Usu City and Changji City, the second class included Hutubi County, Miquan County, Fukang City, Jimsar County, Qitai County and Mori Kazak Autonomous County, the third class included Karamay City and Urumqi City, the fourth class included Kuitun City and Shawan County, and the fifth class included Jinghe County, Shihezi City and Manas County. The vulnerability reflected the level of eco-environment change and socioeconomic development, and the vulnerability assessment could be a good way to ensure the sustainable development. Aiming to decrease the vulnerability, various districts belonging to different class of vulnerability should establish relevant tactics according to the vulnerability factors to accelerate the region's sustainable development.

  2. Distributions of recent gullies on hillslopes with different slopes and aspects in the Black Soil Region of Northeast China. (United States)

    Wang, Dichen; Fan, Haoming; Fan, Xiangguo


    Gully erosion is an important environmental problem worldwide and the main process by which water and soil losses occur in the Black Soil Region (BSR) of Northeast China. At the end of 2012, 295,663 gullies were present in this region. However, few studies have examined the gullies of the Black Soil Region as a whole. Studying the distribution of recent gullies can reveal the pattern of gully distribution and can help predict their spatial development according to the soil and water conservation regionalization of China. This study examines the recorded gullies in the BSR of Northeast China, which is included in the first census of water resources in China and in six sub-regions of the soil and water conservation regionalization of China. Specifically, digital elevation model (DEM) data are combined with data on gullies occurring on hillslopes with different slopes and aspects to study the distribution of these features. The results illustrate that gully density, developing gully density, and the proportion of cutting land initially increase with increasing slope up to some threshold value, then decrease as the slope increases further. The patterns of stable gullies are divided into unimodal and bimodal types. Three patterns of gully intensity are identified. The areas and lengths of gullies are larger on sunny slopes, but larger numbers of gullies are present on shaded slopes. In addition, more space is available for gully development in the Hulun Buir hilly and plain sub-region and the Changbai Mountain-Wanda Mountain sub-region than in the other sub-regions.

  3. [Mechanisms of grass in slope erosion control in Loess sandy soil region of Northwest China]. (United States)

    Zhao, Chun-Hong; Gao, Jian-En; Xu, Zhen


    By adopting the method of simulated precipitation and from the viewpoint of slope hydrodynamics, in combining with the analysis of soil resistance to erosion, a quantitative study was made on the mechanisms of grass in controlling the slope erosion in the cross area of wind-water erosion in Loess Plateau of Northwest China under different combinations of rainfall intensity and slope gradient, aimed to provide basis to reveal the mechanisms of vegetation in controlling soil erosion and to select appropriate vegetation for the soil and water conservation in Loess Plateau. The grass Astragalus adsurgens with the coverage about 40% could effectively control the slope erosion. This grass had an efficiency of more than 70% in reducing sediment, and the grass root had a greater effect than grass canopy. On bare slope and on the slopes with the grass plant or only the grass root playing effect, there existed a functional relation between the flow velocity on the slopes and the rainfall intensity and slope gradient (V = DJ(0.33 i 0.5), where V is flow velocity, D is the comprehensive coefficient which varies with different underlying surfaces, i is rainfall intensity, and J is slope gradient). Both the grass root and the grass canopy could markedly decrease the flow velocity on the slopes, and increase the slope resistance, but the effect of grass root in decreasing flow velocity was greater while the effect in increasing resistance was smaller than that of grass canopy. The effect of grass root in increasing slope resistance was mainly achieved by increasing the sediment grain resistance, while the effect of canopy was mainly achieved by increasing the slope form resistance and wave resistance. The evaluation of the soil resistance to erosion by using a conceptual model of sediment generation by overland flow indicated that the critical shear stress value of bare slope and of the slopes with the grass plant or only the grass root playing effect was 0.533, 1.672 and 0

  4. Seed population dynamics on abandoned slopes in the hill and gully Loess Plateau region of China (United States)

    Yu, Weijie; Jiao, Juying


    Recovery of natural vegetation is an effective but slow approach to control the soil erosion in the Chinese hill and gully Loess Plateau region. As seed stage is particularly vulnerable to environmental conditions, characteristics of seed population should be needed to study for determining whether the recovery of natural vegetation is limited during this stage on the abandoned slopes in this region. The study was performed on three abandoned slopes in a watershed with an area of 8.27 km2in the Shaanxi province of China. The differences in soil seed banks were investigated in two different points in time, late March2011 and early April 2013. Main factors of seed population dynamics, such as seed yield of dominant species, seed inputs by seed rain as well as seed outputs through seed loss by overland flow and seedling emergence, were monitored from late March 2011 to early April 2013. In this study, seed rain densities of the main later successional species, i.e., Lespedeza davurica, Stipa bungeana and Artemisia gmelinii accounted for 51.5-71.6% of their own seed yields. The soil seed bank density in early April 2013 was larger than that in late March 2011. The density of seed inputs by seed rain was 10186 seeds•m-2, and the total seed bank, including seed rain and seeds present in the soil seed bank in late March 2011, reached a density of 15018 seeds•m-2 during the study period. Seed densities of loss due to overland flow and seedling emergence were 79 seeds•m-2 from 20 species and 938 seedlings•m-2 that belonged to 38 species during a study period, and the seed output through them accounted for 0.5% and 6.3% of the total seed bank, respectively. The study concluded that overland flow could not result in large numbers of seeds loss and seeds were accumulating in the soil seed bank due to seed rain, and vegetation succession might be limited by curbed spatial seed dispersal and seedling establishment.

  5. Frequency and sources of basin floor turbidites in alfonso basin, Gulf of California, Mexico: Products of slope failures (United States)

    Gonzalez-Yajimovich, Oscar E.; Gorsline, Donn S.; Douglas, Robert G.


    Alfonso Basin is a small margin basin formed by extensional tectonics in the actively rifting, seismically active Gulf of California. The basin is centered at 24°40' N and 110° 38' W, and is a closed depression (maximum depth 420 m) with an effective sill depth of about 320 m (deepest sill), a width of 20 km and length of 25 km. Basin floor area below a depth of 350 m is about 260 km 2. The climate is arid to semiarid but was wetter during the early (ca. 10,000-7000 Calendar years Before Present [BP]) and middle Holocene (ca. 7000-4000 Cal. Years BP). Basin-wide turbidity currents reach the floor of Alfonso Basin at centennial to millennial intervals. The peninsular drainages tributary to the basin are small and have maximum flood discharges of the order of 10 4m 3. The basin-floor turbidites thicker than 1 cm have volumes of the order of 10 6m 3 to 10 8m 3 and require a much larger source. The largest turbidite seen in our cores is ca. 1 m thick in the central basin floor and was deposited 4900 Calendar Years Before Present (BP). Two smaller major events occurred about 1500 and 2800 Cal. Years BP. Seismicity over the past century of record shows a clustering of larger epicenters along faults forming the eastern Gulf side of Alfonso Basin. In that period there have been four earthquakes with magnitudes above 7.0 but all are distant from the basin. Frequency of such earthquakes in the basin vicinity is probably millennial. It is concluded that the basin-wide turbidites thicker than 1 cm must be generated by slope failures on the eastern side of the basin at roughly millennial intervals. The thin flood turbidites have a peninsular source at centennial frequencies.

  6. Coir geotextile for slope stabilization and cultivation - A case study in a highland region of Kerala, South India (United States)

    Vishnudas, Subha; Savenije, Hubert H. G.; Van der Zaag, Pieter; Anil, K. R.

    A sloping field is not only vulnerable to soil erosion it may also suffer from soil moisture deficiency. Farmers that cultivate on slopes everywhere face similar problems. Conservation technologies may reduce soil and nutrient losses, and thus enhance water holding capacity and soil fertility. But although these technologies promote sustainable crop production on steep slopes, the construction of physical structure such as bench terraces are often labour intensive and expensive to the farmers, since construction and maintenance require high investments. Here we studied the efficiency of coir geotextile with and without crop cultivation in reducing soil moisture deficiency on marginal slopes in Kerala, India. From the results it is evident that the slopes treated with geotextile and crops have the highest moisture retention capacity followed by geotextiles alone, and that the control plot has the lowest moisture retention capacity. As the poor and marginal farmers occupy the highland region, this method provides an economically viable option for income generation and food security along with slope stabilization.

  7. Regional geomorphology of the continental slope of NW India: Delineation of the signatures of deep-seated structures

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O.S.; Almeida, F.; Moraes, C.

    . These features are surface manifestations of the anticlinal features extending along the shelf in this region. Unevenness (order of 100-300 m) due to slumping is also observed at the base of the slope. Based on the correlation between tectonic structures...

  8. Clay sediment accumulation rates on the monsoon-dominated western continental shelf and slope region of India

    Digital Repository Service at National Institute of Oceanography (India)

    Borole, D.V.

    Clay accumulation rates shown in sediment cores from the nearshore to outer continental shelf and slope regions in water depths of 10-1246 m on the western continental margins of India were determined by the 210Pb dating technique. The 210Pb excess...

  9. Integration of two-phase solid fluid equations in a catchment model for flashfloods, debris flows and shallow slope failures

    KAUST Repository

    Bout, B.; Lombardo, Luigi; van Westen, C.J.; Jetten, V.G.


    An integrated, modeling method for shallow landslides, debris flows and catchment hydrology is developed and presented in this paper. Existing two-phase debris flow equations and an adaptation on the infinite slope method are coupled with a full

  10. Magnitudes and slopes of real and imaginary amplitudes in the Coulomb interference region of pp and pbarp scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kohara, Anderson Kendi; Ferreira, Erasmo; Kodama, Takeshi [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil)


    Full text: We use exact Derivative Dispersion Relations [?, ?] to investigate properties of the real and imaginary amplitudes in the forward region of pp and pbarp scattering. We emphasize that the effective slope in dσ/dt is formed by different exponential slopes in the real and imaginary amplitudes (called B{sub R} and B{sub I} ). For this purpose a more general treatment of the Coulomb phase is developed. The dσ/dt data in the range from 19 to 1800 GeV for low |t| are analysed in terms of the four quantities σ, ρ, B{sub I}, B{sub R} that are basic for dynamical models . The usual assumption that B{sub I} and B{sub R} are the same, with σ not depending strongly on t, does not agree with dispersion relations, for which B{sub R} > B{sub I} , and with the expectation that the first real zero approaches t=0 as the energy increases. Our work uses dispersion relations to disentangle the quantities that represent observables in terms of imaginary and real parts, intrinsically combined with the Coulomb contribution. To investigate real slopes we use new forms of dispersion relations [?]. With the difference between imaginary and real slopes , the future RHIC and LHC data will require the extended analysis with B{sub R} as a free quantity. We investigate in detail the region from 19 to 30 GeV where the real amplitude in pp scattering may vanish. The data for ρ are contradictory in this range. We investigate the meaning of the real slope B{sub R} in this region where the parameter ρ is very small, and construct coherent description of the data. In the high energy region we obtain scattering parameters for the RHIC and LHC experiments. (author)

  11. A water balance study of four landfill cover designs varying in slope for semiarid regions

    International Nuclear Information System (INIS)

    Nyhan, J.W.; Schofield, T.G.; Salazar, J.A.


    The goal of disposing of radioactive and hazardous waste in shallow landfills is to reduce risk to human health and to the environment by isolating contaminants until they no longer pose a hazard. In order to achieve this, the performance of a landfill cover design without an engineered barrier (Conventional Design) was compared with three designs containing either a hydraulic barrier (EPA Design) or a capillary barrier (Loam and Clay Loam Capillary Barrier Designs). Water balance parameters were measured since 1991 at six-hour intervals for four different landfill cover designs in 1.0- by 10.0-m plots with downhill slopes of 5, 10, 15, and 25%. Whereas runoff generally accounted for only 2-3% of the precipitation losses on these designs, similar values for evapotranspiration ranged from 86% to 91%, with increased evapotranspiration occurring with increases in slope. Consequently, interflow and seepage usually decreased with increasing slope for each landfill cover design. Seepage consisted of up to 10% of the precipitation on the Conventional Design, whereas the hydraulic barrier in the EPA Design effectively controlled seepage at all slopes, and both of the capillary designs worked effectively to eliminate seepage at the higher slopes

  12. Structural highs on the western continental slope of India: Implications for regional tectonics

    Digital Repository Service at National Institute of Oceanography (India)

    Mukhopadhyay, R.; Rajesh, M.; De, Suritha; Chakraborty, B.; Jauhari, P.

    structural highs of variable height. Four of these highs are located over the Upper Slope Ridge and a similar number on the Prathap Ridge. Of these, four highs have summit height N is greater than 1000 m, two have heights between 500 and 999 m, while...

  13. Process analysis of deep slope failures in České středohoří neovolcanites

    Czech Academy of Sciences Publication Activity Database

    Rybář, Jan; Vilímek, V.; Cílek, Václav

    8(115) (2000), s. 39-46 ISSN 1212-1576 R&D Projects: GA ČR GA205/98/1551 Institutional research plan: CEZ:AV0Z3046908 Keywords : deep slope deformations * creep * landsliding Subject RIV: DB - Geology ; Mineralogy

  14. Linking slope stability and climate change: the Nordfjord region, western Norway, case study (United States)

    Vasskog, K.; Waldmann, N.; Ariztegui, D.; Simpson, G.; Støren, E.; Chapron, E.; Nesje, A.


    Valleys, lakes and fjords are spectacular features of the Norwegian landscape and their sedimentary record recall past climatic, environmental and glacio-isostatic changes since the late glacial. A high resolution multi-proxy study is being performed on three lakes in western Norway combining different geophysical methods and sediment coring with the aim of reconstructing paleoclimate and to investigate how the frequency of hazardous events in this area has changed through time. A very high resolution reflection seismic profiling revealed a series of mass-wasting deposits. These events, which have also been studied in radiocarbon-dated cores, suggest a changing impact of slope instability on lake sedimentation since the late glacial. A specially tailored physically-based mathematical model allowed a numerical simulation of one of these mass wasting events and related tsunami, which occurred during a devastating rock avalanche in 1936 killing 74 persons. The outcome has been further validated against historical, marine and terrestrial information, providing a model that can be applied to comparable basins at various temporal and geographical scales. Detailed sedimentological and geochemical studies of selected cores allows characterizing the sedimentary record and to disentangle each mass wasting event. This combination of seismic, sedimentary and geophysical data permits to extend the record of mass wasting events beyond historical times. The geophysical and coring data retrieved from these lakes is a unique trace of paleo-slope stability generated by isostatic rebound and climate change, thus providing a continuous archive of slope stability beyond the historical record. The results of this study provide valuable information about the impact of climate change on slope stability and source-to-sink processes.

  15. Triangular facets of slope in the region of Tudela (Ebro Basin, Navarra, Spain)

    International Nuclear Information System (INIS)

    Marin, C.; Desir, G.; Gutierrez, M.


    Some triangular slope facets are localized to the south of Bardenas Reales (central-west of Ebro Basin), elaborated on Tudela Formation deposits, Aragonian in age. Three of them have been dated by OSL resulting on ages of 35,588±2,488 yr. BP, 35,355±2,446 yr. BP and 40.185±2,411 yr. BP. The origin of these facets is ought to an alternation between accumulation and incision phases produced by vegetation cover variation percentage. Those vegetation cover changes are estimated to be due to climatic changes. (Author) 21 refs.

  16. Influence of weathering and pre-existing large scale fractures on gravitational slope failure: insights from 3-D physical modelling

    Directory of Open Access Journals (Sweden)

    D. Bachmann


    Full Text Available Using a new 3-D physical modelling technique we investigated the initiation and evolution of large scale landslides in presence of pre-existing large scale fractures and taking into account the slope material weakening due to the alteration/weathering. The modelling technique is based on the specially developed properly scaled analogue materials, as well as on the original vertical accelerator device enabling increases in the 'gravity acceleration' up to a factor 50. The weathering primarily affects the uppermost layers through the water circulation. We simulated the effect of this process by making models of two parts. The shallower one represents the zone subject to homogeneous weathering and is made of low strength material of compressive strength σl. The deeper (core part of the model is stronger and simulates intact rocks. Deformation of such a model subjected to the gravity force occurred only in its upper (low strength layer. In another set of experiments, low strength (σw narrow planar zones sub-parallel to the slope surface (σwl were introduced into the model's superficial low strength layer to simulate localized highly weathered zones. In this configuration landslides were initiated much easier (at lower 'gravity force', were shallower and had smaller horizontal size largely defined by the weak zone size. Pre-existing fractures were introduced into the model by cutting it along a given plan. They have proved to be of small influence on the slope stability, except when they were associated to highly weathered zones. In this latter case the fractures laterally limited the slides. Deep seated rockslides initiation is thus directly defined by the mechanical structure of the hillslope's uppermost levels and especially by the presence of the weak zones due to the weathering. The large scale fractures play a more passive role and can only influence the shape and the volume of the sliding units.

  17. Can deep seated gravitational slope deformations be activated by regional tectonic strain: First insights from displacement measurements in caves from the Eastern Alps

    Czech Academy of Sciences Publication Activity Database

    Baron, I.; Plan, L.; Grasemann, B.; Mitrovic, I.; Lenhardt, W.; Hausmann, H.; Stemberk, Josef


    Roč. 259, APR 15 (2016), 81-89 ISSN 0169-555X Grant - others:Austrian Science Fund(AT) P25884-N29 Institutional support: RVO:67985891 Keywords : tectonic strain * slope failure * earthquake Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.958, year: 2016

  18. Soil movements and surface erosion rates on rocky slopes in the mountain areas of the karst region of Southwest China (United States)

    Zhang, X. B.; Bai, X. Y.; Long, Y.


    The karst region of Southwest China with an area of 54 × 104 km2 is one of the largest karst areas in the world and experiences subtropical climate. Hill-depressions are common landforms in the mountain areas of this region. Downslope soil movement on the ground by surface water erosion and soil sinking into underground holes by creeping or pipe erosion are mayor types of soil movements on rocky carbonate slopes. The 137Cs technique was used to date the sediment deposits in six karst depressions, to estimate average surface erosion rates on slopes from their catchments. The estimates of soil loss rates obtained from this study evidenced considerable variability. A value of 1.0 t km-2 year-1 was obtained for a catchment under original dense karst forest, but the erosion rates ranged between 19.3 t km-2 year-1 and 48.7 t km-2 year-1 in four catchments under secondary forest or grasses, where the original forest cover had been removed in the Ming and Qing dynasties, several hundred years ago. The highest rate of 1643 t km-2 year-1 was obtained for a catchment underlain by clayey carbonate rocks, where the soil cover was thicker and more extensive than in the other catchments and extensive land reclamation for cultivation had occurred during the period 1979-1981, immediately after the Cultural Revolution.

  19. Land Use Suitability Assessment in Low-Slope Hilly Regions under the Impact of Urbanization in Yunnan, China

    Directory of Open Access Journals (Sweden)

    Gui Jin


    Full Text Available Nowadays, the conflict between land development and land conservation has become increasingly serious in China. The plan called “town of mountain” is carried out in many nonplain areas to alleviate the conflict. To avoid geological disasters and ecological risks in those areas, land use suitability assessment is of great importance. In this paper, the fuzzy weight of evidence model is applied into land use suitability assessment in low-slope hilly regions in Yunnan, China. Fuzzy weight of evidences is calculated to determine 9 map layers. Finally, posterior probabilities are modified after synthesizing each map layer, which are used to generate a land use suitability map. The results show that 9.33%, 26.18%, 45.98%, and 18.51% of low-slope hilly regions are separately highly suitable, moderately suitable, marginally suitable, and unsuitable for development. Besides, highly and moderately suitable areas are mainly located in towns with excellent natural and socioeconomic conditions. The largest areas which are marginally suitable for development are most widely distributed. Unsuitable areas are mainly distributed far away from towns and water sources. The findings of the research will promote the rational use and scientific management of the land.

  20. Age evaluation and causation of rock-slope failures along the western margin of the Antrim Lava Group (ALG), Northern Ireland, based on cosmogenic isotope (36Cl) surface exposure dating (United States)

    Southall, David W.; Wilson, Peter; Dunlop, Paul; Schnabel, Christoph; Rodés, Ángel; Gulliver, Pauline; Xu, Sheng


    The temporal pattern of postglacial rock-slope failure in a glaciated upland area of Ireland (the western margin of the Antrim Lava Group) was evaluated using both 36Cl exposure dating of surface boulders on run-out debris and 14C dating of basal organic soils from depressions on the debris. The majority of the 36Cl ages ( 21-15 ka) indicate that major failures occurred during or immediately following local deglaciation ( 18-17 ka). Other ages ( 14-9 ka) suggest some later, smaller-scale failures during the Lateglacial and/or early Holocene. The 14C ages (2.36-0.15 cal ka BP) indicate the very late onset of organic accumulation and do not provide close limiting age constraints. Rock-slope failure during or immediately following local deglaciation was probably in response to some combination of glacial debuttressing, slope steepening and paraglacial stress release. Later failures may have been triggered by seismic activity associated with glacio-isostatic crustal uplift and/or permafrost degradation consequent upon climate change. The 36Cl ages support the findings of previous studies that show the deglacial - Lateglacial period in northwest Ireland and Scotland to have been one of enhanced rock-slope failure. Table S2 Concentrations of main elements (as oxides) etc.

  1. Rainfall Characteristic on the Slopes of Mount Merapi Region (Empirical Formula, Duration, Distribution, And Critical Line Woro River

    Directory of Open Access Journals (Sweden)

    Pudak Juni Laksana


    Full Text Available Debris flow on the slopes of Mount Merapi area became a serious natural disasters because it has great destructive force and velocity. Rainfall with a certain intensity and duration is one component triggering debris flow. Rainfall has variability of the temporal and spatial characteristics influenced by various factors, such as topography and climate. Dharma (2012 suggested to define the characteristics of the intensity of rainfall using rainfall data with a shorter duration with statistical tests to establish the best empirical IDF formula.  This research was using of 30 minutes rainfall data for short duration (<3 hours and a spreadsheet software representing duration and distribution of the rainfall. The most appropriate rainfall intensity formula was done by the empirical IDF formula, i.e. Sherman, Kimijima, Hasper and Mononobe. Rainfall intensity analysis applied Frequency Analysis Software (based on Microsoft Excel. Debris flow occurrence was analyzed using MLIT for method A to establish standard rainfall index.  Sherman formula performed the best fit to the IDF characteristics of rainfall in the region of the slopes of Mount Merapi. Rainfall distribution pattern showed high intensity rainfall in the first hour and then decreased in the next hour which means distribution for the duration of 3 hours, 12%, 28%, 25%, 16%, 12%, and 7%, respectively with an interval of 30 minutes. Based on critical line, 5 mm of standard rainfall index was gained in the case of warning (R1 and 28 mm in the case of evacuation (R2.

  2. Slope Failure Hazards at Basalt Geomorphosites: A Comparative Analysis of the Giant's Causeway World Heritage Site, UK and Penghu Marine Geopark, Taiwan. (United States)

    Gruendemann, Ciaran; Chung Lin, Jiun; Smith, Bernard


    Columnar basalt landscapes hold a fascination that transcends geographical and cultural boundaries. It is because of this that they feature so prominently on the global register of significant geomorphosites. Arguably the most iconic of these basalt landscapes is the Giant's Causeway in Northern Ireland, a status recognized by its inscription as a World Heritage Site. Recognition at this level invariably brings visitor pressure, and with it concern as to the impact they exert on site integrity. Rarely, however, is the same overt concern expressed for the risks that such sites pose to the visitors - or not at least until disaster strikes. Yet, the very features that make these sites attractive - tall, exposed, largely unconstrained columns - render many of them intrinsically unstable, prone to catastrophic collapse and potentially hazardous to visitors. In this presentation we highlight the nature of these slope instability issues through a comparative analysis of two geographically contrasting basalt geomorphosites. Investigations of slope hazard at the Giant's Causeway have shown that many are linked to the distinctive structural characteristics and weathering patterns of flood basalts. Typically, individual flows comprise a columnar ‘colonnade', topped by a blocky ‘entablature' and separated from the flows above and below it by a structurally weaker, but often less-permeable, palaeosol that formed during periods of volcanic quiescence. The collapse of columns is often facilitated by a combination of weathering along ever-widening joints and wedging outwards by debris that falls into them. This gradual distortion of the colonnade makes columns increasingly susceptible to collapse. Often this is triggered by intense rainfall (perhaps following a dry spell) that rapidly infiltrates joints and is ponded on the underlying palaeosol. The precise nature of the failure (toppling or outwards rotation of the column base) is largely dictated by the nature of the

  3. EroGRASS : Failure of grass cover layers at seaward and shoreward dike slopes. design, construction and performance

    NARCIS (Netherlands)

    Verhagen, H.J.; Verheij, H.J.; Cao, T.M.; Dassanayake, D.; Roelvink, D.; Piontkowitz, T.


    A large number of the dikes in the North Sea and Baltic Sea regions are covered with grass that is exposed to hydraulic loading from waves and currents during storm surges. During previous storm surges the grass cover layers often showed large strength and remained undamaged. A clear physical

  4. Assessment of Rock Slope Stability in Limestone Quarries in the Tournai's Region (Belgium) Using Structural Data (United States)

    Tshibangu, Jean-Pierre; Deloge, K. Pierre-Alexandre; Deschamps, Benoît; Coudyzer, Christophe

    The Tournais region is characterised by famous outcrops of carboniferous limestone which is mined out for cement and raw material production. The four main quarries found in the Region, i.e. Gaurain-Ramecroix, Milieu, Antoing and Lemay; are owned by the three main cement producers in Belgium: Italcimenti, Holcim and CBR. The global production of limestone is about 20 millions tons per year, giving big pits with depths up to 150 m. With the growth of the pits, the quarries are approaching each other leading to the problem of managing the reserves contained in the separating walls and their mechanical stability. The limestone deposit is composed of different seams having varying thickness, chemical com- position and even mechanical properties. The deposit has an overall horizontal dip and is intersected by two main sets of discontinuities with a spacing of about 10 m or less. It is also crossed by a set of east to west faults but the quarries are implanted in the in between areas, so to not be crossed by these faults. The layers and specially the shallow ones are characterised by a typical karstic weathering giving open or filled cavities. This paper presents the global work quarried out in order to study the stability of the Lemays quarry. First a description of the orientation and spacing of discontinuities is presented, and an attempt made to correlate to the development of weathering. Mechanical laboratory tests have been performed and a qualification of the rock mass assessed. A coupled approach is then presented using a mining planning analysis and mechanical simulation (i.e. Finite Element method).

  5. Slope movements

    International Nuclear Information System (INIS)

    Wagner, P.


    On this poster some reasons of slope movements on the territory of the Slovak Republic are presented. Slope movements induced deterioration of land and forests, endangering of towns villages, and communications as well as hydro-engineering structures. Methods of preventing and stabilisation of slope movements are presented.

  6. Interesting insights into instability of slopes and rock fall in the morphodynamic Himalayan terrane (United States)

    Singh, T. N.; Vishal, V.; Pradhan, S. P.


    Himalayan mountain ranges are tectonically and seismically very active and experience many disastrous events with time due to slope failure. Frequent failures of rock cut slopes cause obstruction in traffic and often lead to fatalities. In recent years, the number of tragedies has increased when associated with regional phenomena such at the Kedarnath tragedy of 2013 and the Gorkha earthquake of 2015. The influence of such phenomena on the stability of slopes along important national highways and key settlement areas only raise the risk to lives and property. We conducted a multi-approach investigation for some key slopes along the National Highway 58 in Uttarakhand Himalaya, India. A very detailed field work was conducted to identify the unstable slopes and those with some history of failure. The pertinent geomechanical characteristics of the representative rock samples were determined in the laboratory. Based on the structural data, kinematic analysis was carried out. Finally the slopes were simulated using FDM based simulator, Flac/Slope for analysing the health of the slopes and Rockfall 4.0 to investigate the phenomenon of rockfall along the Highway. It was found that few slopes were weak due to the inherent weak rock materials while few slopes made up of high strength rocks were effectively weak due to prone-to-failure orientation of the joints. Quantification of bounce-height of rock blocks during fall, their energy, velocity and displacement along the slope was also done. Using 3-D simulations, few critically-stable slopes that appear to be stable, were identified. Little ground movement could be capable of triggering a large scale failure in the area. Slopes in the studied region are under threat to failure and need immediate proper planning using the suggested remedial measures.

  7. Comparative reproductive biology of three dominant myctophids of the genus Diaphus on the slope region of the East China Sea (United States)

    Sassa, Chiyuki; Tanaka, Hiroshige; Ohshimo, Seiji


    We examined the reproductive biology of three dominant pseudoceanic myctophids, Diaphus garmani, D. chrysorhynchus, and D. watasei, on the slope region of the East China Sea. Overall, females were more abundant in D. garmani and D. chrysorhynchus, while males were more abundant in D. watasei. The gonadosomatic index (GSI) at 50% sexual maturity of females of D. garmani, D. chrysorhynchus, and D. watasei was 3.65, 3.92, and 6.27, respectively. Based on these criteria, females of each species can mature at sizes larger than 42, 71, and 120 mm standard length (SL), respectively. In all three species, GSI of females showed high values during summer, i.e. the primary spawning season, and occurrence of females with hydrated ovaries was restricted to the daytime (0600-1530 h) in the mesopelagic layer of 270-450 m depth. Oocytes at various sizes were found in mature ovaries, indicating that they are multiple spawners. Spawning frequencies were estimated to be approximately 3-9 days. Mean egg size at hydration and batch fecundity was respectively smallest and lowest in D. garmani (0.60 mm and 612-2200 eggs) and largest and highest in D. watasei (0.65 mm and 10,356-44,879 eggs). Batch fecundity increased linearly with SL in all species, with a steeper slope in D. watasei. Diaphus garmani is characterized by early maturation at a smaller size, while D. watasei channels a larger part of the energy budget into somatic growth during the juvenile and later immature stages (<120 mm SL) than the other two species and subsequently reproduces at a larger size as mature adults.

  8. Runoff, nitrogen (N) and phosphorus (P) losses from purple slope cropland soil under rating fertilization in Three Gorges Region. (United States)

    Bouraima, Abdel-Kabirou; He, Binghui; Tian, Taiqiang


    Soil erosion along with soil particles and nutrients losses is detrimental to crop production. We carried out a 5-year (2010 to 2014) study to characterize the soil erosion and nitrogen and phosphorus losses caused by rainfall under different fertilizer application levels in order to provide a theoretical evidence for the agricultural production and coordinate land management to improve ecological environment. The experiment took place under rotation cropping, winter wheat-summer maize, on a 15° slope purple soil in Chongqing (China) within the Three Gorges Region (TGR). Four treatments, control (CK) without fertilizer, combined manure with chemical fertilizer (T1), chemical fertilization (T2), and chemical fertilizer with increasing fertilization (T3), were designed on experimental runoff plots for a long-term observation aiming to study their effects on soil erosion and nutrients losses. The results showed that fertilization reduced surface runoff and nutrient losses as compared to CK. T1, T2, and T3, compared to CK, reduced runoff volume by 35.7, 29.6, and 16.8 %, respectively and sediment yield by 40.5, 20.9, and 49.6 %, respectively. Regression analysis results indicated that there were significant relationships between soil loss and runoff volume in all treatments. The combined manure with chemical fertilizer (T1) treatment highly reduced total nitrogen and total phosphorus losses by 41.2 and 33.33 %, respectively as compared with CK. Through this 5-year experiment, we can conclude that, on the sloping purple soil, the combined application of manure with fertilizer is beneficial for controlling runoff sediments losses and preventing soil erosion.

  9. Assessment of soil erosion and conservation on agricultural sloping lands using plot data in the semi-arid hilly loess region of China

    Directory of Open Access Journals (Sweden)

    T.X. Zhu


    New hydrological insights for the region: The results revealed that runoff per unit area slightly increased with slope angle on SSP, but reached a maximum at 15° and then decreased with slope angle on LSP. Soil loss per unit area increased with slope angle on both SSP and LSP. An average of 36.4% less runoff but only 3.6% less soil loss per unit area was produced on LSP than on SSP. The S factor calculated using the slope factor equations in USLE/RUSLE was significantly greater than that estimated from the measured soil loss on the plots. Rainstorms with recurrence intervals greater than 2 years were responsible for more than two thirds of the total soil and water loss. The effectiveness in reducing surface runoff by five types of conservation practices was mixed. However, all the conservation practices yielded much less soil loss than cropland.

  10. Increased wetness confounds Landsat-derived NDVI trends in the central Alaska North Slope region, 1985-2011 (United States)

    Raynolds, Martha K.; Walker, Donald A.


    Satellite data from the circumpolar Arctic have shown increases in vegetation indices correlated to warming air temperatures (e.g. Bhatt et al 2013 Remote Sensing 5 4229-54). However, more information is needed at finer scales to relate the satellite trends to vegetation changes on the ground. We examined changes using Landsat TM and ETM+ data between 1985 and 2011 in the central Alaska North Slope region, where the vegetation and landscapes are relatively well-known and mapped. We calculated trends in the normalized difference vegetation index (NDVI) and tasseled-cap transformation indices, and related them to high-resolution aerial photographs, ground studies, and vegetation maps. Significant, mostly negative, changes in NDVI occurred in 7.3% of the area, with greater change in aquatic and barren types. Large reflectance changes due to erosion, deposition and lake drainage were evident. Oil industry-related changes such as construction of artificial islands, roads, and gravel pads were also easily identified. Regional trends showed decreases in NDVI for most vegetation types, but increases in tasseled-cap greenness (56% of study area, greatest for vegetation types with high shrub cover) and tasseled-cap wetness (11% of area), consistent with documented degradation of polygon ice wedges, indicating that increasing cover of water may be masking increases in vegetation when summarized using the water-sensitive NDVI.

  11. Study on Flexible Pavement Failures in Soft Soil Tropical Regions (United States)

    Jayakumar, M.; Chee Soon, Lee


    Road network system experienced rapid upgrowth since ages ago and it started developing in Malaysia during the colonization of British due to its significant impacts in transportation field. Flexible pavement, the major road network in Malaysia, has been deteriorating by various types of distresses which cause descending serviceability of the pavement structure. This paper discusses the pavement condition assessment carried out in Sarawak and Sabah, Malaysia to have design solutions for flexible pavement failures. Field tests were conducted to examine the subgrade strength of existing roads in Sarawak at various failure locations, to assess the impact of subgrade strength on pavement failures. Research outcomes from field condition assessment and subgrade testing showed that the critical causes of pavement failures are inadequate design and maintenance of drainage system and shoulder cross fall, along with inadequate pavement thickness provided by may be assuming the conservative value of soil strength at optimum moisture content, whereas the exiting and expected subgrade strengths at equilibrium moisture content are far below. Our further research shows that stabilized existing recycled asphalt and base materials to use as a sub-base along with bitumen stabilized open graded base in the pavement composition may be a viable solution for pavement failures.

  12. Engaging Local Communities in Arctic Observing Networks: A Collaborative Shoreline Change Risk WebGIS for Alaska's Arctic Slope Region (United States)

    Brady, M.


    This study engaged local community stakeholders in Alaska's Arctic Slope Region to develop a web-based shoreline change risk geographic information system (WebGIS) in collaboration with the North Slope Borough and its residents. The value of the effort includes rich spatial documentation of local risks across the vast, remote, and rapidly changing shoreline, and identification of local manager information needs to direct WebGIS development. The study advances our understanding of shoreline change problems from the perspective of local Arctic communities beyond municipal impacts while building decision support. Over fifty local residents in three communities with collective coastal knowledge that extends across the National Petroleum Reserve - Alaska and Arctic National Wildlife Refuge shared their perspectives on hard copy maps. Sixteen managers provided usability perceptions of a beta WebGIS with shoreline change susceptibility information summarized at relevant asset locations such as subsistence camps. The hard copy maps with 300 "problem places" were digitized for analysis, which revealed problems across the coastline, especially challenges to boating for subsistence hunting such as shoaling cutting off access and creating hazards. The usability workshop revealed specific information needs including the need to monitor impacts at decommissioned national defense radar sites repurposed by locals to centralize oil and gas activity. These results were analyzed using an Instructional Systems Design (ISD) framework consisting of front-end and formative WebGIS evaluation phases. The front-end evaluation is the local input on hard copy maps, which provided local verification of coastal risks. The formative evaluation is the usability workshop with managers, which informed WebGIS development while promoting user buy-in. In terms of product and process, the local knowledge and information needs collected are significant because they establish local engagement with the

  13. Exploring the potential of Sentinel-1 data for regional scale slope instability detection using multi-temporal interferometry (United States)

    Wasowski, Janusz; Bovenga, Fabio; Nutricato, Raffaele; Nitti, Davide Oscar; Chiaradia, Maria Teresa; Refice, Alberto; Pasquariello, Guido


    Launched in 2014, the European Space Agency (ESA) Sentinel-1 satellite carrying a medium resolution (20 m) C-Band Synthetic Aperture Radar (SAR) sensor holds much promise for new applications of multi-temporal interferometry (MTI) in landslide assessment. Specifically, the regularity of acquisitions, timeliness of data delivery, shorter repeat cycle (currently 12 days with Sentinel-1A sensor), and flexible incidence angle geometry, all imply better practical utility of MTI relying on Sentinel-1 with respect to MTI based on data from earlier ESA's satellite radar C-band sensors (ERS1/2, ENVISAT). Furthermore, the upcoming launch of Sentinel-1B will cut down the repeat cycle to 6 days, thereby further improving temporal coherence and quality and coverage of MTI products. Taking advantage of the Interferometric Wide (IW) Swath acquisition mode of Sentinel-1 (images covering a 250 km swath on the ground), in this work we test the potential of such data for regional scale slope instability detection through MTI. Our test area includes the landslide-prone Apennine Mountains of Southern Italy. We rely on over 30 Sentinel-1 images, most of which acquired in 2015, and MTI processing through the SPINUA algorithm (Stable Points INterferometry in Un-urbanized Areas). The potential of MTI results based on Sentinel-1 data is assessed by comparing the detected ground surface displacements with the MTI results obtained for the same test area using the C-Band data acquired by ERS1/2 and ENVISAT in 1990s and 2000s. Although the initial results are encouraging, it seems evident that longer-term (few years) acquisitions of Sentinel-1 are necessary to reliably detect some extremely slow movements, which were observed in the last two decades and are likely to be still present in peri-urban areas of many hilltop towns in the Apennine Mts. The MTI results obtained from Sentinel-1 data are also locally compared with the MTI outcomes based on the high resolution (3 m) TerraSAR-X imagery

  14. Patterns of local-regional failure after primary intensity modulated radiotherapy for nasopharyngeal carcinoma

    International Nuclear Information System (INIS)

    Kong, Fangfang; Ying, Hongmei; Du, Chengrun; Huang, Shuang; Zhou, Junjun; Chen, Junchao; Sun, Lining; Chen, Xiaohui; Hu, Chaosu


    To analyze patterns of local-regional failure after primary intensity modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC). A total of 370 non-metastatic NPC patients consecutively treated with IMRT (with or without chemotherapy) were analyzed. Radiotherapy was administered using a simultaneous integrated boost (SIB) technique at the total prescribed dose of 66-70.4Gy (2.0-2.2Gy per fraction). The location and extent of local-regional failures were transferred to the pretreatment planning computed tomography (CT) for dosimetric analysis. The dose of radiation received by V recur (volume of recurrence) was calculated and analyzed with dose-volume histogram (DVH). Failures were classified as: 'in field' if 95% of V recur was within the 95% isodose, 'marginal' if 20% to 95% of V recur was within the 95% isodose, or 'outside' if less than 20% of V recur was inside the 95% isodose. With a median follow up of 26 months, 25 local-regional failures were found in 18 patients. The 1- and 2-year actuarial local-regional control rates for all patients were 99.7% and 95.5% respectively. Among the 22 local–regional failures with available diagnostic images, 16 (64%) occurred within the 95% isodose lines and were considered in-field failures; 3 (12%) were marginal and 3 (12%) were outside-field failures. Intensity-modulated radiotherapy provides excellent local-regional control for NPC. In-field failures are the main patterns for local-regional recurrence. Reducing the coverage of critical adjacent tissues in CTV purposefully for potential subclinical diseases was worth of study. Great attention in all IMRT steps is necessary to reduce potential causes of marginal failures. More studies about radioresistance are needed to reduce in-field failures

  15. Distribution of some biochemical compounds in sediments of the shelf and slope regions of the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.; Dhargalkar, V.K.; Braganca, A.

    Surficial sediment samples collected from the continental shelf and slope of the Bay of Bengal were studied for the distribution of organic carbon and its constituent fractions such as carbohydrates, proteins, amino acids and lipids. Organic carbon...

  16. Effect of rainfall intensity and slope steepness on the development of soil erosion in the Southern Cis-Ural region (A model experiment) (United States)

    Sobol, N. V.; Gabbasova, I. M.; Komissarov, M. A.


    The effect of rainfall intensity on the erosion of residual calcareous agrogray soils and clay-illuvial agrochernozems in the Southern Cis-Ural region on slopes of different inclination and vegetation type has been studied by simulating with a small-size sprinkler. It has been shown that soil loss linearly depends on rainfall intensity (2, 4, and 6 mm/min) and slope inclination (3° and 7°). When the rainfall intensity and duration, and the slope inclination increase, soil loss by erosion from agrogray soils increases higher than from agrochernozems. On the plowland with a slope of 3°, runoff begins 12, 10, and 5 min, on the average, after the beginning of rains at these intensities. When the slope increases to 7°, runoff begins earlier by 7, 6, and 4 min, respectively. After the beginning of runoff and with its increase by 1 mm, the soil loss from slopes of 3° and 7° reaches 4.2 and 25.7 t/ha on agrogray soils and 1.4 and 4.7 t/ha on agrochernozems, respectively. Fallow soils have higher erosion resistance, and the soil loss little depends on the slope gradient: it gradually increases to 0.3-1.0 t/ha per 1 mm of runoff with increasing rainfall intensity and duration. The content of physical clay in eroded material is higher than in the original soils. Fine fractions prevail in this material, which increases their humus content. The increase in rainfall intensity and duration to 4 and 6 mm/min results in the entrapment of coarse silt and sand by runoff.

  17. [Chemical denudation rates and carbon dioxide sink in Koxkar glacierised region at the south slope of Mt. Tianshan, China]. (United States)

    Wang, Jian; Xu, Jun-li; Zhang, Shi-qiang; Liu, Shi-yin; Han, Hai-dong


    Chemical denudation rates and carbon dioxide sink were from water samples from ice-melt water, precipitation and river water were collected daily from June 21st to September 10th in 2004 in the Koxkar glacier region, south slope of Mt. Tianshan, China. The law of conservation of mass was applied for calculating chemical denudation fluxes and transient carbon dioxide sink. It is found that: 1) There were average of 60.7 kg x (km2 x d)(-1) and 60.2 kg x (km2 x d)(-1) solutes supplied by precipitation and ice melt-water respectively which accounted for about 7.7% and 7.6% of the total solutes of bulk river water [791.2 kg x (km2 x d)(-1)]. Consequently, the rate of chemical denudation derived from the crustal flux was 558.0 kg x (km2 x d)(-1), accounting for 70.5%. 2) Carbonation weathering was 308.9 kg x (km2 x d)(-1), and heavier than that of the other chemical denudations. The crustal concentration of bicarbonates (HCO3-) is attributed chiefly to the carbonation of carbonates (limestone and dolomite) and aluminosilicates/silicates. A further important source of bicarbonates and sulphates is pyrite oxidation coupled with limestone/dolomite dissolution. The transient carbon dioxide sink can be estimated by ion balance law, which is 81.0 kg x (km2 x d)(-1), accounting for 14.2%. 3) The chemical denudation rates was 641.1 kg x (km2 x d)(-1) with relationship of specific conductivity to concentrations of dissolved carbonate in water, which is only 4.4% less than that obtained from mass balance method without regard to carbon dioxide sink. The study also implied important to evaluate chemical denudation fluxes of poor data in western mountain area, China. However, because of without chemical analysis and ion partitioning, the transient CO2 drawdown cannot be established.

  18. A preliminary pit slope stability study Kvanefjeld, South Greenland

    International Nuclear Information System (INIS)

    Kalvig, P.


    On the basis of 1300 field measurements of joint planes, four individual structural regions have been outlined in the Kvanefjeld area. Potential failure planes and planes which are unlikely to be involved in slope failures are identified. Failures seem, not likely to occur on walls dipping SW or NE respectively, but may occur on walls dipping NM. The factors of safety for each region are calculated in order to determine the sensibility of the overall slope to different overall slope angles. The factors of safety does only exceed the required factor of safety of 1.5 in one of the structural regions. Changing the overall pit slope inclination from 55deg to 45deg improves the security, but even still not satisfactorily for two of the regions. At 45deg overall pit slope in parts of the pit implies additional 14.3 x 10 6 tonnes of non-mineralized material to be mined, thus resulting in a total mineralized- to non-mineralized material ratio about 1.0: 1.7. (author)

  19. assessment of slope stability around gilgel gibe-ii hydroelectric

    African Journals Online (AJOL)

    preferred customer

    1 Gilgel-Gibe II Hydroelectric Project, Fofa Town, Ethiopia ... Key words/phrases: Factor of safety, plane failure, slope design, slope .... condition of potential unstable slopes along the road between Fofa town and Gilgel-Gibe Hydro- power II.

  20. Accuracy Assessment of Lidar-Derived Digital Terrain Model (dtm) with Different Slope and Canopy Cover in Tropical Forest Region (United States)

    Salleh, M. R. M.; Ismail, Z.; Rahman, M. Z. A.


    Airborne Light Detection and Ranging (LiDAR) technology has been widely used recent years especially in generating high accuracy of Digital Terrain Model (DTM). High density and good quality of airborne LiDAR data promises a high quality of DTM. This study focussing on the analysing the error associated with the density of vegetation cover (canopy cover) and terrain slope in a LiDAR derived-DTM value in a tropical forest environment in Bentong, State of Pahang, Malaysia. Airborne LiDAR data were collected can be consider as low density captured by Reigl system mounted on an aircraft. The ground filtering procedure use adaptive triangulation irregular network (ATIN) algorithm technique in producing ground points. Next, the ground control points (GCPs) used in generating the reference DTM and these DTM was used for slope classification and the point clouds belong to non-ground are then used in determining the relative percentage of canopy cover. The results show that terrain slope has high correlation for both study area (0.993 and 0.870) with the RMSE of the LiDAR-derived DTM. This is similar to canopy cover where high value of correlation (0.989 and 0.924) obtained. This indicates that the accuracy of airborne LiDAR-derived DTM is significantly affected by terrain slope and canopy caver of study area.


    Directory of Open Access Journals (Sweden)

    M. R. M. Salleh


    Full Text Available Airborne Light Detection and Ranging (LiDAR technology has been widely used recent years especially in generating high accuracy of Digital Terrain Model (DTM. High density and good quality of airborne LiDAR data promises a high quality of DTM. This study focussing on the analysing the error associated with the density of vegetation cover (canopy cover and terrain slope in a LiDAR derived-DTM value in a tropical forest environment in Bentong, State of Pahang, Malaysia. Airborne LiDAR data were collected can be consider as low density captured by Reigl system mounted on an aircraft. The ground filtering procedure use adaptive triangulation irregular network (ATIN algorithm technique in producing ground points. Next, the ground control points (GCPs used in generating the reference DTM and these DTM was used for slope classification and the point clouds belong to non-ground are then used in determining the relative percentage of canopy cover. The results show that terrain slope has high correlation for both study area (0.993 and 0.870 with the RMSE of the LiDAR-derived DTM. This is similar to canopy cover where high value of correlation (0.989 and 0.924 obtained. This indicates that the accuracy of airborne LiDAR-derived DTM is significantly affected by terrain slope and canopy caver of study area.

  2. Clinical investigation: Regional nodal failure patterns in breast cancer patients treated with mastectomy without radiotherapy

    International Nuclear Information System (INIS)

    Strom, Eric A.; Woodward, Wendy A.; Katz, Angela; Buchholz, Thomas A.; Perkins, George H.; Jhingran, Anuja; Theriault, Richard; Singletary, Eva; Sahin, Aysegul; McNeese, Marsha D.


    Purpose: The purpose of this study was to describe regional nodal failure patterns in patients who had undergone mastectomy with axillary dissection to define subgroups of patients who might benefit from supplemental regional nodal radiation to the axilla or supraclavicular fossa/axillary apex. Methods and Materials: The cohort consisted of 1031 patients treated with mastectomy (including a level I-II axillary dissection) and doxorubicin-based systemic therapy without radiation on five clinical trials at M.D. Anderson Cancer Center. Patient records, including pathology reports, were retrospectively reviewed. All regional recurrences (with or without distant metastasis) were recorded. Median follow-up was 116 months (range, 6-262 months). Results: Twenty-one patients recurred within the low-mid axilla (10-year actuarial rate 3%). Of these, 16 were isolated regional failures (no chest wall failure). The risk of failure in the low-mid axilla was not significantly higher for patients with increasing numbers of involved nodes, increasing percentage of involved nodes, larger nodal size or gross extranodal extension. Only 3 of 100 patients with 20% involved axillary nodes, and the presence of gross extranodal extension (10-year actuarial rates 15%, 14%, and 19%, respectively, p 20% involved axillary nodes, or gross extranodal extension are at increased risk of failure in the supraclavicular fossa/axillary apex and should receive radiation to undissected regions in addition to the chest wall

  3. Determination of the failure probability in the weld region of ap-600 vessel for transient condition

    International Nuclear Information System (INIS)

    Wahyono, I.P.


    Failure probability in the weld region of AP-600 vessel was determined for transient condition scenario. The type of transient is increase of the heat removal from primary cooling system due to sudden opening of safety valves or steam relief valves on the secondary cooling system or the steam generator. Temperature and pressure in the vessel was considered as the base of deterministic calculation of the stress intensity factor. Calculation of film coefficient of the convective heat transfers is a function of the transient time and water parameter. Pressure, material temperature, flaw depth and transient time are variables for the stress intensity factor. Failure probability consideration was done by using the above information in regard with the flaw and probability distributions of Octavia II and Marshall. Calculation of the failure probability by probability fracture mechanic simulation is applied on the weld region. Failure of the vessel is assumed as a failure of the weld material with one crack which stress intensity factor applied is higher than the critical stress intensity factor. VISA II code (Vessel Integrity Simulation Analysis II) was used for deterministic calculation and simulation. Failure probability of the material is 1.E-5 for Octavia II distribution and 4E-6 for marshall distribution for each transient event postulated. The failure occurred at the 1.7th menit of the initial transient under 12.53 ksi of the pressure

  4. Image and Substance Failures in Regional Organisations: Causes, Consequences, Learning and Change?

    Directory of Open Access Journals (Sweden)

    Meng Hsuan Chou


    Full Text Available States often pool their sovereignty, capacity and resources to provide regionally specific public goods, such as security or trade rules, and regional organisations play important roles in international relations as institutions that attempt to secure peace and contribute to achieving other similar global policy goals. We observe failures occurring in these arrangements and activities in two areas: substance and image. To analytically account for this, we distinguish four modes of substance and image change and link these to specific types of failure and (lack of learning. To empirically ground and test our assumptions, we examine instances of image failure in ASEAN (political/security policy and substantive policy failure in EU labour migration policy. In so doing, this article contributes to several different fields of study and concepts that have hitherto rarely engaged with one another: analyses of policy failure from public policy, and regional integration concerns from area studies and international relations. We conclude with suggestions for ways forward to further analyse and understand failures at the international and supranational levels.

  5. Green technologies for reducing slope erosion. (United States)


    As climate change alters precipitation patterns, departments of transportation will increasingly face the problem of : slope failures, which already cost California millions of dollars in repair work annually. Caltrans hopes to prevent : these failur...

  6. The influence of local oil exploration and regional wildfires on summer 2015 aerosol over the North Slope of Alaska

    Directory of Open Access Journals (Sweden)

    J. M. Creamean


    Full Text Available The Arctic is warming at an alarming rate, yet the processes that contribute to the enhanced warming are not well understood. Arctic aerosols have been targeted in studies for decades due to their consequential impacts on the energy budget, both directly and indirectly through their ability to modulate cloud microphysics. Even with the breadth of knowledge afforded from these previous studies, aerosols and their effects remain poorly quantified, especially in the rapidly changing Arctic. Additionally, many previous studies involved use of ground-based measurements, and due to the frequent stratified nature of the Arctic atmosphere, brings into question the representativeness of these datasets aloft. Here, we report on airborne observations from the US Department of Energy Atmospheric Radiation Measurement (ARM program's Fifth Airborne Carbon Measurements (ACME-V field campaign along the North Slope of Alaska during the summer of 2015. Contrary to previous evidence that the Alaskan Arctic summertime air is relatively pristine, we show how local oil extraction activities, 2015's central Alaskan wildfires, and, to a lesser extent, long-range transport introduce aerosols and trace gases higher in concentration than previously reported in Arctic haze measurements to the North Slope. Although these sources were either episodic or localized, they serve as abundant aerosol sources that have the potential to impact a larger spatial scale after emission.

  7. Pattern of loco-regional failure after definitive radiotherapy for non-small cell lung cancer

    DEFF Research Database (Denmark)

    Schytte, Tine; Nielsen, Tine Bjørn; Brink, Carsten


    , and occurrence of distant metastasis. It is challenging to evaluate loco-regional control after definitive radiotherapy for NSCLC since it is difficult to distinguish between radiation-induced damage to the lung tissue and tumour progression/recurrence. In addition it may be useful to distinguish between...... intrapulmonary failure and mediastinal failure to be able to optimize radiotherapy in order to improve loco-regional control even though it is not easy to discriminate between the two sites of failure. Material and methods. This study is a retrospective analysis of 331 NSCLC patients treated with definitive...... with mediastinal relapse. Conclusion. We conclude that focus should be on increasing doses to intrapulmonary tumour volume, when dose escalation is applied to improve local tumour control in NSCLC patients treated with definitive radiotherapy, since most recurrences are located here....

  8. Seabed morphology and gas venting features in the continental slope region of KrishnaeGodavari basin, Bay of Bengal: Implications in gas–hydrate exploration

    Digital Repository Service at National Institute of Oceanography (India)

    Dewangan, P.; Ramprasad, T.; Ramana, M.V.; Mazumdar, A.; Desa, M.; Badesab, F.K.

    by the tectonic settings of the region. For example, structures formed due to salt or shale tectonics govern the occurrence of gas hydrate in northwestern Gulf of Mexico slope and Niger Delta front (Hovland et al., 1997; Milkov and Sassen, 2001). The seismic.... confirms that paleo-cold seeps in KG offshore basin (Mazumdar et al., 2009). Similar cold seep locations and high methane flux are reported from Gulf of Mexico where the salt diapir creates numerous faults which act as pathways for the fluid...

  9. Scalable Failure Masking for Stencil Computations using Ghost Region Expansion and Cell to Rank Remapping

    International Nuclear Information System (INIS)

    Gamell, Marc; Kolla, Hemanth; Mayo, Jackson; Heroux, Michael A.


    In order to achieve exascale systems, application resilience needs to be addressed. Some programming models, such as task-DAG (directed acyclic graphs) architectures, currently embed resilience features whereas traditional SPMD (single program, multiple data) and message-passing models do not. Since a large part of the community's code base follows the latter models, it is still required to take advantage of application characteristics to minimize the overheads of fault tolerance. To that end, this paper explores how recovering from hard process/node failures in a local manner is a natural approach for certain applications to obtain resilience at lower costs in faulty environments. In particular, this paper targets enabling online, semitransparent local recovery for stencil computations on current leadership-class systems as well as presents programming support and scalable runtime mechanisms. Also described and demonstrated in this paper is the effect of failure masking, which allows the effective reduction of impact on total time to solution due to multiple failures. Furthermore, we discuss, implement, and evaluate ghost region expansion and cell-to-rank remapping to increase the probability of failure masking. To conclude, this paper shows the integration of all aforementioned mechanisms with the S3D combustion simulation through an experimental demonstration (using the Titan system) of the ability to tolerate high failure rates (i.e., node failures every five seconds) with low overhead while sustaining performance at large scales. In addition, this demonstration also displays the failure masking probability increase resulting from the combination of both ghost region expansion and cell-to-rank remapping.

  10. Slope and Land Use Changing Effects on Soil Properties and Magnetic Susceptibility in Hilly Lands, Yasouj Region

    Directory of Open Access Journals (Sweden)

    rouhollaah vafaeezadeh


    Full Text Available Introduction: Land use changes are the most reasons which affect natural ecosystem protection. Forest soils have high organic matter and suitable structure, but their land use management change usually affects soil properties and decreases soil quality. There are several outcomes of such land use changes and intensification: accelerated soil erosion and decline of soil nutrient conditions, change of hydrological regimes and sedimentation and loss of primary forests and their biodiversity. Establishing effects of land use and land cover changes on soil properties have implications for devising management strategies for sustainable use. Forest land use change in Yasouj caused soil losses and decreased soil quality. The objectives of this study were to assess some soil physical and chemical properties and soil magnetic susceptibility changes in different land uses and slope position. Materials and Methods: Soil samples were taken from natural forest, degraded forest and dryland farm from different slops (0-10, 10-20 and 20-30 percent in sout east of Yasouj. They were from 0–10 cm depth in a completely randomized design with five replications. Soil moisture and temperature regimes in the study area are xeric and mesic, respectively. Particle size distribution was determined by the hydrometer method and soil organic matter, CaCO3 equivalent and bulk density was determined using standard procedures described in Methods of Soil Analysis book. Magnetic susceptibility was measured at low and high frequency of 0.46 kHz (χlf and 4.6 kHz (χHf respectively with a Bartington MS2D meter using approximately 20 g of soil held in a four-dram clear plastic vial. Frequency dependent susceptibility (χfd is expressed as the difference between the high and the low frequency measurements as a percentage of χ at low frequency. Results and Discussion: Soil texture was affected by land use change from silty clay loam in forest to silty loam in dry land farm

  11. Regional and ethnic differences among patients with heart failure in Asia: the Asian sudden cardiac death in heart failure registry. (United States)

    Lam, Carolyn S P; Teng, Tiew-Hwa Katherine; Tay, Wan Ting; Anand, Inder; Zhang, Shu; Shimizu, Wataru; Narasimhan, Calambur; Park, Sang Weon; Yu, Cheuk-Man; Ngarmukos, Tachapong; Omar, Razali; Reyes, Eugene B; Siswanto, Bambang B; Hung, Chung-Lieh; Ling, Lieng H; Yap, Jonathan; MacDonald, Michael; Richards, A Mark


    To characterize regional and ethnic differences in heart failure (HF) across Asia. We prospectively studied 5276 patients with stable HF and reduced ejection fraction (≤40%) from 11 Asian regions (China, Hong Kong, India, Indonesia, Japan, Korea, Malaysia, Philippines, Singapore, Taiwan, and Thailand). Mean age was 59.6 ± 13.1 years, 78.2% were men, and mean body mass index was 24.9 ± 5.1 kg/m 2 . Majority (64%) of patients had two or more comorbid conditions such as hypertension (51.9%), coronary artery disease (CAD, 50.2%), or diabetes (40.4%). The prevalence of CAD was highest in Southeast Asians (58.8 vs. 38.2% in Northeast Asians). Compared with Chinese ethnicity, Malays (adjusted odds ratio [OR] 1.97, 95% CI 1.63-2.38) and Indians (OR 1.44, 95% CI 1.24-1.68) had higher odds of CAD, whereas Koreans (OR 0.38, 95% CI 0.29-0.50) and Japanese (OR 0.44, 95% CI 0.36-0.55) had lower odds. The prevalence of hypertension and diabetes was highest in Southeast Asians (64.2 and 49.3%, respectively) and high-income regions (59.7 and 46.2%, respectively). There was significant interaction between ethnicity and region, where the adjusted odds were 3.95 (95% CI 2.51-6.21) for hypertension and 4.91 (95% CI 3.07-7.87) for diabetes among Indians from high- vs. low-income regions; and 2.60 (95% CI 1.66-4.06) for hypertension and 2.62 (95% CI 1.73-3.97) for diabetes among Malays from high- vs. low-income regions. These first prospective multi-national data from Asia highlight the significant heterogeneity among Asian patients with stable HF, and the important influence of both ethnicity and regional income level on patient characteristics. NCT01633398. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email:

  12. Displacement of Pile-Reinforced Slopes with a Weak Layer Subjected to Seismic Loads

    Directory of Open Access Journals (Sweden)

    Haizuo Zhou


    Full Text Available The presence of a weak layer in a slope requires special attention because it has a negative impact on slope stability. However, limited insight into the seismic stability of slopes with a weak layer exists. In this study, the seismic stability of a pile-reinforced slope with a weak thin layer is investigated. Based on the limit analysis theory, a translational failure mechanism for an earth slope is developed. The rotational rigid blocks in the previous rotational-translational failure mechanism are replaced by continuous deformation regions, which consist of a sequence of n rigid triangles. The predicted static factor of safety and collapse mechanism in two typical examples of slopes with a weak layer compare well with the results obtained from the available literature and by using the Discontinuity Layout Optimization (DLO technique. The lateral forces provided by the stabilizing piles are evaluated using the theory of plastic deformation. An analytical solution for estimating the critical yield acceleration coefficient for the pile-reinforced slopes is derived. Based on the proposed translational failure mechanism and the corresponding critical yield acceleration coefficient, Newmark’s analytical procedure is employed to evaluate the cumulative displacement. Considering different real earthquake acceleration records as input motion, the effect of stabilizing piles and varying the spacing of piles on the cumulative displacement of slopes with a weak layer is investigated.

  13. Variation in carbon stocks on different slope aspects in seven major forest types of temperate region of Garhwal Himalaya, India. (United States)

    Sharma, C M; Gairola, Sumeet; Baduni, N P; Ghildiyal, S K; Suyal, Sarvesh


    The present study was undertaken in seven major forest types of temperate zone (1500 m a.s.l. to 3100 m a.s.l.) of Garhwal Himalaya to understand the effect of slope aspects on carbon (C) density and make recommendations for forest management based on priorities for C conservation/sequestration. We assessed soil organic carbon (SOC) density, tree density, biomass and soil organic carbon (SOC) on four aspects, viz. north/east (NE), north/west (NW), south-east (SE) and south-west (SW), in forest stands dominated by Abies pindrow, Cedrus deodara, Pinus roxburghii, Cupressus torulosa, Quercus floribunda, Quercus semecarpifolia and Quercus leucotrichophora. TCD ranged between 77.3 CMg ha⁻¹ on SE aspect (Quercus leucotrichophora forest) and 291.6 CMg ha⁻¹ on NE aspect (moist Cedrus deodara forest). SOC varied between 40.3 CMg ha⁻¹ on SW aspect (Himalayan Pinus roxburghii forest) and 177.5 CMg ha⁻¹ on NE aspect (moist Cedrus deodara forest). Total C density (SOC+TCD) ranged between 118.1 CMg ha⁻¹ on SW aspect (Himalayan Pinus roxburghii forest) and 469.1 CMg ha⁻¹ on NE aspect (moist Cedrus deodara forest). SOC and TCD were significantly higher on northern aspects as compared with southern aspects. It is recommended that for C sequestration, the plantation silviculture be exercised on northern aspects, and for C conservation purposes, mature forest stands growing on northern aspects be given priority.

  14. Eco-environment Restoration and Regional Differentiation Characteristics Based on “Building Terrace and Returning Slope Farmland to Forests and Grass”

    Institute of Scientific and Technical Information of China (English)

    Yanhua; LIU; Yong; XU


    Based on the scientific and technological achievements in the past decade in the Loess Hilly-gully Region and the successful demonstration experience in Yan’an Yangou watershed, we summarize the characteristics of eco-environment restoration pattern based on "building terrace and returning slope farmland to forests and grass". According to the data on land use, slope farmland and the agricultural population in 1999, we calculate the area of new terrace that needs to be built, the area of garden plot that needs to be extended, vegetation restoration area and investment demand in counties (cities, districts). Establishing and using some indicators, such as basic farmland extension indicator, garden plot extension indicator, vegetation restoration index and investment demand density, we conduct type classification and analysis of regional differentiation characteristics in 55 counties (cities, districts). The results show that in the Loess Hilly-gully Region, 691 600 hm2 of new terrace needs to be built, 792 000 hm2 of economic forests and orchards need to be extended, 5 410 200 hm2 of vegetation needs to be restored, and the total investment demand is 15.82 billion yuan; in terms of geographical distribution, obviously there are two key areas for eco-environment restoration (one is located in the border area between northern Shaanxi and northwestern Shanxi, and the other is located in the eastern Gansu and southern Ningxia area); the classified regional guidance policies should be formulated as soon as possible, and the limited funds should be concentrated in the key areas.

  15. Triangular facets of slope in the region of Tudela (Ebro Basin, Navarra, Spain); Facetas triangulares de ladera en la region de Tudela (Depresion del Ebro, Navarra, Espana)

    Energy Technology Data Exchange (ETDEWEB)

    Marin, C.; Desir, G.; Gutierrez, M.


    Some triangular slope facets are localized to the south of Bardenas Reales (central-west of Ebro Basin), elaborated on Tudela Formation deposits, Aragonian in age. Three of them have been dated by OSL resulting on ages of 35,588{+-}2,488 yr. BP, 35,355{+-}2,446 yr. BP and 40.185{+-}2,411 yr. BP. The origin of these facets is ought to an alternation between accumulation and incision phases produced by vegetation cover variation percentage. Those vegetation cover changes are estimated to be due to climatic changes. (Author) 21 refs.

  16. TRIGRS - A Fortran Program for Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability Analysis, Version 2.0 (United States)

    Baum, Rex L.; Savage, William Z.; Godt, Jonathan W.


    The Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability Model (TRIGRS) is a Fortran program designed for modeling the timing and distribution of shallow, rainfall-induced landslides. The program computes transient pore-pressure changes, and attendant changes in the factor of safety, due to rainfall infiltration. The program models rainfall infiltration, resulting from storms that have durations ranging from hours to a few days, using analytical solutions for partial differential equations that represent one-dimensional, vertical flow in isotropic, homogeneous materials for either saturated or unsaturated conditions. Use of step-function series allows the program to represent variable rainfall input, and a simple runoff routing model allows the user to divert excess water from impervious areas onto more permeable downslope areas. The TRIGRS program uses a simple infinite-slope model to compute factor of safety on a cell-by-cell basis. An approximate formula for effective stress in unsaturated materials aids computation of the factor of safety in unsaturated soils. Horizontal heterogeneity is accounted for by allowing material properties, rainfall, and other input values to vary from cell to cell. This command-line program is used in conjunction with geographic information system (GIS) software to prepare input grids and visualize model results.

  17. Sensitivity of the probability of failure to probability of detection curve regions

    International Nuclear Information System (INIS)

    Garza, J.; Millwater, H.


    Non-destructive inspection (NDI) techniques have been shown to play a vital role in fracture control plans, structural health monitoring, and ensuring availability and reliability of piping, pressure vessels, mechanical and aerospace equipment. Probabilistic fatigue simulations are often used in order to determine the efficacy of an inspection procedure with the NDI method modeled as a probability of detection (POD) curve. These simulations can be used to determine the most advantageous NDI method for a given application. As an aid to this process, a first order sensitivity method of the probability-of-failure (POF) with respect to regions of the POD curve (lower tail, middle region, right tail) is developed and presented here. The sensitivity method computes the partial derivative of the POF with respect to a change in each region of a POD or multiple POD curves. The sensitivities are computed at no cost by reusing the samples from an existing Monte Carlo (MC) analysis. A numerical example is presented considering single and multiple inspections. - Highlights: • Sensitivities of probability-of-failure to a region of probability-of-detection curve. • The sensitivities are computed with negligible cost. • Sensitivities identify the important region of a POD curve. • Sensitivities can be used as a guide to selecting the optimal POD curve.

  18. Patterns of Failure for Rhabdomyosarcoma of the Perineal and Perianal Region

    International Nuclear Information System (INIS)

    Casey, Dana L.; Wexler, Leonard H.; LaQuaglia, Michael P.; Meyers, Paul A.; Wolden, Suzanne L.


    Purpose: To analyze prognostic factors and patterns of failure for rhabdomyosarcoma of the perineal and perianal region (PRMS), with an emphasis on radiation therapy for locoregional control. Methods and Materials: Detailed records of all 14 patients treated for PRMS at Memorial Sloan-Kettering Cancer Center between 1998 and 2012 were reviewed. The Kaplan-Meier method was used to assess the event-free survival (EFS) and overall survival (OS), and a competing-risks analysis was used to assess the cumulative incidence of local, regional, and distant failures. Results: Median age was 15.8 years (range, 1.1-31.9 years). High-risk features were identified: 9 of 14 patients (64%) had group 3 disease and 3 of 14 (21%) had group 4; 11 of 14 tumors (78%) were alveolar; 12 of 14 tumors (86%) were ≥5 cm; and 9 of 14 patients (64%) had involved lymph nodes (N1). Of those aged ≥10 years at diagnosis, 9 of 10 (90%) had alveolar histology, all had tumors ≥5 cm, and 8 of 10 (80%) presented with N1 disease. The rates of local, regional, and distant failure at 5 years were 17%, 31%, and 52%, respectively. Although 3 of the 4 patients with regional failure received nodal irradiation, only one of the nodal failures occurred in the radiation therapy field. The 5-year EFS was 33%, and OS was 39%. Age ≥10 years was associated with poor outcomes: EFS was 13% in patients aged ≥10 years, compared with 75% in those aged <10 years (P=.04); the OS was 13% in patients aged ≥10 years, compared with 100% in those aged <10 years (P=.04). Conclusions: Patients with PRMS, especially those aged ≥10 years, present with poor prognostic features and continue to have poor outcomes. Given the high incidence of regional node recurrence, we recommend prophylactic ilioinguinal lymph node irradiation for all patients aged ≥10 years. For children aged <10 years, nodal evaluation is essential to determine the role for lymph node irradiation

  19. Evaluation of TRIGRS (transient rainfall infiltration and grid-based regional slope-stability analysis)'s predictive skill for hurricane-triggered landslides: A case study in Macon County, North Carolina (United States)

    Liao, Z.; Hong, Y.; Kirschbaum, D.; Adler, R.F.; Gourley, J.J.; Wooten, R.


    The key to advancing the predictability of rainfall-triggered landslides is to use physically based slope-stability models that simulate the transient dynamical response of the subsurface moisture to spatiotemporal variability of rainfall in complex terrains. TRIGRS (transient rainfall infiltration and grid-based regional slope-stability analysis) is a USGS landslide prediction model, coded in Fortran, that accounts for the influences of hydrology, topography, and soil physics on slope stability. In this study, we quantitatively evaluate the spatiotemporal predictability of a Matlab version of TRIGRS (MaTRIGRS) in the Blue Ridge Mountains of Macon County, North Carolina where Hurricanes Ivan triggered widespread landslides in the 2004 hurricane season. High resolution digital elevation model (DEM) data (6-m LiDAR), USGS STATSGO soil database, and NOAA/NWS combined radar and gauge precipitation are used as inputs to the model. A local landslide inventory database from North Carolina Geological Survey is used to evaluate the MaTRIGRS' predictive skill for the landslide locations and timing, identifying predictions within a 120-m radius of observed landslides over the 30-h period of Hurricane Ivan's passage in September 2004. Results show that within a radius of 24 m from the landslide location about 67% of the landslide, observations could be successfully predicted but with a high false alarm ratio (90%). If the radius of observation is extended to 120 m, 98% of the landslides are detected with an 18% false alarm ratio. This study shows that MaTRIGRS demonstrates acceptable spatiotemporal predictive skill for landslide occurrences within a 120-m radius in space and a hurricane-event-duration (h) in time, offering the potential to serve as a landslide warning system in areas where accurate rainfall forecasts and detailed field data are available. The validation can be further improved with additional landslide information including the exact time of failure for each

  20. Predictors and Patterns of Local, Regional, and Distant Failure in Squamous Cell Carcinoma of the Vulva. (United States)

    Bogani, Giorgio; Cromi, Antonella; Serati, Maurizio; Uccella, Stefano; Donato, Violante Di; Casarin, Jvan; Naro, Edoardo Di; Ghezzi, Fabio


    To identify factors predicting for recurrence in vulvar cancer patients undergoing surgical treatment. We retrospectively evaluated data of consecutive patients with squamous cell vulvar cancer treated between January 1, 1990 and December 31, 2013. Basic descriptive statistics and multivariable analysis were used to design predicting models influencing outcomes. Five-year disease-free survival (DFS) and overall survival (OS) were analyzed using the Cox model. The study included 101 patients affected by vulvar cancer: 64 (63%) stage I, 12 (12%) stage II, 20 (20%) stage III, and 5 (5%) stage IV. After a mean (SD) follow-up of 37.6 (22.1) months, 21 (21%) recurrences occurred. Local, regional, and distant failures were recorded in 14 (14%), 6 (6%), and 3 (3%) patients, respectively. Five-year DFS and OS were 77% and 82%, respectively. At multivariate analysis only stromal invasion >2 mm (hazard ratio: 4.9 [95% confidence interval, 1.17-21.1]; P=0.04) and extracapsular lymph node involvement (hazard ratio: 9.0 (95% confidence interval, 1.17-69.5); P=0.03) correlated with worse DFS, although no factor independently correlated with OS. Looking at factors influencing local and regional failure, we observed that stromal invasion >2 mm was the only factor predicting for local recurrence, whereas lymph node extracapsular involvement predicted for regional recurrence. Stromal invasion >2 mm and lymph node extracapsular spread are the most important factors predicting for local and regional failure, respectively. Studies evaluating the effectiveness of adjuvant treatment in high-risk patients are warranted.

  1. Arctic Submarine Slope Stability (United States)

    Winkelmann, D.; Geissler, W.


    the consequence. Its geometrical configuration and timing is different from submarine slides on other glaciated continental margins. Thus, it raises the question whether slope stability within the Arctic Ocean is governed by processes specific to this environment. The extraordinary thick slabs (up to 1600 m) that were moved translationally during sliding rise the question on the nature of the weak layers associated with this process. Especially theories involving higher pore pressure are being challenged by this observation, because either extreme pore pressures or alternative explanations (e.g. mineralogical and/or textural) can be considered. To assess the actual submarine slope stability and failure potential in the Arctic Ocean, we propose to drill and recover weak layer material of the HYM from the adjacent intact strata by deep drilling under the framework of Integrated Ocean Drilling Program. This is the only method to recover weak layer material from the HYM, because the strata are too thick. We further propose to drill into the adjacent deforming slope to identify material properties of the layers acting as detachment and monitor the deformation.

  2. Natural dam failure in the eastern slope of the Central Andes of Argentina. Numerical modelling of the 2005 Santa Cruz river outburst flood (United States)

    Penna, I.; Daicz, S.; Zlotnik, S.; Derron, M.-H.; Jaboyedoff, M.


    In the Central Andes of Argentina, ephemeral river blockage due to landslides deposition are common phenomena. During the first fortnight of January 2005, 11.5 * 106m3 of rock collapsed from the east slope of the Santa Cruz valley (San Juan province, Argentina). The rock mass displaced from 4300 m a.s.l., down to the valley bottom, at 2900 m a.s.l., and ran up the opposite flank of the valley. This produced the blockage of the Santa Cruz river and generated the Los Erizos lake. The rapid snow melting during the spring season caused the increase of the water level of the reservoir, leading to a process of overtopping on November 12th of 2005. 30 * 106m3 of water were released from the reservoir and the consequent outburst flood displaced along 250 km. From local reports of arrival times, we estimated that the outburst flood reduced its velocity from around 40 km/h near the source area to 6 km/h in its distal section. A road, bridges, and a mining post where destroyed. 75 tourists had to be rescued from the mountains using helicopters, and people from two localities had to be evacuated. Near its distal part, the flood damaged the facilities of the Caracoles power dam, which was under construction, and its inauguration had to be delayed one year due to the damage. The outburst flood produced changes in the morphology of the valley floor along almost all its path (erosion of alluvial fans, talus and terraces, and deposition of boulders). The most significant changes occurred in the first 70 km, especially upstream narrow sections, showing the importance of the backwater effects due to hydraulic ponding. In this work we carried out numerical simulations to obtain the velocity patterns of the flood, and compared them with those obtained from local reports. Furthermore, we analyze the relationship between the dynamics of the flood with the patterns of erosion and deposition near the source area.

  3. Advance in prediction of soil slope instabilities (United States)

    Sigarán-Loría, C.; Hack, R.; Nieuwenhuis, J. D.


    Six generic soils (clays and sands) were systematically modeled with plane-strain finite elements (FE) at varying heights and inclinations. A dataset was generated in order to develop predictive relations of soil slope instabilities, in terms of co-seismic displacements (u), under strong motions with a linear multiple regression. For simplicity, the seismic loads are monochromatic artificial sinusoidal functions at four frequencies: 1, 2, 4, and 6 Hz, and the slope failure criterion used corresponds to near 10% Cartesian shear strains along a continuous region comparable to a slip surface. The generated dataset comprises variables from the slope geometry and site conditions: height, H, inclination, i, shear wave velocity from the upper 30 m, vs30, site period, Ts; as well as the input strong motion: yield acceleration, ay (equal to peak ground acceleration, PGA in this research), frequency, f; and in some cases moment magnitude, M, and Arias intensity, Ia, assumed from empirical correlations. Different datasets or scenarios were created: "Magnitude-independent", "Magnitude-dependent", and "Soil-dependent", and the data was statistically explored and analyzed with varying mathematical forms. Qualitative relations show that the permanent deformations are highly related to the soil class for the clay slopes, but not for the sand slopes. Furthermore, the slope height does not constrain the variability in the co-seismic displacements. The input frequency decreases the variability of the co-seismic displacements for the "Magnitude-dependent" and "Soil-dependent" datasets. The empirical models were developed with two and three predictors. For the sands it was not possible because they could not satisfy the constrains from the statistical method. For the clays, the best models with the smallest errors coincided with the simple general form of multiple regression with three predictors (e.g. near 0.16 and 0.21 standard error, S.E. and 0.75 and 0.55 R2 for the "M

  4. Effects of Long-term Conservation Tillage on Soil Nutrients in Sloping Fields in Regions Characterized by Water and Wind Erosion (United States)

    Tan, Chunjian; Cao, Xue; Yuan, Shuai; Wang, Weiyu; Feng, Yongzhong; Qiao, Bo


    Conservation tillage is commonly used in regions affected by water and wind erosion. To understand the effects of conservation tillage on soil nutrients and yield, a long-term experiment was set up in a region affected by water and wind erosion on the Loess Plateau. The treatments used were traditional tillage (CK), no tillage (NT), straw mulching (SM), plastic-film mulching (PM), ridging and plastic-film mulching (RPM) and intercropping (In). Our results demonstrate that the available nutrients in soils subjected to non-traditional tillage treatments decreased during the first several years and then remained stable over the last several years of the experiment. The soil organic matter and total nitrogen content increased gradually over 6 years in all treatments except CK. The nutrient content of soils subjected to conservative tillage methods, such as NT and SM, were significantly higher than those in soils under the CK treatment. Straw mulching and film mulching effectively reduced an observed decrease in soybean yield. Over the final 6 years of the experiment, soybean yields followed the trend RPM > PM > SM > NT > CK > In. This trend has implications for controlling soil erosion and preventing non-point source pollution in sloping fields by sacrificing some food production.

  5. Cancer of Oral Cavity Abutting the Mandible; Predictors of Loco-regional Failure

    International Nuclear Information System (INIS)

    Saber, T.K.; Hussein, H.A.; Mebeed, A.H.; El Sebai, H.I.; Sami, I.; Farahat, I.G.


    The purpose of this study is to analyze the causes of Loco-regional failure in 51 patients with tumors of the oral cavity abutting the mandible. Patients and Methods: This cross-sectional study (27 patients were operated upon in the retrospective section and 24 patients in the prospective section of the study) was done in the department of Surgical Oncology, National Cancer Institute, Cairo University, from January 2003 to January 2008. Fifty-one patients, with oral cavity cancerous lesions abutting the mandible, were operated upon by segmental mandibulectomy en-bloc with primary tumor resection in addition to modified radical or selective neck dissection according to the status of the cervical lymph nodes. Results: During a median follow-up of 2 years, 29 patients (56.8%) had local recurrences, the incidence of nodal recurrence after neck dissection was detected in 4 patients (7.8%). On multivariate analysis, tumor depth, tumor grade, oral mucosa, soft tissue and bone surgical margins in addition to metastatic lymphadenopathy were independent prognostic factors of loco-regional failure and disease-free survival. Conclusion: Oral cavity cancers abutting the mandible should be treated with great caution by a multidisciplinary oncology team (resection and reconstruction surgeons) as it has a very aggressive biologic behavior. Negative intraoperative pathological margins should be attempted since this is the critical point for patients with cancers abutting the mandible? Further research on the biologic margin and genetic study is required

  6. A more general model for the analysis of the rock slope stability

    Indian Academy of Sciences (India)

    slope stability analysis, the joint surfaces are assumed to be continuous along the potential ... of rock slope stability has many applications in the design of rock slopes, roofs and walls of .... cases the wedge failure analysis can be applied.

  7. [Using 137Cs and 210Pb(ex) to trace the impact of soil erosion on soil organic carbon at a slope farmland in the black soil region]. (United States)

    Fang, Hai-Yan; Sheng, Mei-Ling; Sun, Li-Ying; Cai, Qiang-Guo


    Soil cores were collected from a 28.5 hm2 slope farmland in the black soil region of Northeast China. Based on the sampled data of 137Cs, 210Pb(ex) and SOC, the potentials of applying 137Cs and 210Pb(ex) for assessing SOC redistribution were evaluated, aimed to approach the impact of soil erosion on soil organic carbon (SOC) in black soil region. At both planar and vertical directions, the 137Cs, 210Pb(ex) and SOC in the farmland had similar distribution patterns. Although there were large planar variations in the 137Cs and 210Pb(ex) areal activities and the SOC stock as affected by soil erosion and deposition, the 137Cs, 210Pb(ex) and SOC had similar changing trends over the landscape. Two depth distribution profiles were also used to study the relations of 137Cs and 210Pb(ex) with SOC. At eroded site, the radioactivities of 137Cs and 210Pb(ex) and the SOC mass fraction did not show large variations in 0-25 cm soil layer, but decreased sharply below 25 cm. For the deposition sample, the radioactivities of 137Cs and 210Pb(ex) in 0-100 cm soil increased firstly and then decreased. The SOC mass fraction also had similar depth distribution pattern in this soil layer. The 137Cs and 210Pb(ex) presented positive linear correlations with the SOC, indicating that 137Cs, 210Pb(ex) and SOC moved with the same physical mechanism in the farmland, and fallout 137Cs and 210Pb(ex) could be used to study spatio-temporal distribution characteristics of SOC in the black soil region under the condition of soil erosion.

  8. Slope stability probability classification, Waikato Coal Measures, New Zealand

    Energy Technology Data Exchange (ETDEWEB)

    Lindsay, P.; Gillard, G.R.; Moore, T.A. [CRL Energy, PO Box 29-415, Christchurch (New Zealand); Campbell, R.N.; Fergusson, D.A. [Solid Energy North, Private Bag 502, Huntly (New Zealand)


    Ferm classified lithological units have been identified and described in the Waikato Coal Measures in open pits in the Waikato coal region. These lithological units have been classified geotechnically by mechanical tests and discontinuity measurements. Using these measurements slope stability probability classifications (SSPC) have been quantified based on an adaptation of Hack's [Slope Stability Probability Classification, ITC Delft Publication, Enschede, Netherlands, vol. 43, 1998, 273 pp.] SSPC system, which places less influence on rock quality designation and unconfined compressive strength than previous slope/rock mass rating systems. The Hack weathering susceptibility rating has been modified by using chemical index of alteration values determined from XRF major element analyses. Slaking is an important parameter in slope stability in the Waikato Coal Measures lithologies and hence, a non-subjective method of assessing slaking in relation to the chemical index of alteration has been introduced. Another major component of this adapted SSPC system is the inclusion of rock moisture content effects on slope stability. The main modifications of Hack's SSPC system are the introduction of rock intact strength derived from the modified Mohr-Coulomb failure criterion, which has been adapted for varying moisture content, weathering state and confining pressure. It is suggested that the subjectivity in assessing intact rock strength within broad bands in the initial SSPC system is a major weakness of the initial system. Initial results indicate a close relationship between rock mass strength values, calculated from rock mass friction angles and rock mass cohesion values derived from two established rock mass classification methods (modified Hoek-Brown failure criteria and MRMR) and the adapted SSPC system. The advantage of the modified SSPC system is that slope stability probabilities based on discontinuity-independent and discontinuity-dependent data and a

  9. Compromised Global and Regional Cerebral Blood Flow in Congestive Heart Failure

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J. S.; Kim, J. J.; Im, K. C.; Moon, D. H. [College of Medicine, Univ. of Ulsan, Seoul (Korea, Republic of)


    It has been known that cerebral perfusion is maintained in patients with congestive heart failure (CHF) by a complex series of compensatory mechanisms. However cognitive impairment is a common problem experienced by patients with CHF and may result from deranged cerebral perfusion. We prospectively investigated the global and regional CBF of patients with CHF and compared the results with that of normal controls. Thirty two patients (M/F: 22/10, 4211 yr) with CHF (LVEF=218.1%) and 10 healthy controls (M/F: 6/4, 398 yr) were prospectively studied. No patients had cerebrovascular disease or other disease affecting cognitive function. All patients and normal controls underwent radionuclide angiography including cerebral hemispheres and aortic arch, and brain perfusion SPECT using Tc-99m ECD. Global CBF was measured non-invasively by the application of Patlak plot graphical analysis. Quantitative rCBF images were obtained from SPECT image using global CBF values, regional/global count ratios, and Lassen's linearization correction algorithm. Difference of regional CBF between CHF and normal control were assessed using a SPM99 without global count normalization (uncorrected p<0.0001, extent threshold>100 voxels). Global CBF (41.54.7 ml/min/100g) of the patients with CHF were significantly lower than those (49.15.7 ml/min/100g) of controls (p<0.001). Regional CBF was significantly decreased in frontal, temporal and parietal neocortex of both cerebral hemispheres compared to normal controls. Regional rCBF of basal ganglia, thalamus, and brain stem were preserved, even though global CBF was variably compromised. Our study show that global CBF is significantly decreased in CHF and regional CBF of frontal, parietal and temporal neocortex is compromised preferentially. Further studies would be needed to investigate the relationship of rCBF change and cognitive impairment in patients with CHF.

  10. Regional cerebral blood flow during mechanical hyperventilation in patients with fulminant hepatic failure

    DEFF Research Database (Denmark)

    Strauss, Gitte Irene; Høgh, Peter; Møller, Kirsten


    Hyperventilation is frequently used to prevent or postpone the development of cerebral edema and intracranial hypertension in patients with fulminant hepatic failure (FHF). The influence of such therapy on regional cerebral blood flow (rCBF) remains, however, unknown. In this study the CBF......-distribution pattern was determined within the first 12 hours after development of hepatic encephalopathy (HE) stage 4 before and during hyperventilation. Ten consecutive patients (median age 48 [range 33-57] years) with FHF and 9 healthy controls (median age 54 [24-58] years) had rCBF determined by single photon...... emission computed tomography (SPECT) using intravenous injection of 133Xenon. For determination of high resolution CBF pattern, the patients were also studied with 99mTc-hexa-methylpropyleneamine oxime (HMPAO) in the hyperventilation condition. There was no significant difference in the rCBF distribution...

  11. Geological hazards investigation - relative slope stability map

    Energy Technology Data Exchange (ETDEWEB)

    Han, Dae Suk; Kim, Won Young; Yu, Il Hyon; Kim, Kyeong Su; Lee, Sa Ro; Choi, Young Sup [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)


    The Republic of Korea is a mountainous country; the mountains occupy about three quarters of her land area, an increasing urban development being taken place along the mountainside. For the reason, planners as well as developers and others must realize that some of the urban areas may be threaten by geologic hazards such as landslides and accelerated soil and rock creeps. For the purpose of environmental land-use planning, a mapping project on relative slope-stability was established in 1996. The selected area encompasses about 5,900 km{sup 2} including the topographic maps of Ulsan, Yongchon, Kyongju, Pulguksa, and Kampo, all at a scale of 1:50,000. Many disturbed and undisturbed soil samples, which were collected from the ares of the landslides and unstable slopes, were tested for their physical properties and shear strength. They were classified as GC, SP, SC, SM, SP-SM, SC-SM, CL, ML, and MH according to the Unified Soil Classification System, their liquid limit and plasticity index ranging from 25.3% to as high as 81.3% and from 4.1% to 41.5%, respectively. X-ray analysis revealed that many of the soils contained a certain amount of montmorillonite. Based on the available information as well as both field and laboratory investigation, it was found out that the most common types of slope failures in the study area were both debris and mud flows induced by the heavy rainfalls during the period of rainy season; the flows mostly occurred in the colluvial deposits at the middle and foot of mountains. Thus the deposits generally appear to be the most unstable slope forming materials in the study area. Produced for the study area were six different maps consisting of slope classification map, soil classification map, lineament density map, landslide distribution map, zonal map of rainfall, and geology map, most of them being stored as data base. Using the first four maps and GIS, two sheets of relative slope-stability maps were constructed, each at a scale of 1

  12. Recent and future warm extreme events and high-mountain slope stability. (United States)

    Huggel, C; Salzmann, N; Allen, S; Caplan-Auerbach, J; Fischer, L; Haeberli, W; Larsen, C; Schneider, D; Wessels, R


    The number of large slope failures in some high-mountain regions such as the European Alps has increased during the past two to three decades. There is concern that recent climate change is driving this increase in slope failures, thus possibly further exacerbating the hazard in the future. Although the effects of a gradual temperature rise on glaciers and permafrost have been extensively studied, the impacts of short-term, unusually warm temperature increases on slope stability in high mountains remain largely unexplored. We describe several large slope failures in rock and ice in recent years in Alaska, New Zealand and the European Alps, and analyse weather patterns in the days and weeks before the failures. Although we did not find one general temperature pattern, all the failures were preceded by unusually warm periods; some happened immediately after temperatures suddenly dropped to freezing. We assessed the frequency of warm extremes in the future by analysing eight regional climate models from the recently completed European Union programme ENSEMBLES for the central Swiss Alps. The models show an increase in the higher frequency of high-temperature events for the period 2001-2050 compared with a 1951-2000 reference period. Warm events lasting 5, 10 and 30 days are projected to increase by about 1.5-4 times by 2050 and in some models by up to 10 times. Warm extremes can trigger large landslides in temperature-sensitive high mountains by enhancing the production of water by melt of snow and ice, and by rapid thaw. Although these processes reduce slope strength, they must be considered within the local geological, glaciological and topographic context of a slope.

  13. Reckoning Informal Politics: Expands the Logic of Survival and Failure of Regional Heads

    Directory of Open Access Journals (Sweden)

    Wawan Sobari


    Full Text Available The qualitative research addresses the political logic of why and how the incumbents succeed and fail in direct election for regional heads (pilkada in emerging democratic Indonesia. De Mesquita et al. (2003 believe that, to survive in office, a leader needs to offer a benefit at least equal to the greatest possible benefit offered by a potential challenger. Particular to the pilkada cases in Indonesia, Erb and Sulistiyanto (2009 elaborate several factors connected to “reward and punishment” logic that may lead to the incumbents’ survival and failure in re-election bids. This study expands the logic by revealing that populism, rivalry, and tangibility are the core strategies for the successful incumbents in retaining their offices in four rural and urban regions in East Java. Particularly, the survival of an incumbent hinges on his capacity to manage rivalry risks, namely the capability to manage support and opposition both from formal and informal actors through fair or unfair means. These strategies, then, foster the success of patronage-based winning tactics to retain public office in the pilkada. To better assessment, it calls for the importance of democratic accountability as a complementary perspective (to consolidology in measuring the progress of democracy in the country. 

  14. Erosion and sediment deposition evaluation on slopes under different tillage systems in the Cerrado region using the 137Cs fallout technique

    International Nuclear Information System (INIS)

    Arthur, Robson Clayton Jacques


    In Brazil, the expansion of agricultural areas causes several problems on natural resources. With the increasing occupation of the Cerrado region by agriculture, a series of environmental problems like deforestation, soil erosion and soil compaction are appearing and causing radical transformations in the natural landscape due to removing almost all native vegetation. The conventional tillage system (CTS) is considered an inadequate form of soil management for its frequently irremediable consequences of soil compaction and soil erosion, and the no till system (NTS) makes the maintenance of the soil conditions possible, letting them close to the natural environment, thus reducing rates of soil erosion. The objective of this work was to evaluate the efficiency of riparian forests in the retention of sediments originated for three different tillage systems, through the fallout 137 CS redistribution technique, the Universal Soil Loss Equation (USLE) and some physical and chemical parameters that indicate the structural conditions of the soils of Goiatuba and Jandaia-GO. In the three areas, soil profiles were collected in three layers of 20 cm (0-20, 20-40 and 40-60 cm) at distinct points located along linear transects in the direction of the maximum slope until the riparian forest. In the riparian forest of each area, trenches were opened and soil was sampled to evaluate the activity of 137 Cs and the physical and chemical parameters of soil. Detection of the activity of 137 Cs was made with a gamma ray detector model (GEM-20180P, EG and ORTEC) connected to a multichannel analyzer. The comparison of averages was made using the Tukey test at 5% level of significance. The. results indicated that, the three soil tillage systems presented high rates of soil erosion and deposition of sediments and the riparian forest of the areas under CTS, NTS and pasture, located downstream received great amounts of sediments, and that only the riparian forest of CTS was capable to trap

  15. Modified Stability Charts for Rock Slopes Based on the Hoek-Brown Failure Criterion / Zmodyfikowane Diagramy Stabilności Skalistych Zboczy Otrzymane W Oparciu O Warunek Wytrzymałości Hoeka-Browna (United States)

    Nekouei, Mahdi; Ahangari, Kaveh


    Only an article rendered by Lia et al. in 2008 has represented charts based on Hoek-Brown criterion for rock slopes, however, these charts are not precise and efficient. Because of this problem, a modification is suggested for the mentioned charts in this study. The new charts are calculated according to four methods. Among the methods, one relates to finite element method using Phase2 software. The other three methods are Janbu, Bishop and Fellenius that belong to limit equilibrium method by using Slide software. For each slope angle, the method having high correlation coefficient is selected as the best one. Then, final charts are rendered according to the selected method and its specific equations. Among forty equations, twenty-five ones or 62.5% relate to numerical method and Phase2 software, six ones or 15% belong to Fellenius limit equilibrium, six ones or 15% relate to Bishop limit equilibrium, and three ones or 7.5% belong to Janbu limit equilibrium. In order to validate new charts, slope stability analysis is carried out for several sections of Chadormalu iron ore open pit mine, Iran. The error percentage of new charts in limit equilibrium method using Slide software and in Bishop method for slopes of Chadormalu iron ore mine are rendered and compared. The charts on a basis of Hoek-Brown failure criterion for rock slopes show less than ±4% error. This indicates that these charts are appropriate tools and their safety factor is optimal for rock slopes. Diagramy stabilności skalistych zboczy otrzymane w oparciu o warunek wytrzymałości Hoeka- Browna znaleźć można jedynie w pracy Lia et al. (2008), choć wykresy te nie są absolutnie dokładne i jasne. Dlatego też w niniejszym artykule zaproponowano pewną modyfikację diagramów. Nowe wykresu sporządzono w oparciu o cztery metody. Jedna z metod opiera się na metodzie elementów skończonych i wykorzystuje oprogramowanie Phase2. Pozostałe trzy podejścia to metody Janbu, Bishopa i Felleniusa bazuj

  16. An assessment of biological processes close to the sea bed in a slope region and its significance to the assessment of sea bed disposal of radioactive waste

    International Nuclear Information System (INIS)

    Hargreaves, P.M.; Ellis, C.J.; Angel, M.V.


    Vertical profiles of planktonic and micronektonic biomass observed close to the sea bed along a transect running up the continental slope on the southern flank of the Porcupine Seabight (to the southwest of Ireland) showed that a doubling in biomass concentration occurs from 100 to 10m above the sea bed. Comparison with biomass concentrations at two deep water stations, one in the Seabight and the other in the Rockall Trough, showed that there was a consistent increase in standing crop close to the sea bed over the slope. Supplementary data were collected on the northern flank of the Seabight. Analysis of both taxonomic groups and individual species showed that some taxa were more abundant near the sea floor and extended their vertical ranges to greater depths over the slope than over deep water, other taxa were unaffected. The implications to the problem of assessing the safety of sea bed disposal of high level radioactive waste are summarised. (author)

  17. Geology and Slope Stability Analysis using Markland Method on Road Segment of Piyungan – Patuk, Sleman and Gunungkidul Regencies, Yogyakarta Special Region, Indonesia

    Directory of Open Access Journals (Sweden)

    B. N. Kresna Citrabhuwana


    Full Text Available Road segment of Piyungan - Patuk is a part of Yogyakarta - Wonosari highway, fairly dense traversed by vehicles, from bicycles to buses and trucks. This road crosses hilly topography, causing its sides bounded by quite steep slopes or cliffs. Steep slopes and cliffs are potential to create mass movement. Geologic condition of the surrounding area is built of various volcanic lithology such as breccia, siltstone, sandstone and tuff. There are also geologic structures of joints and faults that affect the stability of the slopes around this road. Slope stability analysis for road segment of Piyungan – Patuk was conducted by applying Markland method. Laboratory testings were done to determine the mechanical and physical properties of rocks that influence the slope strength. Results of the testings show that cohesion and friction angle of volcanic breccia are c = 20.0441 kg/cm2 and  = 56.38˚; cohesion and friction angle of sandstone are cr = 0.6862 kg/cm2, cp = 4.6037 kg/cm2, r = 26.37˚, and p = 32.79˚; cohesion and friction angle of tuff is cr = 1.677 kg/cm2, cp = 7.5553 kg/cm2, r = 17.85˚, and p = 24.19˚. Based on the analysis, some slopes in the study area are potential to move. The movements can be classified into rock fall, debris fall, and rock slides with the sliding plane categorized as planar and wedge. On the other hand, landslide prone zones in the study area can be divided into: Areas with high vulnerability, Areas with moderate vulnerability, and Areas with low vulnerability. Areas prone to landslide should be managed by a series of measures, among others understand natural phenomena, recognizing symptoms of avalanche, attempting to reduce the risk, and land use regulation. The management activities should involve all stakeholders in an integrated manner of implementation.

  18. The upside of failure: how regional student groups learn from their mistakes.

    Directory of Open Access Journals (Sweden)

    Tarun Mishra


    Full Text Available Success is the result of planning, hard work, determination, foresight, and a little bit of luck. Unfortunately, nobody has thought to pave the road to success. Although failure can be discouraging and time-consuming, it presents incredible learning opportunities-the biggest difference between those who succeed and those who abandon their projects lies in their response to adversity. This article reviews events undertaken by the Regional Student Groups (RSGs in India and Argentina, the problems they encountered, and what can be learned from them. RSG-India attempted to organize an online scientific meeting (also known as a virtual conference with geographically dispersed stakeholders, a totally new concept for them. RSG-Argentina tackled the challenge of organizing a two-day symposium, their first event ever. Some of the complications they faced were easy to fix, others led to the cancellation of activities, and all of them resulted in valuable lessons. The main goal of this article is to highlight, through their experiences, the universal importance of a healthy panel of contingency plans.

  19. 3D geodetic monitoring slope deformations

    Directory of Open Access Journals (Sweden)

    Weiss Gabriel


    Full Text Available For plenty of slope failures that can be found in Slovakia is necessary and very important their geodetic monitoring (because of their activity, reactivisations, checks. The paper gives new methodologies for these works, using 3D terrestrial survey technologies for measurements in convenient deformation networks. The design of an optimal type of deformation model for various kinds of landslides and their exact processing with an efficient testing procedure to determine the kinematics of the slope deformations are presented too.

  20. Size Constraints on Late Miocene to Pliocene Submarine Slope Failures along the Colombian Caribbean Subduction Margin as a Basis for Assessing Circum-Caribbean Impact of Future Tsunami Events (United States)

    Leslie, S.; Mann, P.


    The Colombian Caribbean margin provides an ideal setting for the formation of large mass transport deposits (MTDs): 1) the Caribbean Plate is slowly subducting at rates of 20 mm/yr with infrequent large thrust earthquakes and a complete lack of subduction events in the 400-year-long historical record; 2) the margin is a broad zone of active faults including a ~50 km-wide accretionary prism and strike-slip faults landward of the prism; 3) the active margin is draped by the Magdalena delta and submarine fan fed by the Magdalena River, the 26th largest in the world; and 4) the margin is over-steepened to slopes of up to 7° from the combination of tectonic activity and rapid rates of deltaic progradation. Using seismic data we have identified three late Miocene-Pliocene MTDs, the largest of which is between 4500 and 6000 km3, comparable in size to the well-studied Storegga slide of Norway. The tsunamigenic potential of future, analog MTD events are modeled using GeoWave tsunami modeling software. The largest and youngest of these MTDs, the Santa Marta slide, is used as an analog to infer the location and input parameters for the tsunami model. The event is modeled as a translational slide ~46 km long and ~37 km wide with the center of the slide located ~57 km W/NW from the mouth of the present day Magdalena River in water depths of 1500 m. The volume for the initial failure is conservatively estimated at ~680 km3 of material. The resulting tsunami wave from such an event has an initial maximum trough amplitude of -65.8 m and a peak amplitude of 19.2 m. The impact of such a tsunami would include: 1) Kingston, Jamaica (population 938K), tsunami height 7.5 m, peak arrival at 60 min.; 2) Santo Domingo, Dominican Republic (population 965K, height 6 m, peak arrival at 80 min.); and 3) Cartagena, Colombia (population 845K, height 21 m, peak arrival at 34 min.). A number of parameters to the model are varied to analyze sensitivity of modeling results to changes in slide depth

  1. Dynamic and Static Combination Analysis Method of Slope Stability Analysis during Earthquake


    Liang Lu; Zongjian Wang; Xiaoyuan Huang; Bin Zheng; Katsuhiko Arai


    The results of laboratory model tests for simulating the slope failure due to vibration, including unreinforced slope and the slope reinforced by using geotextile, show that the slope failure occurs when a cumulative plastic displacement exceeds a certain critical value. To overcome the defects of conventional stability analysis, which evaluates the slope characteristics only by its strength parameters, a numerical procedure considering the stiffness and deformation of materials and geosynthe...

  2. Heterogeneous Landscapes on Steep Slopes at Low Altitudes as Hotspots of Bird Diversity in a Hilly Region of Nepal in the Central Himalayas

    Czech Academy of Sciences Publication Activity Database

    Basnet, T. B.; Rokaya, Maan Bahadur; Bhattarai, B. P.; Münzbergová, Zuzana


    Roč. 11, č. 3 (2016), s. 1-19, č. článku e0150498. E-ISSN 1932-6203 R&D Projects: GA ČR GP13-10850P Institutional support: RVO:67985939 Keywords : bird diversity * steep slopes * altitude Subject RIV: EF - Botanics Impact factor: 2.806, year: 2016

  3. Seasonal and interannual variability in along-slope oceanic properties off the US West Coast: Inferences from a high-resolution regional model (United States)

    Kurapov, A. L.; Pelland, N. A.; Rudnick, D. L.


    A 6 year, 2009-2014 simulation using a 2 km horizontal resolution ocean circulation model of the Northeast Pacific coast is analyzed with focus on seasonal and interannual variability in along-slope subsurface oceanic properties. Specifically, the fields are sampled on the isopycnal surface σ=26.5 kg m-3 that is found between depths of 150 and 300 m below the ocean surface over the continental slope. The fields analyzed include the depth z26.5, temperature T26.5, along-slope current v26.5, and the average potential vorticity PV between σ = 26.5 and 26.25 kg m-3. Each field is averaged in the cross-shore direction over the continental slope and presented as a function of the alongshore coordinate and time. The seasonal cycle in z26.5 shows a coherent upwelling-downwelling pattern from Mexico to Canada propagating to the north with a speed of 0.5 m s-1. The anomalously deep (-20 m) z26.5 displacement in spring-summer 2014 is forced by the southern boundary condition at 24°N as a manifestation of an emerging strong El Niño. The seasonal cycle in T26.5 is most pronounced between 36°N and 53°N indicating that subarctic waters are replaced by warmer Californian waters in summer with the speed close 0.15 m s-1, which is consistent with earlier estimates of the undercurrent speed and also present v26.5 analyses. The seasonal patterns and anomalies in z26.5 and T26.5 find confirmation in available long-term glider and shipborne observations. The PV seasonality over the slope is qualitatively different to the south and north of the southern edge of Heceta Bank (43.9°N).

  4. Analysis of slope slip surface case study landslide road segment Purwantoro-Nawangan/Bts Jatim Km 89+400

    International Nuclear Information System (INIS)

    Purnomo, Joko Sidik; Purwana, Yusep Muslih; Surjandari, Niken Silmi


    Wonogiri is a region of south eastern part of Central Java province which borders with East Java and Yogyakarta Province. In Physiographic its mostly undulating hills so that the frequent occurrence of landslides, especially during the rainy season. Landslide disaster that just happened that on the road segment Purwantoro-Nawangan / Bts Jatim Km 89 + 400 were included in the authority of the Highways Department of Central Java Province. During this time, Error analysis of slope stability is not caused by a lot of presumption shape of slip surface, but by an error in determining the location of the critical slip surface. This study aims to find the shape and location slip surface landslide on segment Purwantoro - Nawangan Km 89 + 400 with the interpretation of soil test results. This research method is with the interpretation of CPT test and Bore Hole as well as modeling use limit equilibrium method and finite element method. Processing contours of the slopes in the landslide area resulted in three cross section that slopes A-A, B-B and C-C which will be modeling the slopes. Modeling slopes with dry and wet conditions at the third cross section slope. It was found that the form of the slope slip surface are known to be composite depth 1.5-2 m with safety factor values more than 1.2 (stable) when conditions are dry slopes. But its became failure with factor of safety < 0.44 when conditions are wet slopes. (paper)

  5. Model tests of geosynthetic reinforced slopes in a geotechnical centrifuge

    International Nuclear Information System (INIS)

    Aklik, P.


    Geosynthetic-reinforced slopes and walls became very popular in recent years because of their financial, technical, and ecological advantages. Centrifuge modelling is a powerful tool for physical modelling of reinforced slopes and offers the advantage to observe the failure mechanisms of the slopes. In order to replicate the gravity induced stresses of a prototype structure in a geometrically 1/N reduced model, it is necessary to test the model in a gravitational field N times larger than that of the prototype structure. In this dissertation, geotextile-reinforced slope models were tested in a geotechnical centrifuge to identify the possible failure mechanisms. Slope models were tested by varying slope inclination, tensile strengths of the geotextiles, and overlapping lengths. Photographs of the geotextile reinforced slope models in flight were taken with a digital camera and the soil deformations of geotextile reinforced slopes were evaluated with Particle Image Velocimetry (PIV). The experimental results showed that failure of the centrifuge models initiated at midheight of the slope, and occurred due to geotextile breakage instead of pullout. The location of the shear surface is independent of the tensile strength of the geotextile; it is dependent on the shear strength of the soil. It is logical to see that the required acceleration of the centrifuge at slope failure was decreased with increasing slope inclination. An important contribution to the stability of the slope models was provided by the overlapping of the geotextile layers. It has a secondary reinforcement effect when it was prolonged and passed through the shear surface. Moreover, the location of the shear surface observed with PIV analysis exactly matches the tears of the retrieved geotextiles measured carefully after the centrifuge testing. It is concluded that PIV is an efficient tool to instrument the slope failures in a geotechnical centrifuge.(author) [de

  6. Fault slip versus slope deformations: Experience from paleoseismic trenches in the region with low slip-rate faults and strong Pleistocene periglacial mass wasting (Bohemian Massif)

    Czech Academy of Sciences Publication Activity Database

    Špaček, P.; Valenta, Jan; Tábořík, Petr; Ambrož, V.; Urban, M.; Štěpančíková, Petra


    Roč. 451, 7 SEP (2017), s. 56-73 ISSN 1040-6182 R&D Projects: GA ČR GAP210/12/0573; GA MŠk(CZ) LM2015079; GA MŠk 7AMB13AT023 Institutional support: RVO:67985891 Keywords : Active faulting * Paleoseismology * Slope deformation * Solifluction * Colluvium * Quaternary * Bohemian massif Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 2.199, year: 2016

  7. Investigations of slope stability

    Energy Technology Data Exchange (ETDEWEB)

    Nonveiller, E.


    The dynamics of slope slides and parameters for calculating slope stability is discussed. Two types of slides are outlined: rotation slide and translation slide. Slide dynamics are analyzed according to A. Heim. A calculation example of a slide which occurred at Vajont, Yugoslavia is presented. Calculation results differ from those presented by Ciabatti. For investigation of slope stability the calculation methods of A.W. Bishop (1955), N. Morgenstern and M. Maksimovic are discussed. 12 references

  8. Global and regional brain mean diffusivity changes in patients with heart failure. (United States)

    Woo, Mary A; Palomares, Jose A; Macey, Paul M; Fonarow, Gregg C; Harper, Ronald M; Kumar, Rajesh


    Heart failure (HF) patients show gray and white matter changes in multiple brain sites, including autonomic and motor coordination areas. It is unclear whether the changes represent acute or chronic tissue pathology, a distinction necessary for understanding pathological processes that can be resolved with diffusion tensor imaging (DTI)-based mean diffusivity (MD) procedures. We collected four DTI series from 16 HF (age 55.1 ± 7.8 years, 12 male) and 26 control (49.7 ± 10.8 years, 17 male) subjects with a 3.0-Tesla magnetic resonance imaging scanner. MD maps were realigned, averaged, normalized, and smoothed. Global and regional MD values from autonomic and motor coordination sites were calculated by using normalized MD maps and brain masks; group MD values and whole-brain smoothed MD maps were compared by analysis of covariance (covariates; age and gender). Global brain MD (HF vs. controls, units × 10(-6) mm(2) /sec, 1103.8 ± 76.6 vs. 1035.9 ± 69.4, P = 0.038) and regional autonomic and motor control site values (left insula, 1,085.4 ± 95.7 vs. 975.7 ± 65.4, P = 0.001; right insula, 1,050.2 ± 100.6 vs. 965.7 ± 58.4, P = 0.004; left hypothalamus, 1,419.6 ± 165.2 vs. 1,234.9 ± 136.3, P = 0.002; right hypothalamus, 1,446.5 ± 178.8 vs. 1,273.3 ± 136.9, P = 0.004; left cerebellar cortex, 889.1 ± 81.9 vs. 796.6 ± 46.8, P right cerebellar cortex, 797.8 ± 50.8 vs. 750.3 ± 27.5, P = 0.001; cerebellar deep nuclei, 1,236.1 ± 193.8 vs. 1,071.7 ± 107.1, P = 0.002) were significantly higher in HF vs. control subjects, indicating chronic tissue changes. Whole-brain comparisons showed increased MD values in HF subjects, including limbic, basal-ganglia, thalamic, solitary tract nucleus, frontal, and cerebellar regions. Brain injury occurs in autonomic and motor control areas, which may contribute to deficient function in HF patients. The chronic tissue changes likely

  9. GIS-based seismic shaking slope vulnerability map of Sicily (Central Mediterranean) (United States)

    Nigro, Fabrizio; Arisco, Giuseppe; Perricone, Marcella; Renda, Pietro; Favara, Rocco


    Earthquakes often represent very dangerouses natural events in terms of human life and economic losses and their damage effects are amplified by the synchronous occurrence of seismically-induced ground-shaking failures in wide regions around the seismogenic source. In fact, the shaking associated with big earthquakes triggers extensive landsliding, sometimes at distances of more than 100 km from the epicenter. The active tectonics and the geomorphic/morphodinamic pattern of the regions affected by earthquakes contribute to the slopes instability tendency. In fact, earthquake-induced groun-motion loading determines inertial forces activation within slopes that, combined with the intrinsic pre-existing static forces, reduces the slope stability towards its failure. Basically, under zero-shear stress reversals conditions, a catastrophic failure will take place if the earthquake-induced shear displacement exceeds the critical level of undrained shear strength to a value equal to the gravitational shear stress. However, seismic stability analyses carried out for various infinite slopes by using the existing Newmark-like methods reveal that estimated permanent displacements smaller than the critical value should also be regarded as dangerous for the post-earthquake slope safety, in terms of human activities use. Earthquake-induced (often high-speed) landslides are among the most destructive phenomena related to slopes failure during earthquakes. In fact, damage from earthquake-induced landslides (and other ground-failures), sometimes exceeds the buildings/infrastructures damage directly related to ground-shaking for fault breaking. For this matter, several hearthquakes-related slope failures methods have been developed, for the evaluation of the combined hazard types represented by seismically ground-motion landslides. The methodologies of analysis of the engineering seismic risk related to the slopes instability processes is often achieved through the evaluation of the

  10. Characterising weak layers that accommodate submarine landslides on the Northwest African continental slope (United States)

    Urlaub, M.; Krastel, S.; Geersen, J.; Schwenk, T.


    Numerous studies invoke weak layers to explain the occurrence of large submarine landslides (>100 km³), in particular those on very gentle slopes (translational, such that failure takes place along bedding-parallel surfaces at different stratigraphic depths. This suggests that failure occurs along weak layers, which are deposited repeatedly over time. Using high resolution seismic reflection data we trace several failure surfaces of the Cap Blanc Slide complex offshore Northwest Africa to ODP-Site 658. Core-seismic integration shows that the failure surfaces coincide with diatom oozes that are topped by clay. Along Northwest Africa diatom-rich sediments are typically deposited at the end of glacial periods. In the seismic data these oozes show up as distinct high amplitude reflectors due to their characteristic low densities. Similar high-amplitude reflectors embedded into low-reflective seismic units are commonly observed in shallow sediments (<100 m below seafloor) along the entire Northwest African continental slope. The failure surfaces of at least three large landslides coincide with such reflectors. As the most recent Pleistocene glacial periods likely influenced sediment deposition along the entire Northwest African margin in a similar manner we hypothesize that diatom oozes play a critical role for the generation of submarine landslides off Northwest Africa as well as globally within subtropical regions. An initiative to drill the Northwest African continental slope with IODP is ongoing, within which this hypothesis shall be tested.

  11. Assessment of Slope Stability of Various Cut Slopes with Effects of Weathering by Using Slope Stability Probability Classification (SSPC) (United States)

    Ersöz, Timur; Topal, Tamer


    Rocks containing pore spaces, fractures, joints, bedding planes and faults are prone to weathering due to temperature differences, wetting-drying, chemistry of solutions absorbed, and other physical and chemical agents. Especially cut slopes are very sensitive to weathering activities because of disturbed rock mass and topographical condition by excavation. During and right after an excavation process of a cut slope, weathering and erosion may act on this newly exposed rock material. These acting on the material may degrade and change its properties and the stability of the cut slope in its engineering lifetime. In this study, the effect of physical and chemical weathering agents on shear strength parameters of the rocks are investigated in order to observe the differences between weathered and unweathered rocks. Also, slope stability assessment of cut slopes affected by these weathering agents which may disturb the parameters like strength, cohesion, internal friction angle, unit weight, water absorption and porosity are studied. In order to compare the condition of the rock materials and analyze the slope stability, the parameters of weathered and fresh rock materials are found with in-situ tests such as Schmidt hammer and laboratory tests like uniaxial compressive strength, point load and direct shear. Moreover, slake durability and methylene blue tests are applied to investigate the response of the rock to weathering and presence of clays in rock materials, respectively. In addition to these studies, both rock strength parameters and any kind of failure mechanism are determined by probabilistic approach with the help of SSPC system. With these observations, the performances of the weathered and fresh zones of the cut slopes are evaluated and 2-D slope stability analysis are modeled with further recommendations for the cut slopes. Keywords: 2-D Modeling, Rock Strength, Slope Stability, SSPC, Weathering

  12. Slippery Slope Arguments

    NARCIS (Netherlands)

    van der Burg, W.; Chadwick, R.F.


    Slippery slope arguments hold that one should not take some action (which in itself may be innocuous or even laudable) in order to prevent one from being dragged down a slope towards some clearly undesirable situation. Their typical purpose is to prevent changes in the status quo and, therefore,

  13. Slope stability and erosion control: Ecotechnological solutions

    NARCIS (Netherlands)

    Norris, J.E.; Stokes, A.; Mickovski, S.B.; Cammeraat, E.; van Beek, R.; Nicoll, B.C.; Achim, A.


    This book is designed to assist the civil and geotechnical engineer, geomorphologist, forester, landscape architect or ecologist in choosing ecotechnological solutions for slopes that are prone to a variety of mass movements e.g. shallow failure or erosion. Within this book, the 'engineer' is used

  14. An alternative soil nailing system for slope stabilization: Akarpiles (United States)

    Lim, Chun-Lan; Chan, Chee-Ming


    This research proposes an innovative solution for slope stabilization with less environmental footprint: AKARPILES. In Malaysia, landslide has become common civil and environmental problems that cause impacts to the economy, safety and environment. Therefore, effective slope stabilization method helps to improve the safety of public and protect the environment. This study focused on stabilizing surfacial slope failure. The idea of AKARPILES was generated from the tree roots system in slope stabilization. After the piles are installed in the slope and intercepting the slip plane, grout was pumped in and discharged through holes on the piles. The grout then filled the pores in the soil with random flow within the slip zone. SKW mixture was used to simulate the soil slope. There were two designs being proposed in this study and the prototypes were produced by a 3D printer. Trial mix of the grout was carried out to obtain the optimum mixing ratio of bentonite: cement: water. A series of tests were conducted on the single-pile-reinforced slope under vertical slope crest loading condition considering different slope gradients and nail designs. Parameters such as ultimate load, failure time and failure strain were recorded and compared. As comparison with the unreinforced slope, both designs of AKARPILES showed better but different performances in the model tests.

  15. Applying micromechanic failure models for description of failure modes in the ductile-brittle transition region; Einsatz mikromechanischer Schaedigungsmodelle im sproed-duktilen Uebergangsbereich

    Energy Technology Data Exchange (ETDEWEB)

    Bernauer, G.


    The work reported was to examine whether the modified Gurson model and the Beremin model can be applied to the brittle-ductile transition region of a ferritic steel, and whether the material`s behaviour can be characterized with a failure model integrating the two models mentioned above into one. Any possible improvements of this approach were to be found. The report at first gives a brief list of terminology and formulas used. Chapter 3 explains the microscopic processes typically observed in the transition region in connection with the failure modes of ductile fracture and cleavage fracture, and shows possible approaches for modelling. Chapter 4 defines the specimens and materials, and chapter 5 explains the experiments as well as the microscopic analyses of the fracture surfaces. Chapter 6 presents subsequent calculations representing the processes observed. Based on the stress distributions thus derived, the Beremin model is re-examined for further development. Chapter 7 summarizes the results obtained. (orig./CB) [Deutsch] Ziel der Arbeit ist, zu untersuchen, ob das modifizierte Gurson-Modell und das Beremin-Modell im sproed-duktilen Uebergangsbereich eines ferritischen Stahls einsetzbar sind und ob das Werkstoffverhalten mit einem aus beiden Modellen kombinierten Schaedigungsmodell berechnet werden kann. Gegebenenfalls sind Verbesserungen herbeizufuehren. Die vorliegende Arbeit beginnt mit einer kurzen Einfuehrung der verwendeten Begriffe und Formalismen. In Kap. 3 werden die mikroskopischen Vorgaenge bei den im Uebergangsbereich typischerweise auftretenden Versagensarten duktiler Bruch und Spaltbruch vorgestellt und verschiedene Moeglichkeiten ihrer Modellierung aufgezeigt. Nach der Vorstellung des Probenwerkstoffs werden in Kap. 4 die Experimente beschrieben und die mikroskopischen Untersuchungen der Bruchflaechen in Kap. 5 dargestellt. Die Nachrechnungen der Experimente werden in Kap. 6 vorgestellt. Auf der Grundlage der dadurch bereitgestellten

  16. Factors affecting seismic response of submarine slopes

    Directory of Open Access Journals (Sweden)

    G. Biscontin


    Full Text Available The response of submerged slopes on the continental shelf to seismic or storm loading has become an important element in the risk assessment for offshore structures and 'local' tsunami hazards worldwide. The geological profile of these slopes typically includes normally consolidated to lightly overconsolidated soft cohesive soils with layer thickness ranging from a few meters to hundreds of meters. The factor of safety obtained from pseudo-static analyses is not always a useful measure for evaluating the slope response, since values less than one do not necessarily imply slope failure with large movements of the soil mass. This paper addresses the relative importance of different factors affecting the response of submerged slopes during seismic loading. The analyses use a dynamic finite element code which includes a constitutive law describing the anisotropic stress-strain-strength behavior of normally consolidated to lightly overconsolidated clays. The model also incorporates anisotropic hardening to describe the effect of different shear strain and stress histories as well as bounding surface principles to provide realistic descriptions of the accumulation of the plastic strains and excess pore pressure during successive loading cycles. The paper presents results from parametric site response analyses on slope geometry and layering, soil material parameters, and input ground motion characteristics. The predicted maximum shear strains, permanent deformations, displacement time histories and maximum excess pore pressure development provide insight of slope performance during a seismic event.

  17. Preliminary Slope Stability Study Using Slope/ W

    International Nuclear Information System (INIS)

    Nazran Harun; Mohd Abd Wahab Yusof; Kamarudin Samuding; Mohd Muzamil Mohd Hashim; Nurul Fairuz Diyana Bahrudin


    Analyzing the stability of earth structures is the oldest type of numerical analysis in geotechnical engineering. Limit equilibrium types of analyses for assessing the stability of earth slopes have been in use in geotechnical engineering for many decades. Modern limit equilibrium software is making it possible to handle ever-increasing complexity within an analysis. It is being considered as the potential method in dealing with complex stratigraphy, highly irregular pore-water pressure conditions, various linear and nonlinear shear strength models and almost any kind of slip surface shape. It allows rapid decision making by providing an early indication of the potential suitability of sites based on slope stability analysis. Hence, a preliminary slope stability study has been developed to improve the capacity of Malaysian Nuclear Agency (Nuclear Malaysia) in assessing potential sites for Borehole Disposal for Disused Sealed Radioactive Sources. The results showed that geometry of cross section A-A ' , B-B ' , C-C ' and D-D ' achieved the factor of safety not less than 1.4 and these are deemed acceptable. (author)

  18. Regional cerebral blood flow in elderly patients with heart failure evaluated with SPECT

    International Nuclear Information System (INIS)

    Alves, T.C.T.F.; Fraguas, R.; Busatto, G.; Garrido, G.; Buchpiguel, C.A.; Rays, J.; Wajngarten, M.; Robilotta, C.C.; Meneghetti, J.C.


    Introduction: Heart failure (HF) may be related to brain dysfunction due to reduced cerebral blood flow (CBF) and white matter lesions. However, no studies have yet used quantitative regional CBF (rCBF) techniques to demonstrate the presence of significant functional abnormalities in representative samples of cardiac patients compared with normal controls. Aim: The purpose of this study was to investigate the rCBF distribution as assessed with SPECT in a group of elderly patients with HF in comparison with a normal control group. The hypothesis were: (1) HF would be associated with rCBF reductions in comparison to healthy controls. Methodology: We studied a group of 36 HF patients functional class II or III from New York Heart Association (NYHA), divided in 19 depressed (74.6 +/- 6.8 years) and 17 non depressed (73.7 +/- 5.4 years), and compared to 19 normal subjects (71.1 +/- 4.8 years), matched for age, sex, cerebral dominance and social level. Brain perfusion was evaluated with a double-headed SPECT system (Sophy-DST) with high-resolution collimators (128x128 matrix, 128 views, 30s/view) after 30mcI 99mTc-HMPAO injection. Group differences were investigated using SPM99, with a p<0.001 statistical threshold (uncorrected for multiple comparisons). Results: Significant rCBF reductions were seen in the HF non depressed group relative to healthy controls in the right lateral temporal lobe, cuneus and precuneus, as well as in a small area of the medial prefrontal cortex. In the HF depressed group, significant cortical rCBF reductions relative to healthy controls were seen in similar locations but more extensively. In addition, the HF depressed group showed significant rCBF reductions relative to controls limbic and subcortical areas, including the right parahypocampal gyrus, posterior cingulate, thalamus and caudate at the border of the lateral ventricle, and bilaterally in the posterior insula. Conclusion: The presence of greater areas of hypoperfusion in the HF

  19. Design of Rock Slope Reinforcement: An Himalayan Case Study (United States)

    Tiwari, Gaurav; Latha, Gali Madhavi


    The stability analysis of the two abutment slopes of a railway bridge proposed at about 359 m above the ground level, crossing a river and connecting two hill faces in the Himalayas, India, is presented. The bridge is located in a zone of high seismic activity. The rock slopes are composed of a heavily jointed rock mass and the spacing, dip and dip direction of joint sets are varying at different locations. Geological mapping was carried out to characterize all discontinuities present along the slopes. Laboratory and field investigations were conducted to assess the geotechnical properties of the intact rock, rock mass and joint infill. Stability analyses of these rock slopes were carried out using numerical programmes. Loads from the foundations resting on the slopes and seismic accelerations estimated from site-specific ground response analysis were considered. The proposed slope profile with several berms between successive foundations was simulated in the numerical model. An equivalent continuum approach with Hoek and Brown failure criterion was initially used in a finite element model to assess the global stability of the slope abutments. In the second stage, finite element analysis of rock slopes with all joint sets with their orientations, spacing and properties explicitly incorporated into the numerical model was taken up using continuum with joints approach. It was observed that the continuum with joints approach was able to capture the local failures in some of the slope sections, which were verified using wedge failure analysis and stereographic projections. Based on the slope deformations and failure patterns observed from the numerical analyses, rock anchors were designed to achieve the target factors of safety against failure while keeping the deformations within the permissible limits. Detailed design of rock anchors and comparison of the stability of slopes with and without reinforcement are presented.

  20. Effect of rainfall on the reliability of an infinite slope


    Yuan, J.; Papaioannou, I.; Mok, C. M.; Straub, D.


    Rainfall is one of the most common factors triggering landslides, since infiltration of water into the soil has a significant impact on pore water pressure buildup that affects slope stability. In this study, the influence of the wetting front development on the reliability of an infinite slope is analyzed. The failure condition of the slope is expressed in terms of the factor of safety. Rainfall infiltration is simulated by a time-dependent model, based on the Green and Ampt assumptions. The...

  1. Rock Mass Classification of Karstic Terrain in the Reservoir Slopes of Tekeze Hydropower Project (United States)

    Hailemariam Gugsa, Trufat; Schneider, Jean Friedrich


    Hydropower reservoirs in deep gorges usually experience slope failures and mass movements. History also showed that some of these projects suffered severe landslides, which left lots of victims and enormous economic loss. Thus, it became vital to make substantial slope stability studies in such reservoirs to ensure safe project development. This study also presents a regional scale instability assessment of the Tekeze Hydropower reservoir slopes. Tekeze hydropower project is a newly constructed double arch dam that completed in August 2009. It is developed on Tekeze River, tributary of Blue Nile River that runs across the northern highlands of Ethiopia. It cuts a savage gorge 2000m deep, the deepest canyon in Africa. The dam is the highest dam in Ethiopia at 188m, 10 m higher than China's Three Gorges Dam. It is being developed by Chinese company at a cost of US350M. The reservoir is designed at 1140 m elevation, as retention level to store more than 9000 million m3 volume of water that covers an area of 150 km2, mainly in channel filling form. In this study, generation of digital elevation model from ASTER satellite imagery and surface field investigation is initially considered for further image processing and terrain parameters' analyses. Digitally processed multi spectral ASTER ortho-images drape over the DEM are used to have different three dimensional perspective views in interpreting lithological, structural and geomorphological features, which are later verified by field mapping. Terrain slopes are also delineated from the relief scene. A GIS database is ultimately developed to facilitate the delineation of geotechnical units for slope rock mass classification. Accordingly, 83 geotechnical units are delineated and, within them, 240 measurement points are established to quantify in-situ geotechnical parameters. Due to geotechnical uncertainties, four classification systems; namely geomorphic rock mass strength classification (RMS), slope mass rating (SMR

  2. Unstable slope management program. (United States)


    This Rapid Response Project gathered information on existing unstable slope management programs, with a : focus on asset management practices in the United States and overseas. On the basis of this study, the research : team summarized and recommende...

  3. Rock slope design guide. (United States)


    This Manual is intended to provide guidance for the design of rock cut slopes, rockfall catchment, and : rockfall controls. Recommendations presented in this manual are based on research presented in Shakoor : and Admassu (2010) entitled Rock Slop...

  4. Rock Slope Design Criteria (United States)


    Based on the stratigraphy and the type of slope stability problems, the flat lying, Paleozoic age, sedimentary : rocks of Ohio were divided into three design units: 1) competent rock design unit consisting of sandstones, limestones, : and siltstones ...

  5. Rationale, design and baseline results of the Treatment Optimisation in Primary care of Heart failure in the Utrecht region (TOPHU) study : a cluster randomised controlled trial

    NARCIS (Netherlands)

    Valk, Mark J.; Hoes, Arno W.; Mosterd, Arend; Landman, Marcel A.; Broekhuizen, Berna D L; Rutten, Frans H.


    BACKGROUND: Heart failure (HF) is mainly detected and managed in primary care, but the care is considered suboptimal. We present the rationale, design and baseline results of the Treatment Optimisation in Primary care of Heart failure in the Utrecht region (TOPHU) study. In this study we assess the

  6. Economic Loss to the Brazilian Regions Due to the Doha Round Failure


    Pereira, Matheus Wemerson Gomes; Teixeira, Erly Cardoso; Gurgel, Angelo Costa


    We build a database and model to develop general equilibrium analysis of the Brazilian economy at the level of the five macro regions. The model is multiregional at global level as also at the Brazilian level. The project is coupled to the GTAP model through disaggregation of the original Brazilian input-output matrix and trade flows and follows the GTAPinGAMS structure and syntax to generate the General Equilibrium Analysis Project for the Brazilian Economy (PAEG). The regional database is t...

  7. Study on the response of unsaturated soil slope based on the effects of rainfall intensity and slope angle (United States)

    Ismail, Mohd Ashraf Mohamad; Hamzah, Nur Hasliza


    Rainfall has been considered as the major cause of the slope failure. The mechanism leading to slope failures included the infiltration process, surface runoff, volumetric water content and pore-water pressure of the soil. This paper describes a study in which simulated rainfall events were used with 2-dimensional soil column to study the response of unsaturated soil behavior based on different slope angle. The 2-dimensional soil column is used in order to demonstrate the mechanism of the slope failure. These unsaturated soil were tested with four different slope (15°, 25°, 35° and 45°) and subjected to three different rainfall intensities (maximum, mean and minimum). The following key results were obtained: (1) the stability of unsaturated soil decrease as the rainwater infiltrates into the soil. Soil that initially in unsaturated state will start to reach saturated state when rainwater seeps into the soil. Infiltration of rainwater will reduce the matric suction in the soil. Matric suction acts in controlling soil shear strength. Reduction in matric suction affects the decrease in effective normal stress, which in turn diminishes the available shear strength to a point where equilibrium can no longer be sustained in the slope. (2) The infiltration rate of rainwater decreases while surface runoff increase when the soil nearly achieve saturated state. These situations cause the soil erosion and lead to slope failure. (3) The steepness of the soil is not a major factor but also contribute to slope failures. For steep slopes, rainwater that fall on the soil surface will become surface runoff within a short time compare to the water that infiltrate into the soil. While for gentle slopes, water that becomes surface runoff will move slowly and these increase the water that infiltrate into the soil.

  8. Small scale tests on the progressive retreat of soil slopes (United States)

    Voulgari, Chrysoula; Utili, Stefano; Castellanza, Riccardo


    In this paper, the influence due to the presence of cracks on the morphologic evolution of natural cliffs subject to progressive retreat induced by weathering is investigated through small scale laboratory tests. Weathering turns hard rocks into soft rocks that maintain the structure of the intact rocks, but are characterised by higher void ratios and reduced bond strengths; soft rocks are transformed into granular soils generally called residual soils. A number of landslides develop in slopes due to weathering which results in the progressive retrogression of the slope face and the further degradation within the weathering zone. Cracks, that are widely present, can be a result of weathering and they can cause a significant decrease in their stability, as they provide preferential flow channels which increase the soil permeability and decrease the soil strength. The geological models employed until now are mainly empirical. Several researchers have tried to study the stability of slopes through experimental procedures. Centrifuge modelling is widely used to investigate the failure of slopes. Small scale tests are also an important approach, in order to study the behaviour of a slope under certain conditions, such as the existence of water, as they allow the observation of the infiltration processes, the movement of the weathering front, deformation and failure. However, the deformation response of a slope subject to weathering is not yet thoroughly clarified. In this work, a set of experiments were conducted to investigate weathering induced successive landslides. Weathering was applied to the slope model by wetting the slope crest through a rainfall simulator device. The moisture content of the soil during the tests was monitored by soil moisture sensors that were buried inside the slope model. High resolution cameras were recording the behaviour of the slope model. GeoPIV was used to analyse the frames and obtain the deformations of the slope model during the

  9. Runoff from armored slopes

    International Nuclear Information System (INIS)

    Codell, R.B.


    Models exist for calculating overland flow on hillsides but no models have been found which explicitly deal with runoff from armored slopes. Flow on armored slopes differs from overland flow, because substantial flow occurs beneath the surface of the rock layer at low runnoff, and both above and below the surface for high runoff. In addition to the lack of a suitable model, no estimates of the PMP exist for such small areas and for very short durations. This paper develops a model for calculating runoff from armored embankments. The model considers the effect of slope, drainage area and ''flow concentration'' caused by irregular grading or slumping. A rainfall-duration curve based on the PMP is presented which is suitable for very small drainage areas. The development of the runoff model and rainfall-duration curve is presented below, along with a demonstration of the model on the design of a hypothetical tailings embankment

  10. The Central American Regional Payment System: Reasons for its Failure and Reconversion (1989-1993

    Directory of Open Access Journals (Sweden)

    Rafael de Juan Peñalosa


    Full Text Available This article, entitled “The Central American regional payment system: focusses and its reconversion”, is placed in the context of the recent strengthening of those mechanisms responsible for the reactivation of the Central American process of regional economic integration. With the aim of starting up a Central American regional payment system within the framework of the evolution and development of the regional integration of the Central American isthmus, the member countries of the Central American Common Market asked the European Community for technical assistance regarding its creationand application. After careful study by the EC this petition met with a positive response fitting as it did within the context of the policy of cooperation between the European Union and the countries of the Central American region. This in turn led to the signing of the Central American Payment System Financing Treaty in the Irish capital, Dublin, coinciding as it did with the San Jose VI Conference (9/10 March, 1990 which subsequently enjoyed diplomatic as well as financial and technical support as well as an intense development throughout the latter years of the Nineties.

  11. Preliminary Analysis of Slope Stability in Kuok and Surrounding Areas

    Directory of Open Access Journals (Sweden)

    Dewandra Bagus Eka Putra


    Full Text Available The level of slope influenced by the condition of the rocks beneath the surface. On high level of slopes, amount of surface runoff and water transport energy is also enlarged. This caused by greater gravity, in line with the surface tilt from the horizontal plane. In other words, topsoil eroded more and more. When the slope becomes twice as steep, then the amount of erosion per unit area be 2.0 - 2.5 times more. Kuok and surrounding area is the road access between the West Sumatra and Riau which plays an important role economies of both provinces. The purpose of this study is to map the locations that have fairly steep slopes and potential mode of landslides. Based on SRTM data obtained,  the roads in Kuok area has a minimum elevation of + 33 m and a maximum  + 217.329 m. Rugged road conditions with slope ranging from 24.08 ° to 44.68 ° causing this area having frequent landslides. The result of slope stability analysis in a slope near the Water Power Plant Koto Panjang, indicated that mode of active failure is toppling failure or rock fall and the potential zone of failure is in the center part of the slope.

  12. Laboratory Experiments on Steady State Seepage-Induced Landslides Using Slope Models and Sensors

    Directory of Open Access Journals (Sweden)

    Sandra G. Catane


    Full Text Available A thorough understanding of the failure initiation process is crucial in the development of physicallybased early warning system for landslides and slope failures. Laboratory-scale slope models were constructed and subjected to instability through simulated groundwater infiltration. This is done by progressively increasing the water level in the upslope tank and allowing water to infiltrate laterally towards the toe of the slope. Physical changes in the slope models were recorded by tilt sensors and video cameras. When the model slope was destabilized, the chronology of events occurred in the following sequence: (1 bulging at the toe, (2 seepage at the toe, (3 initial failure of soil mass, (4 piping, (5 retrogressive failure, (6 formation of tension cracks and (7 major failure of soil mass. Tension cracks, piping and eventual failure are manifestations of differential settlements due to variations in void ratio. Finite element analysis indicates that instability and subsequent failures in the model slope were induced primarily by high hydraulic gradients in the toe area. Seepage, initial deformation and subsequent failures were manifested in the toe area prior to failure, providing a maximum of 36 min lead time. Similar lead times are expected in slopes of the same material as shown in many case studies of dam failure. The potential of having a longer lead time is high for natural slopes made of materials with higher shear strength thus evacuation is possible. The tilt sensors were able to detect the initial changes before visual changes manifested, indicating the importance of instrumental monitoring.

  13. Prevention of iodine deficiency in the Tyumen region: success or failure?

    Directory of Open Access Journals (Sweden)

    Ludmila Aleksandrovna Suplotova


    Full Text Available Aim. To evaluate the effectiveness of regional programs for the prevention of iodine deficiency in the Tyumen region and explore the awareness and behaviors of different groups of the population in matters of iodine prophylaxis in the conditions absence of federal law on universal salt iodization. Materials and methods. The results are presented of the realization of regional programs for the prevention of iodine deficiency in the Tyumen region for the period 1994–2014 years. As part of the medical monitoring examined 18,906 prepubertal children 8–12 years with the use of a unified system of identification of iodine deficiency. The results of sociological research are presented, as part of a public health monitoring conducted by surveying students (n = 744 and their parents (n = 677 on a representative sample. Results. Iodine nutrition use was normalization through 3 years against the background of the realization regional program of iodine prophylaxis since 1997 in the Tyumen region, as evidenced by normalization of urinary iodine excretion in prepubertal children. The median urinary iodine in prepubertal children significantly increased from baseline 71.4 mg/l to 142 mg/l in 2009, and as a result decreased the frequency of goiter in children 8–10 years from 87% to 8%, which corresponds to mild endemic goiter region. It noted a lack of awareness of parents of iodine deficiency in the area of residence (54.8% informed their parents of schoolchildren; indicator is linked to gender, age (p < 0.01, education (p < 0.001, and where do you live respondents (p < 0.001. Knowledge of the existence and availability of prevention of iodine deficiency showed 75% of parents and 46.6% of students. Regular use of iodized salt in the home diet (“always used” and “often iodized salt than non-iodised” 57.4% of parents say. To identify various models of preventive behaviors of parents of schoolchildren in the prevention of iodine deficiency

  14. Western Slope Colorado

    International Nuclear Information System (INIS)

    Epis, R.C.; Callender, J.F.


    A conference on the geology and geologic resources of the Western Slope of western Colorado and eastern Utah is presented. Fourteen papers from the conference have been abstracted and indexed for the Department of Energy's Energy Data Base. These papers covered such topics as uranium resources, oil shale deposits, coal resources, oil and gas resources, and geothermal resources of the area

  15. Rock slope instabilities in Norway: First systematic hazard and risk classification of 22 unstable rock slopes (United States)

    Böhme, Martina; Hermanns, Reginald L.; Oppikofer, Thierry; Penna, Ivanna


    Unstable rock slopes that can cause large failures of the rock-avalanche type have been mapped in Norway for almost two decades. Four sites have earlier been characterized as high-risk objects based on expertise of few researchers. This resulted in installing continuous monitoring systems and set-up of an early-warning system for those four sites. Other unstable rock slopes have not been ranked related to their hazard or risk. There are ca. 300 other sites known of which 70 sites were installed for periodic deformation measurements using multiple techniques (Global Navigation Satellite Systems, extensometers, measurement bolts, and others). In 2012 a systematic hazard and risk classification system for unstable rock slopes was established in Norway and the mapping approach adapted to that in 2013. Now, the first 22 sites were classified for hazard, consequences and risk using this classification system. The selection of the first group of sites to be classified was based on an assumed high hazard or risk and importance given to the sites by Norwegian media and the public. Nine of the classified 22 unstable rock slopes are large sites that deform inhomogeneously or are strongly broken up in individual blocks. This suggests that different failure scenarios are possible that need to be analyzed individually. A total of 35 failure scenarios for those nine unstable rock slopes were considered. The hazard analyses were based on 9 geological parameters defined in the classification system. The classification system will be presented based on the Gamanjunni unstable rock slope. This slope has a well developed back scarp that exposes 150 m preceding displacement. The lateral limits of the unstable slope are clearly visible in the morphology and InSAR displacement data. There have been no single structures observed that allow sliding kinematically. The lower extend of the displacing rock mass is clearly defined in InSAR data and by a zone of higher rock fall activity. Yearly

  16. Reckoning Informal Politics: Expands the Logic of Survival and Failure of Regional Heads


    Wawan Sobari


    The qualitative research addresses the political logic of why and how the incumbents succeed and fail in direct election for regional heads (pilkada) in emerging democratic Indonesia. De Mesquita et al. (2003) believe that, to survive in office, a leader needs to offer a benefit at least equal to the greatest possible benefit offered by a potential challenger. Particular to the pilkada cases in Indonesia, Erb and Sulistiyanto (2009) elaborate several factors connected to “reward and punishmen...

  17. Slope activity in Gale crater, Mars (United States)

    Dundas, Colin M.; McEwen, Alfred S.


    High-resolution repeat imaging of Aeolis Mons, the central mound in Gale crater, reveals active slope processes within tens of kilometers of the Curiosity rover. At one location near the base of northeastern Aeolis Mons, dozens of transient narrow lineae were observed, resembling features (Recurring Slope Lineae) that are potentially due to liquid water. However, the lineae faded and have not recurred in subsequent Mars years. Other small-scale slope activity is common, but has different spatial and temporal characteristics. We have not identified confirmed RSL, which Rummel et al. (Rummel, J.D. et al. [2014]. Astrobiology 14, 887–968) recommended be treated as potential special regions for planetary protection. Repeat images acquired as Curiosity approaches the base of Aeolis Mons could detect changes due to active slope processes, which could enable the rover to examine recently exposed material.

  18. The logarithmic slope in diffractive DIS

    International Nuclear Information System (INIS)

    Gay Ducati, M.B.; Goncalves, V.P.; Machado, M.V.T.


    The logarithmic slope of diffractive structure function is a potential observable to separate the hard and soft contributions in diffraction, allowing to disentangle the QCD dynamics at small-x region. In this paper we extend our previous analyzes and calculate the diffractive logarithmic slope for three current approaches in the literature: (i) the Bartels-Wusthoff model, based on perturbative QCD, (ii) the CKMT model, based on Regge theory and (iii) the Golec-Biernat-Wusthoff model which assumes that the saturation phenomena is present in the HERA kinematic region. We analyze the transition region of small to large momentum transfer and verify that future experimental results on the diffractive logarithmic slope could discriminate between these approaches

  19. Analysing a Chinese Regional Integrated Healthcare Organisation Reform Failure using a Complex Adaptive System Approach

    Directory of Open Access Journals (Sweden)

    Wenxi Tang


    Full Text Available Introduction: China’s organised health system has remained outdated for decades. Current health systems in many less market-oriented countries still adhere to traditional administrative-based directives and linear planning. Furthermore, they neglect the responsiveness and feedback of institutions and professionals, which often results in reform failure in integrated care. Complex adaptive system theory (CAS provides a new perspective and methodology for analysing the health system and policy implementation.  Methods: We observed the typical case of Qianjiang’s Integrated Health Organization Reform (IHO for 2 years to analyse integrated care reforms using CAS theory. Via questionnaires and interviews, we observed 32 medical institutions and 344 professionals. We compared their cooperative behaviours from both organisational and inter-professional levels between 2013 and 2015, and further investigated potential reasons for why medical institutions and professionals did not form an effective IHO. We discovered how interested parties in the policy implementation process influenced reform outcome, and by theoretical induction, proposed a new semi-organised system and corresponding policy analysis flowchart that potentially suits the actual realisation of CAS.  Results: The reform did not achieve its desired effect. The Qianjiang IHO was loosely integrated rather than closely integrated, and the cooperation levels between organisations and professionals were low. This disappointing result was due to low mutual trust among IHO members, with the main contributing factors being insufficient financial incentives and the lack of a common vision.  Discussion and Conclusions: The traditional 'organised health system' is old-fashioned. Rather than being completely organised or adaptive, the health system is currently more similar to a s'emi-organised system'. Medical institutions and professionals operate in a middle ground between complete adherence

  20. Success and failure factors in the regional health information system design process--results from a constructive evaluation study. (United States)

    Nykänen, P; Karimaa, E


    To identify success and failure factors in the design process of a regional health information system. A constructive evaluation study including interviews, observations, usability study and document analysis. Modelling was found to be a key element for the successful implementation of a health information system. The developed service chain model helped to define use cases and to implement seamless service chains. User participation in the design process was a success factor resulting in good user acceptance and signs of positive impacts on work practices. Evaluation study also helped system developers to guide the system's further development. An important failure factor identified was the lack of semantic interoperability of the system components. The results emphasize the socio-technical nature of health information systems. The starting point for development should be thorough insight into the health care work practices where the information systems are to be used. Successful system design should start from modelling of work processes, data and information flows and definition of concepts and their relations. Health informatics as a scientific discipline provides theories and models for the design and development process.

  1. A Novel Risk Stratification to Predict Local-Regional Failures in Urothelial Carcinoma of the Bladder After Radical Cystectomy

    International Nuclear Information System (INIS)

    Baumann, Brian C.; Guzzo, Thomas J.; He Jiwei; Keefe, Stephen M.; Tucker, Kai; Bekelman, Justin E.; Hwang, Wei-Ting; Vaughn, David J.; Malkowicz, S. Bruce; Christodouleas, John P.


    Purpose: Local-regional failures (LF) following radical cystectomy (RC) plus pelvic lymph node dissection (PLND) with or without chemotherapy for invasive urothelial bladder carcinoma are more common than previously reported. Adjuvant radiation therapy (RT) could reduce LF but currently has no defined role because of previously reported morbidity. Modern techniques with improved normal tissue sparing have rekindled interest in RT. We assessed the risk of LF and determined those factors that predict recurrence to facilitate patient selection for future adjuvant RT trials. Methods and Materials: From 1990-2008, 442 patients with urothelial bladder carcinoma at University of Pennsylvania were prospectively followed after RC plus PLND with or without chemotherapy with routine pelvic computed tomography (CT) or magnetic resonance imaging (MRI). One hundred thirty (29%) patients received chemotherapy. LF was any pelvic failure detected before or within 3 months of distant failure. Competing risk analyses identified factors predicting increased LF risk. Results: On univariate analysis, pathologic stage ≥pT3, <10 nodes removed, positive margins, positive nodes, hydronephrosis, lymphovascular invasion, and mixed histology significantly predicted LF; node density was marginally predictive, but use of chemotherapy, number of positive nodes, type of surgical diversion, age, gender, race, smoking history, and body mass index were not. On multivariate analysis, only stage ≥pT3 and <10 nodes removed were significant independent LF predictors with hazard ratios of 3.17 and 2.37, respectively (P<.01). Analysis identified 3 patient subgroups with significantly different LF risks: low-risk (≤pT2), intermediate-risk (≥pT3 and ≥10 nodes removed), and high-risk (≥pT3 and <10 nodes) with 5-year LF rates of 8%, 23%, and 42%, respectively (P<.01). Conclusions: This series using routine CT and MRI surveillance to detect LF confirms that such failures are relatively common in

  2. A Novel Risk Stratification to Predict Local-Regional Failures in Urothelial Carcinoma of the Bladder After Radical Cystectomy

    Energy Technology Data Exchange (ETDEWEB)

    Baumann, Brian C. [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania (United States); Guzzo, Thomas J. [Department of Urology, University of Pennsylvania, Philadelphia, Pennsylvania (United States); He Jiwei [Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, Pennsylvania (United States); Keefe, Stephen M. [Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania (United States); Tucker, Kai; Bekelman, Justin E. [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania (United States); Hwang, Wei-Ting [Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, Pennsylvania (United States); Vaughn, David J. [Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania (United States); Malkowicz, S. Bruce [Department of Urology, University of Pennsylvania, Philadelphia, Pennsylvania (United States); Christodouleas, John P., E-mail: [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania (United States)


    Purpose: Local-regional failures (LF) following radical cystectomy (RC) plus pelvic lymph node dissection (PLND) with or without chemotherapy for invasive urothelial bladder carcinoma are more common than previously reported. Adjuvant radiation therapy (RT) could reduce LF but currently has no defined role because of previously reported morbidity. Modern techniques with improved normal tissue sparing have rekindled interest in RT. We assessed the risk of LF and determined those factors that predict recurrence to facilitate patient selection for future adjuvant RT trials. Methods and Materials: From 1990-2008, 442 patients with urothelial bladder carcinoma at University of Pennsylvania were prospectively followed after RC plus PLND with or without chemotherapy with routine pelvic computed tomography (CT) or magnetic resonance imaging (MRI). One hundred thirty (29%) patients received chemotherapy. LF was any pelvic failure detected before or within 3 months of distant failure. Competing risk analyses identified factors predicting increased LF risk. Results: On univariate analysis, pathologic stage {>=}pT3, <10 nodes removed, positive margins, positive nodes, hydronephrosis, lymphovascular invasion, and mixed histology significantly predicted LF; node density was marginally predictive, but use of chemotherapy, number of positive nodes, type of surgical diversion, age, gender, race, smoking history, and body mass index were not. On multivariate analysis, only stage {>=}pT3 and <10 nodes removed were significant independent LF predictors with hazard ratios of 3.17 and 2.37, respectively (P<.01). Analysis identified 3 patient subgroups with significantly different LF risks: low-risk ({<=}pT2), intermediate-risk ({>=}pT3 and {>=}10 nodes removed), and high-risk ({>=}pT3 and <10 nodes) with 5-year LF rates of 8%, 23%, and 42%, respectively (P<.01). Conclusions: This series using routine CT and MRI surveillance to detect LF confirms that such failures are relatively common

  3. Slope earthquake stability

    CERN Document Server

    Changwei, Yang; Jing, Lian; Wenying, Yu; Jianjing, Zhang


    This book begins with the dynamic characteristics of the covering layerbedrock type slope, containing monitoring data of the seismic array, shaking table tests, numerical analysis and theoretical derivation. Then it focuses on the landslide mechanism and assessment method. It also proposes a model that assessing the hazard area based on the field investigations. Many questions, exercises and solutions are given. Researchers and engineers in the field of Geotechnical Engineering and Anti-seismic Engineering can benefit from it.

  4. Logisnet: A tool for multimethod, multiple soil layers slope stability analysis (United States)

    Legorreta Paulin, G.; Bursik, M.


    Shallow landslides and slope failures have been studied from several points of view (inventory, heuristic, statistic, and deterministic). In particular, numerous methods embedded in Geographic Information Systems (GIS) applications have been developed to assess slope stability. However, little work has been done on the systematic comparison of different techniques and the incorporation of vertical contrasts of geotechnical properties in multiple soil layers. In this research, stability is modeled by using LOGISNET, an acronym for Multiple Logistic Regression, Geographic Information System, and Neural Network. The main purpose of LOGISNET is to provide government planners and decision makers a tool to assess landslide susceptibility. The system is fully operational for models handling an enhanced cartographic-hydrologic model (SINMAP) and multiple logistic regression. The enhanced implementation of SINMAP was tested at regional scale in the Highway 101 corridor in Del Norte County, California, and its susceptibility map was found to have improved factor of safety estimates based on comparison with landslide inventory maps. The enhanced SINMAP and multiple logistic regression subsystems have functions that allow the user to include vertical variation in geotechnical properties through summation of forces in specific soil layers acting on failure planes for a local or regional-scale mapping. The working group of LOGISNET foresees the development of an integrated tool system to handle and support the prognostic studies of slope instability, and communicate the results to the public through maps.


    Directory of Open Access Journals (Sweden)

    George Pararas-Carayannis


    Full Text Available The paroxysmal phases of Krakatau's volcanic activity on August 26-27, 1883, included numerous submarine Surtsean (phreatomagmatic eruptions, three sub air Plinian eruptions from the three main craters of Krakatau on Rakata island, followed by a fourth gigantic, sub air, Ultra-Plinian explosion. Landslides, flank failures, subsidences and a multiphase massive caldera collapse of the volcano - beginning near the Perbowetan crater on the northern portion of Rakata and followed by a collapse of the Danan crater - occurred over a period of at least 10 hours. The first of the three violent explosions occurred at 17: 07 Greenwich time (GMT on August 26.The second and third eruptions occurred at 05:30 GMT and at 06:44 GMT on August 27. Each of these events, as well as expanding gases from the submarine phreatomagmatic eruptions, lifted the water surrounding the island into domes or truncated cones that must have been about 100 meters or more in height. The height of the resulting waves attenuated rapidly away from the source because of their short periods and wavelengths. It was the fourth colossal explosion (VEI=6 and the subsequent massive f lank failure and caldera collapse of two thirds of Rakata Island, at 10:02 a.m., on August 27 that generated the most formidable of the destructive tsunami waves. A smaller fifth explosion, which occurred at 10:52 a.m., must have generated another large water cone and sizable waves. The final collapse of a still standing wall of Krakatau - which occurred several hours later at 16:38, generated additional waves.The near field effects of the main tsunami along the Sunda Strait in Western Java and Southern Sumatra, were devastating. Within an hour after the fourth explosion/caldera collapse, waves reaching heights of up to 37 m (120 feet destroyed 295 towns and villages and drowned a total of 36,417 people. Because of their short period and wavelength, the wave heights attenuated rapidly with distance away from the

  6. Failure of lysosome clustering and positioning in the juxtanuclear region in cells deficient in rapsyn (United States)

    Aittaleb, Mohamed; Chen, Po-Ju; Akaaboune, Mohammed


    ABSTRACT Rapsyn, a scaffold protein, is required for the clustering of acetylcholine receptors (AChRs) at contacts between motor neurons and differentiating muscle cells. Rapsyn is also expressed in cells that do not express AChRs. However, its function in these cells remains unknown. Here, we show that rapsyn plays an AChR-independent role in organizing the distribution and mobility of lysosomes. In cells devoid of AChRs, rapsyn selectively induces the clustering of lysosomes at high density in the juxtanuclear region without affecting the distribution of other intracellular organelles. However, when the same cells overexpress AChRs, rapsyn is recruited away from lysosomes to colocalize with AChR clusters on the cell surface. In rapsyn-deficient (Rapsn−/−) myoblasts or cells overexpressing rapsyn mutants, lysosomes are scattered within the cell and highly dynamic. The increased mobility of lysosomes in Rapsn−/− cells is associated with a significant increase in lysosomal exocytosis, as evidenced by increased release of lysosomal enzymes and plasma membrane damage when cells were challenged with the bacterial pore-forming toxin streptolysin-O. These findings uncover a new link between rapsyn, lysosome positioning, exocytosis and plasma membrane integrity. PMID:26330529

  7. Comparing Potential Unstable Sites and Stable Sites on Revegetated Cut-Slopes of Mountainous Terrain in Korea

    Directory of Open Access Journals (Sweden)

    Sung-Ho Kil


    Full Text Available This study employs a diverse set of variables to explain slope stabilization on stable versus failure-prone revegetated cut-slopes in Korea. A field survey was conducted at potential unstable sites and stable sites using 23 variables. Through a non-parametric test of the field survey results, 15 variables were identified as primary determinants of slope failure. Of these variables, one described physical characteristics (elapsed year; four variables described vegetation properties (plant community, vegetation coverage rate, number of trees, and number of herbs; and 10 variables represented soil properties (porosity, soil hardness, water content, sand ratio and silt ratio of soil texture, tensile strength, permeability coefficient, soil depth, soil acidity, salt concentration, and organic matter. Slope angle, which was mainly considered in previous studies, of variables in physical characteristics was not statistically selected as one of the 15 variables because most of sites were located on steep slopes. The vegetation community, vegetation coverage, and number of trees influence slope stabilization. Vegetation coverage is highly correlated with other soil and vegetation variables, making it a major indicator of slope stabilization. All soil variables were related to slope failure such that subsequent slope failure was related to the method of slope revegetation rather than the environmental condition of the slope. Slope failure did not occur in revegetated slopes that matched the characteristics of the surrounding landscape and contained a large number of native trees. Most soil and vegetation variables showed differing values for whether a revegetated slope is potentially unstable or stable.

  8. The Q-Slope Method for Rock Slope Engineering (United States)

    Bar, Neil; Barton, Nick


    Q-slope is an empirical rock slope engineering method for assessing the stability of excavated rock slopes in the field. Intended for use in reinforcement-free road or railway cuttings or in opencast mines, Q-slope allows geotechnical engineers to make potential adjustments to slope angles as rock mass conditions become apparent during construction. Through case studies across Asia, Australia, Central America, and Europe, a simple correlation between Q-slope and long-term stable slopes was established. Q-slope is designed such that it suggests stable, maintenance-free bench-face slope angles of, for instance, 40°-45°, 60°-65°, and 80°-85° with respective Q-slope values of approximately 0.1, 1.0, and 10. Q-slope was developed by supplementing the Q-system which has been extensively used for characterizing rock exposures, drill-core, and tunnels under construction for the last 40 years. The Q' parameters (RQD, J n, J a, and J r) remain unchanged in Q-slope. However, a new method for applying J r/ J a ratios to both sides of potential wedges is used, with relative orientation weightings for each side. The term J w, which is now termed J wice, takes into account long-term exposure to various climatic and environmental conditions such as intense erosive rainfall and ice-wedging effects. Slope-relevant SRF categories for slope surface conditions, stress-strength ratios, and major discontinuities such as faults, weakness zones, or joint swarms have also been incorporated. This paper discusses the applicability of the Q-slope method to slopes ranging from less than 5 m to more than 250 m in height in both civil and mining engineering projects.

  9. Application of Persistent Scatterer Interferometry (PSI) in monitoring slope movements in Nainital, Uttarakhand Lesser Himalaya, India (United States)

    Yhokha, Akano; Goswami, Pradeep K.; Chang, Chung-Pai; Yen, Jiun-Yee; Ching, Kuo-En; Aruche, K. Manini


    Orogenic movements and sub-tropical climate have rendered the slopes of the Himalayan region intensely deformed and weathered. As a result, the incidences of slope failure are quite common all along the Himalayan region. The Lesser Himalayan terrane is particularly vulnerable to mass-movements owing to geological fragility, and many parts of it are bearing a high-risk of associated disaster owing to the high population density. An important step towards mitigation of such disasters is the monitoring of slope movement. Towards this, the Persistent Scatterer Interferometry (PSI) technique can be applied. In the present study, the PSI technique is employed in Lesser Himalayan town of Nainital in Uttarakhand state of India to decipher and monitor slope movements. A total of 15 multi-date ENVISAT ASAR satellite images, acquired during August 2008 to August 2010 period, were subjected to PSI, which revealed a continuous creep movement along the hillslopes located towards the eastern side of the Nainital lake. The higher reaches of the hill seem to be experiencing accelerated creep of {˜ }21 mm/year, which decreases downslope to {˜ }5 mm/year. Based on spatial pattern of varying PSI Mean LOS Velocity (MLV) values, high (H), moderate (M), low (L) and very low (S) creeping zones have been delineated in the hillslopes. Given the long history of mass movements and continuously increasing anthropogenic activities in Nainital, these results call for immediate measures to avert any future disaster in the town.

  10. Some considerations on the seismic stability of large slopes surrounding the nuclear power plant

    International Nuclear Information System (INIS)

    Ito, Hiroshi; Watanabe, Hiroyuki; Imaide, Hiroshi


    As a part of the researches with regard to the seismic stability of large scale slope, the authors have carried out the model test, in which the static failure has been generated by inclining the slope model. In this report, the results of static inclination tests of slope model are described and discussions are done from viewpoints of, 1. the mechanical behaviours and failure state of slope during the inclination test, 2. comparison between the results obtained by the static failure test (that is, inclination test) and those of another report with regard to the dynamic failure test which had been performed using the shaking table, and the relationship between an equivalent seismic coefficient obtained by static failure test and acceleration by dynamic failure test, 3. relationship between the failure state of inclination test and the factor of convensional circular arc slip method. (author)

  11. Effects of grapevine root density and reinforcement on slopes prone to shallow slope instability (United States)

    Meisina, Claudia; Bordoni, Massimiliano; Bischetti, Gianbattista; Vercesi, Alberto; Chiaradia, Enrico; Cislaghi, Alessio; Valentino, Roberto; Bittelli, Marco; Vergani, Chiara; Chersich, Silvia; Giuseppina Persichillo, Maria; Comolli, Roberto


    Slope erosion and shallow slope instabilities are the major factors of soil losses in cultivated steep terrains. These phenomena also cause loss of organic matter and plants nutrients, together with the partial or total destruction of the structures, such as the row tillage pattern of the vineyards, which allow for the plants cultivation. Vegetation has long been used as an effective tool to decrease the susceptibility of a slope to erosion and to shallow landslides. In particular, the scientific research focused on the role played by the plant roots, because the belowground biomass has the major control on the potential development of soil erosion and of shallow failures. Instead, a comprehensive study that analyzes the effects of the roots of agricultural plants on both soil erosion and slope instability has not been carried out yet. This aspect should be fundamental where sloped terrains are cultivated with plants of great economical relevance, as grapevine. To contribute to fill this gap, in this study the features of root density in the soil profile have been analyzed in slopes cultivated with vineyards, located on a sample hilly area of Oltrepò Pavese (northern Italy). In this area, the viticulture is the most important branch of the local economy. Moreover, several events of rainfall-induced slope erosion and shallow landslides have occurred in this area in the last 6 years, causing several economical damages linked to the destruction of the vineyards and the loss of high productivity soils. Grapevine root distribution have been measured in different test-site slopes, representative of the main geological, geomorphological, pedological, landslides distribution, agricultural features, in order to identify particular patterns on root density that can influence the development of slope instabilities. Roots have been sampled in each test-site for characterizing their strength, in terms of the relation between root diameter and root force at rupture. Root

  12. Evaluating a slope-stability model for shallow rain-induced landslides using gage and satellite data (United States)

    Yatheendradas, S.; Kirschbaum, D.; Baum, Rex L.; Godt, Jonathan W.


    Improving prediction of landslide early warning systems requires accurate estimation of the conditions that trigger slope failures. This study tested a slope-stability model for shallow rainfall-induced landslides by utilizing rainfall information from gauge and satellite records. We used the TRIGRS model (Transient Rainfall Infiltration and Grid-based Regional Slope-stability analysis) for simulating the evolution of the factor of safety due to rainfall infiltration. Using a spatial subset of a well-characterized digital landscape from an earlier study, we considered shallow failure on a slope adjoining an urban transportation roadway near the Seattle area in Washington, USA.We ran the TRIGRS model using high-quality rain gage and satellite-based rainfall data from the Tropical Rainfall Measuring Mission (TRMM). Preliminary results with parameterized soil depth values suggest that the steeper slope values in this spatial domain have factor of safety values that are extremely close to the failure limit within an extremely narrow range of values, providing multiple false alarms. When the soil depths were constrained using a back analysis procedure to ensure that slopes were stable under initial condtions, the model accurately predicted the timing and location of the landslide observation without false alarms over time for gage rain data. The TRMM satellite rainfall data did not show adequately retreived rainfall peak magnitudes and accumulation over the study period, and as a result failed to predict the landslide event. These preliminary results indicate that more accurate and higher-resolution rain data (e.g., the upcoming Global Precipitation Measurement (GPM) mission) are required to provide accurate and reliable landslide predictions in ungaged basins.

  13. Tiltmeter Indicates Sense of Slope (United States)

    Lonborg, J. O.


    Tiltmeter indicates sense and magnitude of slope used in locations where incline not visible to operator. Use of direct rather than alternating current greatly simplifies design of instrument capable of indicating sense of slope.

  14. Precursor slope distress leading up to the 2010 Mount Meager landslide, British Columbia (United States)

    Roberti, Gioachino; Ward, Brent; van Wyk de Vries, Benjamin; Friele, Pierre; Clague, John; Perotti, Luigi; Giardino, Marco


    Volcanoes are highly prone to landslides, in part due to erosion of the flanks by glaciers and streams. Mount Meager (British Columbia, Canada) is a glacier-clad volcano that is one of the most landslide-prone areas in Canada, due in part to glacial erosion. In 2010, the south flank of the volcano failed catastrophically, generating one of the largest (˜50 x 106 m 3) landslides in Canadian history. We document the evolution of the edifice up to the time of this failure using an archive of historic aerial photographs spanning the period from 1948 to 2006. Oblique digital photos taken after the landslide yielded information on the geology and internal structure of the volcano. All photos were processed with Structure from Motion (SfM) photogrammetry. We used the SfM products to produce pre-and post-failure geomorphic maps that document glacier and edifice changes. The maps show that a glacier below the 2010 landslide source area re-advanced in the 1980s, then rapidly retreated up to the present. Our photographic reconstruction documents 60 years of progressive development of tension cracks, bulging, and precursor failures (1998, 2009) at the toe of the 2010 failure zone. The final 2010 collapse was conditioned by glacial debuttressing and triggered by hot summer weather accompanied by ice and snow melt. Meltwater increased porewater pressures in fragmented and fractured material at the base of the 2010 failure zone, causing it to mobilize, which in turn triggered several secondary failures controlled by lithology and faults. The landslide retrogressed from the base of the slope to near the peak of Mount Meager and involved basement rock and the overlying volcanic sequence. Elsewhere on the flanks of Mount Meager, large fractures have developed in recently deglaciated areas, conditioning these slopes for collapse and debris avalanches. Potential failures in these areas have larger volumes than the 2010 landslide. Atmospheric warming over the next several decades will

  15. A Hybrid FEM-ANN Approach for Slope Instability Prediction (United States)

    Verma, A. K.; Singh, T. N.; Chauhan, Nikhil Kumar; Sarkar, K.


    Assessment of slope stability is one of the most critical aspects for the life of a slope. In any slope vulnerability appraisal, Factor Of Safety (FOS) is the widely accepted index to understand, how close or far a slope from the failure. In this work, an attempt has been made to simulate a road cut slope in a landslide prone area in Rudrapryag, Uttarakhand, India which lies near Himalayan geodynamic mountain belt. A combination of Finite Element Method (FEM) and Artificial Neural Network (ANN) has been adopted to predict FOS of the slope. In ANN, a three layer, feed- forward back-propagation neural network with one input layer and one hidden layer with three neurons and one output layer has been considered and trained using datasets generated from numerical analysis of the slope and validated with new set of field slope data. Mean absolute percentage error estimated as 1.04 with coefficient of correlation between the FOS of FEM and ANN as 0.973, which indicates that the system is very vigorous and fast to predict FOS for any slope.

  16. A multidisciplinary methodological approach for slope stability assessment of an area prone to shallow landslides (United States)

    Bordoni, Massimiliano; Meisina, Claudia; Valentino, Roberto; Bittelli, Marco; Battista Bischetti, Gian; Vercesi, Alberto; Chersich, Silvia; Giuseppina Persichillo, Maria


    Rainfall-induced shallow landslides are widespread slope instabilities phenomena in several hilly and mountainous contexts all over the world. Due to their high density of diffusion also in small areas, they can provoke important damages to terrains, infrastructures, buildings, and, sometimes, loss of human lives. Shallow landslides affect superficial soils of limited thickness (generally lower than 2 m), located above weathered or not bedrock levels. Their triggering mechanism is strictly linked to the hydrological response of the soils to rainfall events. Thus, it becomes fundamental a comprehensive analysis of the soil properties which can influence the susceptibility of a slope to shallow landslides. In this study, a multidisciplinary approach was followed for the characterization of the soils and the individuation of the triggering conditions in an area particularly prone to shallow failures, for slope stability assessment. This area corresponded to the hilly sector of North-Eastern Oltrepò Pavese (Lombardy Region, Northern Italy), where the density of shallow landslides is really high, reaching more than 36 landslides per km2. The soils of the study area were analyzed through a multidisciplinary characterization, which took into account for the main geotechnical, mechanical and mineralogical parameters and also for the main pedological features of the materials. This approach allowed for identifying the main features and the horizons which could influence the soil behavior in relation to the conditions that are preparatory to shallow landslides development. In a test-site slope, representative of the main geomorphological, geological and landslides distribution characteristics typical of the study area, a continuous in time monitoring of meteorological (rainfall amount, air temperature, air humidity, atmospheric pressure, net solar radiation, wind speed and direction) and hydrological (soil water content, pore water pressure) parameters was implemented. In

  17. Bioengineering case studies sustainable stream bank and slope stabilization

    CERN Document Server

    Goldsmith, Wendi; McCullah, John


    This unique volume describes and evaluates 30 projects from across the United States where bio-stabilization was employed to address a detrimental naturally occurring process or byproduct of the built environment. Bio-stabilization (or soil bioengineering) refers to the use of plant materials, primarily live cuttings, arranged in the ground in different arrays to reinforce soils and protect upland slopes and/or stream banks against surficial erosion and shallow slope failures. Examples included in the collection represent different regions of the country and their specific conditions and challenges. Each project is illustrated with a number of distinctive photographs to support the reader's understanding and showcase the wide scope of projects and techniques presented. This book also: ·         Presents a range of well-documented case studies on key techniques and best practices for bio-stabilization projects ·         Emphasizes evaluation and comparison of different techniques and challeng...

  18. The Alaska North Slope spill analysis

    International Nuclear Information System (INIS)

    Pearson, Leslie; Robertson, Tim L.; DeCola, Elise; Rosen, Ira


    This paper reports Alaska North Slope crude oil spills, provides information to help operators identify risks and presents recommendations for future risk reduction and mitigation measures that may reduce the frequency and severity of future spills from piping infrastructure integrity loss. The North Slope spills analysis project was conducted during 2010 by compiling available spill data, and analyzing the cause of past spills in wells and associated piping, flowlines, process centers with their associated piping and above ground storage tanks, and crude oil transmission pipelines. An expert panel, established to provide independent review of this analysis and the presented data, identified seven recommendations on measures, programs, and practices to monitor and address common causes of failures while considering information provided from regulators and operators. These recommendations must be evaluated by the State of Alaska which will consider implementation options to move forward. Based on the study observations, future analyses may show changes to some of the observed trends.

  19. Sequential biventricular pacing improves regional contractility, longitudinal function and dyssynchrony in patients with heart failure and prolonged QRS

    Directory of Open Access Journals (Sweden)

    Ring Margareta


    Full Text Available Abstract Aims Biventricular pacing (BiP is an effective treatment in systolic heart failure (HF patients with prolonged QRS. However, approximately 35% of the patients receiving BiP are classified as non-responders. The aim of this study is to evaluate the acute effects of VV-optimization on systolic heart function. Methods Twenty-one HF patients aged 72 (46-88 years, QRS 154 (120-190 ms, were studied with echocardiography, Tissue Doppler Imaging (TDI and 3D-echo the first day after receiving a BiP device. TDI was performed; during simultaneous pacing (LV-lead pacing 4 ms before the RV-lead and during sequential pacing (LV 20 and 40 ms before RV and RV 20 and 40 ms before LV-lead pacing. Systolic heart function was studied by tissue tracking (TT for longitudinal function and systolic maximal velocity (SMV for regional contractility and signs of dyssynchrony assessed by time-delays standard deviation of aortic valve opening to SMV, AVO-SMV/SD and tissue synchronization imaging (TSI. Results The TT mean value preoperatively was 4,2 ± 1,5 and increased at simultaneous pacing to 5,0 ± 1,2 mm (p Conclusions VV-optimization in the acute phase improves systolic heart function more than simultaneous BiP pacing. Long-term effects should be evaluated in prospective randomized trials.

  20. Evidence for submarine landslides and continental slope erosion related to fault reactivation during the last glaciation offshore eastern Canada (United States)

    Saint-Ange, F.; Campbell, C.; MacKillop, K.; Mosher, D. C.; Piper, D. J.; Roger, J.


    Many studies have proposed that reactivation of dormant faults during deglaciation is a source of neotectonic activity in glaciated regions, but few have demonstrated the relationship to submarine landslides. In this study, seabed morphology and shallow geology of the outer continental margin adjacent to the Charlie Gibbs Fracture Zone off Newfoundland, Canada was investigated for evidence of this relationship. The glacial history and morphology of the margin suggest that the entire continental shelf in the area, coincident with major continental crustal lineaments, was ice-covered during the Last glacial cycle, and transverse troughs delineate the paleo-icestream drainage patterns. A recent investigation of Notre Dame Trough revealed the existence of large sediment failures on the shelf. The current study investigates complex seafloor erosion and widespread mass transport deposition (MTD) on the continental slope seaward of Notre Dame Trough, using recently-acquired high resolution seismic reflection data and piston cores. The new data reveal that a trough mouth fan (TMF) is present on the slope seaward of Notre Dame Trough. The Notre Dame TMF is characterized by a succession of stacked debris flows, but does not show a lobate shape in plan view like other classic TMFs. Instead, the Notre Dame TMF has abruptly-truncated margins suggesting post-depositional failure and erosion of the fan deposits. Seismic reflection data show that the locations of the failures along the TMF margin are coincident with a set of shallow faults; however the current dataset does not image the deeper portion of the faults. On the upper slope immediately south of the TMF, a narrow and deeply incised canyon is located along-trend with the Notre Dame Trough. The location of this canyon appears to be controlled by a fault. Downslope from this canyon, along the southern margin of the TMF, a 25 km wide, flat-floored, U-shaped valley was eroded into a succession of stacked MTD-filled channels

  1. Assessing slope stability in unplanned settlements in developing countries. (United States)

    Anderson, Malcolm G; Holcombe, Liz; Renaud, Jean-Philippe


    Unplanned housing in developing countries is often located on steep slopes. Frequently no building code is enforced for such housing and mains water is provided with no drainage provision. Both of these factors can be particularly significant in terms of landslide risk if, as is so often the case, such slopes lack any planned drainage provision. There is thus a need to develop a model that facilitates the assessment of slope stability in an holistic context, incorporating a wide range of factors (including surface cover, soil water topographic convergence, slope loading and point source water leakage) in order that appropriate advice can be given as to the general controls on slope stability in such circumstances. This paper outlines a model configured for this specific purpose and describes an application to a site in St. Lucia, West Indies, where there is active slope movement in an unplanned housing development on relatively steep topography. The model findings are in accord with the nature of the current failure at the site, provide guidance as to the significance of slope drainage and correspond to inferences drawn from an application of resistance envelope methods to the site. In being able to scenario test a uniquely wide range of combinations of factors, the model structure is shown to be highly valuable in assessing dominant slope stability process controls in such complex environments.

  2. Mapping on Slope Seepage Problem using Electrical Resistivity Imaging (ERI) (United States)

    Hazreek, Z. A. M.; Nizam, Z. M.; Aziman, M.; Dan, M. F. Md; Shaylinda, M. Z. N.; Faizal, T. B. M.; Aishah, M. A. N.; Ambak, K.; Rosli, S.; Rais, Y.; Ashraf, M. I. M.; Alel, M. N. A.


    The stability of slope may influenced by several factors such as its geomaterial properties, geometry and environmental factors. Problematic slope due to seepage phenomenon will influenced the slope strength thus promoting to its failure. In the past, slope seepage mapping suffer from several limitation due to cost, time and data coverage. Conventional engineering tools to detect or mapped the seepage on slope experienced those problems involving large and high elevation of slope design. As a result, this study introduced geophysical tools for slope seepage mapping based on electrical resistivity method. Two spread lines of electrical resistivity imaging were performed on the slope crest using ABEM SAS 4000 equipment. Data acquisition configuration was based on long and short arrangement, schlumberger array and 2.5 m of equal electrode spacing interval. Raw data obtained from data acquisition was analyzed using RES2DINV software. Both of the resistivity results show that the slope studied consists of three different anomalies representing top soil (200 – 1000 Ωm), perched water (10 – 100 Ωm) and hard/dry layer (> 200 Ωm). It was found that seepage problem on slope studied was derived from perched water zones with electrical resistivity value of 10 – 100 Ωm. Perched water zone has been detected at 6 m depth from the ground level with varying thickness at 5 m and over. Resistivity results have shown some good similarity output with reference to borehole data, geological map and site observation thus verified the resistivity results interpretation. Hence, this study has shown that the electrical resistivity imaging was applicable in slope seepage mapping which consider efficient in term of cost, time, data coverage and sustainability.

  3. 16 determination of posterior tibia slope and slope deterioration

    African Journals Online (AJOL)

    normal slope and mechanical axis of the knee (7). The slope is reported to deepen in osteoarthritis; meaning increased articular surface contact and increased tibial translation (8). Total knee replacement aims to restore the mechanical axis of the natural knee joint. This axis will be changed by an altered PTS; yet after.

  4. Geochemistry of zinc in the sediments of the western continental shelf and slope of India

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, P.S.N.; Paropkari, A.L.; Rao, Ch.M.

    The bulk geochemistry of zinc in the sediments of the western continental shelf and slope of India and also the partition geochemistry of the sediments of the shelf and slope regions between Ratnagiri and Mangalore have been studied. The studies...

  5. US North Slope gas and Asian LNG markets (United States)

    Attanasi, E.D.


    Prospects for export of liquified natural gas (LNG) from Alaska's North Slope are assessed. Projected market conditions to 2010 show that new LNG capacity beyond announced expansions will be needed to meet regional demand and that supplies will probably come from outside the region. The estimated delivered costs of likely suppliers show that Alaska North Slope gas will not be competitive. The alternative North Slope gas development strategies of transport and sale to the lower 48 states and use on the North Slope for either enhanced oil recovery or conversion to liquids are examined. The alternative options require delaying development until US gas prices increase, exhaustion of certain North Slope oil fields, or advances occur in gas to liquid fuels conversion technology. ?? 1995.

  6. Numerical Modelling of Seismic Slope Stability (United States)

    Bourdeau, Céline; Havenith, Hans-Balder; Fleurisson, Jean-Alain; Grandjean, Gilles

    Earthquake ground-motions recorded worldwide have shown that many morphological and geological structures (topography, sedimentary basin) are prone to amplify the seismic shaking (San Fernando, 1971 [Davis and West 1973] Irpinia, 1980 [Del Pezzo et al. 1983]). This phenomenon, called site effects, was again recently observed in El Salvador when, on the 13th of January 2001, the country was struck by a M = 7.6 earthquake. Indeed, while horizontal accelerations on a rock site at Berlin, 80 km from the epicentre, did not exceed 0.23 g, they reached 0.6 g at Armenia, 110 km from the epicentre. Armenia is located on a small hill underlaid by a few meters thick pyroclastic deposits. Both the local topography and the presence of surface layers are likely to have caused the observed amplification effects, which are supposed to have contributed to the triggering of some of the hundreds of landslides related to this seismic event (Murphy et al. 2002). In order to better characterize the way site effects may influence the triggering of landslides along slopes, 2D numerical elastic and elasto-plastic models were developed. Various geometrical, geological and seismic conditions were analysed and the dynamic behaviour of the slope under these con- ditions was studied in terms of creation and location of a sliding surface. Preliminary results suggest that the size of modelled slope failures is dependent on site effects.

  7. Storm-driven delivery of sediment to the continental slope: Numerical modeling for the northern Gulf of Mexico (United States)

    Harris, C. K.; Kniskern, T. A.; Arango, H.


    The supply of sediment from the continental shelf to deeper waters is of critical importance for building continental margin repositories of sediment, and may also factor into episodic events on the continental slope such as turbidity currents and slope failures. While numerical sediment transport models have been developed for coastal and continental shelf areas, they have not often been used to infer sediment delivery to deeper waters. A three-dimensional coupled hydrodynamic - suspended sediment transport model for the northern Gulf of Mexico has been developed and run to evaluate the types of conditions that are associated with delivery of suspended sediment to the continental slope. Accounting for sediment delivery by riverine plumes and for sediment resuspension by energetic waves and currents, the sediment transport calculations were implemented within the Regional Ocean Modeling System (ROMS). The model domain represents the northern Gulf of Mexico shelf and slope including the Mississippi birdfoot delta and the Mississippi and DeSoto Canyons. To investigate the role of storms in driving down-slope sediment fluxes, model runs that encompassed fall, 2007 through late summer, 2008 the summer and fall of 2008 were analyzed. This time period included several winter storms, and the passage of two hurricanes (Ike and Gustav) over the study area. Preliminary results indicated that sediment delivery to the continental slope was triggered by the passage of these storm events, and focused at certain locations, such as submarine canyons. Additionally, a climatological analysis indicates that storm track influences both the wind-driven currents and wave energy on the shelf, and as such plays an important role in determining which storms trigger delivery of suspended continental shelf sediment to the adjacent slope.

  8. 75 FR 65366 - Recovery Policy RP9524.2, Landslides and Slope Stability Related to Public Facilities (United States)


    ...] Recovery Policy RP9524.2, Landslides and Slope Stability Related to Public Facilities AGENCY: Federal... the final Recovery Policy RP9524.2, Landslides and Slope Stability Related to Public Facilities, which... facilities threatened by landslides or slope failures; as well as the eligibility of permanent repairs to...

  9. Slope Hazard and Risk Assessment in the Tropics: Malaysia' Experience (United States)

    Mohamad, Zakaria; Azahari Razak, Khamarrul; Ahmad, Ferdaus; Manap, Mohamad Abdul; Ramli, Zamri; Ahmad, Azhari; Mohamed, Zainab


    The increasing number of geological hazards in Malaysia has often resulted in casualties and extensive devastation with high mitigation cost. Given the destructive capacity and high frequency of disaster, Malaysia has taken a step forward to address the multi-scale landslide risk reduction emphasizing pre-disaster action rather than post-disaster reaction. Slope hazard and risk assessment in a quantitative manner at regional and national scales remains challenging in Malaysia. This paper presents the comprehensive methodology framework and operational needs driven by modern and advanced geospatial technology to address the aforementioned issues in the tropics. The Slope Hazard and Risk Mapping, the first national project in Malaysia utilizing the multi-sensor LIDAR has been critically implemented with the support of multi- and trans-disciplinary partners. The methodological model has been formulated and evaluated given the complexity of risk scenarios in this knowledge driven project. Instability slope problems in the urban, mountainous and tectonic landscape are amongst them, and their spatial information is of crucial for regional landslide assessment. We develop standard procedures with optimal parameterization for susceptibility, hazard and risk assessment in the selected regions. Remarkably, we are aiming at producing an utmost complete landslide inventory in both space and time. With the updated reliable terrain and landscape models, the landslide conditioning factor maps can be accurately derived depending on the landslide types and failure mechanisms which crucial for hazard and risk assessment. We also aim to improve the generation of elements at risk for landslide and promote integrated approaches for a better disaster risk analysis. As a result, a new tool, notably multi-sensor LIDAR technology is a very promising tool for an old geological problem and its derivative data for hazard and risk analysis is an effective preventive measure in Malaysia

  10. SU-D-204-07: Retrospective Correlation of Dose Accuracy with Regions of Local Failure for Early Stage Lung Cancer Patients Treated with Stereotactic Body Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Devpura, S; Li, H; Liu, C; Fraser, C; Ajlouni, M; Movsas, B; Chetty, I [Henry Ford Health System, Detroit, MI (United States)


    Purpose: To correlate dose distributions computed using six algorithms for recurrent early stage non-small cell lung cancer (NSCLC) patients treated with stereotactic body radiotherapy (SBRT), with outcome (local failure). Methods: Of 270 NSCLC patients treated with 12Gyx4, 20 were found to have local recurrence prior to the 2-year time point. These patients were originally planned with 1-D pencil beam (1-D PB) algorithm. 4D imaging was performed to manage tumor motion. Regions of local failures were determined from follow-up PET-CT scans. Follow-up CT images were rigidly fused to the planning CT (pCT), and recurrent tumor volumes (Vrecur) were mapped to the pCT. Dose was recomputed, retrospectively, using five algorithms: 3-D PB, collapsed cone convolution (CCC), anisotropic analytical algorithm (AAA), AcurosXB, and Monte Carlo (MC). Tumor control probability (TCP) was computed using the Marsden model (1,2). Patterns of failure were classified as central, in-field, marginal, and distant for Vrecur ≥95% of prescribed dose, 95–80%, 80–20%, and ≤20%, respectively (3). Results: Average PTV D95 (dose covering 95% of the PTV) for 3-D PB, CCC, AAA, AcurosXB, and MC relative to 1-D PB were 95.3±2.1%, 84.1±7.5%, 84.9±5.7%, 86.3±6.0%, and 85.1±7.0%, respectively. TCP values for 1-D PB, 3-D PB, CCC, AAA, AcurosXB, and MC were 98.5±1.2%, 95.7±3.0, 79.6±16.1%, 79.7±16.5%, 81.1±17.5%, and 78.1±20%, respectively. Patterns of local failures were similar for 1-D and 3D PB plans, which predicted that the majority of failures occur in centraldistal regions, with only ∼15% occurring distantly. However, with convolution/superposition and MC type algorithms, the majority of failures (65%) were predicted to be distant, consistent with the literature. Conclusion: Based on MC and convolution/superposition type algorithms, average PTV D95 and TCP were ∼15% lower than the planned 1-D PB dose calculation. Patterns of failure results suggest that MC and convolution

  11. Effect of hydraulic hysteresis on the stability of infinite slopes under steady infiltration (United States)

    Chen, Pan; Mirus, Benjamin B.; Lu, Ning; Godt, Jonathan W.


    Hydraulic hysteresis, including capillary soil water retention (SWR), air entrapment SWR, and hydraulic conductivity, is a common phenomenon in unsaturated soils. However, the influence of hydraulic hysteresis on suction stress, and subsequently slope stability, is generally ignored. This paper examines the influence of each of these three types of hysteresis on slope stability using an infinite slope stability analysis under steady infiltration conditions. First, hypothetical slopes for representative silty and sandy soils are examined. Then a monitored hillslope in the San Francisco Bay Area, California is assessed, using observed rainfall conditions and measured hydraulic and geotechnical properties of the colluvial soil. Results show that profiles of suction stress and the corresponding factor of safety are generally strongly affected by hydraulic hysteresis. Results suggest that each of the three types of hydraulic hysteresis may play a major role in the occurrence of slope failure, indicating that ignoring hydraulic hysteresis will likely lead to underestimates of failure potential and hence to inaccurate slope stability analysis.


    Directory of Open Access Journals (Sweden)

    M. Rifat KAHYAOĞLU


    Full Text Available Neogene aged units of a densely populated region of Western Turkey along the Aegean Sea coastline is susceptible to landslides causing frequent economic loss especially following raining seasons. Several landslides took place in the area covering a narrow band of the coastline between Izmir and Söke (Aydın. Countermeasures against these relatively small-scale slope failures in the region often involve construction of either reinforced concrete retaining walls or stabilizing piles, which can be easily constructed by local contractors. In this study borings, in-situ and laboratory soil mechanics tests, geophysical and geological investigations have been performed in order to investigate the landslide occurred in the yard of an elementary school in Söke township. The analysis of two rows of piled retaining system constructed to reuse the school building against a potential slides are presented. Three inclinometer measurements have been performed after completion of the bored pile system. It has been concluded that the measured and the calculated displacement values are both small. There is no problem of the built project by means of moments and displacements.

  13. Eros: Shape, topography, and slope processes (United States)

    Thomas, P.C.; Joseph, J.; Carcich, B.; Veverka, J.; Clark, B.E.; Bell, J.F.; Byrd, A.W.; Chomko, R.; Robinson, M.; Murchie, S.; Prockter, L.; Cheng, A.; Izenberg, N.; Malin, M.; Chapman, C.; McFadden, L.A.; Kirk, R.; Gaffey, M.; Lucey, P.G.


    Stereogrammetric measurement of the shape of Eros using images obtained by NEAR's Multispectral Imager provides a survey of the major topographic features and slope processes on this asteroid. This curved asteroid has radii ranging from 3.1 to 17.7 km and a volume of 2535 ?? 20 km3. The center of figure is within 52 m of the center of mass provided by the Navigation team; this minimal difference suggests that there are only modest variations in density or porosity within the asteroid. Three large depressions 10, 8, and 5.3 km across represent different stages of degradation of large impact craters. Slopes on horizontal scales of ???300 m are nearly all less than 35??, although locally scarps are much steeper. The area distribution of slopes is similar to those on Ida, Phobos, and Deimos. Regions that have slopes greater than 25?? have distinct brighter markings and have fewer large ejecta blocks than do flatter areas. The albedo patterns that suggest downslope transport of regolith have sharper boundaries than those on Phobos, Deimos, and Gaspra. The morphology of the albedo patterns, their lack of discrete sources, and their concentration on steeper slopes suggest transport mechanisms different from those on the previously well-observed small bodies, perhaps due to a reduced relative effectiveness of impact gardening on Eros. Regolith is also transported in talus cones and in connected, sinuous paths extending as much as 2 km, with some evident as relatively darker material. Talus material in at least one area is a discrete superposed unit, a feature not resolved on other small bodies. Flat-floored craters that apparently contain ponded material also suggest discrete units that are not well mixed by impacts. ?? 2002 Elsevier Science (USA).

  14. Determination Of Slope Instability Using Spatially Integrated Mapping Framework (United States)

    Baharuddin, I. N. Z.; Omar, R. C.; Roslan, R.; Khalid, N. H. N.; Hanifah, M. I. M.


    The determination and identification of slope instability are often rely on data obtained from in-situ soil investigation work where it involves the logistic of machineries and manpower, thus these aspects may increase the cost especially for remote locations. Therefore a method, which is able to identify possible slope instability without frequent ground walkabout survey, is needed. This paper presents the method used in prediction of slope instability using spatial integrated mapping framework which applicable for remote areas such as tropical forest and natural hilly terrain. Spatial data such as geology, topography, land use map, slope angle and elevation were used in regional analysis during desktop study. Through this framework, the occurrence of slope instability was able to be identified and was validate using a confirmatory site- specific analysis.

  15. Temporal behavior of deep-seated gravitational slope deformations: A review

    Czech Academy of Sciences Publication Activity Database

    Pánek, T.; Klimeš, Jan


    Roč. 156, MAY (2016), s. 14-38 ISSN 0012-8252 Institutional support: RVO:67985891 Keywords : deep-seated gravitational slope deformations * catastrophic slope failures * deformation rates * dating * monitoring Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 7.051, year: 2016

  16. Slope Safety Calculation With A Non-Linear Mohr Criterion Using Finite Element Method

    DEFF Research Database (Denmark)

    Clausen, Johan; Damkilde, Lars


    Safety factors for soil slopes are calculated using a non-linear Mohr envelope. The often used linear Mohr-Coulomb envelope tends to overestimate the safety as the material parameters are usually determined at much higher stress levels, than those present at slope failure. Experimental data...

  17. Characterization of Unstable Rock Slopes Through Passive Seismic Measurements (United States)

    Kleinbrod, U.; Burjanek, J.; Fäh, D.


    Catastrophic rock slope failures have high social impact, causing significant damage to infrastructure and many casualties throughout the world each year. Both detection and characterization of rock instabilities are therefore of key importance. An analysis of ambient vibrations of unstable rock slopes might be a new alternative to the already existing methods, e.g. geotechnical displacement measurements. Systematic measurements have been performed recently in Switzerland to study the seismic response of potential rockslides concerning a broad class of slope failure mechanisms and material conditions. Small aperture seismic arrays were deployed at sites of interest for a short period of time (several hours) in order to record ambient vibrations. Each measurement setup included a reference station, which was installed on a stable part close to the instability. Recorded ground motion is highly directional in the unstable parts of the rock slope, and significantly amplified with respect to stable areas. These effects are strongest at certain frequencies, which were identified as eigenfrequencies of the unstable rock mass. In most cases the directions of maximum amplification are perpendicular to open cracks and in good agreement with the deformation directions obtained by geodetic measurements. Such unique signatures might improve our understanding of slope structure and stability. Thus we link observed vibration characteristics with available results of detailed geological characterization. This is supported by numerical modeling of seismic wave propagation in fractured media with complex topography.For example, a potential relation between eigenfrequencies and unstable rock mass volume is investigated.

  18. Infinite slope stability under steady unsaturated seepage conditions (United States)

    Lu, Ning; Godt, Jonathan W.


    We present a generalized framework for the stability of infinite slopes under steady unsaturated seepage conditions. The analytical framework allows the water table to be located at any depth below the ground surface and variation of soil suction and moisture content above the water table under steady infiltration conditions. The framework also explicitly considers the effect of weathering and porosity increase near the ground surface on changes in the friction angle of the soil. The factor of safety is conceptualized as a function of the depth within the vadose zone and can be reduced to the classical analytical solution for subaerial infinite slopes in the saturated zone. Slope stability analyses with hypothetical sandy and silty soils are conducted to illustrate the effectiveness of the framework. These analyses indicate that for hillslopes of both sandy and silty soils, failure can occur above the water table under steady infiltration conditions, which is consistent with some field observations that cannot be predicted by the classical infinite slope theory. A case study of shallow slope failures of sandy colluvium on steep coastal hillslopes near Seattle, Washington, is presented to examine the predictive utility of the proposed framework.

  19. North Slope (Wahluke Slope) expedited response action cleanup plan

    Energy Technology Data Exchange (ETDEWEB)


    The purpose of this action is to mitigate any threat to public health and the environment from hazards on the North Slope and meet the expedited response action (ERA) objective of cleanup to a degree requiring no further action. The ERA may be the final remediation of the 100-I-3 Operable Unit. A No Action record of decision (ROD) may be issued after remediation completion. The US Department of Energy (DOE) currently owns or administers approximately 140 mi{sup 2} (about 90,000 acres) of land north and east of the Columbia River (referred to as the North Slope) that is part of the Hanford Site. The North Slope, also commonly known as the Wahluke Slope, was not used for plutonium production or support facilities; it was used for military air defense of the Hanford Site and vicinity. The North Slope contained seven antiaircraft gun emplacements and three Nike-Ajax missile positions. These military positions were vacated in 1960--1961 as the defense requirements at Hanford changed. They were demolished in 1974. Prior to government control in 1943, the North Slope was homesteaded. Since the initiation of this ERA in the summer of 1992, DOE signed the modified Hanford Federal Agreement and Consent Order (Tri-Party Agreement) with the Washington Department of Ecology (Ecology) and the US Environmental Protection Agency (EPA), in which a milestone was set to complete remediation activities and a draft closeout report by October 1994. Remediation activities will make the North Slope area available for future non-DOE uses. Thirty-nine sites have undergone limited characterization to determine if significant environmental hazards exist. This plan documents the results of that characterization and evaluates the potential remediation alternatives.

  20. North Slope (Wahluke Slope) expedited response action cleanup plan

    International Nuclear Information System (INIS)


    The purpose of this action is to mitigate any threat to public health and the environment from hazards on the North Slope and meet the expedited response action (ERA) objective of cleanup to a degree requiring no further action. The ERA may be the final remediation of the 100-I-3 Operable Unit. A No Action record of decision (ROD) may be issued after remediation completion. The US Department of Energy (DOE) currently owns or administers approximately 140 mi 2 (about 90,000 acres) of land north and east of the Columbia River (referred to as the North Slope) that is part of the Hanford Site. The North Slope, also commonly known as the Wahluke Slope, was not used for plutonium production or support facilities; it was used for military air defense of the Hanford Site and vicinity. The North Slope contained seven antiaircraft gun emplacements and three Nike-Ajax missile positions. These military positions were vacated in 1960--1961 as the defense requirements at Hanford changed. They were demolished in 1974. Prior to government control in 1943, the North Slope was homesteaded. Since the initiation of this ERA in the summer of 1992, DOE signed the modified Hanford Federal Agreement and Consent Order (Tri-Party Agreement) with the Washington Department of Ecology (Ecology) and the US Environmental Protection Agency (EPA), in which a milestone was set to complete remediation activities and a draft closeout report by October 1994. Remediation activities will make the North Slope area available for future non-DOE uses. Thirty-nine sites have undergone limited characterization to determine if significant environmental hazards exist. This plan documents the results of that characterization and evaluates the potential remediation alternatives

  1. Slope, Scarp and Sea Cliff Instability Susceptibility Mapping for Planning Regulations in Almada County, Portugal (United States)

    Marques, Fernando; Queiroz, Sónia; Gouveia, Luís; Vasconcelos, Manuel


    In Portugal, the modifications introduced in 2008 and 2012 in the National Ecological Reserve law (REN) included the mandatory study of slope instability, including slopes, natural scarps, and sea cliffs, at municipal or regional scale, with the purpose of avoiding the use of hazardous zones with buildings and other structures. The law also indicates specific methods to perform these studies, with different approaches for slope instability, natural scarps and sea cliffs. The methods used to produce the maps required by REN law, with modifications and improvements to the law specified methods, were applied to the 71 km2 territory of Almada County, and included: 1) Slope instability mapping using the statistically based Information Value method validated with the landslide inventory using ROC curves, which provided an AAC=0.964, with the higher susceptibility zones which cover at least 80% of the landslides of the inventory to be included in REN map. The map was object of a generalization process to overcome the inconveniences of the use of a pixel based approach. 2) Natural scarp mapping including setback areas near the top, defined according to the law and setback areas near the toe defined by the application of the shadow angle calibrated with the major rockfalls which occurred in the study area; 3) Sea cliffs mapping including two levels of setback zones near the top, and one setback zone at the cliffs toe, which were based on systematic inventories of cliff failures occurred between 1947 and 2010 in a large scale regional littoral monitoring project. In the paper are described the methods used and the results obtained in this study, which correspond to the final maps of areas to include in REN. The results obtained in this study may be considered as an example of good practice of the municipal authorities in terms of solid, technical and scientifically supported regulation definitions, hazard prevention and safe and sustainable land use management.

  2. A new design equation for drained stability of conical slopes in cohesive-frictional soils

    Directory of Open Access Journals (Sweden)

    Boonchai Ukritchon


    Full Text Available New plasticity solutions to the drained stability of conical slopes in homogeneous cohesive-frictional soils were investigated by axisymmetric finite element limit analysis. Three parameters were studied, i.e. excavated height ratios, slope inclination angles, and soil friction angles. The influences of these parameters on the stability factor and predicted failure mechanism of conical slopes were discussed. A new design equation developed from a nonlinear regression of the lower bound solution was proposed for drained stability analyses of a conical slope in practice. Numerical examples were given to demonstrate a practical application of the proposed equation to stability evaluations of conical slopes with both associated and non-associated flow rules. Keywords: Limit analysis, Slope stability, Conical slope, Unsupported excavation, Cohesive-frictional soils

  3. Eastern slopes grizzly bear project

    Energy Technology Data Exchange (ETDEWEB)



    The cumulative effects of human activities on the grizzly bears in the central Canadian Rockies are not well known. As a result, a project was initiated in 1994 to address the urgent requirement for accurate scientific information on the habitat and populations of grizzly bears in the area of the Banff National Park and Kananaskis Country. This area is probably the most heavily used and developed area where the grizzly still survives. The information gathered throughout the course of this study will be used to better protect and manage the bears and other sensitive carnivores in the region. Using telemetry, researchers are monitoring 25 grizzly bears which were radio-collared in a 22,000 square-kilometer area in the upper Bow Valley drainage of the eastern Alberta slopes. The researchers involved in the project are working with representatives from Husky Oil and Talisman Energy on the sound development of the Moose Mountain oil and gas field without adversely affecting the grizzly bear population. Information collected over seven years indicated that the grizzly bears have few and infrequent offspring. Using the information gathered so far, the location of the Moose Mountain to Jumping Pound pipeline was carefully selected, since the bears recover very slowly from high mortality, and also considering that the food and cover had already been compromised by the high number of roads, trails and other human activities in the area. The status of the population and habitat of the grizzly bear will be assessed upon the conclusion of the field research phase in 2001. Models will be updated using the data obtained during eight years and will assist in the understanding of complex variables that affect grizzly bears.

  4. Slope failure as an upslope source of stream wood (United States)

    Daniel. Miller


    Large woody debris is recognized as an important component of stream geomorphology and stream ecosystem function, and forest-land management is recognized as an important control on the quantity (and size and species distributions) of wood available for recruitment to streams. Much of the wood present in streams comes from adjacent forests, and riparian management...

  5. Acceleration Test Method for Failure Prediction of the End Cap Contact Region of Sodium Cooled Fast Reactor Fuel Rod

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyung-Kyu; Lee, Young-Ho; Lee, Hyun-Seung; Lee, Kang-Hee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)


    This paper reports the results of an acceleration test to predict the contact-induced failure that could occur at the cylinder-to-hole joint for the fuel rod of a sodium-cooled fast reactor (SFR). To incorporate the fuel life of the SFR currently under development at KAERI (around 35,000 h), the acceleration test method of reliability engineering was adopted in this work. A finite element method was used to evaluate the flow-induced vibration frequency and amplitude for the test parameter values. Five specimens were tested. The failure criterion during the life of the SFR fuel was applied. The S-N curve of the HT-9, the material of concern, was used to obtain the acceleration factor. As a result, a test time of 16.5 h was obtained for each specimen. It was concluded that the B{sub 0.004} life would be guaranteed for the SFR fuel rods with 99% confidence if no failure was observed at any of the contact surfaces of the five specimens.

  6. Regional interaction between myocardial sympathetic denervation, contractile dysfunction, and fibrosis in heart failure with preserved ejection fraction: {sup 11}C-hydroxyephedrine PET study

    Energy Technology Data Exchange (ETDEWEB)

    Aikawa, Tadao; Naya, Masanao; Obara, Masahiko [Hokkaido University, Department of Cardiovascular Medicine, Faculty of Medicine and Graduate School of Medicine, Sapporo (Japan); Oyama-Manabe, Noriko [Hokkaido University Hospital, Department of Diagnostic and Interventional Radiology, Sapporo (Japan); Manabe, Osamu [Hokkaido University, Department of Nuclear Medicine, Faculty of Medicine and Graduate School of Medicine, Sapporo (Japan); Magota, Keiichi [Hokkaido University Hospital, Division of Medical Imaging and Technology, Sapporo (Japan); Ito, Yoichi M. [Hokkaido University, Department of Biostatistics, Faculty of Medicine and Graduate School of Medicine, Sapporo (Japan); Katoh, Chietsugu [Hokkaido University, Department of Biomedical Science and Engineering, Faculty of Health Sciences, Sapporo (Japan); Tamaki, Nagara [Kyoto Prefectural University of Medicine, Department of Radiology, Kyoto (Japan)


    This investigation aimed to identify significant predictors of regional sympathetic denervation quantified by {sup 11}C-hydroxyephedrine (HED) positron emission tomography (PET) in patients with heart failure with preserved left ventricular ejection fraction (HFpEF). Included in the study were 34 patients (age 63 ± 15 years, 23 men) with HFpEF (left ventricular ejection fraction ≥40%) and 11 age-matched volunteers without heart failure. Cardiac magnetic resonance imaging was performed to measure left ventricular size and function, and the extent of myocardial late gadolinium enhancement (LGE). {sup 11}C-HED PET was performed to quantify myocardial sympathetic innervation that was expressed as a {sup 11}C-HED retention index (RI, %/min). To identify predictors of regional {sup 11}C-HED RI in HFpEF patients, we propose a multivariate mixed-effects model for repeated measures over segments with an unstructured covariance matrix. Global {sup 11}C-HED RI was significantly lower and more heterogeneous in HFpEF patients than in volunteers (P < 0.01 for all). Regional {sup 11}C-HED RI was correlated positively with systolic wall thickening (r = 0.42, P < 0.001) and negatively with the extent of LGE (r = -0.43, P < 0.001). Segments in HFpEF patients with a large extent of LGE had the lowest regional {sup 11}C-HED RI among all segments (P < 0.001 in post hoc tests). Multivariate analysis demonstrated that systolic wall thickening and the extent of LGE were significant predictors of regional {sup 11}C-HED RI in HFpEF patients (both P ≤ 0.001). Regional sympathetic denervation was associated with contractile dysfunction and fibrotic burden in HFpEF patients, suggesting that regional sympathetic denervation may provide an integrated measure of myocardial damage in HFpEF. (orig.)

  7. Predictors of failure of awake regional anesthesia for neonatal hernia repair: data from the General Anesthesia compared to Spinal anesthesia (GAS) study: comparing apnoea and neurodevelopmental outcomes (United States)

    Frawley, Geoff; Bell, Graham; Disma, Nicola; Withington, Davinia E.; de Graaff, Jurgen C.; Morton, Neil S.; McCann, Mary Ellen; Arnup, Sarah J.; Bagshaw, Oliver; Wolfler, Andrea; Bellinger, David; Davidson, Andrew J.


    Background Awake regional anesthesia (RA) is a viable alternative to general anesthesia (GA) for infants undergoing lower abdominal surgery. Benefits include lower incidence of postoperative apnea and avoidance of anesthetic agents that may increase neuroapoptosis and worsen neurocognitive outcomes. The General Anesthesia compared to Spinal anesthesia (GAS) study compares neurodevelopmental outcomes following awake RA or GA in otherwise healthy infants. Our aim was to describe success and failure rates of RA in this study and report factors associated with failure. Methods This was a nested cohort study within a prospective randomized, controlled, observer blind, equivalence trial. Seven hundred twenty two infants ≤ 60 weeks postmenstrual age, scheduled for herniorrhaphy under anesthesia were randomly assigned to receive RA (spinal, caudal epidural or combined spinal caudal anesthetic) or GA with sevoflurane. The data of 339 infants, where spinal or combined spinal caudal anesthetic was attempted, was analyzed. Possible predictors of failure were assessed including: patient factors, technique, experience of site and anesthetist and type of local anesthetic. Results RA was sufficient for the completion of surgery in 83.2% of patients. Spinal anesthesia was successful in 86.9% of cases and combined spinal caudal anesthetic in 76.1%. Thirty four patients required conversion to GA and an additional 23 (6.8%) required brief sedation. Bloody tap on the first attempt at lumbar puncture was the only risk factor significantly associated with block failure (OR = 2.46). Conclusions The failure rate of spinal anesthesia was low. Variability in application of combined spinal caudal anesthetic limited attempts to compare the success of this technique to spinal alone. PMID:26001028

  8. Potential Risk Assessment of Mountain Torrent Disasters on Sloping Fields in China (United States)

    GAO, X.


    China's sloping fields have the problems of low production and serious soil erosion, and mountain torrent disasters will bring more serious soil and water loss to traditional extensive exploitation of sloping field resources. In this paper, China's sloping fields were classified into three grades, such as slightly steep, steep and very steep grade. According to the geological hazards prevention and control regulation, the historical data of China's mountain torrent disasters were spatially interpolated and divided into five classes, such as extremely low, low, middle, high and extremely high level. And the risk level map of mountain torrents was finished in ArcGIS. By using overlaying analysis on sloping fields and risk level map, the potential risk regionalization map of sloping fields in various slope grades was obtained finally. The results shows that the very steep and steep sloping fields are mainly distributed in the first or second stage terraces in China. With the increase of hazard risk level, the area of sloping fields decreases rapidly and the sloping fields in extremely low and low risk levels of mountain torrents reach 98.9%. With the increase of slope grade, the area of sloping fields in various risk levels also declines sharply. The sloping fields take up approximately 60 65% and 26 30% in slightly steep and steep grade areas separately at different risk level. The risk regionalization map can provide effective information for returning farmland to forests or grassland and reducing water and soil erosion of sloping fields in the future.


    Directory of Open Access Journals (Sweden)

    Ivan Tomašić


    Full Text Available This paper presents an analysis of a complexity of interrelated structural, petrologic and climatic factors that considerably affect the instabilities in the open cast mine of Gradna, near Samobor. The instabilities provoke the slope failures such as slides and slumps of rock material. During the protracted periodical investigations, the relationship among the factors of regional geology, tectonics, structural geology, petrography, engineering geology, rock mechanics and the rock mining technology was observed in the area. The local control of hydrogeologic properties, as well as climatic fluctuations of temperature and precipitation on the slope stability, was also recognized. It turned out that the structural relationships, characteristic of the manifold cataclased dolomite, stimulated the development of local instabilities, particularly during the period of low temperatures affecting the process of ground-water accumulation. When the temperatures are worm, the ground-water circulation is slow, exerting only the small-scale influence on the local instabilities (the paper is published in Croatian.

  10. Virological and immunological failure of HAART and associated risk factors among adults and adolescents in the Tigray region of Northern Ethiopia. (United States)

    Hailu, Genet Gebrehiwet; Hagos, Dawit Gebregziabher; Hagos, Amlsha Kahsay; Wasihun, Araya Gebreyesus; Dejene, Tsehaye Asmelash


    Human immunodeficiency virus/Acquired immunodeficiency syndrome associated morbidity and mortality has reduced significantly since the introduction of highly active antiretroviral therapy. As a result of increasing access to highly active antiretroviral therapy, the survival and quality of life of the patients has significantly improved globally. Despite this promising result, regular monitoring of people on antiretroviral therapy is recommended to ensure whether there is an effective treatment response or not. This study was designed to assess virological and immunological failure of highly active antiretroviral therapy users among adults and adolescents in the Tigray region of Northern Ethiopia, where scanty data are available. A retrospective follow up study was conducted from September 1 to December 30, 2016 to assess the magnitude and factors associated with virological and immunological failure among 260 adults and adolescents highly active antiretroviral therapy users who started first line ART between January 1, 2008 to March 1, 2016. A standardized questionnaire was used to collect socio-demographic and clinical data. SPSS Version21 statistical software was used for analysis. Bivariate and multivariate logistic regression analyses were conducted to identify factors associated to virological and immunological failure. Statistical association was declared significant if p-value was ≤ 0.05. A total of 30 (11.5%) and 17 (6.5%) participants experienced virological and immunological failure respectively in a median time of 36 months of highly active antiretroviral therapy. Virological failure was associated with non-adherence to medications, aged < 40 years old, having CD4+ T-cells count < 250 cells/μL and male gender. Similarly, immunological failure was associated with non-adherence, tuberculosis co-infection and Human immunodeficiency virus RNA ≥1000 copies/mL. The current result shows that immunological and virological failure is a problem in a setting

  11. Rockfall-induced impact force causing a debris flow on a volcanoclastic soil slope: a case study in southern Italy (United States)

    Budetta, P.


    On 10 January 2003, a rockfall of approximately 10 m3 affected a cliff some 25 m high located along the northern slopes of Mt. St. Angelo (Nocera Inferiore, province of Salerno) in the southern Italian region of Campania. The impact of boulders on the lower sector of the slope, along which detrital-pyroclastic soils outcrop, triggered a small channelled debris flow of about 500 m3. Fortunately, no damage nor victims resulted from the landslide. Several marks of the impacts were observed at the cliff toe and outside the collapsed area, and the volumes of some fallen boulders were subsequently measured. By means of in-situ surveys, it was possible to reconstruct the cliff's geo-structural layout in detail. A rockfall back-analysis was subsequently performed along seven critical profiles of the entire slope (surface area of about 4000 m2). The results of this numerical modelling using the lumped-mass method were then used to map the kinetic iso-energy curves. In the triggering area of the debris flow, for a falling boulder of 1 m3, the mean kinetic energy was estimated at 120 kJ, this value being equivalent to an impact force, on an inclined surface, of some 800 kN. After landing, due to the locally high slope gradient (about 45°), and low angle of trajectory at impact (about 23°), some boulders slid down the slope as far as the endpoints. The maximum depth of penetration into the ground by a sliding block was estimated at about 16 cm. Very likely, owing to the high impact force of boulders on the saturated soil slope outcropping at the cliff base, the debris flow was triggered under undrained loading conditions. Initial failure was characterized by a translational slide involving a limited, almost elliptical area where the pyroclastic cover shows greater thickness in comparison with the surrounding areas.

  12. Assessing deep-seated landslide susceptibility using 3-D groundwater and slope-stability analyses, southwestern Seattle, Washington (United States)

    Brien, Dianne L.; Reid, Mark E.


    In Seattle, Washington, deep-seated landslides on bluffs along Puget Sound have historically caused extensive damage to land and structures. These large failures are controlled by three-dimensional (3-D) variations in strength and pore-water pressures. We assess the slope stability of part of southwestern Seattle using a 3-D limit-equilibrium analysis coupled with a 3-D groundwater flow model. Our analyses use a high-resolution digital elevation model (DEM) combined with assignment of strength and hydraulic properties based on geologic units. The hydrogeology of the Seattle area consists of a layer of permeable glacial outwash sand that overlies less permeable glacial lacustrine silty clay. Using a 3-D groundwater model, MODFLOW-2000, we simulate a water table above the less permeable units and calibrate the model to observed conditions. The simulated pore-pressure distribution is then used in a 3-D slope-stability analysis, SCOOPS, to quantify the stability of the coastal bluffs. For wet winter conditions, our analyses predict that the least stable areas are steep hillslopes above Puget Sound, where pore pressures are elevated in the outwash sand. Groundwater flow converges in coastal reentrants, resulting in elevated pore pressures and destabilization of slopes. Regions predicted to be least stable include the areas in or adjacent to three mapped historically active deep-seated landslides. The results of our 3-D analyses differ significantly from a slope map or results from one-dimensional (1-D) analyses.


    Directory of Open Access Journals (Sweden)

    P. E. Miller


    Full Text Available Road and rail networks are essential components of national infrastructures, underpinning the economy, and facilitating the mobility of goods and the human workforce. Earthwork slopes such as cuttings and embankments are primary components, and their reliability is of fundamental importance. However, instability and failure can occur, through processes such as landslides. Monitoring the condition of earthworks is a costly and continuous process for network operators, and currently, geospatial data is largely underutilised. The research presented here addresses this by combining airborne laser scanning and multispectral aerial imagery to develop a methodology for assessing landslide hazard. This is based on the extraction of key slope stability variables from the remotely sensed data. The methodology is implemented through numerical modelling, which is parameterised with the slope stability information, simulated climate conditions, and geotechnical properties. This allows determination of slope stability (expressed through the factor of safety for a range of simulated scenarios. Regression analysis is then performed in order to develop a functional model relating slope stability to the input variables. The remotely sensed raster datasets are robustly re-sampled to two-dimensional cross-sections to facilitate meaningful interpretation of slope behaviour and mapping of landslide hazard. Results are stored in a geodatabase for spatial analysis within a GIS environment. For a test site located in England, UK, results have shown the utility of the approach in deriving practical hazard assessment information. Outcomes were compared to the network operator’s hazard grading data, and show general agreement. The utility of the slope information was also assessed with respect to auto-population of slope geometry, and found to deliver significant improvements over the network operator’s existing field-based approaches.

  14. Assessment of contralateral neck failure in 229 cases of carcinoma of the tonsillar region treated with techniques designed to spare contralateral parotid function

    International Nuclear Information System (INIS)

    O'Sullivan, B.; Warde, P.; Grice, B.; Goh, C.; Keane, T.; Payne, D.; Liu, F-F.; McLean, M.; Waldron, J.; Cummings, B.


    Purpose/Objective: Radiation-induced xerostomia is a frequent cause of morbidity in head and neck cancer patients. To minimize this complication unilateral techniques (UT) designed to treat the primary tumor and ipsilateral neck have been used for many years in selected cases at our institution. Although such techniques exclude the contralateral parotid from the high dose target volume, they also leave the contralateral neck nodes untreated. The purpose of the study was to evaluate the risk of failure in the opposite neck. Materials and Methods: We identified 229 patients treated with UT from a series of 641 cases with carcinoma of the tonsillar region treated with curative intent between 1970 and 1991. Detailed documentation of the tumor, the radiation dosimetry, the sites of failure, and outcome including local, regional, and distant failure, and late complications, were performed. Actuarial 5-year plots were used to calculate local control, regional control, and survival rates. Results: Median age was 61 years (74 females/155 males); median follow-up 8 years (range 6 months to 21 years). AJCC (1992) T categories were T1:73, T2:120, T3:30, T4:6. The N category distribution was: N0:136, N1:53, N2a:29, N2b:8, and N3:8 cases. Base of tongue and palate were involved in 49 and 82 cases respectively. Irradiation techniques consisted of ipsilateral wedge pairs with Cobalt of 6MV photons in 210 cases (92%), while the remainder were electrons with or without photons. Customized compensators were used in the majority of cases in addition to the use of wedge filters. 75% received 50 Gy in 4 weeks, 10% received 60 Gy in 6 weeks, while the remainder received other doses intended to be curative. A radioactive implant was also used in 20 patients. The 5-year actuarial rates were as follows: overall local control: 76%, regional node control: 80%; cause specific survival: 80%. A total of 7 patients manifested regional disease in the opposite neck (crude rate of 3% or 7 of 229

  15. Overpressure, Flow Focusing, Compaction and Slope Stability on the continental slope: Insights from IODP Expedition 308 (United States)

    Flemings, P. B.


    Integrated Ocean Drilling Program Expepedition 308 used direct measurements of pore pressure, analysis of hydromechanical properties, and geological analysis to illuminate how sedimentation, flow focusing, overpressure, and slope stability couple beneath the seafloor on the deepwater continental slope in the Gulf of Mexico. We used pore pressure penetrometers to measure severe overpressures (60% of the difference between lithostatic stress and hydrostatic pressure) that extend from the seafloor for 100’s of meters. We ran uniaxial consolidation experiments on whole core and found that although permeability is relatively high near the seafloor, the sediments are highly compressible. As a result, the coefficient of consolidation (the hydraulic diffusivity) is remarkably constant over a large range of effective stresses. This behavior accounts for the high overpressure that begins near the seafloor and extends to depth. Forward modeling suggests that flow is driven laterally along a permeable unit called the Blue Unit. Calculations suggest that soon after deposition, lateral flow lowered the effective stress and triggered the submarine landslides that we observe. Later in the evolution of this system, overpressure may have pre-conditioned the slope to failure by earthquakes. Results from IODP Expedition 308 illustrate how pore pressure and sedimentation control the large-scale form of continental margins, how submarine landslides form, and provide strategies for designing stable drilling programs.

  16. Evolution of strain localization in variable-width three-dimensional unsaturated laboratory-scale cut slopes (United States)

    Morse, Michael S.; Lu, Ning; Wayllace, Alexandra; Godt, Jonathan W.


    To experimentally validate a recently developed theory for predicting the stability of cut slopes under unsaturated conditions, the authors measured increasing strain localization in unsaturated slope cuts prior to abrupt failure. Cut slope width and moisture content were controlled and varied in a laboratory, and a sliding door that extended the height of the free face of the slope was lowered until the cut slope failed. A particle image velocimetry tool was used to quantify soil displacement in the x-y">x-y (horizontal) and x-z">x-z (vertical) planes, and strain was calculated from the displacement. Areas of maximum strain localization prior to failure were shown to coincide with the location of the eventual failure plane. Experimental failure heights agreed with the recently developed stability theory for unsaturated cut slopes (within 14.3% relative error) for a range of saturation and cut slope widths. A theoretical threshold for sidewall influence on cut slope failures was also proposed to quantify the relationship between normalized sidewall width and critical height. The proposed relationship was consistent with the cut slope experiment results, and is intended for consideration in future geotechnical experiment design. The experimental data of evolution of strain localization presented herein provide a physical basis from which future numerical models of strain localization can be validated.

  17. Comparison of slope stability in two Brazilian municipal landfills. (United States)

    Gharabaghi, B; Singh, M K; Inkratas, C; Fleming, I R; McBean, E


    The implementation of landfill gas to energy (LFGTE) projects has greatly assisted in reducing the greenhouse gases and air pollutants, leading to an improved local air quality and reduced health risks. The majority of cities in developing countries still dispose of their municipal waste in uncontrolled 'open dumps.' Municipal solid waste landfill construction practices and operating procedures in these countries pose a challenge to implementation of LFGTE projects because of concern about damage to the gas collection infrastructure (horizontal headers and vertical wells) caused by minor, relatively shallow slumps and slides within the waste mass. While major slope failures can and have occurred, such failures in most cases have been shown to involve contributory factors or triggers such as high pore pressures, weak foundation soil or failure along weak geosynthetic interfaces. Many researchers who have studied waste mechanics propose that the shear strength of municipal waste is sufficient such that major deep-seated catastrophic failures under most circumstances require such contributory factors. Obviously, evaluation of such potential major failures requires expert analysis by geotechnical specialists with detailed site-specific information regarding foundation soils, interface shearing resistances and pore pressures both within the waste and in clayey barrier layers or foundation soils. The objective of this paper is to evaluate the potential use of very simple stability analyses which can be used to study the potential for slumps and slides within the waste mass and which may represent a significant constraint on construction and development of the landfill, on reclamation and closure and on the feasibility of a LFGTE project. The stability analyses rely on site-specific but simple estimates of the unit weight of waste and the pore pressure conditions and use "generic" published shear strength envelopes for municipal waste. Application of the slope stability

  18. Stability Evaluation of Volcanic Slope Subjected to Rainfall and Freeze-Thaw Action Based on Field Monitoring

    Directory of Open Access Journals (Sweden)

    Shima Kawamura


    Full Text Available Rainfall-induced failures of natural and artificial slopes such as cut slopes, which are subjected to freezing and thawing, have been frequently reported in Hokkaido, Japan. In particular, many failures occur intensively from spring to summer seasons. Despite numerous field studies, explanation of their mechanical behavior based on in situ data has not yet been completely achieved due to the difficulty in grasping failure conditions. This study aims at clarifying the aspects of in-situ volcanic slopes subjected to rainfall and freeze-thaw action. The changes in soil moisture, pore pressure, deformations, and temperatures in the slope were investigated using soil moisture meters, tensiometers, thermocouple sensors, clinometers, settlement gauges, an anemovane, a snow gauge, and a rainfall gauge. The data generated from these measures indicated deformation in the slope examined mainly proceeded during the drainage process according to changes in soil moisture. Based on this data, a prediction method for failures is discussed in detail.

  19. Slope stability and rockfall assessment of volcanic tuffs using RPAS with 2-D FEM slope modelling (United States)

    Török, Ákos; Barsi, Árpád; Bögöly, Gyula; Lovas, Tamás; Somogyi, Árpád; Görög, Péter


    Steep, hardly accessible cliffs of rhyolite tuff in NE Hungary are prone to rockfalls, endangering visitors of a castle. Remote sensing techniques were employed to obtain data on terrain morphology and to provide slope geometry for assessing the stability of these rock walls. A RPAS (Remotely Piloted Aircraft System) was used to collect images which were processed by Pix4D mapper (structure from motion technology) to generate a point cloud and mesh. The georeferencing was made by Global Navigation Satellite System (GNSS) with the use of seven ground control points. The obtained digital surface model (DSM) was processed (vegetation removal) and the derived digital terrain model (DTM) allowed cross sections to be drawn and a joint system to be detected. Joint and discontinuity system was also verified by field measurements. On-site tests as well as laboratory tests provided additional engineering geological data for slope modelling. Stability of cliffs was assessed by 2-D FEM (finite element method). Global analyses of cross sections show that weak intercalating tuff layers may serve as potential slip surfaces. However, at present the greatest hazard is related to planar failure along ENE-WSW joints and to wedge failure. The paper demonstrates that RPAS is a rapid and useful tool for generating a reliable terrain model of hardly accessible cliff faces. It also emphasizes the efficiency of RPAS in rockfall hazard assessment in comparison with other remote sensing techniques such as terrestrial laser scanning (TLS).

  20. Slope stability and rockfall assessment of volcanic tuffs using RPAS with 2-D FEM slope modelling

    Directory of Open Access Journals (Sweden)

    Á. Török


    Full Text Available Steep, hardly accessible cliffs of rhyolite tuff in NE Hungary are prone to rockfalls, endangering visitors of a castle. Remote sensing techniques were employed to obtain data on terrain morphology and to provide slope geometry for assessing the stability of these rock walls. A RPAS (Remotely Piloted Aircraft System was used to collect images which were processed by Pix4D mapper (structure from motion technology to generate a point cloud and mesh. The georeferencing was made by Global Navigation Satellite System (GNSS with the use of seven ground control points. The obtained digital surface model (DSM was processed (vegetation removal and the derived digital terrain model (DTM allowed cross sections to be drawn and a joint system to be detected. Joint and discontinuity system was also verified by field measurements. On-site tests as well as laboratory tests provided additional engineering geological data for slope modelling. Stability of cliffs was assessed by 2-D FEM (finite element method. Global analyses of cross sections show that weak intercalating tuff layers may serve as potential slip surfaces. However, at present the greatest hazard is related to planar failure along ENE–WSW joints and to wedge failure. The paper demonstrates that RPAS is a rapid and useful tool for generating a reliable terrain model of hardly accessible cliff faces. It also emphasizes the efficiency of RPAS in rockfall hazard assessment in comparison with other remote sensing techniques such as terrestrial laser scanning (TLS.

  1. Consequentialism and the slippery slope: a response to Clark. (United States)

    Hughes, J


    Michael Clark has recently argued that the slippery slope argument against voluntary euthanasia is 'entirely consequentialist' and that its use to justify continued prohibition of voluntary euthanasia involves a failure to treat patients who request assistance in ending their lives as ends in themselves. This article argues that in fact the slippery slope is consistent with most forms of deontology, and that it need not involve any violation of the principle that people should be treated as ends, depending upon how that principle is construed. It is concluded that supporters of voluntary euthanasia cannot dismiss the slippery slope argument on the basis of deontological principles but must take seriously the consequences that it postulates and engage in factual argument about their likely extent and about the likely effectiveness of any proposed safeguards.

  2. Case studies of slope stability radar used in coal mines

    Energy Technology Data Exchange (ETDEWEB)

    Noon, D. [GroundProbe Pty Ltd., South Brisbane, Qld. (Australia)


    This paper presents case studies about how the Slope Stability Radar (SSR) system provided adequate warning to safeguard people and equipment prior to highwall and low wall failure at two Australian coal mines. At Drayton mine, the SSR was able to provide the mine with sufficient warning to move the shovel and trucks away from the highwall, while personnel safely watched 50,000 tonnes of bulk material coming down from the wall. At Mt Owen mine, the SSR alarm allowed the mine to evacuate equipment and personnel four hours prior to a 30,000,000 tonne low wall failure. These two case studies demonstrate how the SSR system was able to continuously monitor the stability of these critical slopes, enabling greater mine productivity whilst maintaining the highest quality of safety. 2 refs., 7 figs., 1 tab.

  3. Antecedent topography and morphological controls on sediment accumulation and slope stability of the U.S. Atlantic margin (United States)

    Hill, J. C.; Brothers, D. S.; Ten Brink, U. S.; Andrews, B. D.


    The U.S. Atlantic margin encompasses a wide variety of slope failure processes, ranging from small canyon-confined failures on the upper slope to large, open slope landslides originating in deeper water. Here we used a suite of high-resolution multibeam bathymetry and detailed multichannel seismic data coverage to investigate the relationship between modern seafloor morphology, pre-existing stratigraphy and sediment accumulation patterns. We suggest that a combination of sediment supply and antecedent margin physiography, whereby variations in margin evolution during the Miocene have influenced the modern seafloor morphology, controls both the location of slope sediment accumulation and the style of slope failure. Oversteepened margins with angular shelf breaks and steep upper slopes, referred to as oblique margins, are characterized by downslope mass transport and densely-spaced canyon formation. These margins are most likely the locus of canyon-confined failures and smaller lower slope fan-apron failures (e.g., much of the Mid-Atlantic). Sigmoidal margins with prograded slopes, a rounded shelf edge, and a low gradient slope morphology can support significant sediment accumulation across a broad area, with limited canyon development. These margins are often associated with high sediment supply and are prone to large, upper slope slab-style failures (e.g., the Hudson Apron, southwestern New England, the Currituck and Cape Fear Slide complexes). Areas with morphologies in between these two end members are characterized by limited shelf-edge accommodation space and large-scale lower slope accumulation and onlap, representing transitional stages of equilibrium slope adjustment. Large failures along these intermediate-type margins tend to develop lower on the slope where thick wedges of onlapping sediment are found (e.g., around Washington Canyon, Cape Lookout and southeastern New England). As antecedent topography and sediment loading appear to play an important role

  4. Regional Longitudinal Deformation Improves Prediction of Ventricular Tachyarrhythmias in Patients With Heart Failure With Reduced Ejection Fraction

    DEFF Research Database (Denmark)

    Biering-Sørensen, Tor; Knappe, Dorit; Pouleur, Anne-Catherine


    BACKGROUND: Left ventricular dysfunction is a known predictor of ventricular arrhythmias. We hypothesized that measures of regional longitudinal deformation by speckle-tracking echocardiography predict ventricular tachyarrhythmias and provide incremental prognostic information over clinical...... in the model, only a decreasing myocardial function in the inferior myocardial wall predicted VT/VF (hazard ratio, 1.05 [1.00-1.11]; P=0.039). Only strain obtained from the inferior myocardial wall provided incremental prognostic information for VT/VF over clinical and echocardiographic parameters (C statistic...... 0.71 versus 0.69; P=0.005). CONCLUSIONS: Assessment of regional longitudinal myocardial deformation in the inferior region provided incremental prognostic information over clinical and echocardiographic risk factors in predicting ventricular tachyarrhythmias. CLINICAL TRIAL REGISTRATION: URL: http...

  5. Impact of Rain Water Infiltration on the Stability of Earth Slopes

    Directory of Open Access Journals (Sweden)

    Muhammad Farooq Ahmed


    Full Text Available Slope failure occurs very often in natural and man-made slopes which are subjected to frequent changes in ground water level, rapid drawdown, rainfall and earthquakes. The current study discusses the significance of water infiltration, pore water pressure and degree of saturation that affect the stability of earth slopes. Rainwater infiltration not only mechanically reduces the shear strength of a slope material, but also chemically alters the mineral composition of the soil matrix. It results in the alteration of macro structures which in turn decreases the factor of safety. A few case studies are discussed in this paper to quantitatively observe the variation in factor of safety (FOS of various earth slopes by changing the degree of saturation. The results showed that most of the earth slopes get failed or become critical when the degree of saturation approaches to 50 % or more.

  6. Landform Degradation and Slope Processes on Io: The Galileo View (United States)

    Moore, Jeffrey M.; Sullivan, Robert J.; Chuang, Frank C.; Head, James W., III; McEwen, Alfred S.; Milazzo, Moses P.; Nixon, Brian E.; Pappalardo, Robert T.; Schenk, Paul M.; Turtle, Elizabeth P.; hide


    The Galileo mission has revealed remarkable evidence of mass movement and landform degradation on Io. We recognize four major slope types observed on a number of intermediate resolution (250 m/pixel) images and several additional textures on very high resolution (10 m/pixel) images. Slopes and scarps on Io often show evidence of erosion, seen in the simplest form as alcove-carving slumps and slides at all scales. Many of the mass movement deposits on Io are probably mostly the consequence of block release and brittle slope failure. Sputtering plays no significant role. Sapping as envisioned by McCauley et al. remains viable. We speculate that alcove-lined canyons seen in one observation and lobed deposits seen along the bases of scarps in several locations may reflect the plastic deformation and 'glacial' flow of interstitial volatiles (e.g., SO2) heated by locally high geothermal energy to mobilize the volatile. The appearance of some slopes and near-slope surface textures seen in very high resolution images is consistent with erosion from sublimation-degradation. However, a suitable volatile (e.g., H2S) that can sublimate fast enough to alter Io's youthful surface has not been identified. Disaggregation from chemical decomposition of solid S2O and other polysulfur oxides may conceivably operate on Io. This mechanism could degrade landforms in a manner that resembles degradation from sublimation, and at a rate that can compete with resurfacing.

  7. Physical Analysis Work for Slope Stability at Shah Alam, Selangor (United States)

    Ishak, M. F.; Zaini, M. S. I.


    Slope stability analysis is performed to assess the equilibrium conditions and the safe design of a human-made or natural slope to find the endangered areas. Investigation of potential failure and determination of the slope sensitivity with regard to safety, reliability and economics were parts of this study. Ground anchor is designed to support a structure in this study. Ground anchor were implemented at the Mechanically Stabilized Earth (MSE) wall along Anak Persiaran Jubli Perak to overcome the further cracking of pavement parking, concrete deck and building of the Apartments. A result from the laboratory testing of soil sample such as index test and shear strength test were applied to the Slope/W software with regard to the ground anchors that were implemented. The ground anchors were implemented to increase the value of the factor of safety (FOS) of the MSE Wall. The value of the factor of safety (FOS) before implementing the ground anchor was 0.800 and after the ground anchor was implemented the value increase to 1.555. The increase percentage of factor of safety by implementing on stability of slope was 94.38%.

  8. Effects of slope smoothing in river channel modeling (United States)

    Kim, Kyungmin; Liu, Frank; Hodges, Ben R.


    In extending dynamic river modeling with the 1D Saint-Venant equations from a single reach to a large watershed there are critical questions as to how much bathymetric knowledge is necessary and how it should be represented parsimoniously. The ideal model will include the detail necessary to provide realism, but not include extraneous detail that should not exert a control on a 1D (cross-section averaged) solution. In a Saint-Venant model, the overall complexity of the river channel morphometry is typically abstracted into metrics for the channel slope, cross-sectional area, hydraulic radius, and roughness. In stream segments where cross-section surveys are closely spaced, it is not uncommon to have sharp changes in slope or even negative values (where a positive slope is the downstream direction). However, solving river flow with the Saint-Venant equations requires a degree of smoothness in the equation parameters or the equation set with the directly measured channel slopes may not be Lipschitz continuous. The results of non-smoothness are typically extended computational time to converge solutions (or complete failure to converge) and/or numerical instabilities under transient conditions. We have investigated using cubic splines to smooth the bottom slope and ensure always positive reference slopes within a 1D model. This method has been implemented in the Simulation Program for River Networks (SPRNT) and is compared to the standard HEC-RAS river solver. It is shown that the reformulation of the reference slope is both in keeping with the underlying derivation of the Saint-Venant equations and provides practical numerical stability without altering the realism of the simulation. This research was supported in part by the National Science Foundation under grant number CCF-1331610.

  9. Slope instability in complex 3D topography promoted by convergent 3D groundwater flow (United States)

    Reid, M. E.; Brien, D. L.


    Slope instability in complex topography is generally controlled by the interaction between gravitationally induced stresses, 3D strengths, and 3D pore-fluid pressure fields produced by flowing groundwater. As an example of this complexity, coastal bluffs sculpted by landsliding commonly exhibit a progression of undulating headlands and re-entrants. In this landscape, stresses differ between headlands and re-entrants and 3D groundwater flow varies from vertical rainfall infiltration to lateral groundwater flow on lower permeability layers with subsequent discharge at the curved bluff faces. In plan view, groundwater flow converges in the re-entrant regions. To investigate relative slope instability induced by undulating topography, we couple the USGS 3D limit-equilibrium slope-stability model, SCOOPS, with the USGS 3D groundwater flow model, MODFLOW. By rapidly analyzing the stability of millions of potential failures, the SCOOPS model can determine relative slope stability throughout the 3D domain underlying a digital elevation model (DEM), and it can utilize both fully 3D distributions of pore-water pressure and material strength. The two models are linked by first computing a groundwater-flow field in MODFLOW, and then computing stability in SCOOPS using the pore-pressure field derived from groundwater flow. Using these two models, our analyses of 60m high coastal bluffs in Seattle, Washington showed augmented instability in topographic re-entrants given recharge from a rainy season. Here, increased recharge led to elevated perched water tables with enhanced effects in the re-entrants owing to convergence of groundwater flow. Stability in these areas was reduced about 80% compared to equivalent dry conditions. To further isolate these effects, we examined groundwater flow and stability in hypothetical landscapes composed of uniform and equally spaced, oscillating headlands and re-entrants with differing amplitudes. The landscapes had a constant slope for both

  10. Self-Reported Sleep Duration, Napping, and Incident Heart Failure: Prospective Associations in the British Regional Heart Study. (United States)

    Wannamethee, S Goya; Papacosta, Olia; Lennon, Lucy; Whincup, Peter H


    To examine the associations between self-reported nighttime sleep duration and daytime sleep and incident heart failure (HF) in men with and without preexisting cardiovascular disease (CVD). Population-based prospective study. General practices in 24 British towns. Men aged 60-79 without prevalent HF followed for 9 years (N = 3,723). Information on incident HF cases was obtained from primary care records. Assessment of sleep was based on self-reported sleep duration at night and daytime napping. Self-reported short nighttime sleep duration and daytime sleep of longer than 1 hour were associated with preexisting CVD, breathlessness, depression, poor health, physical inactivity, and manual social class. In all men, self-reported daytime sleep of longer than 1 hour duration was associated with significantly greater risk of HF after adjustment for potential confounders (adjusted hazard ratio (aHR) = 1.69, 95% CI = 1.06-2.71) than in those who reported no daytime napping. Self-reported nighttime sleep duration was not associated with HF risk except in men with preexisting CVD (napping of longer than 1 hour is associated with greater risk of HF in older men. Self-reported short sleep (<6 hours) in men with CVD is associated with particularly high risk of developing HF. © 2016 The Authors. The Journal of the American Geriatrics Society published by Wiley Periodicals, Inc. on behalf of The American Geriatrics Society.

  11. Landslides of Palestinian Region (United States)

    Alwahsh, H.


    Natural disasters are extreme sudden events caused by environmental and natural actors that take away the lives of many thousands of people each year and damage large amount of properties. They strike anywhere on earth, often without any warning. A risk maps of natural disaster are very useful to identify the places that might be adversely affected in the event of natural disaster. The earthquakes are one of natural disaster that have the greatest hazards and will cause loss of life and properties due to damaging the structures of building, dams, bridges. In addition, it will affect local geology and soil conditions. The site effects play an important role in earthquake risk because of its amplification or damping simulation. Another parameter in developing risk map is landslide, which is also one of the most important topics in site effect hazards. Palestine region has been suffering landslide hazards because of the topographical and geological conditions of this region. Most Palestine consists of mountainous area, which has great steep slopes and the type of soil is mainly grayish to yellowish silty clay (Marl Soil). Due to the above mentioned factors many landslides have been occurred from Negev south to the northern borders of Palestine. An example of huge and destruction landslide in a Palestine authority is the landslide in the White Mountain area in the city of Nablus, which occurred in 1997. The geotechnical and geophysical investigation as well as slope stability analysis should be considered in making landslide maps that are necessary to develop risk levels of the natural disaster. Landslides occurred in slopes that are created naturally or by human beings. Failure of soil mass occurs, and hence landslide of soil mass happen due to sliding of soil mass along a plane or curved surface. In general, the slopes become unstable when the shear stresses (driving force) generated in the soil mass exceed the available shearing resistance on the rupture surface

  12. Experimental test of theory for the stability of partially saturated vertical cut slopes (United States)

    Morse, Michael M.; Lu, N.; Wayllace, Alexandra; Godt, Jonathan W.; Take, W.A.


    This paper extends Culmann's vertical-cut analysis to unsaturated soils. To test the extended theory, unsaturated sand was compacted to a uniform porosity and moisture content in a laboratory apparatus. A sliding door that extended the height of the free face of the slope was lowered until the vertical cut failed. Digital images of the slope cross section and upper surface were acquired concurrently. A recently developed particle image velocimetry (PIV) tool was used to quantify soil displacement. The PIV analysis showed strain localization at varying distances from the sliding door prior to failure. The areas of localized strain were coincident with the location of the slope crest after failure. Shear-strength and soil-water-characteristic parameters of the sand were independently tested for use in extended analyses of the vertical-cut stability and of the failure plane angle. Experimental failure heights were within 22.3% of the heights predicted using the extended theory.

  13. Size distributions and failure initiation of submarine and subaerial landslides (United States)

    ten Brink, Uri S.; Barkan, R.; Andrews, B.D.; Chaytor, J.D.


    Landslides are often viewed together with other natural hazards, such as earthquakes and fires, as phenomena whose size distribution obeys an inverse power law. Inverse power law distributions are the result of additive avalanche processes, in which the final size cannot be predicted at the onset of the disturbance. Volume and area distributions of submarine landslides along the U.S. Atlantic continental slope follow a lognormal distribution and not an inverse power law. Using Monte Carlo simulations, we generated area distributions of submarine landslides that show a characteristic size and with few smaller and larger areas, which can be described well by a lognormal distribution. To generate these distributions we assumed that the area of slope failure depends on earthquake magnitude, i.e., that failure occurs simultaneously over the area affected by horizontal ground shaking, and does not cascade from nucleating points. Furthermore, the downslope movement of displaced sediments does not entrain significant amounts of additional material. Our simulations fit well the area distribution of landslide sources along the Atlantic continental margin, if we assume that the slope has been subjected to earthquakes of magnitude ??? 6.3. Regions of submarine landslides, whose area distributions obey inverse power laws, may be controlled by different generation mechanisms, such as the gradual development of fractures in the headwalls of cliffs. The observation of a large number of small subaerial landslides being triggered by a single earthquake is also compatible with the hypothesis that failure occurs simultaneously in many locations within the area affected by ground shaking. Unlike submarine landslides, which are found on large uniformly-dipping slopes, a single large landslide scarp cannot form on land because of the heterogeneous morphology and short slope distances of tectonically-active subaerial regions. However, for a given earthquake magnitude, the total area

  14. Experimental study on slope sliding and debris flow evolution with and without barrier

    Directory of Open Access Journals (Sweden)

    Ji-kun Zhao


    Full Text Available A constitutive model on the evolution of debris flow with and without a barrier was established based on the theory of the Bingham model. A certain area of the Laoshan Mountain in Nanjing, Jiangsu Province, in China was chosen for experimental study, and the slope sliding and debris flow detection system was utilized. The change curve of the soil moisture content was attained, demonstrating that the moisture content of the shallow soil layer increases faster than that of the deep soil layer, and that the growth rate of the soil moisture content of the steep slope is large under the first weak rainfall, and that of the gentle slope is significantly affected by the second heavy rainfall. For the steep slope, slope sliding first occurs on the upper slope surface under heavy rainfall and further develops along the top platform and lower slope surface, while under weak rainfall the soil moisture content at the lower part of the slope first increases because of the high runoff velocity, meaning that failure occurring there is more serious. When a barrier was placed at a high position on a slope, debris flow was separated and distributed early and had less ability to carry solids, and the variation of the greatest depth of erosion pits on soil slopes was not significant.

  15. Regional Lymph Node Uptake of [{sup 18}F]Fluorodeoxyglucose After Definitive Chemoradiation Therapy Predicts Local-Regional Failure of Locally Advanced Non-Small Cell Lung Cancer: Results of ACRIN 6668/RTOG 0235

    Energy Technology Data Exchange (ETDEWEB)

    Markovina, Stephanie [Mallinckrodt Institute of Radiology and Alvin J. Siteman Cancer Center, Washington University School of Medicine, St. Louis, Missouri (United States); Duan, Fenghai [Department of Biostatistics and Center for Statistical Sciences, Brown University School of Public Health, Providence, Rhode Island (United States); Snyder, Bradley S. [Center for Statistical Sciences, Brown University School of Public Health, Providence, Rhode Island (United States); Siegel, Barry A. [Mallinckrodt Institute of Radiology and Alvin J. Siteman Cancer Center, Washington University School of Medicine, St. Louis, Missouri (United States); Machtay, Mitchell [Department of Radiation Oncology, Case Western Reserve University, Cleveland, Ohio (United States); Bradley, Jeffrey D., E-mail: [Mallinckrodt Institute of Radiology and Alvin J. Siteman Cancer Center, Washington University School of Medicine, St. Louis, Missouri (United States)


    Purpose: The American College of Radiology Imaging Network (ACRIN) 6668/Radiation Therapy Oncology Group (RTOG) 0235 study demonstrated that standardized uptake values (SUV) on post-treatment [{sup 18}F]fluorodeoxyglucose-positron emission tomography (FDG-PET) correlated with survival in locally advanced non-small cell lung cancer (NSCLC). This secondary analysis determined whether SUV of regional lymph nodes (RLNs) on post-treatment FDG-PET correlated with patient outcomes. Methods and Materials: Included for analysis were patients treated with concurrent chemoradiation therapy, using radiation doses ≥60 Gy, with identifiable FDG-avid RLNs (distinct from primary tumor) on pretreatment FDG-PET, and post-treatment FDG-PET data. ACRIN core laboratory SUV measurements were used. Event time was calculated from the date of post-treatment FDG-PET. Local-regional failure was defined as failure within the treated RT volume and reported by the treating institution. Statistical analyses included Wilcoxon signed rank test, Kaplan-Meier curves (log rank test), and Cox proportional hazards regression modeling. Results: Of 234 trial-eligible patients, 139 (59%) had uptake in both primary tumor and RLNs on pretreatment FDG-PET and had SUV data from post-treatment FDG-PET. Maximum SUV was greater for primary tumor than for RLNs before treatment (P<.001) but not different post-treatment (P=.320). Post-treatment SUV of RLNs was not associated with overall survival. However, elevated post-treatment SUV of RLNs, both the absolute value and the percentage of residual activity compared to the pretreatment SUV were associated with inferior local-regional control (P<.001). Conclusions: High residual metabolic activity in RLNs on post-treatment FDG-PET is associated with worse local-regional control. Based on these data, future trials evaluating a radiation therapy boost should consider inclusion of both primary tumor and FDG-avid RLNs in the boost volume to maximize local-regional

  16. Regional assessment of seismically induced slope instabilities in the Lorca Basin (Murcia): Implementation of New marks method in a GIS; Evaluacion regional de inestabilidades de ladera por efecto sismico en la Cuenca de Lorca (Murcia): Implementacion del metodo de Newmark en un SIG

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez Peces, M. J.; Garcia Mayordomo, J.; Azanon Hernandez, J. M.; Jabaloy Sanchez, A.


    The Lorca Basin (Murcia, SE Spain) exhibits a high seismic activity because some of the most active faults in Spain have been identified in the surroundings of this basin and there are well known cases of rock-falls associated to specific earthquakes (e.g., Mula 1999, Bullas 2002, La Paca 2005). In this area, we have used a geographic information system (GIS) to develop an implementation for the Newmarks sliding rigid block method at a regional scale. In addition, we have particularly proposed a new small variation of Newmarks method to consider soil and topographic amplification effects. Subsequently, we produce Newmark displacement maps for both deterministic and probabilistic seismic scenarios in the Lorca Basin. The estimation of static safety factor for each pixel of study area has allowed obtaining the critical acceleration (ac) map that represents seismically induced slope instability susceptibility. The obtained Newmark displacement maps allowed us to identify areas with the highest potential seismic hazard as well as interesting areas for future particular studies. The results predict the majority of identified instabilities in previous studies (mainly, rock-falls) and rock-falls associated with specific earthquakes with values of Newmark displacement lower than 2 cm. Larger instabilities and landslides occur with Newmark displacement higher than 2 cm assuming that a great earthquake (Mw=6.7-6.8) take place. (Author)


    Directory of Open Access Journals (Sweden)

    Hüseyin ŞENSOY, Şahin PALTA


    Full Text Available Water is one of the most important erosive forces. A great number of factors also play a role in erosion process and slope characteristic is also one of them. The steepness and length of the slope are important factors for runoff and soil erosion. Another slope factor that has an effect on erosion is the shape of the slope. Generally, different erosion and runoff characteristics exist in different slopes which can be classified as uniform, concave, convex and complex shape. In this study, the effects of slope shape on erosion are stated and emphasized by taking similar researches into consideration.

  18. Influence of filling-drawdown cycles of the Vajont reservoir on Mt. Toc slope stability (United States)

    Paronuzzi, Paolo; Rigo, Elia; Bolla, Alberto


    In the present work, the 1963 Vajont landslide has been back-analyzed in detail to examine the influence of reservoir operations (filling and drawdown) on Mt. Toc slope stability. The combined seepage-slope stability analyses carried out show that the main destabilizing factor that favored the 1963 Vajont landslide was the reservoir-induced water table that formed as a consequence of rapid seepage inflow within the submerged toe of the slope — decrease in the factor of safety (FOS) up to 12% compared to the initial slope stability condition, i.e., in the absence of the Vajont reservoir. Rainfall would only have been a decisive factor if the initial stability condition of the Mt. Toc slope had already been very close to failure (decrease in FOS caused by heavy or prolonged rainfall is about 3-4%, for the worst case scenario analyzed). The permeability of the shear zone material occurring at the base of the prehistoric Vajont rockslide has been evaluated at 5 × 10- 4 m/s, and back-calculated values of the friction angles Φ range from 17.5° to 27.5°. When considering mountain reservoirs, slope failures can occur during both filling and drawdown phases. In the Vajont case, owing to the highly permeable materials of the shear zone, slope stability decreased during filling and increased during drawdown. Another displacement-dependent phenomenon of a mechanical nature - progressive failure of the NE landslide constraint - has to be considered to understand the slope collapse that occurred during the last drawdown (26 September-9 October 1963). The results of the combined seepage-slope stability models indicate that permeability of bank-forming material and filling-drawdown rates of reservoirs can strongly influence slope stability. Slow lowering of the reservoir level is a necessary measure to reduce the occurrence of very dangerous transient negative peaks of FOS.

  19. The Stability Analysis Method of the Cohesive Granular Slope on the Basis of Graph Theory. (United States)

    Guan, Yanpeng; Liu, Xiaoli; Wang, Enzhi; Wang, Sijing


    This paper attempted to provide a method to calculate progressive failure of the cohesivefrictional granular geomaterial and the spatial distribution of the stability of the cohesive granular slope. The methodology can be divided into two parts: the characterization method of macro-contact and the analysis of the slope stability. Based on the graph theory, the vertexes, the edges and the edge sequences are abstracted out to characterize the voids, the particle contact and the macro-contact, respectively, bridging the gap between the mesoscopic and macro scales of granular materials. This paper adopts this characterization method to extract a graph from a granular slope and characterize the macro sliding surface, then the weighted graph is analyzed to calculate the slope safety factor. Each edge has three weights representing the sliding moment, the anti-sliding moment and the braking index of contact-bond, respectively, . The safety factor of the slope is calculated by presupposing a certain number of sliding routes and reducing Weight repeatedly and counting the mesoscopic failure of the edge. It is a kind of slope analysis method from mesoscopic perspective so it can present more detail of the mesoscopic property of the granular slope. In the respect of macro scale, the spatial distribution of the stability of the granular slope is in agreement with the theoretical solution.

  20. Monitoring System for Slope Stability under Rainfall by using MEMS Acceleration Sensor IC tags

    International Nuclear Information System (INIS)

    Murakami, S; Dairaku, A; Komine, H; Saito, O; Sakai, N; Isizawa, T; Maruyama, I


    Real-time warning system for slope failure under rainfall is available to disaster prevention and mitigation. Monitoring of multi-point and wireless measurements is effective because it is difficult to conclude the most dangerous part in a slope. The purpose of this study is to propose a method of monitoring system with multi-point and wireless measurements for a slope stability using MEMS acceleration sensor IC tags. MEMS acceleration sensor IC tag is an acceleration sensor microminiaturized by a technology of Micro Electro Mechanical Systems on board IC tag. Especially, low cost of the sensor will yield to the realization of the system. In order to investigate the applicability of the proposed system, a large-scale model test of artificial slope subjected to rainfall has been performed. MEMS acceleration sensor IC tags has been located on the slope and ground acceleration caused by forced vibration has been measured until the model slope collapses. The experimental results show that the MEMS acceleration sensor IC tag is comfortably available under rainfall, the characteristics of ground accelerations varies with changing the condition of the slope subjected to rainfall, and the proposed method can be applied to a real-time monitoring system for slope failure under rainfall.

  1. Cross-slope Movement Patterns in Landslides (United States)

    Petley, D.; Murphy, W.; Bulmer, M. H.; Keefer, D.


    There is growing evidence that there is a significant element of cross-slope movement in many large landslide systems. These movements may result in changing states of stress between landslide blocks that can establish complex displacement patterns. Such motions, which are not considered in traditional two-dimensional limit-equilibrium analyses, are important in the investigation of a variety of landslide types, such as those triggered by earthquakes. In addition, these movements may introduce considerable errors into the interpretation of strain patterns as derived from InSAR studies. Finally, even traditional interpretation techniques may lead to the amount of total displacement being underestimated. These observations suggest that a three dimensional form of analysis may be more appropriate for large landslide complexes. The significance of such cross-slope movements are being investigated using a detailed investigation of the Lishan landslide complex in Central Taiwan. This landslide system, which was reactivated in 1990 related to the construction of a hotel. The total recorded movements have been approximately 1.5 m over an area of sliding that is estimated to be 450 m wide and 200 m long. Extensive damage has been caused to roads and buildings within the town. Remediation work has resulted largely in the stabilization of the landslide complex. Detailed geomorphological mapping has revealed that the landslide complex is composed of two main components. The first, immediately upslope of the hotel construction site, is a relatively shallow earthflow. The second, which has formed a large headscarp upslope from the main road in the centre of the town, is a deeper translational slide. Both appear to have been reactivations of previous failures. While the displacement patterns of the earthflow indicate a relatively simple downslope movement, the vectors derived from kinematic analysis of surface features have indicated that the movement of the deeper

  2. The Impact of The Energy-time Distribution of The Ms 7.0 Lushan Earthquake on Slope Dynamic Reliability (United States)

    Liu, X.; Griffiths, D.; Tang, H.


    fuzzy failure probability, dynamic reliability index, and dynamic FOS, are obtained utilizing the statistical windows of duration that are extracted according to the characteristics of energy distribution of slope dynamic response. Third, the regional impact of the Lushan earthquake on slope stability was evaluated by the above new method. Two soil slope stability standard test problems were selected to represent homogeneous and heterogeneous soil slopes and were analyzed in the conditions of 123 groups of three-component acceleration records of the Lushan Ms 7.0 earthquake. As a result, the reduction percentage of dynamic FOS in the range covered by the 123 observations were obtained and presented as a contour map. This evaluation shows that the impact of the Lushan earthquake on slope stability generally decreased with distance from the epicenter. However, the reduction rates from the core epicenter area to the outside area in different directions varied due to the influences of the geological structures and other factors. Indeed, the contour map depicting the reduction percentage of slope dynamic FOS in the Longmenshan area can be an important tool in the efforts of earthquake disaster mitigation. In sum, this research provides new ideas and available examples for assessing the area-specific potential risk for earthquake induced slope failures.

  3. Slope Stability Analysis for Shallow Landslides using TRIGRS: A Case Study for Sta. Cruz, Zambales, Philippines (United States)

    Mendoza, J. P. A.


    The Philippines, being located in the circum-Pacific, bounded by multiple subduction zones, open seas and ocean, is one of the most hazard-prone countries in the world (Benson, 1997). This widespread recurrence of natural hazards in the country requires much attention for disaster management (Aurelio, 2006). On the average, 21 typhoons enter the Philippine area of responsibility annually with 6-9 making a landfall. Several rainfall-induced landslide events are reported annually particularly during and after the inundation of major typhoons which imposes hazards to communities and causes destruction of properties due to the moving mass and possible flash floods it may induce. Shallow landslides are the most commonly observed failure involving soil-mantled slopes and are considered major geohazards, often causing property damage and other economic loss. Hence numerous studies on landslide susceptibility including numerical models based on infinite slope equation are used in order to identify slopes prone to occurrences of shallow landslides. The study aims to determine the relationships between the slope and elevation to the factor of safety for laterite-mantled topography by incorporating precipitation values in the determination of landslide susceptibility. Using a DEM, flow direction map and slope map of the Sta Cruz (Zambales, Philippines), the FORTRAN based program TRIGRS, was used to generate the values for the factors of safety in the study area. Overlays with a generated slope map and elevation map were used to determine relationships of the mentioned factors and the factors of safety. A slope in a topography mantled with lateritic soil will fail at a slope angle higher than 20 degrees. Generally, the factor of safety decreases as the slope angle increases; this increases the probability and risk of slope failure. Elevation has no bearing on the computation for the factor of safety. The factor of safety is heavily dependent on the slope angle. The value of

  4. Stability Analysis Method for Rock Slope with an Irregular Shear Plane Based on Interface Model

    Directory of Open Access Journals (Sweden)

    Changqing Qi


    Full Text Available Landslide developed in rock mass usually has irregular shear plane. An approach for calculating distributed factor of safety of the irregular shear plane was put forward in this paper. The presented method can obtain not only the detailed stability status at any grid node of a complex shear plane but also the global safety of the slope. Thus, it is helpful to thoroughly understand the mechanism of slope failure. Comparing with the result obtained through the limit equilibrium method, the presented method was proved to be more accurate and suitable for stability analysis of rock slope with a thin shear plane. The stability of a potentially unstable rock slope was analyzed based on the presented method at the end of this paper. The detailed local stability, global stability, and the potential failure mechanism were provided.

  5. Some considerations on the seismic stability of large slopes surrounding the nuclear power plant

    International Nuclear Information System (INIS)

    Ito, Hiroshi; Watanabe, Hiroyuki


    As a series of the research on the seismic stabilities of a large scale slope surrounding the Nuclear Power Plant, the numerical simulation and analytical stability calculation are conducted in order to clarify the applicability of static stability evaluation method (conventional circular arc slip method, static non-linear F.E. analysis) and dynamic one (2-dimensional dynamic F.E. analysis). The discussions on these slope stability methods are done and the followings are clarified, i) The results of numerical simulation by dynamic F.E. analysis concerning the response property and the failure mode are qualitatively corresponded with the behaviour of dynamic failure test. ii) From the results of static and dynamic stability analysis, it is concluded that the conventional circular arc slip method gives the severest evaluation for slope stability. iii) It is proposed that the seismic coefficient for static slope stability analysis should be used the value of the equivalent instant acceleration. (author)

  6. Radiological monitoring of northern slopes of Mogoltau

    International Nuclear Information System (INIS)

    Murtazaev, Kh.; Boboev, B.D.; Bolibekov, Sh.; Akhmedov, M.Z.


    Present article is devoted to radiological monitoring of northern slopes of Mogoltau. The physicochemical properties of water of northern slopes of Mogoltau were studied. The radiation monitoring of northern slopes of Mogoltau was carried out during several years under various weather conditions. The exposure rate of human settlements of northern part of Mogoltau was defined.

  7. A 5000km2 data set along western Great Bahama Bank illustrates the dynamics of carbonate slope deposition (United States)

    Schnyder, Jara S. D.; Jo, Andrew; Eberli, Gregor P.; Betzler, Christian; Lindhorst, Sebastian; Schiebel, Linda; Hebbeln, Dierk; Wintersteller, Paul; Mulder, Thierry; Principaud, Melanie


    An approximately 5000km2 hydroacoustic and seismic data set provides the high-resolution bathymetry map of along the western slope of Great Bahama Bank, the world's largest isolated carbonate platform. This large data set in combination with core and sediment samples, provides and unprecedented insight into the variability of carbonate slope morphology and the processes affecting the platform margin and the slope. This complete dataset documents how the interplay of platform derived sedimentation, distribution by ocean currents, and local slope and margin failure produce a slope-parallel facies distribution that is not governed by downslope gradients. Platform-derived sediments produce a basinward thinning sediment wedge that is modified by currents that change directions and strength depending on water depth and location. As a result, winnowing and deposition change with water depth and distance from the margin. Morphological features like the plunge pool and migrating antidunes are the result of currents flowing from the banktop, while the ocean currents produce contourites and drifts. These continuous processes are punctuated by submarine slope failures of various sizes. The largest of these slope failures produce several hundred of km2 of mass transport complexes and could generate tsunamis. Closer to the Cuban fold and thrust belt, large margin collapses pose an equal threat for tsunami generation. However, the debris from margin and slope failure is the foundation for a teeming community of cold-water corals.

  8. Model slope infiltration experiments for shallow landslides early warning (United States)

    Damiano, E.; Greco, R.; Guida, A.; Olivares, L.; Picarelli, L.


    Occurrence of fast landslides has become more and more dangerous during the last decades, due to the increased density of settlements, industrial plants and infrastructures. Such problem is particularly worrying in Campania (Southern Italy), where the fast population growth led a diffuse building activity without planning: indeed, recent flowslides caused hundreds of victims and heavy damages to buildings, roads and other infrastructures. Large mountainous areas in Campania are mantled by loose pyroclastic granular soils up to a depth of a few meters from top soil surface. These soils have usually a grain size that falls in the domain of silty sands, including pumice interbeds (gravelly sands), with saturated hydraulic conductivities up to the order of 10-1 cm/min. Such deposits often cover steep slopes, which stability is guaranteed by the apparent cohesion due to suction under unsaturated conditions, that are the most common conditions for these slopes [Olivares and Picarelli, 2001]. Whereas rainfall infiltration causes soil to approach saturation, suction vanishes and slope failure may occur. Besides soil physical properties, landslide triggering is influenced by several factors, such as rainfall intensity, soil initial moisture and suction, slope inclination, boundary conditions. Whereas slope failure occurs with soil close to being saturated, landslide may develop in form of fast and destructive flowslide. Calibration of reliable mathematical models of such a complex phenomenon requires availability of experimental observations of the major variables of interest, such as soil moisture and suction, soil deformation and displacements, pore water pressure, during the entire process of infiltration until slope failure. Due to the sudden trigger and extremely rapid propagation of such type of landslides, such data sets are rarely available for natural slopes where flowslides occurred. As a consequence landslide risk assessment and early warning in Campania rely on

  9. An emerging methodology of slope hazard assessment for natural gas pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Z.J.; O' Neil, G.; Rizkalla, M. [TransCanada PipeLines Ltd., Calgary, AB (Canada)


    A new slope assessment methodology has been developed by TransCanada PipeLines Ltd. in an effort to switch from a reactive to a proactive hazard management approach and to optimize maintenance expenditure. The company operates 37,000 km of natural gas gathering and transmission pipelines, portions of which traverse slopes and stream crossings. The newly developed rainfall-ground movement model provides site-specific ground movement predictions for approximately 1100 slopes and establishes a risk-ranked list of slopes upon which maintenance decisions can be based. The input to the predictive model is derived from internal and public information regarding site conditions. This information serves as input to a pipe-soil interaction model to determine the probability of pipeline failure for each slope. The ground movement for this model is limited to creep-type which is typically less than 100 mm per year. Landslides are not addressed in this paper. A system-wide database has been constructed for slopes to prioritize the slope movement hazards. The slope information includes geotechnical data such as bedrock geology, surficial geology, slope details, precipitation and erosion potential. Information related to the pipeline includes the location, age, size, as well as design pressure and temperature. 13 refs., 2 figs.

  10. A nomogram for interpreting slope stability of fine-grained deposits in modern and ancient-marine environments. (United States)

    Booth, J.S.; Sangrey, D.A.; Fugate, J.K.


    This nomogram was designed to aid in interpreting the causes of mass movement in modern and ancient settings, to provide a basis for evaluating and predicting slope stability under given conditions and to further the understanding of the relationships among the several key factors that control slope stability. Design of the nomogram is based on effective stress and combines consolidation theory as applicable to depositional environments with the infinite-slope model of slope-stability analysis. If infinite-slope conditions are assumed to exist, the effective overburden stress can be used to derive a factor of safety against static slope failure by using the angle of internal friction and the slope angle. -from Authors

  11. Effect of variations in rainfall intensity on slope stability in Singapore


    Christofer Kristo; Harianto Rahardjo; Alfrendo Satyanaga


    Numerous scientific evidence has given credence to the true existence and deleterious impacts of climate change. One aspect of climate change is the variations in rainfall patterns, which affect the flux boundary condition across ground surface. A possible disastrous consequence of this change is the occurrence of rainfall-induced slope failures. This paper aims to investigate the variations in rainfall patterns in Singapore and its effect on slope stability. Singapore's historical rainfall d...

  12. Comparison study between traditional and finite element methods for slopes under heavy rainfall

    Directory of Open Access Journals (Sweden)

    M. Rabie


    Moreover, slope stability concerning rainfall and infiltration is analyzed. Specially, two kinds of infiltrations (saturated and unsaturated are considered. Many slopes become saturated during periods of intense rainfall or snowmelt, with the water table rising to the ground surface, and water flowing essentially parallel to the direction of the “slope” and “Influence” of the change in shear strength, density, pore-water pressure and seepage force in soil slices on the slope stability is explained. Finally, it is found that classical limit equilibrium methods are highly conservative compared to the finite element approach. For assessment the factor of safety for slope using the later technique, no assumption needs to be made in advance about the shape or location of the failure surface, slice side forces and their directions. This document outlines the capabilities of the finite element method in the analysis of slope stability problems.

  13. The Use of Ground Penetrating Radar and Electrical Resistivity Imaging for the Characterisation of Slope Movements in Expansive Marls (United States)

    Rey, Isabel; Martínez, Julián; Cortada, Unai; Hildago, Mª Carmen


    Slope movements are one of the natural hazards that most affect linear projects, becoming an important waste of money and time for building companies. Thus, studies to identify the processes that provoke these movements, as well as to characterise the landslides are necessary. For this purpose, geophysical prospecting techniques as Ground Penetrating Radar (GPR) and Electrical Resistivity Imaging (ERI) could become useful. However, the effectiveness of these techniques in slope movement characterisation is affected by many factors, like soil humidity, grain size or failure plane depth. Therefore, studies that determine the usefulness of these techniques in different kind of soils and slope movements are required. In this study, GPR and ERI techniques efficiency for the analysis of slope movements in Upper Miocene expansive marls was evaluated. In particular, two landslides in an old regional road in the province of Jaen (Spain) were studied. A total of 53 GPR profiles were made, 31 with a 250 MHz frequency antenna and 22 with an 800 MHz frequency antenna. Marl facies rapidly attenuated the signal of the electromagnetic waves, which means that this technique only provided information of the first two meters of the subsoil. In spite of this low depth of penetration, it is necessary to point out the precision and detail undertaken. Thus, both GPR antennas gave information of the thicknesses and quality-continuity of the different soil layers. In addition, several restoration phases of the linear work were detected. Therefore, this technique was useful to detect the current state and history of the structure, even though it could not detect the shear surface of the slope movement. On the other hand, two profiles of electrical tomography were made, one in each studied sector. The profiles were configured with a total length of 189 m, with 64 electrodes and a spacing of 3 m. This allowed investigating up to 35 m depth. This penetration capability enabled to detect the

  14. Spatial distribution models of erosion on slopes cultivated with vineyards

    International Nuclear Information System (INIS)

    Armaez, J.; Ortigosa, L.; Ruiz-Falno, P.; Llorente, J. A.; Lasanta, T.


    Soils cultivated with vineyards have high rates of erosion. In the Mediterranean area, this is related to the environmental characteristics and the management of cultivation techniques. Indeed, in this region the rainfall intensity and the location of vineyards on slopes favour the erosive activity of runoff. The total area of vineyards in La Rioja (Spain) is currently almost 40,000 ha. Vineyards are located on hillsides between 400 and 60 m.a.s.l. Of the vineyards of La Rioja 81,7% are planted on slopes with a gradient between 3 degree centigrade and 9 degree centigrade. (Author) 5 refs.

  15. Instability risk assessment of construction waste pile slope based on fuzzy entropy (United States)

    Ma, Yong; Xing, Huige; Yang, Mao; Nie, Tingting


    Considering the nature and characteristics of construction waste piles, this paper analyzed the factors affecting the stability of the slope of construction waste piles, and established the system of the assessment indexes for the slope failure risks of construction waste piles. Based on the basic principles and methods of fuzzy mathematics, the factor set and the remark set were established. The membership grade of continuous factor indexes is determined using the "ridge row distribution" function, while that for the discrete factor indexes was determined by the Delphi Method. For the weight of factors, the subjective weight was determined by the Analytic Hierarchy Process (AHP) and objective weight by the entropy weight method. And the distance function was introduced to determine the combination coefficient. This paper established a fuzzy comprehensive assessment model of slope failure risks of construction waste piles, and assessed pile slopes in the two dimensions of hazard and vulnerability. The root mean square of the hazard assessment result and vulnerability assessment result was the final assessment result. The paper then used a certain construction waste pile slope as the example for analysis, assessed the risks of the four stages of a landfill, verified the assessment model and analyzed the slope's failure risks and preventive measures against a slide.

  16. Numerical modelling of hydrologically-driven slope instability by means of porous media mechanics (United States)

    Kakogiannou, Evanthia; Sanavia, Lorenzo; Lora, Marco; Schrefler, Bernhard


    Heavy rainfall can trigger slope failure which generally involves shallow soil deposit of different grading and origin usually in a state of partial saturation. In this case of slope instability, the behaviour of the soil slope is closely related not only to the distribution of pore-water pressure but also to the stress state during rainfall infiltration involving both mechanical and hydrological processes. In order to understand better these physical key processes, in this research work, the modelling of rainfall induced slope failure is considered as a coupled variably saturated hydro-mechanical problem. Therefore, the geometrically linear finite element code Comes-Geo for non-isothermal elasto-plastic multiphase solid porous materials is used, as developed by B.A. Schrefler and his co-workers. In this context, a detailed numerical analysis of an experimental slope stability test due to rainfall infiltration is presented. The main goals of this work are to understand the triggering mechanisms during the progressive failure, the effect of using different constitutive models of the mechanical soil behavior on the numerical results and the use of the second order work criterion on the detection of slope instability.

  17. Time-dependent evolution of rock slopes by a multi-modelling approach (United States)

    Bozzano, F.; Della Seta, M.; Martino, S.


    This paper presents a multi-modelling approach that incorporates contributions from morpho-evolutionary modelling, detailed engineering-geological modelling and time-dependent stress-strain numerical modelling to analyse the rheological evolution of a river valley slope over approximately 102 kyr. The slope is located in a transient, tectonically active landscape in southwestern Tyrrhenian Calabria (Italy), where gravitational processes drive failures in rock slopes. Constraints on the valley profile development were provided by a morpho-evolutionary model based on the correlation of marine and river strath terraces. Rock mass classes were identified through geomechanical parameters that were derived from engineering-geological surveys and outputs of a multi-sensor slope monitoring system. The rock mass classes were associated to lithotechnical units to obtain a high-resolution engineering-geological model along a cross section of the valley. Time-dependent stress-strain numerical modelling reproduced the main morpho-evolutionary stages of the valley slopes. The findings demonstrate that a complex combination of eustatism, uplift and Mass Rock Creep (MRC) deformations can lead to first-time failures of rock slopes when unstable conditions are encountered up to the generation of stress-controlled shear zones. The multi-modelling approach enabled us to determine that such complex combinations may have been sufficient for the first-time failure of the S. Giovanni slope at approximately 140 ka (MIS 7), even without invoking any trigger. Conversely, further reactivations of the landslide must be related to triggers such as earthquakes, rainfall and anthropogenic activities. This failure involved a portion of the slope where a plasticity zone resulted from mass rock creep that evolved with a maximum strain rate of 40% per thousand years, after the formation of a river strath terrace. This study demonstrates that the multi-modelling approach presented herein is a useful

  18. Slope Safety Factor Calculations With Non-Linear Yield Criterion Using Finite Elements

    DEFF Research Database (Denmark)

    Clausen, Johan; Damkilde, Lars


    The factor of safety for a slope is calculated with the finite element method using a non-linear yield criterion of the Hoek-Brown type. The parameters of the Hoek-Brown criterion are found from triaxial test data. Parameters of the linear Mohr-Coulomb criterion are calibrated to the same triaxial...... are carried out at much higher stress levels than present in a slope failure, this leads to the conclusion that the use of the non-linear criterion leads to a safer slope design...

  19. Regional Lymph Node Uptake of ["1"8F]Fluorodeoxyglucose After Definitive Chemoradiation Therapy Predicts Local-Regional Failure of Locally Advanced Non-Small Cell Lung Cancer: Results of ACRIN 6668/RTOG 0235

    International Nuclear Information System (INIS)

    Markovina, Stephanie; Duan, Fenghai; Snyder, Bradley S.; Siegel, Barry A.; Machtay, Mitchell; Bradley, Jeffrey D.


    Purpose: The American College of Radiology Imaging Network (ACRIN) 6668/Radiation Therapy Oncology Group (RTOG) 0235 study demonstrated that standardized uptake values (SUV) on post-treatment ["1"8F]fluorodeoxyglucose-positron emission tomography (FDG-PET) correlated with survival in locally advanced non-small cell lung cancer (NSCLC). This secondary analysis determined whether SUV of regional lymph nodes (RLNs) on post-treatment FDG-PET correlated with patient outcomes. Methods and Materials: Included for analysis were patients treated with concurrent chemoradiation therapy, using radiation doses ≥60 Gy, with identifiable FDG-avid RLNs (distinct from primary tumor) on pretreatment FDG-PET, and post-treatment FDG-PET data. ACRIN core laboratory SUV measurements were used. Event time was calculated from the date of post-treatment FDG-PET. Local-regional failure was defined as failure within the treated RT volume and reported by the treating institution. Statistical analyses included Wilcoxon signed rank test, Kaplan-Meier curves (log rank test), and Cox proportional hazards regression modeling. Results: Of 234 trial-eligible patients, 139 (59%) had uptake in both primary tumor and RLNs on pretreatment FDG-PET and had SUV data from post-treatment FDG-PET. Maximum SUV was greater for primary tumor than for RLNs before treatment (P<.001) but not different post-treatment (P=.320). Post-treatment SUV of RLNs was not associated with overall survival. However, elevated post-treatment SUV of RLNs, both the absolute value and the percentage of residual activity compared to the pretreatment SUV were associated with inferior local-regional control (P<.001). Conclusions: High residual metabolic activity in RLNs on post-treatment FDG-PET is associated with worse local-regional control. Based on these data, future trials evaluating a radiation therapy boost should consider inclusion of both primary tumor and FDG-avid RLNs in the boost volume to maximize local-regional control.

  20. Current measurements collected at three moorings deployed across the Chukchi continental slope west of the Chukchi Rise in the Chukchi Borderland region to measure the Arctic Ocean boundary current, 2002-08 to 2002-09 (NODC Accession 0002693) (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A 35-day NSF-sponsored cruise aboard the USCGC Polar Star has studied in depth the physical oceanography of the Chukchi Borderland and Mendeleev Ridge regions. An...

  1. Using Controlled Landslide Initiation Experiments to Test Limit-Equilibrium Analyses of Slope Stability (United States)

    Reid, M. E.; Iverson, R. M.; Brien, D. L.; Iverson, N. R.; Lahusen, R. G.; Logan, M.


    Most studies of landslide initiation employ limit equilibrium analyses of slope stability. Owing to a lack of detailed data, however, few studies have tested limit-equilibrium predictions against physical measurements of slope failure. We have conducted a series of field-scale, highly controlled landslide initiation experiments at the USGS debris-flow flume in Oregon; these experiments provide exceptional data to test limit equilibrium methods. In each of seven experiments, we attempted to induce failure in a 0.65m thick, 2m wide, 6m3 prism of loamy sand placed behind a retaining wall in the 31° sloping flume. We systematically investigated triggering of sliding by groundwater injection, by prolonged moderate-intensity sprinkling, and by bursts of high intensity sprinkling. We also used vibratory compaction to control soil porosity and thereby investigate differences in failure behavior of dense and loose soils. About 50 sensors were monitored at 20 Hz during the experiments, including nests of tiltmeters buried at 7 cm spacing to define subsurface failure geometry, and nests of tensiometers and pore-pressure sensors to define evolving pore-pressure fields. In addition, we performed ancillary laboratory tests to measure soil porosity, shear strength, hydraulic conductivity, and compressibility. In loose soils (porosity of 0.52 to 0.55), abrupt failure typically occurred along the flume bed after substantial soil deformation. In denser soils (porosity of 0.41 to 0.44), gradual failure occurred within the soil prism. All failure surfaces had a maximum length to depth ratio of about 7. In even denser soil (porosity of 0.39), we could not induce failure by sprinkling. The internal friction angle of the soils varied from 28° to 40° with decreasing porosity. We analyzed stability at failure, given the observed pore-pressure conditions just prior to large movement, using a 1-D infinite-slope method and a more complete 2-D Janbu method. Each method provides a static

  2. Forecasting giant, catastrophic slope collapse: lessons from Vajont, Northern Italy (United States)

    Kilburn, Christopher R. J.; Petley, David N.


    Rapid, giant landslides, or sturzstroms, are among the most powerful natural hazards on Earth. They have minimum volumes of ˜10 6-10 7 m 3 and, normally preceded by prolonged intervals of accelerating creep, are produced by catastrophic and deep-seated slope collapse (loads ˜1-10 MPa). Conventional analyses attribute rapid collapse to unusual mechanisms, such as the vaporization of ground water during sliding. Here, catastrophic collapse is related to self-accelerating rock fracture, common in crustal rocks at loads ˜1-10 MPa and readily catalysed by circulating fluids. Fracturing produces an abrupt drop in resisting stress. Measured stress drops in crustal rock account for minimum sturzstrom volumes and rapid collapse accelerations. Fracturing also provides a physical basis for quantitatively forecasting catastrophic slope failure.

  3. Mars Climate History: Insights From Impact Crater Wall Slope Statistics (United States)

    Kreslavsky, Mikhail A.; Head, James W.


    We use the global distribution of the steepest slopes on crater walls derived from Mars Orbiter Laser Altimeter profile data to assess the magnitudes of degradational processes with latitude, altitude, and time. We independently confirm that Amazonian polar/high-latitude crater slope modification is substantial, but that craters in the low latitudes have essentially escaped significant slope modification since the Early Hesperian. We find that the total amount of crater wall degradation in the Late Noachian is very small in comparison to the circumpolar regions in the Late Amazonian, an observation that we interpret to mean that the Late Noachian climate was not characterized by persistent and continuous warm and wet conditions. A confirmed elevational zonality in degradation in the Early Hesperian is interpreted to mean that the atmosphere was denser than today.

  4. Stability of infinite slopes under transient partially saturated seepage conditions (United States)

    Godt, Jonathan W.; ŞEner-Kaya, BaşAk; Lu, Ning; Baum, Rex L.


    Prediction of the location and timing of rainfall-induced shallow landslides is desired by organizations responsible for hazard management and warnings. However, hydrologic and mechanical processes in the vadose zone complicate such predictions. Infiltrating rainfall must typically pass through an unsaturated layer before reaching the irregular and usually discontinuous shallow water table. This process is dynamic and a function of precipitation intensity and duration, the initial moisture conditions and hydrologic properties of the hillside materials, and the geometry, stratigraphy, and vegetation of the hillslope. As a result, pore water pressures, volumetric water content, effective stress, and thus the propensity for landsliding vary over seasonal and shorter time scales. We apply a general framework for assessing the stability of infinite slopes under transient variably saturated conditions. The framework includes profiles of pressure head and volumetric water content combined with a general effective stress for slope stability analysis. The general effective stress, or suction stress, provides a means for rigorous quantification of stress changes due to rainfall and infiltration and thus the analysis of slope stability over the range of volumetric water contents and pressure heads relevant to shallow landslide initiation. We present results using an analytical solution for transient infiltration for a range of soil texture and hydrological properties typical of landslide-prone hillslopes and show the effect of these properties on the timing and depth of slope failure. We follow by analyzing field-monitoring data acquired prior to shallow landslide failure of a hillside near Seattle, Washington, and show that the timing of the slide was predictable using measured pressure head and volumetric water content and show how the approach can be used in a forward manner using a numerical model for transient infiltration.

  5. Respiratory Failure (United States)

    Respiratory failure happens when not enough oxygen passes from your lungs into your blood. Your body's organs, ... brain, need oxygen-rich blood to work well. Respiratory failure also can happen if your lungs can' ...

  6. Heart Failure (United States)

    Heart failure is a condition in which the heart can't pump enough blood to meet the body's needs. Heart failure does not mean that your heart has stopped ... and shortness of breath Common causes of heart failure are coronary artery disease, high blood pressure and ...

  7. Analysis of rainfall-induced slope instability using a field of local factor of safety (United States)

    Lu, Ning; Şener-Kaya, Başak; Wayllace, Alexandra; Godt, Jonathan W.


    Slope-stability analyses are mostly conducted by identifying or assuming a potential failure surface and assessing the factor of safety (FS) of that surface. This approach of assigning a single FS to a potentially unstable slope provides little insight on where the failure initiates or the ultimate geometry and location of a landslide rupture surface. We describe a method to quantify a scalar field of FS based on the concept of the Coulomb stress and the shift in the state of stress toward failure that results from rainfall infiltration. The FS at each point within a hillslope is called the local factor of safety (LFS) and is defined as the ratio of the Coulomb stress at the current state of stress to the Coulomb stress of the potential failure state under the Mohr-Coulomb criterion. Comparative assessment with limit-equilibrium and hybrid finite element limit-equilibrium methods show that the proposed LFS is consistent with these approaches and yields additional insight into the geometry and location of the potential failure surface and how instability may initiate and evolve with changes in pore water conditions. Quantitative assessments applying the new LFS field method to slopes under infiltration conditions demonstrate that the LFS has the potential to overcome several major limitations in the classical FS methodologies such as the shape of the failure surface and the inherent underestimation of slope instability. Comparison with infinite-slope methods, including a recent extension to variably saturated conditions, shows further enhancement in assessing shallow landslide occurrence using the LFS methodology. Although we use only a linear elastic solution for the state of stress with no post-failure analysis that require more sophisticated elastoplastic or other theories, the LFS provides a new means to quantify the potential instability zones in hillslopes under variably saturated conditions using stress-field based methods.

  8. Aspect-Driven Changes in Slope Stability Due to Ecohydrologic Feedbacks (United States)

    Poulos, M. J.; Pierce, J. L.; Flores, A. N.; Benner, S. G.; Smith, T. J.; McNamara, J. P.


    Seasonally integrated variation in insolation drives feedbacks among evapotranspiration, soil moisture, weathering, and erosion that lead to pronounced contrasts in slope angles and vegetation on north and south-facing hillslopes. Spatial variations in insolation associated with north-south contrasts in topographic aspect leads to corresponding variation in local microclimates and ecohydrologic regimes that, in turn, impact spatial patterns of weathering and erosion, ultimately impacting slope angles on north and south-facing slopes. Aspect-sensitive environments appear to be poised on a balance point between ecohydrologic systems, and may be especially susceptible to climate change. In the semi-arid Colorado Plateau of northeastern Arizona, cliffs often form on south-facing slopes where soil moisture is insufficient for weathering of clay-cemented sandstone that is susceptible to hydration. In contrast, cliffs are rare on northerly slopes, which are dominated by mantles of weathered sandstone and colluvium (Burnett et al., 2008, doi:10.1029/2007JF000789). However, in semi-arid regions of the Idaho Batholith, preliminary results indicate some north-facing slopes are significantly steeper than south-facing slopes. We hypothesize that in semi-arid areas with observable increases in vegetation on north vs. south-facing slopes, north-facing slopes will be steeper due to increased soil cohesion, increased capture of wind-borne loess due to vegetative wind-baffling, and differences in the type and magnitude of erosive processes. In moister areas where aspect does not visibly control vegetation type and density, differences in slope angles with aspect should not be observed. We investigate tectonically quiescent regions of the mostly-homogenous granodioritic Idaho Batholith to locate areas sensitive to aspect-induced variations in insolation and compare slope characteristics on north and south-facing slopes. Hillslopes within the Dry Creek Experimental Watershed, in the

  9. The Hydromechanics of Vegetation for Slope Stabilization (United States)

    Mulyono, A.; Subardja, A.; Ekasari, I.; Lailati, M.; Sudirja, R.; Ningrum, W.


    Vegetation is one of the alternative technologies in the prevention of shallow landslide prevention that occurs mostly during the rainy season. The application of plant for slope stabilization is known as bioengineering. Knowledge of the vegetative contribution that can be considered in bioengineering was the hydrological and mechanical aspects (hydromechanical). Hydrological effect of the plant on slope stability is to reduce soil water content through transpiration, interception, and evapotranspiration. The mechanical impact of vegetation on slope stability is to stabilize the slope with mechanical reinforcement of soils through roots. Vegetation water consumption varies depending on the age and density, rainfall factors and soil types. Vegetation with high ability to absorb water from the soil and release into the atmosphere through a transpiration process will reduce the pore water stress and increase slope stability, and vegetation with deep root anchoring and strong root binding was potentially more significant to maintain the stability of the slope.

  10. Assessment of submarine landslides hazard through geotechnical and rheological analysis of sediments on the French Atlantic continental slope (United States)

    Toucanne, S.; Howlett, S.; Garziglia, S.; Silva Jacinto, R.; Courgeon, S.; Sabine, M.; Riboulot, V.; Marsset, B.


    In the aftermath of the devastating tsunami on the Japanese coast in 2011, a French multi-partnership project called TANDEM has been launched to assess the impact of tsunamis generated or propagated in the vicinity of French Channel and Atlantic coastlines. Tsunami are usually generated by earthquakes, but can also be triggered by submarine landslides. This study focuses on submarine landslides along the French Atlantic continental slope using data that were mainly collected in August 2015 during the GITAN cruise (R/V Pourquoi Pas?). Following geomorphological, geophysical and sedimentological analysis of the Bay of Biscay, efforts were oriented towards the determination of the sediment properties controlling landslide dynamics from in situ and laboratory measurements. Preliminary results show over 700 landslide scars on the French Atlantic continental slope, with most of them occurring between 400 and 1000m water depth and in canyon environments. The Plio-Quaternary sediments draping the majority of the Bay of Biscay are generally normally consolidated and composed of high plasticity clays. They show similar geomechanical properties throughout the area studied, with linear evolutions with depth and good reproducibility for rheological parameters such as Storage and Loss modulus. These similarities allow to extend geotechnical and rheological models to a regional scale in the Bay of Biscay. Our multi-disciplinary approach will provide the tools to assess continental slope failures and submarine landslides generation. Finally, we will aim to qualify and quantify the volumes and flow properties of sediment transported obtained through slope-stability modeling on SAMU-3D and rheology modelling on Nixes-SPH. These results will provide the TANDEM actors with the information necessary to simulate tsunami wave generation.

  11. Slope Estimation from ICESat/GLAS

    Directory of Open Access Journals (Sweden)

    Craig Mahoney


    Full Text Available We present a novel technique to infer ground slope angle from waveform LiDAR, known as the independent slope method (ISM. The technique is applied to large footprint waveforms (\\(\\sim\\ mean diameter from the Ice, Cloud and Land Elevation Satellite (ICESat Geoscience Laser Altimeter System (GLAS to produce a slope dataset of near-global coverage at \\(0.5^{\\circ} \\times 0.5^{\\circ}\\ resolution. ISM slope estimates are compared against high resolution airborne LiDAR slope measurements for nine sites across three continents. ISM slope estimates compare better with the aircraft data (R\\(^{2}=0.87\\ and RMSE\\(=5.16^{\\circ}\\ than the Shuttle Radar Topography Mission Digital Elevation Model (SRTM DEM inferred slopes (R\\(^{2}=0.71\\ and RMSE\\(=8.69^{\\circ}\\ ISM slope estimates are concurrent with GLAS waveforms and can be used to correct biophysical parameters, such as tree height and biomass. They can also be fused with other DEMs, such as SRTM, to improve slope estimates.

  12. Slope Stability Problems and Back Analysis in Heavily Jointed Rock Mass: A Case Study from Manisa, Turkey (United States)

    Akin, Mutluhan


    This paper presents a case study regarding slope stability problems and the remedial slope stabilization work executed during the construction of two reinforced concrete water storage tanks on a steep hill in Manisa, Turkey. Water storage tanks of different capacities were planned to be constructed, one under the other, on closely jointed and deformed shale and sandstone units. The tank on the upper elevation was constructed first and an approximately 20-m cut slope with two benches was excavated in front of this upper tank before the construction of the lower tank. The cut slope failed after a week and the failure threatened the stability of the upper water tank. In addition to re-sloping, a 15.6-m deep contiguous retaining pile wall without anchoring was built to support both the cut slope and the upper tank. Despite the construction of a retaining pile wall, a maximum of 10 mm of displacement was observed by inclinometer measurements due to the re-failure of the slope on the existing slip surface. Permanent stability was achieved after the placement of a granular fill buttress on the slope. Back analysis based on the non-linear (Hoek-Brown) failure criterion indicated that the geological strength index (GSI) value of the slope-forming material is around 21 and is compatible with the in situ-determined GSI value (24). The calculated normal-shear stress plots are also consistent with the Hoek-Brown failure envelope of the rock mass, indicating that the location of the sliding surface, GSI value estimated by back analysis, and the rock mass parameters are well defined. The long-term stability analysis illustrates a safe slope design after the placement of a permanent toe buttress.

  13. Slope of the Slope Derivative Surface used to characterize the complexity of the seafloor around St. John, USVI (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Slope of slope was calculated from the bathymetry surface for each raster cell by applying the ArcGIS Spatial Analyst 'Slope' Tool to a previously created slope...

  14. Hydrologic design for riprap on embankment slopes

    International Nuclear Information System (INIS)

    Codell, R.B.


    Waste impoundments for uranium tailings and other hazardous substances are often protected by compacted earth and clay, covered with a layer of loose rock (riprap). The report outlines procedures that could be followed to design riprap to withstand forces caused by runoff resulting from extreme rainfall directly on the embankment. The Probable Maximum Precipitation for very small areas is developed from considerations of severe storms of short duration at mid-latitudes. A two-dimensional finite difference model is then used to calculate the runoff from severe rainfall events. The procedure takes into account flow both beneath and above the rock layer and approximates the concentration in flow which could be caused by a non-level or slumped embankment. The sensitivity to various assumptions, such as the shape and size of the rock, the thickness of the layer, and the shape of the embankment, suggests that peak runoff from an armored slope could be attenuated with proper design. Frictional relationships for complex flow regimes are developed on the basis of flow through rock-filled dams and in mountain streams. These relationships are tested against experimental data collected in laboratory flumes; the tests provide excellent results. The resulting runoff is then used in either the Stephenson or safety factor method to find the stable rock diameter. The rock sizes determined by this procedure for a given flow have been compared with data on the failure of rock layers in experimental flumes, again with excellent results. Computer programs are included for implementing the method. 15 refs., 21 figs., 9 tabs

  15. Landslide Hazard Assessment near Kedarnath Temple in Himalayan region considering cloudburst tragedy in 2013 (United States)

    Ansari, T. A.; Singh, T. N., Sr.


    The world famous Shri Kedarnath Temple in Uttarakhand state of India is located in the western extremity of the young and dynamically active Central Himalaya. As Indian plate is moving towards Eurasian plate which has steep slopes, highly variable altitudes and uncertain climatic conditions. Due to high seismic activity Himalayan rock mass is highly fractured, shattered and inherently weakness pose threat for landslide. On 16th and 17th June 2013, was witness an extreme climatic events of century in the history of the region, the high intensity rainfall, (> 400mm) caused number of landslide which have adverse economic and societal impacts, including the potential for heavy loss of human and widespread devastation of natural resources, infrastructures. The study region is at high altitude around 3583 meters, which is affected from impact of glacial melt due to climate change and future increase in rainfall subjected to high level uncertainty of landslides. Aerial and field survey has been done of the region and most vulnerable landslide locations of hill slope and road cut slope are studied for future prospect of safety. SLIDE 6.0, PHASE27 (numerical software) for slope stability, geomechanical profile of rock and kinematics analysis to know the type of failures. Rock quality tunneling index (Q), Geological strength (GSI), Slope mass Rating (SMR) and factor of safety were determined to know the slope instability. Our finding provides an important aspect for future safety as provide the information for landslide warning system and engineering countermeasures.

  16. Rockfall-induced impact force causing a debris flow on a volcanoclastic soil slope: a case study in southern Italy

    Directory of Open Access Journals (Sweden)

    P. Budetta


    Full Text Available On 10 January 2003, a rockfall of approximately 10 m3 affected a cliff some 25 m high located along the northern slopes of Mt. St. Angelo (Nocera Inferiore, province of Salerno in the southern Italian region of Campania. The impact of boulders on the lower sector of the slope, along which detrital-pyroclastic soils outcrop, triggered a small channelled debris flow of about 500 m3. Fortunately, no damage nor victims resulted from the landslide. Several marks of the impacts were observed at the cliff toe and outside the collapsed area, and the volumes of some fallen boulders were subsequently measured. By means of in-situ surveys, it was possible to reconstruct the cliff's geo-structural layout in detail. A rockfall back-analysis was subsequently performed along seven critical profiles of the entire slope (surface area of about 4000 m2. The results of this numerical modelling using the lumped-mass method were then used to map the kinetic iso-energy curves. In the triggering area of the debris flow, for a falling boulder of 1 m3, the mean kinetic energy was estimated at 120 kJ, this value being equivalent to an impact force, on an inclined surface, of some 800 kN. After landing, due to the locally high slope gradient (about 45°, and low angle of trajectory at impact (about 23°, some boulders slid down the slope as far as the endpoints. The maximum depth of penetration into the ground by a sliding block was estimated at about 16 cm. Very likely, owing to the high impact force of boulders on the saturated soil slope outcropping at the cliff base, the debris flow was triggered under undrained loading conditions. Initial failure was characterized by a translational slide involving a limited, almost elliptical area where the pyroclastic cover shows greater thickness in comparison with the surrounding areas.

  17. Bearing Capacity of Strip Footings near Slopes Using Lower Bound Limit Analysis

    Directory of Open Access Journals (Sweden)

    Javad Mofidi rouchi


    Full Text Available Stability of foundations near slopes is one of the important and complicated problems in geotechnical engineering, which has been investigated by various methods such as limit equilibrium, limit analysis, slip-line, finite element and discrete element. The complexity of this problem is resulted from the combination of two probable failures: foundation failure and overall slope failure. The current paper describes a lower bound solution for estimation of bearing capacity of strip footings near slopes. The solution is based on the finite element formulation and linear programming technique, which lead to a collapse load throughout a statically admissible stress field. Three-nodded triangular stress elements are used for meshing the domain of the problem, and stress discontinuities occur at common edges of adjacent elements. The Mohr-Coulomb yield function and an associated flow rule are adopted for the soil behavior. In this paper, the average limit pressure of strip footings, which are adjacent to slopes, is considered as a function of dimensionless parameters affecting the stability of the footing-on-slope system. These parameters, particularly the friction angle of the soil, are investigated separately and relevant charts are presented consequently. The results are compared to some other solutions that are available in the literature in order to verify the suitability of the methodology used in this research.

  18. Analysing hydro-mechanical behaviour of reinforced slopes through centrifuge modelling (United States)

    Veenhof, Rick; Wu, Wei


    Every year, slope instability is causing casualties and damage to properties and the environment. The behaviour of slopes during and after these kind of events is complex and depends on meteorological conditions, slope geometry, hydro-mechanical soil properties, boundary conditions and the initial state of the soils. This study describes the effects of adding reinforcement, consisting of randomly distributed polyolefin monofilament fibres or Ryegrass (Lolium), on the behaviour of medium-fine sand in loose and medium dense conditions. Direct shear tests were performed on sand specimens with different void ratios, water content and fibre or root density, respectively. To simulate the stress state of real scale field situations, centrifuge model tests were conducted on sand specimens with different slope angles, thickness of the reinforced layer, fibre density, void ratio and water content. An increase in peak shear strength is observed in all reinforced cases. Centrifuge tests show that for slopes that are reinforced the period until failure is extended. The location of shear band formation and patch displacement behaviour indicate that the design of slope reinforcement has a significant effect on the failure behaviour. Future research will focus on the effect of plant water uptake on soil cohesion.

  19. Contraceptive failure

    DEFF Research Database (Denmark)

    Rasch, Vibeke


    Most studies focusing on contraceptive failure in relation to pregnancy have focused on contraceptive failure among women having induced abortions, thereby neglecting those women who, despite contraceptive failure, accept the pregnancy and intend to carry the fetus to term. To get a more complete...... picture of the problem of contraceptive failure, this study focuses on contraceptive failure among women with diverse pregnancy outcomes. In all, 3520 pregnant women attending Odense University Hospital were included: 373 had induced abortions, 435 had spontaneous abortions, 97 had ectopic pregnancies......, and 2614 received antenatal care. The variables studied comprise age, partner relationship, number of births, occupational and economical situation, and contraceptive use.Contraceptive failure, defined as contraceptive use (condom, diaphragm, IUD, oral contraception, or another modern method...

  20. Assessment and mapping of slope stability based on slope units: A ...

    Indian Academy of Sciences (India)

    Shallow landslide; infinite slope stability equation; return period precipitation; assessment; slope unit. ... 2010), logistic regression ... model to assess the hazard of shallow landslides ..... grating a fuzzy k-means classification and a Bayesian.

  1. Integrating GIS-based geologic mapping, LiDAR-based lineament analysis and site specific rock slope data to delineate a zone of existing and potential rock slope instability located along the grandfather mountain window-Linville Falls shear zone contact, Southern Appalachian Mountains, Watauga County, North Carolina (United States)

    Gillon, K.A.; Wooten, R.M.; Latham, R.L.; Witt, A.W.; Douglas, T.J.; Bauer, J.B.; Fuemmeler, S.J.


    Landslide hazard maps of Watauga County identify >2200 landslides, model debris flow susceptibility, and evaluate a 14km x 0.5km zone of existing and potential rock slope instability (ZEPRSI) near the Town of Boone. The ZEPRSI encompasses west-northwest trending (WNWT) topographic ridges where 14 active/past-active rock/weathered rock slides occur mainly in rocks of the Grandfather Mountain Window (GMW). The north side of this ridgeline is the GMW / Linville Falls Fault (LFF) contact. Sheared rocks of the Linville Falls Shear Zone (LFSZ) occur along the ridge and locally in the valley north of the contact. The valley is underlain principally by layered granitic gneiss comprising the Linville Falls/Beech Mountain/Stone Mountain Thrust Sheet. The integration of ArcGIS??? - format digital geologic and lineament mapping on a 6m LiDAR (Light Detecting and Ranging) digital elevation model (DEM) base, and kinematic analyses of site specific rock slope data (e.g., presence and degree of ductile and brittle deformation fabrics, rock type, rock weathering state) indicate: WNWT lineaments are expressions of a regionally extensive zone of fractures and faults; and ZEPRSI rock slope failures concentrate along excavated, north-facing LFF/LFSZ slopes where brittle fabrics overprint older metamorphic foliations, and other fractures create side and back release surfaces. Copyright 2009 ARMA, American Rock Mechanics Association.

  2. Heart Failure


    McMurray, John; Ponikowski, Piotr


    Heart failure occurs in 3% to 4% of adults aged over 65 years, usually as a consequence of coronary artery disease or hypertension, and causes breathlessness, effort intolerance, fluid retention, and increased mortality. The 5-year mortality in people with systolic heart failure ranges from 25% to 75%, often owing to sudden death following ventricular arrhythmia. Risks of cardiovascular events are increased in people with left ventricular systolic dysfunction (LVSD) or heart failure.

  3. Internal waves and temperature fronts on slopes

    Directory of Open Access Journals (Sweden)

    S. A. Thorpe

    Full Text Available Time series measurements from an array of temperature miniloggers in a line at constant depth along the sloping boundary of a lake are used to describe the `internal surf zone' where internal waves interact with the sloping boundary. More small positive temperature time derivatives are recorded than negative, but there are more large negative values than positive, giving the overall distribution of temperature time derivatives a small negative skewness. This is consistent with the internal wave dynamics; fronts form during the up-slope phase of the motion, bringing cold water up the slope, and the return flow may become unstable, leading to small advecting billows and weak warm fronts. The data are analysed to detect `events', periods in which the temperature derivatives exceed a set threshold. The speed and distance travelled by `events' are described. The motion along the slope may be a consequence of (a instabilities advected by the flow (b internal waves propagating along-slope or (c internal waves approaching the slope from oblique directions. The propagation of several of the observed 'events' can only be explained by (c, evidence that the internal surf zone has some, but possibly not all, the characteristics of the conventional 'surface wave' surf zone, with waves steepening as they approach the slope at oblique angles.

    Key words. Oceanography: general (benthic boundary layers; limnology, Oceanography: physical (internal and inertial waves

  4. Slope Stability. CEGS Programs Publication Number 15. (United States)

    Pestrong, Raymond

    Slope Stability is one in a series of single-topic problem modules intended for use in undergraduate and earth science courses. The module, also appropriate for use in undergraduate civil engineering and engineering geology courses, is a self-standing introduction to studies of slope stability. It has been designed to supplement standard…

  5. Air pocket removal from downward sloping pipes

    NARCIS (Netherlands)

    Pothof, I.W.M.; Clemens, F.H.L.R.


    Air-water flow is an undesired condition in water pipelines and hydropower tunnels. Water pipelines and wastewater pressure mains in particular are subject to air pocket accumulation in downward sloping reaches, such as inverted siphons or terrain slopes. Air pockets cause energy losses and an

  6. Phytoplankton biovolume is independent from the slope of the size spectrum in the oligotrophic atlantic ocean

    KAUST Repository

    Moreno-Ostos, Enrique; Blanco, José Marí a; Agusti, Susana; Lubiá n, Luis M.; Rodrí guez, Valeriano; Palomino, Roberto L.; Llabré s, Moira; Rodrí guez, Jaime


    high phytoplankton biovolume in productive regions with flatter spectrum slope and the opposite in oligotrophic ecosystems. Rather than this, the relationship between high biovolume phytoplankton assemblages and flatter size-abundance spectra does

  7. Research on the stability evaluation of slope

    Energy Technology Data Exchange (ETDEWEB)



    In order to create the guideline corresponding to a new regulatory standard, such as criteria in the ground-slope stability evaluation method, we have conducted an analysis and discussion of the shaking table test results using a large slope model. As a result, it was found that in that phase of the vertical motion and the horizontal motion affects the amplification characteristics of the ground motion, need to be considered in assessing the safety of the slope and the influence of the phase difference amplification or local. We also conduct a study on countermeasure construction slope by shaking table test, the effect of the countermeasure construction of pile and anchors deterrence could be confirmed. Focusing on the new method can reproduce the behavior of large deformation and discontinuity, with respect to the advancement of slope analysis, we identify issues on the maintenance and code applicability of each analysis method. (author)

  8. Rock slopes and reservoirs - lessons learned

    International Nuclear Information System (INIS)

    Moore, D.P.


    Lessons learned about slope stability in the course of four decades of monitoring, and in some cases stabilizing, slopes along British Columbia's hydroelectric reservoirs are discussed. The lessons are illustrated by short case histories of some of the more important slopes such as Little Chief Slide, Dutchman's Ridge, Downie Slide, Checkerboard Creek and Wahleach. Information derived from the monitoring and other investigations are compared with early interpretations of geology and slope performance. The comparison serves as an indicator of progress in slope stability determination and as a measure of the value of accumulated experience in terms of the potential consequences to safety and cost savings over the long life-span of hydroelectric projects.14 refs., 2 tabs., 15 figs

  9. Sedimentary dynamics and high-frequency sequence stratigraphy of the southwestern slope of Great Bahama Bank (United States)

    Wunsch, Marco; Betzler, Christian; Eberli, Gregor P.; Lindhorst, Sebastian; Lüdmann, Thomas; Reijmer, John J. G.


    New geophysical data from the leeward slope of Great Bahama Bank show how contour currents shape the slope and induce re-sedimentation processes. Along slope segments with high current control, drift migration and current winnowing at the toe of slope form a deep moat. Here, the slope progradation is inhibited by large channel incisions and the accumulation of large mass transport complexes, triggered by current winnowing. In areas where the slope is bathed by weaker currents, the accumulation of mass transport complexes and channel incision is rather controlled by the position of the sea level. Large slope failures were triggered during the Mid-Pleistocene transition and Mid-Brunhes event, both periods characterized by changes in the cyclicity or the amplitude of sea-level fluctuations. Within the seismic stratigraphic framework of third order sequences, four sequences of higher order were identified in the succession of the upper Pleistocene. These higher order sequences also show clear differences in function of the slope exposure to contour currents. Two stochastic models emphasize the role of the contour currents and slope morphology in the facies distribution in the upper Pleistocene sequences. In areas of high current influence the interplay of erosional and depositional processes form a complex facies pattern with downslope and along strike facies alterations. In zones with lower current influence, major facies alternations occur predominately in downslope direction, and a layer-cake pattern characterizes the along strike direction. Therefore, this study highlights that contour currents are an underestimated driver for the sediment distribution and architecture of carbonate slopes.

  10. Prediction of slope stability using artificial neural network (case study: Noabad, Mazandaran, Iran)

    International Nuclear Information System (INIS)

    Choobbasti, A J; Farrokhzad, F; Barari, A


    Investigations of failures of soil masses are subjects touching both geology and engineering. These investigations call the joint efforts of engineering geologists and geotechnical engineers. Geotechnical engineers have to pay particular attention to geology, ground water, and shear strength of soils in assessing slope stability. Artificial neural networks (ANNs) are very sophisticated modeling techniques, capable of modeling extremely complex functions. In particular, neural networks are nonlinear. In this research, with respect to the above advantages, ANN systems consisting of multilayer perceptron networks are developed to predict slope stability in a specified location, based on the available site investigation data from Noabad, Mazandaran, Iran. Several important parameters, including total stress, effective stress, angle of slope, coefficient of cohesion, internal friction angle, and horizontal coefficient of earthquake, were used as the input parameters, while the slope stability was the output parameter. The results are compared with the classical methods of limit equilibrium to check the ANN model's validity. (author)

  11. Slope-scale dynamic states of rockfalls (United States)

    Agliardi, F.; Crosta, G. B.


    Rockfalls are common earth surface phenomena characterised by complex dynamics at the slope scale, depending on local block kinematics and slope geometry. We investigated the nature of this slope-scale dynamics by parametric 3D numerical modelling of rockfalls over synthetic slopes with different inclination, roughness and spatial resolution. Simulations were performed through an original code specifically designed for rockfall modeling, incorporating kinematic and hybrid algorithms with different damping functions available to model local energy loss by impact and pure rolling. Modelling results in terms of average velocity profiles suggest that three dynamic regimes (i.e. decelerating, steady-state and accelerating), previously recognized in the literature through laboratory experiments on granular flows, can set up at the slope scale depending on slope average inclination and roughness. Sharp changes in rock fall kinematics, including motion type and lateral dispersion of trajectories, are associated to the transition among different regimes. Associated threshold conditions, portrayed in "phase diagrams" as slope-roughness critical lines, were analysed depending on block size, impact/rebound angles, velocity and energy, and model spatial resolution. Motion in regime B (i.e. steady state) is governed by a slope-scale "viscous friction" with average velocity linearly related to the sine of slope inclination. This suggest an analogy between rockfall motion in regime B and newtonian flow, whereas in regime C (i.e. accelerating) an analogy with a dilatant flow was observed. Thus, although local behavior of single falling blocks is well described by rigid body dynamics, the slope scale dynamics of rockfalls seem to statistically approach that of granular media. Possible outcomes of these findings include a discussion of the transition from rockfall to granular flow, the evaluation of the reliability of predictive models, and the implementation of criteria for a

  12. Rapid evolution of the paraglacial Moosfluh rock slope instability (Swiss Alps) captured by Sentinel-1 (United States)

    Manconi, Andrea; Glueer, Franziska; Loew, Simon


    The Great Aletsch Region (GAR, Swiss Alps) has undergone to several cycles of glacial advancement and retreat, which have deeply affected the evolution of the surrounding landscape. Currently, this region is one of the places where the effects of climate change can be strikingly observed, as the Aletsch glacier is experiencing a remarkable retreat with rates in the order of 50 meters every year. In particular, a deep-seated slope instability located in the area called "Moosfluh" has shown during the past 20 years evidences of a slow but progressive increase of surface displacement. The moving mass associated to the Moosfluh rockslide affects an area of about 2 km2 and entails a volume estimated in the order of 150-200 Mm3. In the late summer 2016, an unusual acceleration of the Moosfluh rockslide was observed. Compared to previous years, when ground deformations were in the order of few centimeters, in the period September-October 2016 maximum velocities have reached locally 1 m/day. Such a critical evolution resulted in an increased number of local rock failures and caused the generation of several deep tensile cracks, hindering the access to hiking paths visited by tourists. Moreover, surface deformations have also affected the Moosfluh cable car station, located near the crest of the unstable slope. In this critical framework, the information available on ground was not enough to disentangle the spatial extent of the most active region. To investigate that, we have processed a number of Sentinel-1 SAR images acquired over the GAR. We paired images with maximum temporal baseline spanning 12 and 24 days, in order to preserve the highest possible interferometric coherence over the target area. Secondly, by stacking surface displacements obtained from the differential interferograms, we have increased the signal-to-noise ratio to produce velocity maps of the Moosfluh landslide over the period of interest. This approach has allowed us to constrain the lateral borders

  13. Postural Stability Margins as a Function of Support Surface Slopes.

    Directory of Open Access Journals (Sweden)

    Aviroop Dutt-Mazumder

    Full Text Available This investigation examined the effects of slope of the surface of support (35°, 30°, 20°, 10° Facing(Toe Down, 0° Flat and 10°, 20°, 25° Facing (Toe Up and postural orientation on the margins of postural stability in quiet standing of young adults. The findings showed that the center of pressure-CoP (displacement, area and length had least motion at the baseline (0° Flat platform condition that progressively increased as a function of platform angle in both facing up and down directions. The virtual time to collision (VTC dynamics revealed that the spatio-temporal margins to the functional stability boundary were progressively smaller and the VTC time series also more regular (SampEn-Sample Entropy as slope angle increased. Surface slope induces a restricted stability region with lower dimension VTC dynamics that is more constrained when postural orientation is facing down the slope. These findings provide further evidence that VTC acts as a control variable in standing posture that is influenced by the emergent dynamics of the individual-environment-task interaction.

  14. Postural Stability Margins as a Function of Support Surface Slopes. (United States)

    Dutt-Mazumder, Aviroop; Slobounov, Seymon M; Challis, John Henry; Newell, Karl Maxim


    This investigation examined the effects of slope of the surface of support (35°, 30°, 20°, 10° Facing(Toe) Down, 0° Flat and 10°, 20°, 25° Facing (Toe) Up) and postural orientation on the margins of postural stability in quiet standing of young adults. The findings showed that the center of pressure-CoP (displacement, area and length) had least motion at the baseline (0° Flat) platform condition that progressively increased as a function of platform angle in both facing up and down directions. The virtual time to collision (VTC) dynamics revealed that the spatio-temporal margins to the functional stability boundary were progressively smaller and the VTC time series also more regular (SampEn-Sample Entropy) as slope angle increased. Surface slope induces a restricted stability region with lower dimension VTC dynamics that is more constrained when postural orientation is facing down the slope. These findings provide further evidence that VTC acts as a control variable in standing posture that is influenced by the emergent dynamics of the individual-environment-task interaction.

  15. Late Holocene Radiocarbon Variability in Northwest Atlantic Slope Waters

    Energy Technology Data Exchange (ETDEWEB)

    Sherwood, O; Edinger, E; Guilderson, T P; Ghaleb, B; Risk, M J; Scott, D B


    Deep-sea gorgonian corals secrete a 2-part skeleton of calcite, derived from dissolved inorganic carbon at depth, and gorgonin, derived from recently fixed and exported particulate organic matter. Radiocarbon contents of the calcite and gorgonin provide direct measures of seawater radiocarbon at depth and in the overlying surface waters, respectively. Using specimens collected from Northwest Atlantic slope waters, we generated radiocarbon records for surface and upper intermediate water layers spanning the pre- and post bomb-{sup 14}C eras. In Labrador Slope Water (LSW), convective mixing homogenizes the pre-bomb {Delta}{sup 14}C signature (-67 {+-} 4{per_thousand}) to at least 1000 m depth. Surface water bomb-{sup 14}C signals were lagged and damped (peaking at {approx} +45{per_thousand} in the early 1980s) relative to other regions of the northwest Atlantic, and intermediate water signals were damped further. Off southwest Nova Scotia, the vertical gradient in {Delta}{sup 14}C is much stronger. In surface water, pre-bomb {Delta}{sup 14}C averaged -75 {+-} 5{per_thousand}. At 250-475 m depth, prebomb {Delta}{sup 14}C oscillated quasi-decadally between -80 and -100{per_thousand}, likely reflecting interannual variability in the presence of Labrador Slope Water vs. Warm Slope Water (WSW). Finally, subfossil corals reveal no systematic changes in vertical {Delta}{sup 14}C gradients over the last 1200 years.

  16. Three-dimensional modelling of slope stability using the Local Factor of Safety concept (United States)

    Moradi, Shirin; Huisman, Sander; Beck, Martin; Vereecken, Harry; Class, Holger


    Slope stability is governed by coupled hydrological and mechanical processes. The slope stability depends on the effective stress, which in turn depends on the weight of the soil and the matrix potential. Therefore, changes in water content and matrix potential associated with infiltration will affect slope stability. Most available models describing these coupled hydro-mechanical processes either rely on a one- or two-dimensional representation of hydrological and mechanical properties and processes, which obviously is a strong simplification in many applications. Therefore, the aim of this work is to develop a three-dimensional hydro-mechanical model that is able to capture the effect of spatial and temporal variability of both mechanical and hydrological parameters on slope stability. For this, we rely on DuMux, which is a free and open-source simulator for flow and transport processes in porous media that facilitates coupling of different model approaches and offers flexibility for model development. We use the Richards equation to model unsaturated water flow. The simulated water content and matrix potential distribution is used to calculate the effective stress. We only consider linear elasticity and solve for statically admissible fields of stress and displacement without invoking failure or the redistribution of post-failure stress or displacement. The Local Factor of Safety concept is used to evaluate slope stability in order to overcome some of the main limitations of commonly used methods based on limit equilibrium considerations. In a first step, we compared our model implementation with a 2D benchmark model that was implemented in COMSOL Multiphysics. In a second step, we present in-silico experiments with the newly developed 3D model to show the effect of slope morphology, spatial variability in hydraulic and mechanical material properties, and spatially variable soil depth on simulated slope stability. It is expected that this improved physically

  17. Reconstructed and analyzed X-ray computed tomography data of investment-cast and additive-manufactured aluminum foam for visualizing ligament failure mechanisms and regions of contact during a compression test

    Directory of Open Access Journals (Sweden)

    Kristoffer E. Matheson


    Full Text Available Three stochastic open-cell aluminum foam samples were incrementally compressed and imaged using X-ray Computed Tomography (CT. One of the samples was created using conventional investment casting methods and the other two were replicas of the same foam that were made using laser powder bed fusion. The reconstructed CT data were then examined in Paraview to identify and highlight the types of failure of individual ligaments. The accompanying sets of Paraview state files and STL files highlight the different ligament failure modes incrementally during compression for each foam. Ligament failure was classified as either “Fracture” (red or “Collapse” (blue. Also, regions of neighboring ligaments that came into contact that were not originally touching were colored yellow. For further interpretation and discussion of the data, please refer to Matheson et al. (2017 [1].

  18. Wave run-up on sandbag slopes

    Directory of Open Access Journals (Sweden)

    Thamnoon Rasmeemasmuang


    Full Text Available On occasions, sandbag revetments are temporarily applied to armour sandy beaches from erosion. Nevertheless, an empirical formula to determine the wave run -up height on sandbag slopes has not been available heretofore. In this study a wave run-up formula which considers the roughness of slope surfaces is proposed for the case of sandbag slopes. A series of laboratory experiments on the wave run -up on smooth slopes and sandbag slopes were conducted in a regular-wave flume, leading to the finding of empirical parameters for the formula. The proposed empirical formula is applicable to wave steepness ranging from 0.01 to 0.14 and to the thickness of placed sandbags relative to the wave height ranging from 0.17 to 3.0. The study shows that the wave run-up height computed by the formula for the sandbag slopes is 26-40% lower than that computed by the formula for the smooth slopes.

  19. Incidence and risk factors of first-line antiretroviral treatment failure among human immunodeficiency virus-infected children in Amhara regional state, Ethiopia: a retrospective follow-up study. (United States)

    Sisay, Malede Mequanent; Ayele, Tadesse Awoke; Gelaw, Yalemzewod Assefa; Tsegaye, Adino Tesfahun; Gelaye, Kassahun Alemu; Melak, Melkitu Fentie


    This study aimed to assess the incidence and risk factors of treatment failure among HIV/AIDS-infected children who were on antiretroviral therapy (ART) in Amhara National Regional State, Ethiopia. A retrospective follow-up study was conducted from January 2010 to March 2016. A total of 824 children under the age of 15 who had started ART were included in the study. Data were collected from children's medical charts and ART registration logbook using a standard checklist. A Weibull regression model was used to identify the risk factors of treatment failure. Adjusted HRs (AHRs) with 95% CIs were used to declare statistical significance. The mean (±SD) age of the children was 6.4±3.6 years, with a median (IQR) follow-up of 30.5 (14.6-51.4) months. Sixty-three children (7.7%, 95% CI 5.8 to 9.5) developed treatment failure, 17 (27.0%) of whom were immunological and 46 (73.0%) were clinical failures. The incidence rate of treatment failure was 22.1/10 000 person-months. The cumulative probability of failure was 0.4, with 28 562.5 person-month observations. Lack of disclosure (AHR=4. 4, 95% CI 1.8 to 11.3), opportunistic infections during initiation of ART (AHR=2.3, 95% CI 1.3 to 4.1) and prolonged follow-up (AHR=0.06, 95% CI 0.02 to 0.18) were the main predictors of treatment failure. This study revealed that the incidence of treatment failure remains a significant public health concern in Ethiopia. Undisclosed HIV status to children, the presence of opportunistic infections during initiation of ART and prolonged follow-up were found to be the main predictors of treatment failure. Hence, early detection of treatment failure and further studies on viral monitoring need to be considered. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  20. Drifter observations of the Hebrides slope current and nearby circulation patterns

    Directory of Open Access Journals (Sweden)

    M. Burrows


    Full Text Available The mean flow at and around the Hebrides and Shetland Shelf slope is measured with ARGOS tracked drifters. Forty-two drifters drogued at 50 m were deployed in three circles over the Hebrides slope at 56.15°N in two releases, one on 5th December, 1995 and the second on 5-9th May, 1996. The circles span a distance of some 20 km from water depths of 200 m to 1200 m. Drifters are initially advected poleward along-slope by the Hebrides slope current at between 0.05 and 0.70 m s-1 in a laterally constrained (25-50 km wide jet-like flow. Drifters released in winter remained in the slope current for over 2000 km whilst summer drifters were lost from the slope current beyond the Wyville-Thomson Ridge, a major topographic feature at 60°N. Dispersion from the slope region into deeper waters occurs at bathymetric irregularities, particularly at the Anton Dohrn Seamount close to which the slope current is found to bifurcate, both in summer and winter, and at the Wyville-Thomson Ridge where drifters move into the Faeroe Shetland Channel. Dispersion onto the continental shelf occurs sporadically along the Hebrides slope. The initial dispersion around the Hebrides slope is remarkably sensitive to initial position, most of the drifters released in shallower water moving onto the shelf, whilst those in 1000 m or more are mostly carried away from the slope into deeper water near the Anton Dohrn Seamount. The dispersion coefficients estimated in directions parallel and normal to the local direction of the 500 m contour, approximately the position of the slope current core, are approximately 8.8 × 103 m2 s-1 and 0.36 × 103 m2 s-1, respectively, during winter, and 11.4 × 103 m2 s-1 and 0.36 × 103 m2 s-1, respectively, during summer. At the slope there is a minimum in across-slope mean velocity, Reynolds stress, and across-slope eddy correlations. The mean across-slope velocity associated with mass flux is about 4 × 10-3 m s-1 shelfward across the shelf break

  1. Lunar surface engineering properties experiment definition. Volume 2: Mechanics of rolling sphere-soil slope interaction (United States)

    Hovland, H. J.; Mitchell, J. K.


    The soil deformation mode under the action of a rolling sphere (boulder) was determined, and a theory based on actual soil failure mechanism was developed which provides a remote reconnaissance technique for study of soil conditions using boulder track observations. The failure mechanism was investigated by using models and by testing an instrumented spherical wheel. The wheel was specifically designed to measure contact pressure, but it also provided information on the failure mechanism. Further tests included rolling some 200 spheres down sand slopes. Films were taken of the rolling spheres, and the tracks were measured. Implications of the results and reevaluation of the lunar boulder tracks are discussed.

  2. Intrusions of Kuroshio and Shelf Waters on Northern Slope of South China Sea in Summer 2015 (United States)

    Li, Denghui; Zhou, Meng; Zhang, Zhaoru; Zhong, Yisen; Zhu, Yiwu; Yang, Chenghao; Xu, Mingquan; Xu, Dongfeng; Hu, Ziyuan


    The northern slope region of the South China Sea (SCS) is a biological hot spot characterized by high primary productivity and biomasses transported by cross-shelf currents, which support the spawning and growth of commercially and ecologically important fish species. To understand the physical and biogeochemical processes that promote the high primary production of this region, we conducted a cruise from June 10 and July 2, 2015. In this study, we used fuzzy cluster analysis and optimum multiparameter analysis methods to analyze the hydrographic data collected during the cruise to determine the compositions of the upper 55-m water masses on the SCS northern slope and thereby elucidate the cross-slope transport of shelf water (SHW) and the intrusions of Kuroshio water (KW). We also analyzed the geostrophic currents derived from acoustic Doppler current profiler measurements and satellite data. The results reveal the surface waters on the northern slope of the SCS to be primarily composed of waters originating from South China Sea water (SCSW), KW, and SHW. The SCSW dominated a majority of the study region at percentages ranging between 60% and 100%. We found a strong cross-slope current with speeds greater than 50 cm s-1 to have carried SHW into and through the surveyed slope area, and KW to have intruded onto the slope via mesoscale eddies, thereby dominating the southwestern section of the study area.

  3. Spatial distribution and hazard degree of soil erosion of sloping croplands in northeast China (United States)

    Zhang, T.


    Soil erosion is causing damage to the sloping croplands of northeast China and threatening the food security of the nation. However, little is known about the problem in macro scale. This study aims to investigate the area, slope gradient, soil erosion rate and year limit of erosion of the sloping croplands in whole northeast China and different geomorphologic regions, soil types, watersheds and administrative divisions of it, to estimate quantitatively the necessity and urgency of soil conservation and to offer advices. Meteorological data, topography data, geomorphology data, soil data and landuse data were collected. The China Soil Loss Equation was applied. The results indicated that: (1) Total area of the sloping croplands of northeast China is 195000 km2. They mainly distributed in Changbai mountainous region, eastern Songnen plain and Daxinganling mountainous region, with dark-brown earth, black soil and brown earth as main soil types. Total area of the sloping croplands steeper than 5 degree is 31000 km2. They mainly distributed in the mountain regions, with dark-brown earth and brown earth as main soil types. (2) The soil erosion rates of 92% of the sloping croplands have exceeded the soil loss tolerance in the national standard (0.15 mm/a). These croplands need to be conserved. The A horizon depths of 66% of the sloping croplands are less than 30 cm , while the year limit of A horizon erosion of 59% of the sloping croplands are less than 100 a. These croplands need to be conserved immediately. (3) Contour farming is suitable to 84% of the sloping croplands and deserves more attention. The sloping croplands steeper than 15 degree and those located in the aeolian sandy soil and some others soil types contributed little in grain production with high hazard degrees of erosion and should be reused for other purposes, as soon as possible. (4) The Changbai mountainous region, Daxinganling mountainous region, the dark-brown earth region and the brown earth region

  4. Research on fast ecological restoration technology of high and steep rocky slope of highway (United States)

    Qin, Xin


    Along with the development of the western region, the traffic construction in mountainous areas is booming. In the infrastructure, it produced a large number of secondary bare land. Soil erosion is serious. Based on the literature search and analysis of the domestic and international slope ecological restoration technology, this paper proposes a fast and efficient adaptive highway high steep rock slope ecological restoration technology (it has been authorized by the national patent). And it states the systemic structure, working principle and key construction technology. The ecological restoration technique combines the growth characteristics of the vegetation and the characteristics of the rock mass, which not only improves the survival rate of plants, but also stable slope. The results of this study make up for the shortcomings of the existing ecological restoration technology of slope. Compared with the prior art, which have obvious advantages and suitable for the ecological restoration of high steep rock slope.

  5. A preliminary regional assessment of earthquake-induced landslide susceptibility for Vrancea Seismic Region (United States)

    Micu, Mihai; Balteanu, Dan; Ionescu, Constantin; Havenith, Hans; Radulian, Mircea; van Westen, Cees; Damen, Michiel; Jurchescu, Marta


    In seismically-active regions, earthquakes may trigger landslides enhancing the short-to-long term slope denudation and sediment delivery and conditioning the general landscape evolution. Co-seismic slope failures present in general a low frequency - high magnitude pattern which should be addressed accordingly by landslide hazard assessment, with respect to the generally more frequent precipitation-triggered landslides. The Vrancea Seismic Region, corresponding to the curvature sector of the Eastern Romanian Carpathians, represents the most active sub-crustal (focal depth > 50 km) earthquake province of Europe. It represents the main seismic energy source throughout Romania with significant transboundary effects recorded as far as Ukraine and Bulgaria. During the last 300 years, the region featured 14 earthquakes with M>7, among which seven events with magnitude above 7.5 and three between 7.7 and 7.9. Apart from the direct damages, the Vrancea earthquakes are also responsible for causing numerous other geohazards, such as ground fracturing, groundwater level disturbances and possible deep-seated landslide occurrences (rock slumps, rock-block slides, rock falls, rock avalanches). The older deep-seated landslides (assumed to have been) triggered by earthquakes usually affect the entire slope profile. They often formed landslide dams strongly influencing the river morphology and representing potential threats (through flash-floods) in case of lake outburst. Despite the large potential of this research issue, the correlation between the region's seismotectonic context and landslide predisposing factors has not yet been entirely understood. Presently, there is a lack of information provided by the geohazards databases of Vrancea that does not allow us to outline the seismic influence on the triggering of slope failures in this region. We only know that the morphology of numerous large, deep-seated and dormant landslides (which can possibly be reactivated in future

  6. North Slope, Alaska ESI: FISH (Fish Polygons) (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for marine, estuarine, anadromous, and freshwater fish species for the North Slope of Alaska. Vector...

  7. Rock Slope Design Criteria : Executive Summary Report (United States)


    Based on the stratigraphy and the type of slope stability problems, the flat lying, Paleozoic age, sedimentary rocks of Ohio were divided into three design units: 1) competent rock design unit consisting of sandstones, limestones, and siltstones that...

  8. North Slope, Alaska ESI: BIRDS (Bird Polygons) (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for diving birds, gulls and terns, seabirds, shorebirds, and waterfowl for the North Slope of Alaska....

  9. North Slope, Alaska ESI: FACILITY (Facility Points) (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains data for oil field facilities for the North Slope of Alaska. Vector points in this data set represent oil field facility locations. This data...

  10. Percent Agricultural Land Cover on Steep Slopes (United States)

    U.S. Environmental Protection Agency — Clearing land for agriculture tends to increase soil erosion. The amount of erosion is related to the steepness of the slope, farming methods used and soil type....

  11. Slope stability probability classification, Waikato Coal Measures, New Zealand

    Energy Technology Data Exchange (ETDEWEB)

    Lindsay, P.; Campbell, R.; Fergusson, D.A.; Ferm, J.C.; Gillard, G.R.; Moore, T.A. [CRL Energy Ltd., Christchurch (New Zealand)


    Ferm classified lithological units have been identified and described in the Waikato Coal Measures in open pits in the Waikato coal region. These lithological units have been classified geotechnically with mechanical tests and discontinuity measurements. Using these measurements, slope stability probability classification (SSPC) have been quantified based on an adaption of Hack's SSPC system which places less influence on rock quality designation and unconfined compressive strength than previous rock mass rating systems. An attempt has been made to modify the Hack weathering susceptibility rating by using chemical index of alteration values from XRF major element analysis. Another major component of this adapted SSPC system is the inclusion of rock moisture content effects on slope stability. The paper explains the systematic initial approach of using the adapted SSPC system to classify slope stability in the Waikato open pit coal mines. The XRF major element results obtained for lithologies in the Waikato coal region may be a useful mine management tool to quantify stratigraphic thickness and palaeoweathering from wash drill cuttings. 14 refs., 7 figs., 3 tabs.

  12. Heart Failure (United States)

    ... Other diseases. Chronic diseases — such as diabetes, HIV, hyperthyroidism, hypothyroidism, or a buildup of iron (hemochromatosis) or ... transplantation or support with a ventricular assist device. Prevention The key to preventing heart failure is to ...

  13. Stability of Slopes Reinforced with Truncated Piles

    Directory of Open Access Journals (Sweden)

    Shu-Wei Sun


    Full Text Available Piles are extensively used as a means of slope stabilization. A novel engineering technique of truncated piles that are unlike traditional piles is introduced in this paper. A simplified numerical method is proposed to analyze the stability of slopes stabilized with truncated piles based on the shear strength reduction method. The influential factors, which include pile diameter, pile spacing, depth of truncation, and existence of a weak layer, are systematically investigated from a practical point of view. The results show that an optimum ratio exists between the depth of truncation and the pile length above a slip surface, below which truncating behavior has no influence on the piled slope stability. This optimum ratio is bigger for slopes stabilized with more flexible piles and piles with larger spacing. Besides, truncated piles are more suitable for slopes with a thin weak layer than homogenous slopes. In practical engineering, the piles could be truncated reasonably while ensuring the reinforcement effect. The truncated part of piles can be filled with the surrounding soil and compacted to reduce costs by using fewer materials.

  14. Numerical computation of homogeneous slope stability. (United States)

    Xiao, Shuangshuang; Li, Kemin; Ding, Xiaohua; Liu, Tong


    To simplify the computational process of homogeneous slope stability, improve computational accuracy, and find multiple potential slip surfaces of a complex geometric slope, this study utilized the limit equilibrium method to derive expression equations of overall and partial factors of safety. This study transformed the solution of the minimum factor of safety (FOS) to solving of a constrained nonlinear programming problem and applied an exhaustive method (EM) and particle swarm optimization algorithm (PSO) to this problem. In simple slope examples, the computational results using an EM and PSO were close to those obtained using other methods. Compared to the EM, the PSO had a small computation error and a significantly shorter computation time. As a result, the PSO could precisely calculate the slope FOS with high efficiency. The example of the multistage slope analysis indicated that this slope had two potential slip surfaces. The factors of safety were 1.1182 and 1.1560, respectively. The differences between these and the minimum FOS (1.0759) were small, but the positions of the slip surfaces were completely different than the critical slip surface (CSS).

  15. Numerical Computation of Homogeneous Slope Stability

    Directory of Open Access Journals (Sweden)

    Shuangshuang Xiao


    Full Text Available To simplify the computational process of homogeneous slope stability, improve computational accuracy, and find multiple potential slip surfaces of a complex geometric slope, this study utilized the limit equilibrium method to derive expression equations of overall and partial factors of safety. This study transformed the solution of the minimum factor of safety (FOS to solving of a constrained nonlinear programming problem and applied an exhaustive method (EM and particle swarm optimization algorithm (PSO to this problem. In simple slope examples, the computational results using an EM and PSO were close to those obtained using other methods. Compared to the EM, the PSO had a small computation error and a significantly shorter computation time. As a result, the PSO could precisely calculate the slope FOS with high efficiency. The example of the multistage slope analysis indicated that this slope had two potential slip surfaces. The factors of safety were 1.1182 and 1.1560, respectively. The differences between these and the minimum FOS (1.0759 were small, but the positions of the slip surfaces were completely different than the critical slip surface (CSS.

  16. Slope Estimation in Noisy Piecewise Linear Functions. (United States)

    Ingle, Atul; Bucklew, James; Sethares, William; Varghese, Tomy


    This paper discusses the development of a slope estimation algorithm called MAPSlope for piecewise linear data that is corrupted by Gaussian noise. The number and locations of slope change points (also known as breakpoints) are assumed to be unknown a priori though it is assumed that the possible range of slope values lies within known bounds. A stochastic hidden Markov model that is general enough to encompass real world sources of piecewise linear data is used to model the transitions between slope values and the problem of slope estimation is addressed using a Bayesian maximum a posteriori approach. The set of possible slope values is discretized, enabling the design of a dynamic programming algorithm for posterior density maximization. Numerical simulations are used to justify choice of a reasonable number of quantization levels and also to analyze mean squared error performance of the proposed algorithm. An alternating maximization algorithm is proposed for estimation of unknown model parameters and a convergence result for the method is provided. Finally, results using data from political science, finance and medical imaging applications are presented to demonstrate the practical utility of this procedure.

  17. Automatic approach to deriving fuzzy slope positions (United States)

    Zhu, Liang-Jun; Zhu, A.-Xing; Qin, Cheng-Zhi; Liu, Jun-Zhi


    Fuzzy characterization of slope positions is important for geographic modeling. Most of the existing fuzzy classification-based methods for fuzzy characterization require extensive user intervention in data preparation and parameter setting, which is tedious and time-consuming. This paper presents an automatic approach to overcoming these limitations in the prototype-based inference method for deriving fuzzy membership value (or similarity) to slope positions. The key contribution is a procedure for finding the typical locations and setting the fuzzy inference parameters for each slope position type. Instead of being determined totally by users in the prototype-based inference method, in the proposed approach the typical locations and fuzzy inference parameters for each slope position type are automatically determined by a rule set based on prior domain knowledge and the frequency distributions of topographic attributes. Furthermore, the preparation of topographic attributes (e.g., slope gradient, curvature, and relative position index) is automated, so the proposed automatic approach has only one necessary input, i.e., the gridded digital elevation model of the study area. All compute-intensive algorithms in the proposed approach were speeded up by parallel computing. Two study cases were provided to demonstrate that this approach can properly, conveniently and quickly derive the fuzzy slope positions.

  18. Slope stability radar for monitoring mine walls (United States)

    Reeves, Bryan; Noon, David A.; Stickley, Glen F.; Longstaff, Dennis


    Determining slope stability in a mining operation is an important task. This is especially true when the mine workings are close to a potentially unstable slope. A common technique to determine slope stability is to monitor the small precursory movements, which occur prior to collapse. The slope stability radar has been developed to remotely scan a rock slope to continuously monitor the spatial deformation of the face. Using differential radar interferometry, the system can detect deformation movements of a rough wall with sub-millimeter accuracy, and with high spatial and temporal resolution. The effects of atmospheric variations and spurious signals can be reduced via signal processing means. The advantage of radar over other monitoring techniques is that it provides full area coverage without the need for mounted reflectors or equipment on the wall. In addition, the radar waves adequately penetrate through rain, dust and smoke to give reliable measurements, twenty-four hours a day. The system has been trialed at three open-cut coal mines in Australia, which demonstrated the potential for real-time monitoring of slope stability during active mining operations.

  19. Antarctic Ice Sheet Slope and Aspect Based on Icesat's Repeat Orbit Measurement (United States)

    Yuan, L.; Li, F.; Zhang, S.; Xie, S.; Xiao, F.; Zhu, T.; Zhang, Y.


    Accurate information of ice sheet surface slope is essential for estimating elevation change by satellite altimetry measurement. A study is carried out to recover surface slope of Antarctic ice sheet from Ice, Cloud and land Elevation Satellite (ICESat) elevation measurements based on repeat orbits. ICESat provides repeat ground tracks within 200 meters in cross-track direction and 170 meters in along-track direction for most areas of Antarctic ice sheet. Both cross-track and along-track surface slopes could be obtained by adjacent repeat ground tracks. Combining those measurements yields a surface slope model with resolution of approximately 200 meters. An algorithm considering elevation change is developed to estimate the surface slope of Antarctic ice sheet. Three Antarctic Digital Elevation Models (DEMs) were used to calculate surface slopes. The surface slopes from DEMs are compared with estimates by using in situ GPS data in Dome A, the summit of Antarctic ice sheet. Our results reveal an average surface slope difference of 0.02 degree in Dome A. High resolution remote sensing images are also used in comparing the results derived from other DEMs and this paper. The comparison implies that our results have a slightly better coherence with GPS observation than results from DEMs, but our results provide more details and perform higher accuracy in coastal areas because of the higher resolution for ICESat measurements. Ice divides are estimated based on the aspect, and are weakly consistent with ice divides from other method in coastal regions.

  20. The Relationship Between Lithology and Slope Morphology in the Tucson Mountains, Arizona.

    Directory of Open Access Journals (Sweden)

    Kamel Khanchoul


    Full Text Available The relationship between lithology and slope morphology is investigated at eight sites on granitic, andesitic, andsedimentary hillslopes in the Tucson Mountains, Arizona. Several methods are used in the study. Topographic profi lesare constructed. Skewness indices, slope length, and mean slope angles of the different slope profi les are computed andcompared with each other. Debris size analysis has permitted for some profi les, the determination of hillfront/piedmontjunctions. The nature and structural characteristics of the bedrock are the ones that determine the hillslope morphologyin this semi-arid region. There are, as a matter of fact, variations in profi les on the same bedrock nature but differentlyexposed. More precise morphologic studies have been also done in comparing the different lithologic pairs. They havepermitted to show some similarities in shapes. The granitic-andesitic slopes and andesiic-sedimentary slopes are thebest comparisons which show the relationship between lithology and slope morphology. The granitic-sedimentary sloperelationship is shown in the hillfront concavities, mountain front and piedmont mean slope angles.

  1. Combined rock slope stability and shallow landslide susceptibility assessment of the Jasmund cliff area (Rügen Island, Germany

    Directory of Open Access Journals (Sweden)

    A. Günther


    Full Text Available In this contribution we evaluated both the structurally-controlled failure susceptibility of the fractured Cretaceous chalk rocks and the topographically-controlled shallow landslide susceptibility of the overlying glacial sediments for the Jasmund cliff area on Rügen Island, Germany. We employed a combined methodology involving spatially distributed kinematical rock slope failure testing with tectonic fabric data, and both physically- and inventory-based shallow landslide susceptibility analysis. The rock slope failure susceptibility model identifies areas of recent cliff collapses, confirming its value in predicting the locations of future failures. The model reveals that toppling is the most important failure type in the Cretaceous chalk rocks of the area. The shallow landslide susceptibility analysis involves a physically-based slope stability evaluation which utilizes material strength and hydraulic conductivity data, and a bivariate landslide susceptibility analysis exploiting landslide inventory data and thematic information on ground conditioning factors. Both models show reasonable success rates when evaluated with the available inventory data, and an attempt was made to combine the individual models to prepare a map displaying both terrain instability and landslide susceptibility. This combination highlights unstable cliff portions lacking discrete landslide areas as well as cliff sections highly affected by past landslide events. Through a spatial integration of the rock slope failure susceptibility model with the combined shallow landslide assessment we produced a comprehensive landslide susceptibility map for the Jasmund cliff area.

  2. Effects of tibial slope changes in the stability of fixed bearing medial unicompartmental arthroplasty in anterior cruciate ligament deficient knees. (United States)

    Suero, Eduardo M; Citak, Musa; Cross, Michael B; Bosscher, Marianne R F; Ranawat, Anil S; Pearle, Andrew D


    Patients with anterior cruciate ligament (ACL) deficiency may have increased failure rates with UKA as a result of abnormal contact stresses and altered knee kinematics. Variations in the slope of the tibial component in UKA may alter tibiofemoral translation, and affect outcomes. This cadaveric study evaluated tibiofemoral translation during the Lachman and pivot shift tests after changing the slope of a fixed bearing unicondylar tibial component. Sectioning the ACL increased tibiofemoral translation in both the Lachman and pivot shift tests (Pslope leveling (decreasing the posterior slope) of the polyethylene insert in a UKA decreases anteroposterior tibiofemoral translation in the sagittal plane to a magnitude similar to that of the intact knee. With 8° of tibial slope leveling, anterior tibial translation during the Lachman test decreased by approximately 5mm. However, no variation in slope altered the pivot shift kinematics in the ACL deficient knees. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Mechanical Stability of Stratified Sediments along the upper continental Slope off Vesterålen, northern Norway - Insights from in situ CPTU Tests (United States)

    Voelker, D.; Stegmann, S.; Kreiter, S.; L'Heureux, J. S.; Vanneste, M. W. B.; Baeten, N. J.; Knudsen, S.; Rise, L.; Longva, O.; Brendryen, J.; Haflidason, H.; Chand, S.; Mörz, T.; Kopf, A.


    High-resolution single channel-seismic data (3.5 kHz) reveal small-scale submarine landslide structures and superficial deformation features (e.g. tension cracks) along the gently dipping (3°) upper continental slope west of the Vesterålen Archipelago off northern Norway. Previous laboratory-based geotechnical studies attest that the slope is per sestable and that seismic events in an order of magnitude M5.7 may have triggered the slope sediments to fail. Here we present geotechnical in situ data (sedimentary strength, pore pressure), which were obtained with RV Poseidon in summer 2014 using the static CPTU system GOST. The CPTU system provided high-resolution geotechnical profiles of the uppermost sediments to a maximum penetration depth of ~ 20 m at six sites within the landslide features and beside them in undisturbed slope sediments as reference. The CPTU data reveal the occurrence of mechanically weaker zones (MWZ) by the drop of sedimentary strength. These zones are interbedded by coarser, more competent layers. The occurrence of sensitive fine-grained material may be responsible for the loss of strength in the deeper portion (appx. 12 to 18 m below seafloor). An 1D infinite pseudo-static stability analysis attests that the mechanically weaker zones (MWZ) correlate well with portions, where the Factor of Safety (FoS) ≤ 1 (meta-stable to unstable) indicates permanent deformation or failure in case additional dynamic load is induced by an earthquake. Thus, the mechanically weak layers can be considered as one important pre-condition for landslide activity. In conclusion, the integration of in situ CPTU data with geophysical data improves soil characterization and hence foster a better understanding of the pre-conditioning factors for slope instability at the upper continental slope off Vesterålen. Risk assessment for the present-day slope off Vesterålen is particularly crucial, because the opening of the region for offshore oil and gas exploration is

  4. Eastern slopes grizzly bear project : project update

    Energy Technology Data Exchange (ETDEWEB)



    This report updates a study to examine the cumulative effects of human activities on the grizzly bears in the central Canadian Rockies. The project was initiated in 1994 to acquire accurate scientific information on the habitat and populations of grizzly bears in the area of the Banff National Park and Kananaskis Country. This area is probably the most heavily used and developed area where the grizzly still survives. The information gathered throughout the course of the study is used to better protect and manage the bears and other sensitive carnivores in the region. Using telemetry, researchers monitored 25 grizzly bears which were radio-collared in a 22,000 square-kilometer area in the upper Bow Valley drainage of the eastern Alberta slopes. The researchers worked with representatives from Husky Oil and Rigel Energy on the development of the Moose Mountain oil and gas field without adversely affecting the grizzly bear population. Information collected over eight years indicates that the grizzly bears have few and infrequent offspring. Using the information gathered thus far, the location of the Moose Mountain to Jumping Pound pipeline was carefully selected, since the bears suffer from high mortality, and the food and cover had already been compromised by the high number of roads, trails and other human activities in the area. The research concluded in November 2001 provides sufficient information to accurately asses the status of the grizzly bear population and habitat. The data will be analyzed and integrated in 2002 into models that reflect the variables affecting grizzly bears and a final report will be published.

  5. Biogeochemistry of southern Australian continental slope sediments

    International Nuclear Information System (INIS)

    Veeh, H.H.; Crispe, A.J.; Heggie, D.T.


    Sediment cores from the middle to lower slope of the southern continental margin of Australia between the Great Australian Bight and western Tasmania are compared in terms of marine and terrigenous input signals during the Holocene. The mass accumulation rates of carbonate, organic carbon, biogenic Ba. and Al are corrected for lateral sediment input (focusing), using the inventory of excess 230 Th in the sediment normalised to its known production rate in the water column above each site. The biogenic signal is generally higher in the eastern part of the southern margin probably due to enhanced productivity associated with seasonal upwelling off southeastern South Australia and the proximity of the Subtropical Front, which passes just south of Tasmania. The input of Al, representing the terrigenous signal, is also higher in this region reflecting the close proximity of river runoff from the mountainous catchment of southeastern Australia. The distribution pattern of Mn and authigenic U, together with pore-water profiles of Mn ++ , indicate diagenetic reactions driven by the oxidation of buried organic carbon in an oxic to suboxic environment. Whereas Mn is reduced at depth and diffuses upwards to become immobilised in a Mn-rich surface layer. U is derived from seawater and diffuses downward into the sediment, driven by reduction and precipitation at a depth below the reduction zone of Mn. The estimated removal rate of U from seawater by this process is within the range of U removal measured in hemipelagic sediments from other areas, and supports the proposition that hemipelagic sediments are a major sink of U in the global ocean. Unlike Mn, the depth profile of sedimentary Fe appears to be little affected by diagenesis, suggesting that little of the total Fe inventory in the sediment is remobilised and redistributed as soluble Fe. Copyright (1999) Blackwell Science Pty Ltd

  6. Analysis of local slopes at the InSight landing site on Mars (United States)

    Fergason, Robin L.; Kirk, Randolph L.; Cushing, Glen; Galuszka, Donna M.; Golombek, Matthew P.; Hare, Trent M.; Howington-Kraus, Elpitha; Kipp, Devin M; Redding, Bonnie L.


    To evaluate the topography of the surface within the InSight candidate landing ellipses, we generated Digital Terrain Models (DTMs) at lander scales and those appropriate for entry, descent, and landing simulations, along with orthoimages of both images in each stereopair, and adirectional slope images. These products were used to assess the distribution of slopes for each candidate ellipse and terrain type in the landing site region, paying particular attention to how these slopes impact InSight landing and engineering safety, and results are reported here. Overall, this region has extremely low slopes at 1-meter baseline scales and meets the safety constraints of the InSight lander. The majority of the landing ellipse has a mean slope at 1-meter baselines of 3.2°. In addition, a mosaic of HRSC, CTX, and HiRISE DTMs within the final landing ellipse (ellipse 9) was generated to support entry, descent, and landing simulations and evaluations. Several methods were tested to generate this mosaic and the NASA Ames Stereo Pipeline program dem_mosaic produced the best results. For the HRSC-CTX-HiRISE DTM mosaic, more than 99 % of the mosaic has slopes less than 15°, and the introduction of artificially high slopes along image seams was minimized.

  7. The Slippery Slope Argument in the Ethical Debate on Genetic Engineering of Humans. (United States)

    Walton, Douglas


    This article applies tools from argumentation theory to slippery slope arguments used in current ethical debates on genetic engineering. Among the tools used are argumentation schemes, value-based argumentation, critical questions, and burden of proof. It is argued that so-called drivers such as social acceptance and rapid technological development are also important factors that need to be taken into account alongside the argumentation scheme. It is shown that the slippery slope argument is basically a reasonable (but defeasible) form of argument, but is often flawed when used in ethical debates because of failures to meet the requirements of its scheme.

  8. A Critical Review of Landslide Failure Mechanisms (United States)

    Stead, D.; Wolter, A.; Clague, J. J.


    During the last ten years several comprehensive geotechnical studies have been completed on major historic landslides including Randa in Switzerland, Frank in Canada, Aknes in Norway, La Clapiere in France and Vaiont in Italy. In addition, numerous researchers have documented deep-seated gravitational deformations and a wide variety of large prehistoric rock slope failures. The information provided by these studies is evidence of the significant advances made in our ability to map, monitor and model landslides. Over the same period, the mining industry has developed large open pits with slope heights exceeding 1000 m that provide important analogues to high mountain slopes. In this paper we analyse data from the literature to illustrate the importance of brittle fracture, 3D controls, anisotropy, overburden stress, geomorphic processes, groundwater and temperature in major landslides and provide some indicators as to the research required to further understand the complexity of rock slope failure mechanisms. The nature of the landslide failure surface has received inadequate attention in the past, with failure surfaces typically considered in 2D and simulated as discrete, smooth and often planar features. Current work shows that failure surfaces are inherently three-dimensional and have much structural variability across the area of the landslide scarp, reflecting complex structural histories. Such anisotropy and variations may result in multiple events or distinct blocks that move at different rates. Just as most failure surfaces vary spatially, they may also change with depth and thus should more realistically be considered failure zones rather than discrete surfaces. The increasing recognition of the importance of step-path failures, internal dilation and brittle fracture are indicative of the complexity in slope failure surfaces. Related to the variation in failure surface characteristics is the importance of 3D rotational displacements and both the

  9. Effects of Rainfall Characteristics on the Stability of Tropical Residual Soil Slope

    Directory of Open Access Journals (Sweden)

    Rahardjo Harianto


    Full Text Available Global climate change has a significant impact on rainfall characteristics, sea water level and groundwater table. Changes in rainfall characteristics may affect stability of slopes and have severe impacts on sustainable urban living. Information on the intensity, frequency and duration of rainfall is often required by geotechnical engineers for performing slope stability analyses. Many seepage analyses are commonly performed using the most extreme rainfall possible which is uneconomical in designing a slope repair or slope failure preventive measure. In this study, the historical rainfall data were analyzed and investigated to understand the characteristics of rainfall in Singapore. The frequency distribution method was used to estimate future rainfall characteristics in Singapore. New intensity-duration-frequency (IDF curves for rainfall in Singapore were developed for six different durations (10, 20, 30 min and 1, 2 and 24 h and six frequencies (2, 5, 10, 25, 50 and 100 years. The new IDF curves were used in the seepage and slope stability analyses to determine the variation of factor of safety of residual soil slopes under different rainfall intensities in Singapore.

  10. Saturated and unsaturated stability analysis of slope subjected to rainfall infiltration

    Directory of Open Access Journals (Sweden)

    Gofar Nurly


    Full Text Available This paper presents results of saturated and unsaturated stability analysis of typical residual slopes subjected to rainfall infiltration corresponds to 50 years rainfall return period. The slope angles considered were 45° and 70°. The saturated stability analyses were carried out for original and critical ground water level commonly considered by practicing engineer. The analyses were conducted using limit equilibrium method. Unsaturated stability analyses used combination of coupled stress–pore-water pressure analysis to evaluate the effect of rainfall infiltration on the deformation and transient pore-water pressure on slope stability. Slope stability analyses were performed at some times during and after rainfall infiltration. Results show that the critical condition for slope made by sandy material was at the end of rainfall while for clayey material was at some specified times after the rainfall ceased. Unsaturated stability analysis on sandy soil gives higher factor of safety because the soil never reached saturation. Transient analysis using unsaturated soil concept could predict more critical condition of delayed failure of slopes made up of clayey soil.

  11. Freeze/Thaw-Induced Deformation Monitoring and Assessment of the Slope in Permafrost Based on Terrestrial Laser Scanner and GNSS

    Directory of Open Access Journals (Sweden)

    Lihui Luo


    Full Text Available Most previous studies of the Qinghai-Tibet engineering corridor (QTEC have focused on the impacts of climate change on thaw-induced slope failures, whereas few have considered freeze-induced slope failures. Terrestrial laser scanning was used in combination with global navigation satellite systems to monitor three-dimensional surface changes between 2014 and 2015 on the slope of permafrost in the QTEC, which experienced two thawing periods and a freezing period. Soil temperature and moisture sensors were also deployed at 11 depths to reveal the hydrological–thermal dynamics of the active layer. We analyzed scanned surface changes in the slope based on comparisons of multi-temporal point cloud data to determine how the hydrological–thermal process affected active layer deformation during freeze–thaw cycles, thereby comprehensively quantifying the surface deformation. During the two thawing periods, the major structure of the slope exhibited subsidence trends, whereas the major structure of the slope had an uplift trend in the freezing period. The seasonal subsidence trend was caused by thaw settlement and the seasonal uplift trend was probably due to frost heaving. This occurred mainly because the active layer and the upper permafrost underwent a phase transition due to heat transfer. The ground movements occurred approximately in the soil temperature conduction direction between the top of the soil and the permafrost table. The elevation deformation range was mainly −0.20 m to 0.20 m. Surface volume increases with heaving after freezing could have compensated for the loss of thawing twice and still led to the upward swelling of the slope. Thus, this type of slope in permafrost is dominated by frost heave. Deformation characteristics of the slope will support enhanced decision making regarding the implementation of remote sensing and hydrological–thermal measurement technologies to monitor changes in the slopes in permafrost adjacent to

  12. Lava delta deformation as a proxy for submarine slope instability (United States)

    Di Traglia, Federico; Nolesini, Teresa; Solari, Lorenzo; Ciampalini, Andrea; Frodella, William; Steri, Damiano; Allotta, Benedetto; Rindi, Andrea; Marini, Lorenzo; Monni, Niccolò; Galardi, Emanuele; Casagli, Nicola


    the 30 December 2002 landslide, which involved the lava delta and its surrounding areas. InSAR data provided the post-effusive deformation field after the 2007 and 2014 flank eruptions, whereas LEM results highlighted that the accumulation of lava flows on the prone-to-failure SdF submarine slope is the main cause of the detected lava delta deformation. Lava delta instability, measured also at Pico Island (Azores) and Kilauea volcano (Hawaii), is evidence of the broader spectrum of instability phenomena that take place in the coastal or submarine area of the flanks of the volcanoes. At Kilauea, past lava deltas have moved faster than the surrounding slope and the recorded movements relate only to the collapses of the deltas themselves, producing rapid mass wasting near the coasts. In contrast, at Stromboli and Pico, lava deltas move at the same velocity as the surrounding slope. In these cases, the displacement at lava deltas can be considered as a proxy for the deformation of submarine slides. There are very few studies dealing with lava delta deformation, thus, the analysis presented in this work will benefit the monitoring of submarine slopes in other prone-to-failure coastal or island volcanic systems which have the potential to generate tsunamis.

  13. Controls on shallow landslide initiation: Diverse hydrologic pathways, 3D failure geometries, and unsaturated soil suctions (United States)

    Reid, Mark; Iverson, Richard; Brien, Dianne; Iverson, Neal; LaHusen, Richard; Logan, Matthew


    Shallow landslides and ensuing debris flows are a common hazard worldwide, yet forecasting their initiation at a specific site is challenging. These challenges arise, in part, from diverse near-surface hydrologic pathways under different wetting conditions, 3D failure geometries, and the effects of suction in partially saturated soils. Simplistic hydrologic models typically used for regional hazard assessment disregard these complexities. As an alterative to field studies where the effects of these governing factors can be difficult to isolate, we used the USGS debris-flow flume to conduct controlled, field-scale landslide initiation experiments. Using overhead sprinklers or groundwater injectors on the flume bed, we triggered failures using three different wetting conditions: groundwater inflow from below, prolonged moderate-intensity precipitation, and bursts of high-intensity precipitation. Failures occurred in 6 m3 (0.65-m thick and 2-m wide) prisms of loamy sand on a 31° slope; these field-scale failures enabled realistic incorporation of nonlinear scale-dependent effects such as soil suction. During the experiments, we monitored soil deformation, variably saturated pore pressures, and moisture changes using ˜50 sensors sampling at 20 Hz. From ancillary laboratory tests, we determined shear strength, saturated hydraulic conductivities, and unsaturated moisture retention characteristics. The three different wetting conditions noted above led to different hydrologic pathways and influenced instrumental responses and failure timing. During groundwater injection, pore-water pressures increased from the bed of the flume upwards into the sediment, whereas prolonged moderate infiltration wet the sediment from the ground surface downward. In both cases, pore pressures acting on the impending failure surface slowly rose until abrupt failure. In contrast, a burst of intense sprinkling caused rapid failure without precursory development of widespread positive pore

  14. The Upper 1000-m Slope Currents North of the South Shetland Islands and Elephant Island Based on Ship Cruise Observations (United States)

    Du, Guangqian; Zhang, Zhaoru; Zhou, Meng; Zhu, Yiwu; Zhong, Yisen


    While the Antarctic Slope Current (ASC) has been intensively studied for the East Antarctica slope area and the Weddell Sea, its fate in the western Antarctic Peninsula (WAP) region remains much less known. Data from two cruises conducted near the South Shetland Islands (SSIs) and the Elephant Island (EI), one in austral summer of 2004 and one in austral winter of 2006, were analyzed to provide a broad picture of the circulation pattern over the continental slope of the surveyed area, and an insight into the dynamical balance of the circulation. The results indicate that southwestward currents are present over the upper slope in the study area, indicating the ASC in the WAP region. Near the Shackleton Gap (SG) north of the EI, the southwestward slope currents near the shelf break are characterized by a water mass colder and fresher than the ambient water, which produces cross-slope density gradients and then vertical shear of the along-slope (or along-isobath) velocity. The vertical shear is associated with a reversal of the along-slope current from northeastward at surface to southwestward in deeper layers, or a depth-intensification of the southwestward slope currents. The water mass with temperature and salinity characteristics similar to the observed cold and fresh water is also revealed on the southern slope of the Scotia Sea, suggesting that this cold and fresh water is originated from the Scotia Sea slope and flows southwestward through the SG. Over the shelf north of the SSIs, the cold and fresh water mass is also observed and originates mainly from the Bransfield Strait. In this area, vertical structure of the southwestward slope currents is associated with the onshore intrusion of the upper Circumpolar Deep Water that creates cross-slope density gradients.

  15. Role of slope on infiltration: A review (United States)

    Morbidelli, Renato; Saltalippi, Carla; Flammini, Alessia; Govindaraju, Rao S.


    Partitioning of rainfall at the soil-atmosphere interface is important for both surface and subsurface hydrology, and influences many events of major hydrologic interest such as runoff generation, aquifer recharge, and transport of pollutants in surface waters as well as the vadose zone. This partitioning is achieved through the process of infiltration that has been widely investigated at the local scale, and more recently also at the field scale, by models that were designed for horizontal surfaces. However, infiltration, overland flows, and deep flows in most real situations are generated by rainfall over sloping surfaces that bring in additional effects. Therefore, existing models for local infiltration into homogeneous and layered soils and those as for field-scale infiltration, have to be adapted to account for the effects of surface slope. Various studies have investigated the role of surface slope on infiltration based on a theoretical formulations for the dynamics of infiltration, extensions of the Green-Ampt approach, and from laboratory and field experiments. However, conflicting results have been reported in the scientific literature on the role of surface slope on infiltration. We summarize the salient points from previous studies and provide plausible reasons for discrepancies in conclusions of previous authors, thus leading to a critical assessment of the current state of our understanding on this subject. We offer suggestions for future efforts to advance our knowledge of infiltration over sloping surfaces.

  16. Decision Guide for Roof Slope Selection

    Energy Technology Data Exchange (ETDEWEB)

    Sharp, T.R.


    This decision guide has been written for personnel who are responsible for the design, construction, and replacement of Air Force roofs. It provides the necessary information and analytical tools for making prudent and cost-effective decisions regarding the amount of slope to provide in various roofing situations. Because the expertise and experience of the decision makers will vary, the guide contains both basic slope-related concepts as well as more sophisticated technical data. This breadth of information enables the less experienced user to develop an understanding of roof slope issues before applying the more sophisticated analytical tools, while the experienced user can proceed directly to the technical sections. Although much of this guide is devoted to the analysis of costs, it is not a cost-estimating document. It does, however, provide the reader with the relative costs of a variety of roof slope options; and it shows how to determine the relative cost-effectiveness of different options. The selection of the proper roof slope coupled with good roof design, a quality installation, periodic inspection, and appropriate maintenance and repair will achieve the Air Force's objective of obtaining the best possible roofing value for its buildings.

  17. Ambient vibration characterization and monitoring of a rock slope close to collapse (United States)

    Burjánek, Jan; Gischig, Valentin; Moore, Jeffrey R.; Fäh, Donat


    We analyse the ambient vibration response of Alpe di Roscioro (AdR), an incipient rock slope failure located above the village Preonzo in southern Switzerland. Following a major failure in May 2012 (volume ˜210 000 m3), the remaining unstable rock mass (˜140 000 m3) remains highly fractured and disrupted, and has been the subject of intensive monitoring. We deployed a small-aperture seismic array at the site shortly after the 2012 failure. The measured seismic response exhibited strong directional amplification (factors up to 35 at 3.5 Hz), higher than previously recorded on rock slopes. The dominant direction of ground motion was found to be parallel to the predominant direction of deformation and perpendicular to open fractures, reflecting subsurface structure of the slope. We then equipped the site with two semi-permanent seismic stations to monitor the seismic response with the goal of identifying changes caused by internal damage that may precede subsequent failure. Although failure has not yet occurred, our data reveal important variations in the seismic response. Amplification factors and resonant frequencies exhibit seasonal trends related (both directly and inversely) to temperature changes and are sensitive to freezing periods (resonant frequencies increase with temperature and during freezing). We attribute these effects to thermal expansion driving microcrack closure, in addition to ice formation, which increase fracture and bulk rock stiffness. We find the site response at AdR is linear over the measured range of weak input motions spanning two orders of magnitude. Our results further develop and refine ambient vibration methods used in rock slope hazard assessment.

  18. Soil slips and debris flows on terraced slopes (United States)

    Crosta, G. B.; Dal Negro, P.; Frattini, P.

    Terraces cover large areas along the flanks of many alpine and prealpine valleys. Soil slips and soil slips-debris flows are recurrent phenomena along terraced slopes. These landslides cause damages to people, settlements and cultivations. This study investigates the processes related to the triggering of soil slip-debris flows in these settings, analysing those occurred in Valtellina (Central Alps, Italy) on November 2000 after heavy prolonged rainfalls. 260 landslides have been recognised, mostly along the northern valley flank. About 200 soil slips and slumps occurred in terraced areas and a third of them evolved into debris flows. Field work allowed to recognise the settings at soil slip-debris flow source areas. Landslides affected up to 2.5 m of glacial, fluvioglacial and anthropically reworked deposits overlying metamorphic basement. Laboratory and in situ tests allowed to characterise the geotechnical and hydraulic properties of the terrains involved in the initial failure. Several stratigraphic and hydrogeologic factors have been individuated as significant in determining instabilities on terraced slopes. They are the vertical changes of physical soil properties, the presence of buried hollows where groundwater convergence occurs, the rising up of perched groundwater tables, the overflow and lateral infiltration from superficial drainage network, the runoff concentration by means of pathways and the insufficient drainage of retaining walls.

  19. Soil-root Shear Strength Properties of Some Slope Plants

    International Nuclear Information System (INIS)

    Normaniza Osman; Mohamad Nordin Abdullah; Faisal Haji Ali


    Rapid development in hilly areas in Malaysia has become a trend that put a stress to the sloping area. It reduces the factor of safety by reducing the resistant force and therefore leads to slope failure. Vegetation plays a big role in reinforcement functions via anchoring the soils and forms a binding network within the soil layer that tied the soil masses together. In this research, three plant species namely Acacia mangium, Dillenia suffruticosa and Leucaena leucocaphala were assessed in term of their soil-root shear strength properties. Our results showed that Acacia mangium had the highest shear strength values, 30.4 kPa and 50.2 kPa at loads 13.3 kPa and 24.3 kPa, respectively. Leucaena leucocaphala showed the highest in cohesion factor, which was almost double the value in those of Dillenia suffruticosa and Acacia mangium. The root profile analysis indicated Dillenia suffruticosa exhibited the highest values in both root length density and root volume, whilst Leucaena leucocaphala had the highest average of root diameter. (author)

  20. Slope streaks on Mars: A new “wet” mechanism (United States)

    Kreslavsky, Mikhail A.; Head, James W.


    Slope steaks are one of the most intriguing modern phenomena observed on Mars. They have been mostly interpreted as some specific type of granular flow. We propose another mechanism for slope streak formation on Mars. It involves natural seasonal formation of a modest amount of highly concentrated chloride brines within a seasonal thermal skin, and runaway propagation of percolation fronts. Given the current state of knowledge of temperature regimes and the composition and structure of the surface layer in the slope streak regions, this mechanism is consistent with the observational constraints; it requires an assumption that a significant part of the observed chlorine to be in form of calcium and ferric chloride, and a small part of the observed hydrogen to be in form of water ice. This "wet" mechanism has a number of appealing advantages in comparison to the widely accepted "dry" granular flow mechanism. Potential tests for the "wet" mechanism include better modeling of the temperature regime and observations of the seasonality of streak formation.

  1. The great slippery-slope argument. (United States)

    Burgess, J A


    Whenever some form of beneficent killing--for example, voluntary euthanasia--is advocated, the proposal is greeted with a flood of slippery-slope arguments warning of the dangers of a Nazi-style slide into genocide. This paper is an attempt systematically to evaluate arguments of this kind. Although there are slippery-slope arguments that are sound and convincing, typical formulations of the Nazi-invoking argument are found to be seriously deficient both in logical rigour and in the social history and psychology required as a scholarly underpinning. As an antidote, an attempt is made both to identify some of the likely causes of genocide and to isolate some of the more modest but legitimate fears that lie behind slippery-slope arguments of this kind.

  2. On Front Slope Stability of Berm Breakwaters

    DEFF Research Database (Denmark)

    Burcharth, Hans F.


    The short communication presents application of the conventional Van der Meer stability formula for low-crested breakwaters for the prediction of front slope erosion of statically stable berm breakwaters with relatively high berms. The method is verified (Burcharth, 2008) by comparison...... with the reshaping of a large Norwegian breakwater exposed to the North Sea waves. As a motivation for applying the Van der Meer formula a discussion of design parameters related to berm breakwater stability formulae is given. Comparisons of front erosion predicted by the use of the Van der Meer formula with model...... test results including tests presented in Sigurdarson and Van der Meer (2011) are discussed. A proposal is presented for performance of new model tests with the purpose of developing more accurate formulae for the prediction of front slope erosion as a function of front slope, relative berm height...

  3. Failure Modes

    DEFF Research Database (Denmark)

    Jakobsen, K. P.; Burcharth, H. F.; Ibsen, Lars Bo


    The present appendix contains the derivation of ten different limit state equations divided on three different failure modes. Five of the limit state equations can be used independently of the characteristics of the subsoil, whereas the remaining five can be used for either drained or undrained s...

  4. The great slippery-slope argument.


    Burgess, J A


    Whenever some form of beneficent killing--for example, voluntary euthanasia--is advocated, the proposal is greeted with a flood of slippery-slope arguments warning of the dangers of a Nazi-style slide into genocide. This paper is an attempt systematically to evaluate arguments of this kind. Although there are slippery-slope arguments that are sound and convincing, typical formulations of the Nazi-invoking argument are found to be seriously deficient both in logical rigour and in the social hi...

  5. Reclamation of slopes left after surface mining

    Energy Technology Data Exchange (ETDEWEB)

    Zmitko, J [Banske Projekty, Teplice (Czech Republic)


    Discusses land reclamation of abandoned slopes from brown coal surface mining in the North Bohemian brown coal basin in the Czech Republic. Problems associated with reclamation of landslide areas in two former coal mines are evaluated: the Otokar mine in Kostany (mining from 1956 to 1966) and the CSM mine in Pozorka (mining from 1955 to 1967). Land reclamation was introduced 25 years after damage occurred. The following aspects are analyzed: hydrogeologic conditions, range of landslides, types of rocks in landslide areas, water conditions, methods for stabilizing slopes, safety aspects.

  6. Slope movements triggered by heavy rainfall, November 3–5, 1985, in Virginia and West Virginia, U.S.A. (United States)

    Jacobson, Robert B.; Cron, Elizabeth D.; McGeehin, John P.


    Study of slope movements triggered by the storm of November 3–5, 1985, in the central Appalachian Mountains, U.S.A., has helped to define the meteorologic conditions leading to slope movements and the relative importance of land cover, bedrock, surficial geology, and geomorphology in slope movement location. This long-duration rainfall at moderate intensities triggered more than 1,000 slope movements in a 1,040-km2 study area. Most were shallow slips and slip-flows in thin colluvium and residuum on shale slopes. Locations of these failures were sensitive to land cover and slope aspect but were relatively insensitive to topographic setting. A few shallow slope movements were triggered by the same rainfall on interbedded limestone, shale, and sandstone. Several large debris slide-avalanches were triggered in sandstone regolith high on ridges in areas of the highest measured rainfall. Most of these sites were on slopes that dip 30 to 35° and lie parallel to bedding planes, presumably the sites of least stability.

  7. Failure and Redemption of Multifilter Rotating Shadowband Radiometer (MFRSR/Normal Incidence Multifilter Radiometer (NIMFR Cloud Screening: Contrasting Algorithm Performance at Atmospheric Radiation Measurement (ARM North Slope of Alaska (NSA and Southern Great Plains (SGP Sites

    Directory of Open Access Journals (Sweden)

    James Barnard


    Full Text Available Well-known cloud-screening algorithms, which are designed to remove cloud-contaminated aerosol optical depths (AOD from Multifilter Rotating Shadowband Radiometer (MFRSR and Normal Incidence Multifilter Radiometer (NIMFR measurements, have exhibited excellent performance at many middle-to-low latitude sites around world. However, they may occasionally fail under challenging observational conditions, such as when the sun is low (near the horizon and when optically thin clouds with small spatial inhomogeneity occur. Such conditions have been observed quite frequently at the high-latitude Atmospheric Radiation Measurement (ARM North Slope of Alaska (NSA sites. A slightly modified cloud-screening version of the standard algorithm is proposed here with a focus on the ARM-supported MFRSR and NIMFR data. The modified version uses approximately the same techniques as the standard algorithm, but it additionally examines the magnitude of the slant-path line of sight transmittance and eliminates points when the observed magnitude is below a specified threshold. Substantial improvement of the multi-year (1999–2012 aerosol product (AOD and its Angstrom exponent is shown for the NSA sites when the modified version is applied. Moreover, this version reproduces the AOD product at the ARM Southern Great Plains (SGP site, which was originally generated by the standard cloud-screening algorithms. The proposed minor modification is easy to implement and its application to existing and future cloud-screening algorithms can be particularly beneficial for challenging observational conditions.

  8. Subsurface Characterization using Geophysical Seismic Refraction Survey for Slope Stabilization Design with Soil Nailing (United States)

    Ashraf Mohamad Ismail, Mohd; Ng, Soon Min; Hazreek Zainal Abidin, Mohd; Madun, Aziman


    The application of geophysical seismic refraction for slope stabilization design using soil nailing method was demonstrated in this study. The potential weak layer of the study area is first identify prior to determining the appropriate length and location of the soil nail. A total of 7 seismic refraction survey lines were conducted at the study area with standard procedures. The refraction data were then analyzed by using the Pickwin and Plotrefa computer software package to obtain the seismic velocity profiles distribution. These results were correlated with the complementary borehole data to interpret the subsurface profile of the study area. It has been identified that layer 1 to 3 is the potential weak zone susceptible to slope failure. Hence, soil nails should be installed to transfer the tensile load from the less stable layer 3 to the more stable layer 4. The soil-nail interaction will provide a reinforcing action to the soil mass thereby increasing the stability of the slope.

  9. The Socioeconomic Assessment of Sloping Land Conversion Program in China

    DEFF Research Database (Denmark)

    Liu, Zhen

    Abstract This thesis mainly focuses on the socioeconomic impact of the largest Ecological Recovery Program ― the Sloping Land Conversion Program (SLCP), also called Grain for Green Program (GFG) in China. The central government initiated this program in 1999 and it was launched nationwide in 2002...... of which support the policy intention of central government according to our own understanding, whereas the effects differ depending on the group, region and period. This research provides a detailed understanding of the treatment effects of the SLCP and thus, contributes to the on-going political debate...

  10. Shoaling internal solitary waves of depression over gentle slopes (United States)

    Rivera, Gustavo; Diamessis, Peter


    The shoaling of an internal solitary wave (ISW) of depression over gentle slopes is explored through fully nonlinear and non-hydrostatic simulations using a high resolution/accuracy deformed spectral multidomain penalty method. During shoaling, the wave does not disintegrate as in the case of steeper slope but, instead, maintains its symmetric shape. At the core of the wave, an unstable region forms, characterized by the entrapment of heavier-over-light fluid. The formation of this convective instability is attributed to the vertical stretching by the ISW of the near-surface vorticity layer associated with the baroclinic background current. According to recent field observations in the South China Sea, the unstable region drives localized turbulent mixing within the wave, estimated to be up to four times larger than that in the open ocean, in the form of a recirculating trapped core. In this talk, emphasis is placed on the structure of the unstable region and the persistence of a possible recirculating core using simulations which capture 2D wave propagation combined with 3D representation of the transition to turbulence. As such, a preliminary understanding of the underlying fluid mechanics and the potential broader oceanic significance of ISWs with trapped cores is offered. Financial support gratefully acknowledged to NSF OCE Grant 1634257.

  11. Types of Heart Failure (United States)

    ... Introduction Types of Heart Failure Classes of Heart Failure Heart Failure in Children Advanced Heart Failure • Causes and ... and procedures related to heart disease and stroke. Heart Failure Questions to Ask Your Doctor Use these questions ...

  12. Classes of Heart Failure (United States)

    ... Introduction Types of Heart Failure Classes of Heart Failure Heart Failure in Children Advanced Heart Failure • Causes and ... and Advanced HF • Tools and Resources • Personal Stories Heart Failure Questions to Ask Your Doctor Use these questions ...

  13. Direct observations of the Antarctic Slope Current transport at 113°E (United States)

    Peña-Molino, B.; McCartney, M. S.; Rintoul, S. R.


    The Antarctic Slope Current (ASC), defined here as the region of westward flow along the continental slope off Antarctica, forms the southern limb of the subpolar gyres. It regulates the exchange of water across the shelf break and provides a path for interbasin westward transport. Despite its significance, the ASC remains largely unobserved around most of the Antarctic continent. Here we present direct velocity observations from a 17 month current meter moored array deployed across the continental slope between the 1000 and the 4200 m isobaths, in the southeastern Indian Ocean near 113°E. The observed time-mean flow consists of a surface-intensified jet associated with the Antarctic Slope Front (ASF) and a broader bottom-intensified westward flow that extends out to approximately the 4000 m isobath and is strongest along the upper slope. The time-mean transport of the ASC is -29.2 Sv. Fluctuations in the transport are large, typically exceeding the mean by a factor of 2. They are mainly due to changes in the northward extent of the current over the lower slope. However, seasonal changes in the wind also drive variations in the transport of the ASF and the flow in the upper slope. Both mean and variability are largely barotropic, thus invisible to traditional geostrophic methods.

  14. Erosion protection Phytoreinforcement of SCARP steep slopes of the holy virgin’s DITCH

    Directory of Open Access Journals (Sweden)

    Darchiya Valentina Ivanovna


    Full Text Available Erosion protection landscaping embedment of steep subsoil slopes is a time-sensitive issue of road construction and planning of recreational area that are often fit on a challenging picturesque terrain unsuitable for site development. The article provides the results of a 4-year experiment on landscaping and plant fixing of up to 4.5 m soil slopes with 1:1 and 2:1 grades; the experiment was carried out by the MGSU on the territory of a convent in the south of the Nizhniy Novgorod region. The site has slopes oriented towards all cardinals. At some places the slopes are bedimmed by trees. All these factors create a wide range of geo-ecological conditions for lawns. All the slopes are fixed with geo-fibrefill grids; slopes with 2:1 grade are strengthened by auxiliary grids made of reinforced metal bars, anchors and braces on the bottom of the Holy Moat. The paper recommends composition of grass plants as well as techniques to build up lawns suitable for various micro-climate conditions. It also advises the structure of multi-tier plant entity. The suggested methods are tested during a 3-year maintenance of slopes built for constant use.

  15. 30 CFR 77.1911 - Ventilation of slopes and shafts. (United States)


    ... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Slope and Shaft Sinking § 77.1911 Ventilation of slopes and shafts. (a) All slopes and... connected to the slope or shaft opening with fireproof air ducts; (3) Designed to permit the reversal of the...

  16. Reorienting with terrain slope and landmarks. (United States)

    Nardi, Daniele; Newcombe, Nora S; Shipley, Thomas F


    Orientation (or reorientation) is the first step in navigation, because establishing a spatial frame of reference is essential for a sense of location and heading direction. Recent research on nonhuman animals has revealed that the vertical component of an environment provides an important source of spatial information, in both terrestrial and aquatic settings. Nonetheless, humans show large individual and sex differences in the ability to use terrain slope for reorientation. To understand why some participants--mainly women--exhibit a difficulty with slope, we tested reorientation in a richer environment than had been used previously, including both a tilted floor and a set of distinct objects that could be used as landmarks. This environment allowed for the use of two different strategies for solving the task, one based on directional cues (slope gradient) and one based on positional cues (landmarks). Overall, rather than using both cues, participants tended to focus on just one. Although men and women did not differ significantly in their encoding of or reliance on the two strategies, men showed greater confidence in solving the reorientation task. These facts suggest that one possible cause of the female difficulty with slope might be a generally lower spatial confidence during reorientation.

  17. Interrill soil erosion processes on steep slopes (United States)

    To date interrill erosion processes and regimes are not fully understood. The objectives are to 1) identify the erosion regimes and limiting processes between detachment and transport on steep slopes, 2) characterize the interactive effects between rainfall intensity and flow depth on sediment trans...

  18. A Novel Way To Practice Slope. (United States)

    Kennedy, Jane B.


    Presents examples of using a tic-tac-toe format to practice finding the slope and identifying parallel and perpendicular lines from various equation formats. Reports the successful use of this format as a review in both precalculus and calculus classes before students work with applications of analytic geometry. (JRH)

  19. Long-term results of high-dose conformal radiotherapy for patients with medically inoperable T1-3N0 non-small-cell lung cancer: Is low incidence of regional failure due to incidental nodal irradiation?

    International Nuclear Information System (INIS)

    Chen Ming; Hayman, James A.; Haken, Randall K. ten; Tatro, Daniel; Fernando, Shaneli; Kong, F.-M.


    Purpose: To report the results of high-dose conformal irradiation and examine incidental nodal irradiation and nodal failure in patients with inoperable early-stage non-small-cell lung cancer (NSCLC). Methods and Materials: This analysis included patients with inoperable CT-staged T1-3N0M0 NSCLC treated on our prospective dose-escalation trial. Patients were treated with radiation alone (total dose, 63-102.9 Gy in 2.1-Gy daily fractions) with a three-dimensional conformal technique without intentional nodal irradiation. Bilateral highest mediastinal and upper/lower paratracheal, prevascular and retrotracheal, sub- and para-aortic, subcarinal, paraesophageal, and ipsilateral hilar regions were delineated individually. Nodal failure and doses of incidental irradiation were studied. Results: The potential median follow-up was 104 months. For patients who completed protocol treatment, median survival was 31 months. The actuarial overall survival rate was 86%, 61%, 43%, and 21% and the cause-specific survival rate was 89%, 70%, 53%, and 35% at 1, 2, 3, and 5 years, respectively. Weight loss (p = 0.008) and radiation dose in Gy (p = 0.013) were significantly associated with overall survival. In only 22% and 13% of patients examined did ipsilateral hilar and paratracheal (and subaortic for left-sided tumor) nodal regions receive a dose of ≥40 Gy, respectively. Less than 10% of all other nodal regions received a dose of ≥40 Gy. No patients failed initially at nodal sites. Conclusions: Radiation dose is positively associated with overall survival in patients with medically inoperable T1-3N0 NSCLC, though long-term results remain poor. The nodal failure rate is low and does not seem to be due to high-dose incidental irradiation

  20. Sliding surface searching method for slopes containing a potential weak structural surface

    Directory of Open Access Journals (Sweden)

    Aijun Yao


    Full Text Available Weak structural surface is one of the key factors controlling the stability of slopes. The stability of rock slopes is in general concerned with set of discontinuities. However, in soft rocks, failure can occur along surfaces approaching to a circular failure surface. To better understand the position of potential sliding surface, a new method called simplex-finite stochastic tracking method is proposed. This method basically divides sliding surface into two parts: one is described by smooth curve obtained by random searching, the other one is polyline formed by the weak structural surface. Single or multiple sliding surfaces can be considered, and consequently several types of combined sliding surfaces can be simulated. The paper will adopt the arc-polyline to simulate potential sliding surface and analyze the searching process of sliding surface. Accordingly, software for slope stability analysis using this method was developed and applied in real cases. The results show that, using simplex-finite stochastic tracking method, it is possible to locate the position of a potential sliding surface in the slope.

  1. Failure Analysis

    International Nuclear Information System (INIS)

    Iorio, A.F.; Crespi, J.C.


    After ten years of operation at the Atucha I Nuclear Power Station a gear belonging to a pressurized heavy water reactor refuelling machine, failed. The gear box was used to operate the inlet-outlet heavy-water valve of the machine. Visual examination of the gear device showed an absence of lubricant and that several gear teeth were broken at the root. Motion was transmitted with a speed-reducing device with controlled adjustable times in order to produce a proper fitness of the valve closure. The aim of this paper is to discuss the results of the gear failure analysis in order to recommend the proper solution to prevent further failures. (Author)

  2. Infiltration on sloping terrain and its role on runoff generation and slope stability (United States)

    Loáiciga, Hugo A.; Johnson, J. Michael


    A modified Green-and-Ampt model is formulated to quantify infiltration on sloping terrain underlain by homogeneous soil wetted by surficial water application. This paper's theory for quantifying infiltration relies on the mathematical statement of the coupled partial differential equations (pdes) governing infiltration and runoff. These pdes are solved by employing an explicit finite-difference numerical method that yields the infiltration, the infiltration rate, the depth to the wetting front, the rate of runoff, and the depth of runoff everywhere on the slope during external wetting. Data inputs consist of a water application rate or the rainfall hyetograph of a storm of arbitrary duration, soil hydraulic characteristics and antecedent moisture, and the slope's hydraulic and geometric characteristics. The presented theory predicts the effect an advancing wetting front has on slope stability with respect to translational sliding. This paper's theory also develops the 1D pde governing suspended sediment transport and slope degradation caused by runoff influenced by infiltration. Three examples illustrate the application of the developed theory to calculate infiltration and runoff on a slope and their role on the stability of cohesive and cohesionless soils forming sloping terrain.

  3. Evaluating the impacts of slope aspect on forest dynamic succession in Northwest China based on FAREAST model (United States)

    Hu, Shanshan; Ma, Jianyong; Shugart, Herman H.; Yan, Xiaodong


    Mountain forests provide the main water resources and lumber for Northwest China. The understanding of the differences in forests growing among individual slope aspects in mountainous regions is of great significance to the wise management and planning of these natural systems. The aim of this study was to investigate the impacts of slope aspect on forest dynamic succession in Northwest China by using the dynamic forest succession model (FAREAST). First, the simulated forest composition and vertical forest zonation produced by the model were compared against recorded data in three sub-regions of the Altai Mountains. The FAREAST model accurately reproduced the vertical zonation, forest composition, growth curves of the dominant species (Larix sibirica), and forest biomass in the Altai Mountains. Transitions along the forest zones of the Altai Mountains averaged about a 400 m difference between the northern and southern sites. Biomass for forests on north-facing slopes were 11.0, 15.3 and 55.9 t C ha-1 higher than for south-facing slopes in the Northeast, Central and Southeast sub-regions, respectively. Second, our analyses showed that the FAREAST model can be used to predict dynamic forest succession in Northwest China under the influence of slope and aspect. In the Altai Mountains, the north-facing slopes supported the best forest growth, followed by the west- and east-facing slopes. South-facing slopes consistently exhibited the lowest growth, biomass storage and forest diversity.

  4. Assessment of slope stability, Kemmerer Coal Company pit 1-U-D, Frontier, Wyoming

    Energy Technology Data Exchange (ETDEWEB)

    Visca, P J; Call, R D


    This paper presents the results of a study to generate probability of failure schedules for use in an economic optimization analysis. The main objectives of the study were assessment of the possible modes of instability, calculation of the attendant degree of instability for each mode, and final compilation of probability of failure schedules for use in the economic optimization programme. The University of Arizona provided the mine plan configurations from which slope geometries for analysis were determined. (Available from Micromedia Ltd., 144 Front Street West, Toronto, Ontario M5J 1G2, Canada. Quote Contract No. OSQ77-00036)

  5. Analysis of Rainfall Infiltration Law in Unsaturated Soil Slope


    Zhang, Gui-rong; Qian, Ya-jun; Wang, Zhang-chun; Zhao, Bo


    In the study of unsaturated soil slope stability under rainfall infiltration, it is worth continuing to explore how much rainfall infiltrates into the slope in a rain process, and the amount of rainfall infiltrating into slope is the important factor influencing the stability. Therefore, rainfall infiltration capacity is an important issue of unsaturated seepage analysis for slope. On the basis of previous studies, rainfall infiltration law of unsaturated soil slope is analyzed. Considering t...

  6. Corelations between the landslides and the morphological and functional units of slopes in the Transylvanian Basin

    Directory of Open Access Journals (Sweden)

    Gh. ROȘIAN


    Full Text Available The presence of fluvial morphology in the Transylvanian Basin, in form of an alternation of water divides and valley corridors, indicates favourable conditions for the genesis of geomorphologic processes. Under this aspect two sections stand out within this type of processes: river beds and slopes. In this paper, the emphasis is on the processes, developed on slopes. Water erosion and mass movement processes can be observed on their surface. From all mass movement processes, the emphasis will be put on the landslides. They will be observed in correlation with the morphologic and functional units of the slopes from different regional units of Transylvanian Basin. Eight case studies were taken into consideration regarding this aspect. Thus, we noticed that landslides particularly develop in the median part of the slopes which is corresponding to the maximum processual dynamic and transfer unit.

  7. Inversion kinematics at deep-seated gravity slope deformations revealed by trenching techniques


    Pasquaré Mariotto, Federico; Tibaldi, Alessandro


    We compare data from three deep-seated gravitational slope deformations (DSGSDs) where palaeoseismological techniques were applied in artificial trenches. At all trenches, located in metamorphic rocks of the Italian Alps, there is evidence of extensional deformation given by normal movements along slip planes dipping downhill or uphill, and/or fissures, as expected in gravitational failure. However, we document and illustrate – with the aid of trenching – evidenc...

  8. Instrumental record of debris flow initiation during natural rainfall: Implications for modeling slope stability (United States)

    Montgomery, D.R.; Schmidt, K.M.; Dietrich, W.E.; McKean, J.


    The middle of a hillslope hollow in the Oregon Coast Range failed and mobilized as a debris flow during heavy rainfall in November 1996. Automated pressure transducers recorded high spatial variability of pore water pressure within the area that mobilized as a debris flow, which initiated where local upward flow from bedrock developed into overlying colluvium. Postfailure observations of the bedrock surface exposed in the debris flow scar reveal a strong spatial correspondence between elevated piezometric response and water discharging from bedrock fractures. Measurements of apparent root cohesion on the basal (Cb) and lateral (Cl) scarp demonstrate substantial local variability, with areally weighted values of Cb = 0.1 and Cl = 4.6 kPa. Using measured soil properties and basal root strength, the widely used infinite slope model, employed assuming slope parallel groundwater flow, provides a poor prediction of hydrologie conditions at failure. In contrast, a model including lateral root strength (but neglecting lateral frictional strength) gave a predicted critical value of relative soil saturation that fell within the range defined by the arithmetic and geometric mean values at the time of failure. The 3-D slope stability model CLARA-W, used with locally observed pore water pressure, predicted small areas with lower factors of safety within the overall slide mass at sites consistent with field observations of where the failure initiated. This highly variable and localized nature of small areas of high pore pressure that can trigger slope failure means, however, that substantial uncertainty appears inevitable for estimating hydrologie conditions within incipient debris flows under natural conditions. Copyright 2009 by the American Geophysical Union.

  9. Effect of changing slope of grain on ash, maple, and yellow birch in bending strength (United States)

    David E. Kretschmann; James J. Bridwell; Timothy C. Nelson


    The presence of slope of grain (SoG) in wood can severely reduce the bending strength in wood. Failure to recognize the degree to which SoG can reduce strength can be catastrophic if wood is in single member use. In the United States, a growing concern in the sport of baseball relates to the high frequency of multi-piece broken wood bats. It was observed that hard...

  10. Geotechnical characteristics and stability analysis of rock-soil aggregate slope at the Gushui Hydropower Station, southwest China. (United States)

    Zhou, Jia-wen; Shi, Chong; Xu, Fu-gang


    Two important features of the high slopes at Gushui Hydropower Station are layered accumulations (rock-soil aggregate) and multilevel toppling failures of plate rock masses; the Gendakan slope is selected for case study in this paper. Geological processes of the layered accumulation of rock and soil particles are carried out by the movement of water flow; the main reasons for the toppling failure of plate rock masses are the increasing weight of the upper rock-soil aggregate and mountain erosion by river water. Indoor triaxial compression test results show that, the cohesion and friction angle of the rock-soil aggregate decreased with the increasing water content; the cohesion and the friction angle for natural rock-soil aggregate are 57.7 kPa and 31.3° and 26.1 kPa and 29.1° for saturated rock-soil aggregate, respectively. The deformation and failure mechanism of the rock-soil aggregate slope is a progressive process, and local landslides will occur step by step. Three-dimensional limit equilibrium analysis results show that the minimum safety factor of Gendakan slope is 0.953 when the rock-soil aggregate is saturated, and small scale of landslide will happen at the lower slope.

  11. Seismic stability analysis of rock slopes by yield design theory using the generalized Hoek-Brown criterion

    Directory of Open Access Journals (Sweden)

    Belghali Mounir


    Full Text Available The stability of rock slope is studied using the kinematic approach of yield design theory, under the condition of plane strain and by considering the last version of the Hoek-Brown failure criterion. This criterion, which is suitable to intact rock or rock mass highly fractured regarded as isotropic and homogeneous, is widely accepted by the rock mechanics community and has been applied in numerous projects around the world. The failure mechanism used to implement the kinematic approach is a log-spiral rotational mechanism. The stability analysis is carried out under the effects of gravity forces and a surcharge applied along the upper plateau of the slope. To take account of the effects of forces developed in the rock mass during the passage of a seismic wave, the conventional pseudo-static method is adopted. This method is often used in slope stability study for its simplicity and efficiency to simulate the seismic forces. The results found are compared with published numerical solutions obtained from other approaches. The comparison showed that the results are almost equal. The maximum error found is less than 1%, indicating that this approach is effective for analyzing the stability of rock slopes. The relevance of the approach demonstrated, investigations are undertaken to study the influence of some parameters on the stability of the slope. These parameters relate to the mechanical strength of the rock, slope geometry and loading.

  12. The Effect of Saturation on the Slope Sliding in the San Juan de Grijalva Comunity, Chiapas

    Directory of Open Access Journals (Sweden)

    Mora-Ortiz R.S.


    Full Text Available A number of slopes that have been stable during many years may fail when an extraordinary rain period occurs. This phenomenon involves not only the lithology, the geometric and the mechanical characteristics of the slope but also the rain-evaporation-infiltration regime of the site. In this paper, the stability of a slope in the comunity of San Juan de Grijalva, Ostuacán, Chiapas (Mexico that failed during an intense raining period is analyzed. The volume of this slide was over 5 millions of cubics meters of soil and it produced the obstruction of the Grijalva river. The stratigraphic and geometric properties of the slope were determined and undisturbed samples were obtained in the site to determine the mechanical properties of the material. The stability analysis considered the variation of the cohesion of the soil caused by wetting and it was possible to observe the evolution of the safety factor with the water content of the material. Through the analysis of the rain infiltration and the stability of the slope, it has been possible to reproduce the failure process.

  13. Effect of variations in rainfall intensity on slope stability in Singapore

    Directory of Open Access Journals (Sweden)

    Christofer Kristo


    Full Text Available Numerous scientific evidence has given credence to the true existence and deleterious impacts of climate change. One aspect of climate change is the variations in rainfall patterns, which affect the flux boundary condition across ground surface. A possible disastrous consequence of this change is the occurrence of rainfall-induced slope failures. This paper aims to investigate the variations in rainfall patterns in Singapore and its effect on slope stability. Singapore's historical rainfall data from Seletar and Paya Lebar weather stations for the period of 1985–2009 were obtained and analysed by duration using linear regression. A general increasing trend was observed in both weather stations, with a possible shift to longer duration rainfall events, despite being statistically insignificant according to the Mann-Kendall test. Using the derived trends, projected rainfall intensities in 2050 and 2100 were used in the seepage and slope stability analyses performed on a typical residual soil slope in Singapore. A significant reduction in factor of safety was observed in the next 50 years, with only a marginal decrease in factor of safety in the subsequent 50 years. This indicates a possible detrimental effect of variations in rainfall patterns on slope stability in Singapore, especially in the next 50 years. The statistical analyses on rainfall data from Seletar and Paya Lebar weather stations for the period of 1985–2009 indicated that rainfall intensity tend to increase over the years, with a possible shift to longer duration rainfall events in the future. The stability analyses showed a significant decrease in factor of safety from 2003 to 2050 due to increase in rainfall intensity, suggesting that a climate change might have existed beyond 2009 with possibly detrimental effects to slope stability. Keywords: Climate change, Rainfall, Seepage, Slope stability

  14. The role of Soil Water Retention Curve in slope stability analysis in unsaturated and heterogeneous soils. (United States)

    Antinoro, Chiara; Arnone, Elisa; Noto, Leonardo V.


    The mechanisms of rainwater infiltration causing slope instability had been analyzed and reviewed in many scientific works. Rainwater infiltration into unsaturated soil increases the degree of saturation, hence affecting the shear strength properties and thus the probability of slope failure. It has been widely proved that the shear strength properties change with the soil water suction in unsaturated soils; therefore, the accuracy to predict the relationship between soil water content and soil water suction, parameterized by the soil-water characteristic curve, has significant effects on the slope stability analysis. The aim of this study is to investigate how the characterization of SWRC of differently structured unsaturated soils affects the slope stability on a simple infinite slope. In particular, the unimodal and bimodal distributions of the soil pore size were compared. Samples of 40 soils, highly different in terms of structure and texture, were collected and used to calibrate two bimodal SWRCs, i.e. Ross and Smettem (1993) and Dexter et al., (2008). The traditional unimodal van Genuchten (1980) model was also applied for comparison. Slope stability analysis was conducted in terms of Factor of Safety (FS) by applying the infinite slope model for unsaturated soils. In the used formulation, the contribution of the suction effect is tuned by a parameter 'chi' in a rate proportional to the saturation conditions. Different parameterizations of this term were also compared and analyzed. Results indicated that all three SWRC models showed good overall performance in fitting the sperimental SWRCs. Both the RS and DE models described adequately the water retention data for soils with a bimodal behavior confirmed from the analysis of pore size distribution, but the best performance was obtained by DE model confirmed. In terms of FS, the tree models showed very similar results as soil moisture approached to the saturated condition; however, within the residual zone

  15. Restitution slope is principally determined by steady-state action potential duration. (United States)

    Shattock, Michael J; Park, Kyung Chan; Yang, Hsiang-Yu; Lee, Angela W C; Niederer, Steven; MacLeod, Kenneth T; Winter, James


    steady-state APD may contribute to the failure of restitution slope to predict sudden cardiac death. © The Author 2017. Published by Oxford University Press on behalf of the European Society of Cardiology

  16. Evaluating the Effect of Rainfall Infiltration on the Slope Stability of T16 tower of Taipei Mao-kong Gondola by Numerical Methods (United States)

    RUNG, J.


    In this study, a series of rainfall-stability analyses were performed to simulate the failure mechanism and the function of remediation works of the down slope of T-16 tower pier, Mao-Kong gondola (or T-16 Slope) at the hillside of Taipei City using two-dimensional finite element method. The failure mechanism of T-16 Slope was simulated using the rainfall hyetograph of Jang-Mi typhoon in 2008 based on the field investigation data, monitoring data, soil/rock mechanical testing data and detail design plots of remediation works. Eventually, the numerical procedures and various input parameters in the analysis were verified by comparing the numerical results with the field observations. In addition, 48 hrs design rainfalls corresponding to 5, 10, 25 and 50 years return periods were prepared using the 20 years rainfall data of Mu-Zha rainfall observation station, Central Weather Bureau for the rainfall-stability analyses of T-16 Slope to inspect the effect of the compound stabilization works on the overall stability of the slope. At T-16 Slope, without considering the longitudinal and transverse drainages on the ground surface, there totally 4 types of stabilization works were installed to stabilize the slope. From the slope top to the slope toe, the stabilization works of T-16 Slope consists of RC-retaining wall with micro-pile foundation at the up-segment, earth anchor at the up-middle-segment, soil nailing at the middle-segment and retaining pile at the down-segment of the slope. The effect of each individual stabilization work on the slope stability under rainfall condition was examined and evaluated by raising field groundwater level.

  17. Heart failure - tests (United States)

    CHF - tests; Congestive heart failure - tests; Cardiomyopathy - tests; HF - tests ... the best test to: Identify which type of heart failure (systolic, diastolic, valvular) Monitor your heart failure and ...

  18. Why regionalism has failed in Latin America: lack of stateness as an important factor for failure of sovereignty transfer in integration projects

    Directory of Open Access Journals (Sweden)

    Eduardo Pastrana Buelvas


    Full Text Available This paper shows, from an interdisciplinary perspective, the incidence of lack of "stateness" and its construction process in Latin American states, as well as showing the reluctance on the part of Latin American states to transfer sovereignty to regional integrational organizations. First, classical and contemporary ideas of sovereignty are contrasted, in order to understand the development of the sovereignty concept in Latin America and Europe. Second, we interpret how the sovereignty concept has been conceived through Latin American states' formation process. Third, the sovereignty process is adressed within integration thinking and its three big waves: the developmental, neoliberal and post-hegemonic waves. Fourth, the concept of sovereignty in Latin America and its impact on the region are discussed critically. Fifth, current regionalism perspectives are explained. Sixth, the current relationship between sovereignty and regionalization in South America is described. And finally, throughout this paper, we maintain that it is the weakness of "stateness" in the Latin American states which has had an important influence on their reluctance to transfer national sovereignty to regional integration institutions.

  19. Tibial slope correction combined with second revision ACL produces good knee stability and prevents graft rupture. (United States)

    Dejour, David; Saffarini, Mo; Demey, Guillaume; Baverel, Laurent


    Revision ACL reconstruction requires careful analysis of failure causes particularly in cases of two previous graft ruptures. Intrinsic factors as excessive tibial slope or narrow femoral notch increase failure risks but are rarely addressed in revision surgery. The authors report outcomes, at minimum follow-up of 2 years, for second revision ACL reconstructions combined with tibial deflexion osteotomy for correction of excessive slope (>12°). Nine patients that underwent second revision ACL reconstruction combined with tibial deflexion osteotomy were retrospectively studied. The mean age was 30.3 ± 4.4 years (median 28; range 26-37), and mean follow-up was 4.0 ± 2.0 years (median 3.6; range 2.0-7.6). Autografts were harvested from the quadriceps tendon (n = 8) or hamstrings (n = 1), and tibial osteotomy was done by anterior closing wedge, without detachment of the patellar tendon, to obtain a slope of 3° to 5°. All patients had fused osteotomies, stable knees, and there were no intraoperative or postoperative complications. The mean posterior tibial slope decreased from 13.2° ± 2.6° (median 13°; range 12°-18°) preoperatively to 4.4° ± 2.3° (median 4°; range 2°-8°) postoperatively. The mean Lysholm score was 73.8 ± 5.8 (median 74; range 65-82), and the IKDC-SKF was 71.6 ± 6.1 (median 72.8; range 62.2-78.5). The satisfactory results of second revision ACL reconstruction combined with tibial deflexion osteotomy at minimum follow-up of 2 years suggest that tibia slope correction protects reconstructed ACL from fatigue failure in this study. The authors stress the importance of careful analysis failure causes prior to revision ACL reconstruction, and recommend correction of tibial slope if it exceeds 12°, to reduce the risks of graft retear. III.

  20. Erosion and sediment deposition evaluation on slopes under different tillage systems in the Cerrado region using the {sup 137}Cs fallout technique; Analise da distribuicao do fallout do {sup 137}Cs na avaliacao da erosao e deposicao de sedimentos em sistemas de manejo de solo sob Cerrado

    Energy Technology Data Exchange (ETDEWEB)

    Arthur, Robson Clayton Jacques


    In Brazil, the expansion of agricultural areas causes several problems on natural resources. With the increasing occupation of the Cerrado region by agriculture, a series of environmental problems like deforestation, soil erosion and soil compaction are appearing and causing radical transformations in the natural landscape due to removing almost all native vegetation. The conventional tillage system (CTS) is considered an inadequate form of soil management for its frequently irremediable consequences of soil compaction and soil erosion, and the no till system (NTS) makes the maintenance of the soil conditions possible, letting them close to the natural environment, thus reducing rates of soil erosion. The objective of this work was to evaluate the efficiency of riparian forests in the retention of sediments originated for three different tillage systems, through the fallout {sup 137}CS redistribution technique, the Universal Soil Loss Equation (USLE) and some physical and chemical parameters that indicate the structural conditions of the soils of Goiatuba and Jandaia-GO. In the three areas, soil profiles were collected in three layers of 20 cm (0-20, 20-40 and 40-60 cm) at distinct points located along linear transects in the direction of the maximum slope until the riparian forest. In the riparian forest of each area, trenches were opened and soil was sampled to evaluate the activity of {sup 137}Cs and the physical and chemical parameters of soil. Detection of the activity of {sup 137}Cs was made with a gamma ray detector model (GEM-20180P, EG and ORTEC) connected to a multichannel analyzer. The comparison of averages was made using the Tukey test at 5% level of significance. The. results indicated that, the three soil tillage systems presented high rates of soil erosion and deposition of sediments and the riparian forest of the areas under CTS, NTS and pasture, located downstream received great amounts of sediments, and that only the riparian forest of CTS was

  1. Wildlife response on the Alaska North Slope

    International Nuclear Information System (INIS)

    Costanzo, D.; McKenzie, B.


    Recognizing the need for a comprehensive plan to deal with potentially oiled wildlife on the Alaskan North Slope, a multifaceted wildlife protection strategy was developed and implemented during 1991. The strategy incorporated all aspects of wildlife response including protection of critical habitat, hazing, capture and stabilization, long term rehabilitation, and release. The primary wildlife response strategy emphasizes controlling of the release and spreading of spilled oil at the source to prevent or reduce contamination of potentially affected species and/or their habitat. A secondary response strategy concentrates on keeping potentially affected wildlife away from an oiled area through the use of deterrent techniques. Tertiary response involves the capture and treatment of oiled wildlife. Implementation of the strategy included the development of specialized training, the procurement of equipment, and the construction of a bird stabilization center. The result of this initiative is a comprehensive wildlife response capability on the Alaskan North Slope. 1 ref., 5 figs., 3 tabs

  2. Pipeline modeling and assessment in unstable slopes

    Energy Technology Data Exchange (ETDEWEB)

    Caceres, Carlos Nieves [Oleoducto Central S.A., Bogota, Cundinamarca (Colombia); Ordonez, Mauricio Pereira [SOLSIN S.A.S, Bogota, Cundinamarca (Colombia)


    The OCENSA pipeline system is vulnerable to geotechnical problems such as faults, landslides or creeping slopes, which are well-known in the Andes Mountains and tropical countries like Colombia. This paper proposes a methodology to evaluate the pipe behaviour during the soil displacements of slow landslides. Three different cases of analysis are examined, according to site characteristics. The process starts with a simplified analytical model and develops into 3D finite element numerical simulations applied to the on-site geometry of soil and pipe. Case 1 should be used when the unstable site is subject to landslides impacting significant lengths of pipeline, pipeline is straight, and landslide is simple from the geotechnical perspective. Case 2 should be used when pipeline is straight and landslide is complex (creeping slopes and non-conventional stabilization solutions). Case 3 should be used if the pipeline presents vertical or horizontal bends.

  3. [Characteristics of Soil Respiration along Eroded Sloping Land with Different SOC Background on the Hilly Loess Plateau]. (United States)

    Chen, Gai; Xu, Ming-xiang; Zhang, Ya-feng; Wang, Chao-hua; Fan, Hui-min; Wang, Shan-shan


    This study aimed to characterize soil respiration along eroded sloping land at erosion and deposition area under different soil organic carbon(SOC) levels, and linked the relationship between soil respiration and soil temperature, soil moisture, SOC and slope position. Experiments were carried out in the plots of S type slopes include five different soil organic carbon levels in the Loess Hilly Region. The S type slopes were divided into control area at the top of the slope, erosion area at the middle of the slope and deposition area at the toe of the slope. We found that soil temperature had a greater impact on soil respiration in the deposition area, whereas soil moisture had a greater impact on soil respiration in the erosion area compared among control area, erosion area and deposition area. In addition, SOC was the most important factor affecting soil respiration, which can explain soil respiration variation 54. 72%, followed by soil moisture, slope position and soil temperature, which explain soil respiration variation 18. 86% , 16. 13% and 10. 29%, respectively. Soil respiration response to erosion showed obvious on-site and off-site effects along the eroded sloping land. Soil respiration in the erosion area was reduced by 21. 14% compared with control area, and soil respiration in the deposition area was increased by 21. 93% compared with control area. Erosion effect on source and sink of carbon emission was correlated with SOC content of the eroded sloping land. When SOC content was higher than 6. 82, the slope. erosion tended to be a carbon sequestration process, and when SOC content was lower than 3.03, the slope erosion tended to be a process of the carbon emission source. The model could reflect the relationship between soil respiration and independent variables of soil organic carbon content, soil temperature and moisture.

  4. Quantification of Urban Environment's Role in Slope Stability for Landslide Events. (United States)

    Bozzolan, E.; Holcombe, E.; Wagener, T.; Pianosi, F.


    The combination of a rapid and unplanned urban development with a likely future climate change could significantly affect landslide occurrences in the humid tropics, where rainfall events of high intensity and duration are the dominant trigger for landslide risk. The attention of current landslide hazard studies is largely focussed on natural slope processes based on combinations of environmental factors, excluding the role of urbanisation on slope stability. This project aims to understand the relative influence of urbanisation features on local slope stability and to translate the findings to a wider region. Individual slopes are firstly analysed with the software CHASM, a physically based model which combines soil hydrology and slope stability assessment. Instead of relying on existing records, generally lacking for landslides, ranges of plausible preparatory (such as slope, cohesion, friction angles), triggering (rainfall) and aggravating factors (deforestation, house density and water network) are defined and possible combinations of these factors are created by sampling from those ranges. The influence of urban features on site hydrology and stability mechanisms are evaluated and then implemented in denser urban contexts, characteristic of unplanned settlements. The results of CHASMS can be transferred to regional maps in order to identify the areas belonging to the triggering combinations of factors previously found. In this way, areas susceptible to landslides can be detected not only in terms of natural factors but also in relation to the degree of urbanisation. Realistic scenarios can be extrapolated from the areas considered and then analysed again with CHASM. This permits to adapt (and improve) the initial variability ranges of the factors, creating a general-specific cycle able to identify the landslide susceptibility regions and outline a hazard map. Once the triggers are understood, possible consequences can be assessed and mitigation strategies can

  5. Slope parameters of ππ-system

    International Nuclear Information System (INIS)

    Isaev, P.S.; Osipov, A.A.


    The slope parameters of the ππ-system are calculated in the framework of the superconductor-tupe quark model. The analogous calculations are made for πK-system. The amplitudes are obtained by using the box quark diagrams and tree diagrams with the intermediate scalar epsilon(700), Ssup(x)(975), K tilde (1350) mesons and vector rho(770), K* (892) mesons

  6. Stability of sulfur slopes on Io (United States)

    Clow, G. D.; Carr, M. H.


    The mechanical properties of elemental sulfur are such that the upper crust of Io cannot be primarily sulfur. For heat flows in the range 100-1000 ergs/sq cm sec sulfur becomes ductile within several hundred meters of the surface and would prevent the formation of calderas with depths greater than this. However, the one caldera for which precise depth data are available is 2 km deep, and this value may be typical. A study of the mechanical equilibrium of simple slopes shows that the depth to the zone of rapid ductile flow strongly controls the maximum heights for sulfur slopes. Sulfur scarps with heights greater than 1 km will fail for all heat flows greater than 180 ergs/sq cm sec and slope angles greater than 22.5 deg. The observed relief on Io is inconsistent with that anticipated for a predominantly sulfur crust. However, a silicate crust with several percent sulfur included satisfies both the mechanical constraints and the observed presence of sulfur on Io.

  7. Stability of nuclear crater slopes in rock

    International Nuclear Information System (INIS)

    Fleming, Robert W.; Frandsen, Alton D.; LaFrenz, Robert L.


    The United States Army Engineer Nuclear Cratering Group was established in 1962 to participate with the Atomic Energy Commission in a joint research and development program to develop nuclear engineering and construction technology. A major part of this research effort has been devoted to studies of the engineering properties of craters. The program to date has included field investigations of crater properties in various media over a broad range of chemical and nuclear explosive yields, studies of man-made and natural slopes, and studies directed toward the development of analytical and empirical methods of crater stability analysis. From this background, a general understanding has been developed of the effects of a cratering explosion on the surrounding medium and of physical nature of the various crater zones which are produced. The stability of nuclear crater slopes has been a subject of prime interest in the feasibility study being conducted for an Atlantic-Pacific sea-level canal. Based on experimental evidence assembled to date, nuclear crater slopes in dry dock and dry alluvium have an initially stable configuration. There have been five nuclear craters produced to date with yields of 0.4 kt or more on which observations are based and the initial configurations of these craters have remained stable for over seven years. The medium, yield, crater dimensions, and date of event for these craters are summarized. It is interesting to note that the Sedan Crater has been subjected to strong seismic motions from nearby detonations without adverse effects

  8. Geosynthetic clay liners - slope stability field study

    International Nuclear Information System (INIS)

    Carson, D.A.; Daniel, D.E.; Koerner, R.M.; Bonaparte, R.


    A field research project was developed to examine the internal shear performance of geosynthetic clay liners (GCLs). Several combinations of cross sections were assembled using GCL materials that were available at the time of project initiation. The cross sections utilized were intended to simulate landfill cover applications. Thirteen (13) resulting test plots were constructed on two different slope angles, and each plot is instrumented for physical displacement and soil moisture characteristics. Test plots were constructed in a manner that dictated the shear plane in the clay portion of the GCL product. The project purpose is to assess field performance and to verify design parameters associated with the application of GCLs in waste containment applications. Interim research data shows that test slopes on 2H:1V show global deformation, but little internal shear evidence, and the 3H:1V slopes show little deformation at approximately 650 days. The research is ongoing, and this paper presents the most recent information available from the project

  9. Stability of nuclear crater slopes in rock

    Energy Technology Data Exchange (ETDEWEB)

    Fleming, Robert W; Frandsen, Alton D; LaFrenz, Robert L [U.S. Army Engineer Nuclear Cratering Group, Lawrence Radiation Laboratory, Livermore, CA (United States)


    The United States Army Engineer Nuclear Cratering Group was established in 1962 to participate with the Atomic Energy Commission in a joint research and development program to develop nuclear engineering and construction technology. A major part of this research effort has been devoted to studies of the engineering properties of craters. The program to date has included field investigations of crater properties in various media over a broad range of chemical and nuclear explosive yields, studies of man-made and natural slopes, and studies directed toward the development of analytical and empirical methods of crater stability analysis. From this background, a general understanding has been developed of the effects of a cratering explosion on the surrounding medium and of physical nature of the various crater zones which are produced. The stability of nuclear crater slopes has been a subject of prime interest in the feasibility study being conducted for an Atlantic-Pacific sea-level canal. Based on experimental evidence assembled to date, nuclear crater slopes in dry dock and dry alluvium have an initially stable configuration. There have been five nuclear craters produced to date with yields of 0.4 kt or more on which observations are based and the initial configurations of these craters have remained stable for over seven years. The medium, yield, crater dimensions, and date of event for these craters are summarized. It is interesting to note that the Sedan Crater has been subjected to strong seismic motions from nearby detonations without adverse effects.

  10. High slope waste dumps – a proven possibility

    Directory of Open Access Journals (Sweden)

    Igor Svrkota


    Full Text Available This paper is an overview of dumping operations on High Slope Waste Dump at Veliki Krivelj open pit copper mine, RTB Bor, Serbia. The High Slope Waste Dump in Bor is the highest single slope waste dump in the world with the slope height of 405 m. The paper gives the basics and limitations of the designed dumping technology, the redesigned technology, gives an overview of the 13 year long operation and gathered experiences and addresses the main issues of dumping operations in high slope conditions as well as the present condition of the High Slope Waste Dump.

  11. Heart failure - home monitoring (United States)

    ... this page: // Heart failure - home monitoring To use the sharing features on ... your high blood pressure Fast food tips Heart failure - discharge Heart failure - fluids and diuretics Heart failure - what to ...

  12. Towards a geophysical decision-support system for monitoring and managing unstable slopes (United States)

    Chambers, J. E.; Meldrum, P.; Wilkinson, P. B.; Uhlemann, S.; Swift, R. T.; Inauen, C.; Gunn, D.; Kuras, O.; Whiteley, J.; Kendall, J. M.


    Conventional approaches for condition monitoring, such as walk over surveys, remote sensing or intrusive sampling, are often inadequate for predicting instabilities in natural and engineered slopes. Surface observations cannot detect the subsurface precursors to failure events; instead they can only identify failure once it has begun. On the other hand, intrusive investigations using boreholes only sample a very small volume of ground and hence small scale deterioration process in heterogeneous ground conditions can easily be missed. It is increasingly being recognised that geophysical techniques can complement conventional approaches by providing spatial subsurface information. Here we describe the development and testing of a new geophysical slope monitoring system. It is built around low-cost electrical resistivity tomography instrumentation, combined with integrated geotechnical logging capability, and coupled with data telemetry. An automated data processing and analysis workflow is being developed to streamline information delivery. The development of this approach has provided the basis of a decision-support tool for monitoring and managing unstable slopes. The hardware component of the system has been operational at a number of field sites associated with a range of natural and engineered slopes for up to two years. We report on the monitoring results from these sites, discuss the practicalities of installing and maintaining long-term geophysical monitoring infrastructure, and consider the requirements of a fully automated data processing and analysis workflow. We propose that the result of this development work is a practical decision-support tool that can provide near-real-time information relating to the internal condition of problematic slopes.

  13. GIS-based landslide susceptibility mapping for the 2005 Kashmir earthquake region (United States)

    Kamp, Ulrich; Growley, Benjamin J.; Khattak, Ghazanfar A.; Owen, Lewis A.


    The Mw 7.6 October 8, 2005 Kashmir earthquake triggered several thousand landslides throughout the Himalaya of northern Pakistan and India. These were concentrated in six different geomorphic-geologic-anthropogenic settings. A spatial database, which included 2252 landslides, was developed and analyzed using ASTER satellite imagery and geographical information system (GIS) technology. A multi-criterion evaluation was applied to determine the significance of event-controlling parameters in triggering the landslides. The parameters included lithology, faults, slope gradient, slope aspect, elevation, land cover, rivers and roads. The results showed four classes of landslide susceptibility. Furthermore, they indicated that lithology had the strongest influence on landsliding, particularly when the rock is highly fractured, such as in shale, slate, clastic sediments, and limestone and dolomite. Moreover, the proximity of the landslides to faults, rivers, and roads was also an important factor in helping to initiate failures. In addition, landslides occurred particularly in moderate elevations on south facing slopes. Shrub land, grassland, and also agricultural land were highly susceptible to failures, while forested slopes had few landslides. One-third of the study area was highly or very highly susceptible to future landsliding and requires immediate mitigation action. The rest of the region had a low or moderate susceptibility to landsliding and remains relatively stable. This study supports the view that (1) earthquake-triggered landslides are concentrated in specific zones associated with event-controlling parameters; and (2) in the western Himalaya deforestation and road construction contributed significantly to landsliding during and shortly after earthquakes.

  14. Long-Term Drainage from the Riprap Side Slope of a Surface Barrier

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhuanfang


    Surface barriers designed to isolate underground nuclear waste in place are expected to function for at least 1000 years. To achieve this long design life, such barriers need to be protected with side slopes against wind- and water-induced erosion and damage by natural or human activities. However, the side slopes are usually constructed with materials coarser than the barrier. Their hydrological characteristics must be understood so that any drainage from them is considered in the barrier design and will not compromise the barrier function. The Prototype Hanford Barrier, an evapotranspiration-capillary (ETC) barrier, was constructed in 1994 at the Hanford Site in southeastern Washington state, with a gravel side slope and a riprap side slope. The soil water content in the gravel side slope and drainage from both side slopes have been monitored since the completion of construction. The monitoring results show that under natural precipitation the annual drainage rates from the two types of side slopes were very similar and about 5 times the typical recharge from local soil with natural vegetation and 40 times the barrier design criterion. The higher recharge from the side slopes results in some of the drainage migrating laterally to the region beneath the ETC barrier. This edge effect of the enhanced drainage was evaluated for a period of 1000 years by numerical simulation. The edge effect was quantified by the amount of water across the barrier edges and the affecting distance of the barrier edges. These results indicate that design features can be adjusted to reduce the edge effect when necessary.

  15. Using three-dimensional plant root architecture in models of shallow-slope stability. (United States)

    Danjon, Frédéric; Barker, David H; Drexhage, Michael; Stokes, Alexia


    The contribution of vegetation to shallow-slope stability is of major importance in landslide-prone regions. However, existing slope stability models use only limited plant root architectural parameters. This study aims to provide a chain of tools useful for determining the contribution of tree roots to soil reinforcement. Three-dimensional digitizing in situ was used to obtain accurate root system architecture data for mature Quercus alba in two forest stands. These data were used as input to tools developed, which analyse the spatial position of roots, topology and geometry. The contribution of roots to soil reinforcement was determined by calculating additional soil cohesion using the limit equilibrium model, and the factor of safety (FOS) using an existing slope stability model, Slip4Ex. Existing models may incorrectly estimate the additional soil cohesion provided by roots, as the spatial position of roots crossing the potential slip surface is usually not taken into account. However, most soil reinforcement by roots occurs close to the tree stem and is negligible at a distance >1.0 m from the tree, and therefore global values of FOS for a slope do not take into account local slippage along the slope. Within a forest stand on a landslide-prone slope, soil fixation by roots can be minimal between uniform rows of trees, leading to local soil slippage. Therefore, staggered rows of trees would improve overall slope stability, as trees would arrest the downward movement of soil. The chain of tools consisting of both software (free for non-commercial use) and functions available from the first author will enable a more accurate description and use of root architectural parameters in standard slope stability analyses.

  16. Why regionalism has failed in Latin America: lack of stateness as an important factor for failure of sovereignty transfer in integration projects


    Buelvas, Eduardo Pastrana


    This paper shows, from an interdisciplinary perspective, the incidence of lack of "stateness" and its construction process in Latin American states, as well as showing the reluctance on the part of Latin American states to transfer sovereignty to regional integrational organizations. First, classical and contemporary ideas of sovereignty are contrasted, in order to understand the development of the sovereignty concept in Latin America and Europe. Second, we interpret how the sovereignty conce...

  17. On the Antarctic Slope Front and Current crossing of the South Scotia Ridge (United States)

    Orsi, A. H.; Palmer, M.; Gomis, D.; Flexas, M. M.; Kim, Y.-S.; Jordà, G.; Wiederwohl, C.; Álvarez, M.


    To unveil the contorted path followed by the Antarctic Slope Current connecting the Weddell and Scotia Seas, hydrographic stations with unprecedented spatial resolution were occupied on a series of sections across the slope and multiple channels in the double-pronged western portion of the South Scotia Ridge. Fieldwork consisted of two cruises from the ESASSI (January 2008) and ACROSS (February 2009) programs, the Spanish and USA/Argentina components of the International Polar Year core project SASSI (Synoptic Antarctic Shelf-Slope Interaction study). In this region the Antarctic Slope Current can be located by the pronounced in-shore deepening of isopycnals over the continental slope, rendering the strong subsurface temperature and salinity gradients characteristic of the Antarctic Slope Front. Before reaching the gaps in the southern Ridge near 51°W and 50°W, the ASC carries about 3 Sv of upper layer waters, but it splits into shallow and deep branches upon turning north through these two gaps. The shallower branch enters the Hesperides Trough at 51°W, then shows a tight cyclonic loop back to that longitude roughly following the slope's 700-m isobath, and turns again westward through a similar gap in the northern Ridge. In the Scotia Sea the westward-flowing Antarctic Slope Current is found as far west as the Elephant Island along slightly deeper levels of slope (1100 m) before it is blocked by the Antarctic Circumpolar Current south of the Shackleton Fracture Zone (56°W). The deeper branch of the ASC in the Powell Basin crosses the southern Ridge near 50°W and roughly follows the 1600-m isobath before entering the Scotia Sea through the Hesperides Gap farther to the east (49°W). Thereafter the deeper waters carried westward by this branch become undistinguishable from those circulating farther offshore. Repeat cross-slope sections at both southern and northern flanks of the South Scotia Ridge showed significant temporal variability in the characteristics

  18. Slope stabilization guide for Minnesota local government engineers. (United States)


    This user guide provides simple, costeffective methods for stabilizing locally maintained slopes along roadways in Minnesota. Eight slope stabilization techniques are presented that local government engineers can undertake using locally available ...

  19. Stability of the slopes around nuclear power plants in earthquake

    International Nuclear Information System (INIS)

    Ito, Hiroshi


    The evaluation of the stability of the slopes around the buildings of nuclear power plants is important especially with respect to earthquakes. In this connection, the behavior of a slope up to its destruction and the phenomena of the destruction have been examined in the case of an earthquake by both experiment and numerical analysis. The purpose is to obtain the data for the establishment of a method for evaluating the seismic stability of a slope and of the slope design standards. The following results are described: the behavior of a slope and its destruction characteristics in the slope destruction experiment simulating the seismic coefficient method; the vibration of a slope and its destruction characteristics in vibration destruction experiment; the validity of the method of numerical simulation analysis and of stability evaluation for the slope destruction and the vibration destruction experiments, and quantitative destruction mechanism; the comparison of the various stability evaluation methods and the evaluation of seismic forces. (Mori, K.)

  20. VT Lidar Slope (1.6 meter) - 2012 - Addison County (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Addison County 2012 1.6m and related SLOPE datasets. Created using ArcGIS "SLOPE"...

  1. VT Lidar Slope (2 meter) - 2012 - Bennington County (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Bennington County 2012 2.0m and related SLOPE datasets. Created using ArcGIS "SLOPE"...

  2. VT Lidar Slope (1.6 meter) - 2010 - Missisquoi Upper (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Missisquoi Upper 2010 1.6m and related SLOPE datasets. Created using ArcGIS "SLOPE"...

  3. Combining slope stability and groundwater flow models to assess stratovolcano collapse hazard (United States)

    Ball, J. L.; Taron, J.; Reid, M. E.; Hurwitz, S.; Finn, C.; Bedrosian, P.


    Flank collapses are a well-documented hazard at volcanoes. Elevated pore-fluid pressures and hydrothermal alteration are invoked as potential causes for the instability in many of these collapses. Because pore pressure is linked to water saturation and permeability of volcanic deposits, hydrothermal alteration is often suggested as a means of creating low-permeability zones in volcanoes. Here, we seek to address the question: What alteration geometries will produce elevated pore pressures in a stratovolcano, and what are the effects of these elevated pressures on slope stability? We initially use a finite element groundwater flow model (a modified version of OpenGeoSys) to simulate `generic' stratovolcano geometries that produce elevated pore pressures. We then input these results into the USGS slope-stability code Scoops3D to investigate the effects of alteration and magmatic intrusion on potential flank failure. This approach integrates geophysical data about subsurface alteration, water saturation and rock mechanical properties with data about precipitation and heat influx at Cascade stratovolcanoes. Our simulations show that it is possible to maintain high-elevation water tables in stratovolcanoes given specific ranges of edifice permeability (ideally between 10-15 and 10-16 m2). Low-permeability layers (10-17 m2, representing altered pyroclastic deposits or altered breccias) in the volcanoes can localize saturated regions close to the surface, but they may actually reduce saturation, pore pressures, and water table levels in the core of the volcano. These conditions produce universally lower factor-of-safety (F) values than at an equivalent dry edifice with the same material properties (lower values of F indicate a higher likelihood of collapse). When magmatic intrusions into the base of the cone are added, near-surface pore pressures increase and F decreases exponentially with time ( 7-8% in the first year). However, while near-surface impermeable layers

  4. Spectral Slope as an Indicator of Pasture Quality

    Directory of Open Access Journals (Sweden)

    Rachel Lugassi


    Full Text Available In this study, we develop a spectral method for assessment of pasture quality based only on the spectral information obtained with a small number of wavelengths. First, differences in spectral behavior were identified across the near infrared–shortwave infrared spectral range that were indicative of changes in chemical properties. Then, slopes across different spectral ranges were calculated and correlated with the changes in crude protein (CP, neutral detergent fiber (NDF and metabolic energy concentration (MEC. Finally, partial least squares (PLS regression analysis was applied to identify the optimal spectral ranges for accurate assessment of CP, NDF and MEC. Six spectral domains and a set of slope criteria for real-time evaluation of pasture quality were suggested. The evaluation of three level categories (low, medium, high for these three parameters showed a success rate of: 73%–96% for CP, 72%–87% for NDF and 60%–85% for MEC. Moreover, only one spectral range, 1748–1764 nm, was needed to provide a good estimation of CP, NDF and MEC. Importantly, five of the six selected spectral regions were not affected by water absorbance. With some modifications, this rationale can be applied to further analyses of pasture quality from airborne sensors.

  5. Slope instability caused by small variations in hydraulic conductivity (United States)

    Reid, M.E.


    Variations in hydraulic conductivity can greatly modify hillslope ground-water flow fields, effective-stress fields, and slope stability. In materials with uniform texture, hydraulic conductivities can vary over one to two orders of magnitude, yet small variations can be difficult to determine. The destabilizing effects caused by small (one order of magnitude or less) hydraulic conductivity variations using ground-water flow modeling, finite-element deformation analysis, and limit-equilibrium analysis are examined here. Low hydraulic conductivity materials that impede downslope ground-water flow can create unstable areas with locally elevated pore-water pressures. The destabilizing effects of small hydraulic heterogeneities can be as great as those induced by typical variations in the frictional strength (approximately 4??-8??) of texturally similar materials. Common "worst-case" assumptions about ground-water flow, such as a completely saturated "hydrostatic" pore-pressure distribution, do not account for locally elevated pore-water pressures and may not provide a conservative slope stability analysis. In site characterization, special attention should be paid to any materials that might impede downslope ground-water flow and create unstable regions.

  6. Nonlocal impacts of the Loop Current on cross-slope near-bottom flow in the northeastern Gulf of Mexico (United States)

    Nguyen, Thanh-Tam; Morey, Steven L.; Dukhovskoy, Dmitry S.; Chassignet, Eric P.


    Cross-slope near-bottom motions near De Soto Canyon in the northeastern Gulf of Mexico are analyzed from a multidecadal ocean model simulation to characterize upwelling and downwelling, important mechanisms for exchange between the deep ocean and shelf in the vicinity of the 2010 BP Macondo well oil spill. Across the continental slope, large-scale depression and offshore movement of isopycnals (downwelling) occur more frequently when the Loop Current impinges upon the West Florida Shelf slope farther south. Upwelling and onshore movement of isopycnals occurs with roughly the same likelihood regardless of Loop Current impingement on the slope. The remote influence of Loop Current on the De Soto Canyon region downwelling is a consequence of a high-pressure anomaly that extends along the continental slope emanating from the location of Loop Current impact.

  7. Hydrological modelling of a slope covered with shallow pyroclastic deposits from field monitoring data

    Directory of Open Access Journals (Sweden)

    R. Greco


    Full Text Available A one-dimensional hydrological model of a slope covered with pyroclastic materials is proposed. The soil cover is constituted by layers of loose volcanic ashes and pumices, with a total thickness between 1.8 m and 2.5 m, lying upon a fractured limestone bedrock. The mean inclination of the slope is around 40°, slightly larger than the friction angle of the ashes. Thus, the equilibrium of the slope, significantly affected by the cohesive contribution exerted by soil suction in unsaturated conditions, may be altered by rainfall infiltration. The model assumes a single homogeneous soil layer occupying the entire depth of the cover, and takes into account seasonally variable canopy interception of precipitation and root water uptake by vegetation, mainly constituted by deciduous chestnut woods with a dense underbrush growing during late spring and summer. The bottom boundary condition links water potential at the soil–bedrock interface with the fluctuations of the water table of the aquifer located in the fractured limestone, which is conceptually modelled as a linear reservoir. Most of the model parameters have been assigned according to literature indications or from experimental data. Soil suction and water content data measured between 1 January 2011 and 20 July 2011 at a monitoring station installed along the slope allowed the remaining parameters to be identified. The calibrated model, which reproduced very closely the data of the calibration set, has been applied to the simulation of the hydrological response of the slope to the hourly precipitation record of 1999, when a large flow-like landslide was triggered close to the monitored location. The simulation results show that the lowest soil suction ever attained occurred just at the time the landslide was triggered, indicating that the model is capable of predicting slope failure conditions.

  8. Research of geotechnical properties of slope covers from Jamne and Jaszcze stream valleys in Gorce Mts.

    Directory of Open Access Journals (Sweden)

    Tymoteusz Adam Zydroń


    Full Text Available The test results pertaining to geotechnical parameters of slope covers from valleys of two mountainous streams from Gorce Mts. are presented in the paper. The tests were carried out in the context of slope stability estimation of the analyzed watersheds. The field studies included determination of basic physical properties of soil at several sites within the studied area, laboratory tests involved determination of particle size distribution, consistency limits, permeability coefficients and shear strengths, which were carried out at direct shear box and CIU tests in triaxial apparatus. The test results revealed that the tested slope covers can be described as coarse-grained soils with low content of clay fraction, characterized by low plasticity. The values of the internal friction angle of the average bad land were high and ranged from 28 to 38 degrees, whereas cohesion varied from 0 to 7 kPa. Generally, the higher values of angle of internal friction and lower cohesion were obtained from triaxial tests. The values of permeability coefficients determined using the infiltration method allow to characterize tested soils as a semi-permeable medium. The stability calculations using the SINMAP model have shown that a significant part of the analyzed area is prone to mass movements, giving a more conservative assessment of landslide vulnerability than the results of the SOPO report. The probabilistic slope stability calculation results indicate that the likelihood of slope failure increases significantly on the slopes with the inclination exceeding 20 degrees, and the results of the calculations providing a more detailed information of the mass movements susceptibility of the area than were obtained using the SINMAP model.

  9. How hydrological factors initiate instability in a model sandy slope


    Terajima, Tomomi; Miyahira, Ei-ichiro; Miyajima, Hiroyuki; Ochiai, Hirotaka; Hattori, Katsumi


    Knowledge of the mechanisms of rain-induced shallow landslides can improve the prediction of their occurrence and mitigate subsequent sediment disasters. Here, we examine an artificial slope's subsurface hydrology and propose a new slope stability analysis that includes seepage force and the down-slope transfer of excess shear forces. We measured pore water pressure and volumetric water content immediately prior to a shallow landslide on an artificial sandy slope of 32°: The direction of the ...

  10. Drifter observations of the Hebrides slope current and nearby circulation patterns

    Directory of Open Access Journals (Sweden)

    M. Burrows

    Full Text Available The mean flow at and around the Hebrides and Shetland Shelf slope is measured with ARGOS tracked drifters. Forty-two drifters drogued at 50 m were deployed in three circles over the Hebrides slope at 56.15°N in two releases, one on 5th December, 1995 and the second on 5-9th May, 1996. The circles span a distance of some 20 km from water depths of 200 m to 1200 m. Drifters are initially advected poleward along-slope by the Hebrides slope current at between 0.05 and 0.70 m s-1 in a laterally constrained (25-50 km wide jet-like flow. Drifters released in winter remained in the slope current for over 2000 km whilst summer drifters were lost from the slope current beyond the Wyville-Thomson Ridge, a major topographic feature at 60°N. Dispersion from the slope region into deeper waters occurs at bathymetric irregularities, particularly at the Anton Dohrn Seamount close to which the slope current is found to bifurcate, both in summer and winter, and at the Wyville-Thomson Ridge where drifters move into the Faeroe Shetland Channel. Dispersion onto the continental shelf occurs sporadically along the Hebrides slope. The initial dispersion around the Hebrides slope is remarkably sensitive to initial position, most of the drifters released in shallower water moving onto the shelf, whilst those in 1000 m or more are mostly carried away from the slope into deeper water near the Anton Dohrn Seamount. The dispersion coefficients estimated in directions parallel and normal to the local direction of the 500 m contour, approximately the position of the slope current core, are approximately 8.8 × 103 m2 s-1 and 0.36 × 103 m2 s-1, respectively, during winter, and 11.4 × 103 m2 s-1 and 0.36 × 103 m2 s-1, respectively, during summer. At the slope there is a minimum in across-slope mean velocity, Reynolds stress, and

  11. 30 CFR 56.3130 - Wall, bank, and slope stability. (United States)


    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Wall, bank, and slope stability. 56.3130... Mining Methods § 56.3130 Wall, bank, and slope stability. Mining methods shall be used that will maintain wall, bank, and slope stability in places where persons work or travel in performing their assigned...

  12. Conceptualizations of Slope: A Review of State Standards (United States)

    Stanton, Michael; Moore-Russo, Deborah


    Since slope is a fundamental topic that is embedded throughout the U.S. secondary school curriculum, this study examined standards documents for all 50 states to determine how they address the concept of slope. The study used eleven conceptualizations of slope as categories to classify the material in the documents. The findings indicate that all…

  13. Intertidal beach slope predictions compared to field data

    NARCIS (Netherlands)

    Madsen, A.J.; Plant, N.G.


    This paper presents a test of a very simple model for predicting beach slope changes. The model assumes that these changes are a function of both the incident wave conditions and the beach slope itself. Following other studies, we hypothesized that the beach slope evolves towards an equilibrium

  14. Euthanasia, dying well and the slippery slope. (United States)

    Allmark, P


    Arguments in favour of voluntary euthanasia tend to be put in utilitarian terms. This paper suggests an alternative, neo-Aristotelian argument justifying certain individual acts of both suicide and voluntary euthanasia. It goes on to examine the slippery slope arguments against legalizing euthanasia. It is suggested that such arguments cut both ways. However, the suggestion that we ought therefore to permit a social experiment in voluntary euthanasia is set alongside the Dutch experience. The latter seems to imply that if such experiments are to take place then great caution needs to be applied.

  15. Western Ross Sea continental slope gravity currents (United States)

    Gordon, Arnold L.; Orsi, Alejandro H.; Muench, Robin; Huber, Bruce A.; Zambianchi, Enrico; Visbeck, Martin


    Antarctic Bottom Water of the world ocean is derived from dense Shelf Water that is carried downslope by gravity currents at specific sites along the Antarctic margins. Data gathered by the AnSlope and CLIMA programs reveal the presence of energetic gravity currents that are formed over the western continental slope of the Ross Sea when High Salinity Shelf Water exits the shelf through Drygalski Trough. Joides Trough, immediately to the east, offers an additional escape route for less saline Shelf Water, while the Glomar Challenger Trough still farther east is a major pathway for export of the once supercooled low-salinity Ice Shelf Water that forms under the Ross Ice Shelf. The Drygalski Trough gravity currents increase in thickness from ˜100 to ˜400 m on proceeding downslope from ˜600 m (the shelf break) to 1200 m (upper slope) sea floor depth, while turning sharply to the west in response to the Coriolis force during their descent. The mean current pathway trends ˜35° downslope from isobaths. Benthic-layer current and thickness are correlated with the bottom water salinity, which exerts the primary control over the benthic-layer density. A 1-year time series of bottom-water current and hydrographic properties obtained on the slope near the 1000 m isobath indicates episodic pulses of Shelf Water export through Drygalski Trough. These cold (34.75) pulses correlate with strong downslope bottom flow. Extreme examples occurred during austral summer/fall 2003, comprising concentrated High Salinity Shelf Water (-1.9 °C; 34.79) and approaching 1.5 m s -1 at descent angles as large as ˜60° relative to the isobaths. Such events were most common during November-May, consistent with a northward shift in position of the dense Shelf Water during austral summer. The coldest, saltiest bottom water was measured from mid-April to mid-May 2003. The summer/fall export of High Salinity Shelf Water observed in 2004 was less than that seen in 2003. This difference, if real

  16. Seismic Stability of Reinforced Soil Slopes

    DEFF Research Database (Denmark)

    Tzavara, I.; Zania, Varvara; Tsompanakis, Y.


    Over recent decades increased research interest has been observed on the dynamic response and stability issues of earth walls and reinforced soil structures. The current study aims to provide an insight into the dynamic response of reinforced soil structures and the potential of the geosynthetics...... to prevent the development of slope instability taking advantage of their reinforcing effect. For this purpose, a onedimensional (SDOF) model, based on Newmark’s sliding block model as well as a two-dimensional (plane-strain) dynamic finite-element analyses are conducted in order to investigate the impact...

  17. Clustering Moving Objects Using Segments Slopes


    Mohamed E. El-Sharkawi; Hoda M. O. Mokhtar; Omnia Ossama


    Given a set of moving object trajectories, we show how to cluster them using k-meansclustering approach. Our proposed clustering algorithm is competitive with the k-means clusteringbecause it specifies the value of “k” based on the segment’s slope of the moving object trajectories. Theadvantage of this approach is that it overcomes the known drawbacks of the k-means algorithm, namely,the dependence on the number of clusters (k), and the dependence on the initial choice of the clusters’centroi...

  18. Comparative evaluation of B-type natriuretic peptide and mid-regional pro-A-type natriuretic peptide changes from admission to discharge in prognosis of acute decompensated heart failure patients. (United States)

    Stenner, Elisabetta; Buiatti, Alessandra; Barbati, Giulia; Merlo, Marco; Sinagra, Gianfranco; Biasioli, Bruno


    Mid-regional pro-A-type natriuretic peptide (MRproANP) seems to be non-inferior compared to B-type natriuretic peptide (BNP) for heart failure diagnosis and prognosis; however, no previous studies have investigated the MRproANP in-hospital changes in prognostic role. This study aimed to compare the prognostic accuracy of BNP and MRproANP in-hospital changes in acute decompensated heart failure (ADHF) patients. 37 patients with either admission/pre-discharge BNP and MRproANP data, were investigated. The combined endpoint was cardiovascular death/heart transplantation/readmission for HF. BNP and MRproANP had a median decrease of 55% [72;45] and 21% [40; 11] respectively in event-free patients; BNP decrease of 34% [48; 29] but MRproANP increase of 4% [-7; 25] in patients with cardiovascular events. Prognostic accuracy of deltaBNP and deltaMRproANP was similar. MRproANP basically trends up in patients with worse outcome and decreases in event-free patients, likely leading to a simpler interpretation although the prognostic accuracy is similar for both peptides.

  19. Definitions of biochemical failure in prostate cancer following radiation therapy

    International Nuclear Information System (INIS)

    Taylor, Jeremy M.G.; Griffith, Kent A.; Sandler, Howard M.


    Purpose: The American Society for Therapeutic Radiology and Oncology (ASTRO) published a consensus panel definition of biochemical failure following radiation therapy for prostate cancer. In this paper, we develop a series of alternative definitions of biochemical failure. Using data from 688 patients, we evaluated the sensitivity and specificity of the various definitions, with respect to a defined 'clinically meaningful' outcome. Methods and Materials: The ASTRO definition of biochemical failure requires 3 consecutive rises in prostate-specific antigen (PSA). We considered several modifications to the standard definition: to require PSA rises of a certain magnitude, to consider 2 instead of 3 rises, to require the final PSA value to be greater than a fixed cutoff level, and to define biochemical failure based on the slope of PSA over 1, 1.5, or 2 years. A clinically meaningful failure is defined as local recurrence, distant metastases, initiation of unplanned hormonal therapy, unplanned radical prostatectomy, or a PSA>25 later than 6 months after radiation. Results: Requiring the final PSA in a series of consecutive rises to be larger than 1.5 ng/mL increased the specificity of biochemical failure. For a fixed specificity, defining biochemical failure based on 2 consecutive rises, or the slope over the last year, could increase the sensitivity by up to approximately 20%, compared to the ASTRO definition. Using a rule based on the slope over the previous year or 2 rises leads to a slightly earlier detection of biochemical failure than does the ASTRO definition. Even with the best rule, only approximately 20% of true failures are biochemically detected more than 1 year before the clinically meaningful event time. Conclusion: There is potential for improvement in the ASTRO consensus definition of biochemical failure. Further research is needed, in studies with long follow-up times, to evaluate the relationship between various definitions of biochemical failure and

  20. Challenges in monitoring and managing engineered slopes in a changing climate

    Directory of Open Access Journals (Sweden)

    Hughes Paul N


    Full Text Available Geotechnical asset owners need to know which parts of their asset network are vulnerable to climate change induced failure in order to optimise future investment. Protecting these vulnerable slopes requires monitoring systems capable of identifying and alerting to asset operators changes in the internal conditions that precede failure. Current monitoring systems are heavily reliant on point sensors which can be difficult to interpret across slope scale. This paper presents challenges to producing such a system and research being carried out to address some of these using electrical resistance tomography (ERT. Experimental results show that whilst it is possible to measure soil water content indirectly via resistivity the relationship between resistivity and water content will change over time for a given slope. If geotechnical parameters such as pore water pressure are to be estimated using this method then ERT systems will require integrating with more conventional geotechnical instrumentation to ensure correct representative information is provided. The paper also presents examples of how such data can be processed and communicated to asset owners for the purposes of asset management.

  1. A Tilt, Soil Moisture, and Pore Water Pressure Sensor System for Slope Monitoring Applications

    Directory of Open Access Journals (Sweden)

    Rosanno de Dios


    Full Text Available This paper describes the design, implementation and characterization of a sensor network intended for monitoring of slope deformation and potential failures. The sensor network system consists of a tilt and moisture sensor column, a pore water pressure sensor column and a personal computer for data storage and processing. The tilt sensor column consists of several pipe segments containing tri-axial accelerometers and signal processing electronics. Each segment is joined together by flexible joints to allow for the column to deform and subsequently track underground movement. Capacitive-type sensors for soil moisture measurement are also included in the sensor column, which are used to measure the soil moisture at different depths. The measurements at each segment are transferred via a Controller Area Network (CAN bus, where the CAN master node is located at the top of the column above ground. The CAN master node transmits the collected data from the slave nodes via a wireless connection to a personal computer that performs data storage, processing and display via a Python-based graphical user interface (GUI. The entire system was deployed and characterized on a small-scale slope model. Slope failure was induced via water seepage and the system was demonstrated to ably measure the inclination and soil moisture content throughout the landslide event.

  2. Long term SAR interferometry monitoring for assessing changing levels of slope instability hazards (United States)

    Wasowski, J.; Ferretti, A.

    The population growth with increasing impact of man on the environment and urbanisation of areas susceptible to slope failures coupled with the ongoing change in climate patterns will require a shift in the approaches to landslide hazard reduction Indeed there is evidence that landslide activity and related socio-economic loss are increasing in both rich and less developed countries throughout the world Because of this and because the urbanisation of hillside and mountain slopes prone to failure will likely continue in the future the protection of new and pre-existing developed areas via traditional engineering stabilisation works and in situ monitoring is not considered economically feasible Furthermore in most cases the ground control systems are installed post-factum and for short term monitoring and hence their role in preventing disasters is limited Considering the global dimension of the slope instability problem a sustainable road to landslide hazard reduction seems to be via exploitation of EO systems with focus on early detection long term monitoring and early warning Thanks to the wide-area coverage regular schedule and improving resolution of space-borne sensors the EO can foster the auspicious shift from a culture of repair to a culture of awarness and prevention Under this scenario the space-borne synthetic aperture radar differential interferometry DInSAR is attractive because of its capability to provide both wide-area and spatially dense information on surface displacements Since the presence of movements represents a direct evidence of

  3. Large slope instabilities in Northern Chile and Southern Peru (United States)

    Crosta, Giovanni B.; Hermanns, Reginald L.; Valbuzzi, Elena; Frattini, Paolo; Valagussa, Andrea


    2 000 m2, the distribution exhibits a power-law behaviour with scaling exponent, β, equal to -2.24. For comparison, we analysed the power-law behaviour of other earthquake-induced landslide inventories, obtaining similar results, although the geological and seismic conditions may have been very different (Buller, New Zealand, β = -2.42; Iningahua, New Zealand, β = -2.53; Northridge, USA, β = -2.39; Chi-Chi, Taiwan, β = -2.30; Wenchuan Earthquake, China, β = -2.19). Volume estimates and slope stability modelling have been completed to characterize the phenomena and the possible triggering mechanisms. For volume estimate, we reconstructed the pre-failure surface for tens of landslides, in order to characterize the area-volume relationship. By using this relationship, we assigned a volume to all landslides of the inventory. The study area is subject to a high seismicity associated to earthquakes of different type: interplate (superficial and intermediate depth), subduction zone earthquakes, and earthquake along the Coastal Escarpment. By analysing the frequency size relationships for earthquake-induced landslides from literature, it is possible to observe that the higher the earthquake Magnitude, the higher the frequency density curve. To quantify this observation, we used the power-law relationships derived for each inventory to calculate the frequency density associated to selected areas, and we plotted these frequencies as a function of the magnitude of the respective earthquakes. By fitting these values, we derived the expected Magnitude required to generate the landslide distribution of the study area. In conclusion, we argue that the evolution of these landslides is controlled by: deep valley incision, canyon walls undercutting and lateral migration of the river controlled by valley flank instabilities, the Presence of weak lithologies and weak basal layers, the river incision debuttressing the slope toe and especially brings to daylighting the weak basal

  4. Reliability-Based Stability Analysis of Rock Slopes Using Numerical Analysis and Response Surface Method (United States)

    Dadashzadeh, N.; Duzgun, H. S. B.; Yesiloglu-Gultekin, N.


    While advanced numerical techniques in slope stability analysis are successfully used in deterministic studies, they have so far found limited use in probabilistic analyses due to their high computation cost. The first-order reliability method (FORM) is one of the most efficient probabilistic techniques to perform probabilistic stability analysis by considering the associated uncertainties in the analysis parameters. However, it is not possible to directly use FORM in numerical slope stability evaluations as it requires definition of a limit state performance function. In this study, an integrated methodology for probabilistic numerical modeling of rock slope stability is proposed. The methodology is based on response surface method, where FORM is used to develop an explicit performance function from the results of numerical simulations. The implementation of the proposed methodology is performed by considering a large potential rock wedge in Sumela Monastery, Turkey. The accuracy of the developed performance function to truly represent the limit state surface is evaluated by monitoring the slope behavior. The calculated probability of failure is compared with Monte Carlo simulation (MCS) method. The proposed methodology is found to be 72% more efficient than MCS, while the accuracy is decreased with an error of 24%.

  5. A breeze-driven current on sloped littoral waters (United States)

    Tohidi, A.; Jamali, M.


    Various natural phenomena, e. g. uniform/non-uniform solar radiation and diurnal cycles, affect water circulation patterns through aquatic canopies, that is (usually shallow) shorelines of the rivers, lakes, and lagoons. Amongst these factors is vegetation that, plays a crucial role in conserving and dispersing the nutrients, oxygen, temperature, and generally regulating the life and interactions of organisms with each other (ecology) in aquatic canopies. So far, however, very little attention has been paid to the effects of very low, breeze-like, winds over the water surface in these vegetated regions. In this exploratory study, the evolution of a breeze-driven gravity current traveling up the slope towards the shorelines is shown, experimentally. The flow is characterized using Particle Image Velocimetry (PIV) technique. In addition, a detailed dimensional analysis of the parameter space of the phenomenon is conducted. The results strongly corroborate the experimental observations.

  6. Assessment of compressive failure process of cortical bone materials using damage-based model. (United States)

    Ng, Theng Pin; R Koloor, S S; Djuansjah, J R P; Abdul Kadir, M R


    The main failure factors of cortical bone are aging or osteoporosis, accident and high energy trauma or physiological activities. However, the mechanism of damage evolution coupled with yield criterion is considered as one of the unclear subjects in failure analysis of cortical bone materials. Therefore, this study attempts to assess the structural response and progressive failure process of cortical bone using a brittle damaged plasticity model. For this reason, several compressive tests are performed on cortical bone specimens made of bovine femur, in order to obtain the structural response and mechanical properties of the material. Complementary finite element (FE) model of the sample and test is prepared to simulate the elastic-to-damage behavior of the cortical bone using the brittle damaged plasticity model. The FE model is validated in a comparative method using the predicted and measured structural response as load-compressive displacement through simulation and experiment. FE results indicated that the compressive damage initiated and propagated at central region where maximum equivalent plastic strain is computed, which coincided with the degradation of structural compressive stiffness followed by a vast amount of strain energy dissipation. The parameter of compressive damage rate, which is a function dependent on damage parameter and the plastic strain is examined for different rates. Results show that considering a similar rate to the initial slope of the damage parameter in the experiment would give a better sense for prediction of compressive failure. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. arXiv Measurement of the $\\pi^0$ electromagnetic transition form factor slope

    CERN Document Server

    Lazzeroni, C.; Romano, A.; Blazek, T.; Koval, M.; Ceccucci, A.; Danielsson, H.; Falaleev, V.; Gatignon, L.; Goy Lopez, S.; Hallgren, B.; Maier, A.; Peters, A.; Piccini, M.; Riedler, P.; Frabetti, P.L.; Gersabeck, E.; Kekelidze, V.; Madigozhin, D.; Misheva, M.; Molokanova, N.; Movchan, S.; Potrebenikov, Yu.; Shkarovskiy, S.; Zinchenko, A.; Rubin, P.; Baldini, W.; Cotta Ramusino, A.; Dalpiaz, P.; Fiorini, M.; Gianoli, A.; Norton, A.; Petrucci, F.; Savrié, M.; Wahl, H.; Bizzeti, A.; Bucci, F.; Iacopini, E.; Lenti, M.; Veltri, M.; Antonelli, A.; Moulson, M.; Raggi, M.; Spadaro, T.; Eppard, K.; Hita-Hochgesand, M.; Kleinknecht, K.; Renk, B.; Wanke, R.; Winhart, A.; Winston, R.; Bolotov, V.; Duk, V.; Gushchin, E.; Ambrosino, F.; Di Filippo, D.; Massarotti, P.; Napolitano, M.; Palladino, V.; Saracino, G.; Anzivino, G.; Imbergamo, E.; Piandani, R.; Sergi, A.; Cenci, P.; Pepe, M.; Costantini, F.; Doble, N.; Giudici, S.; Pierazzini, G.; Sozzi, M.; Venditti, S.; Balev, S.; Collazuol, G.; DiLella, L.; Gallorini, S.; Goudzovski, E.; Lamanna, G.; Mannelli, I.; Ruggiero, G.; Cerri, C.; Fantechi, R.; Kholodenko, S.; Kurshetsov, V.; Obraztsov, V.; Semenov, V.; Yushchenko, O.; D'Agostini, G.; Leonardi, E.; Serra, M.; Valente, P.; Fucci, A.; Salamon, A.; Bloch-Devaux, B.; Peyaud, B.; Engelfried, J.; Coward, D.; Kozhuharov, V.; Litov, L.; Arcidiacono, R.; Bifani, S.; Biino, C.; Dellacasa, G.; Marchetto, F.; Numao, T.; Retière, F.


    The NA62 experiment collected a large sample of charged kaon decays in 2007 with a highly efficient trigger for decays into electrons. A measurement of the $\\pi^{0}$ electromagnetic transition form factor slope parameter from $1.11\\times10^{6}$ fully reconstructed $K^\\pm \\to \\pi^\\pm \\pi^0_D, \\; \\pi^0_D \\to e^+ e^- \\, \\gamma$ events is reported. The measured value $a = \\left(3.68 \\pm 0.57\\right)\\times 10^{-2}$ is in good agreement with theoretical expectations and previous measurements, and represents the most precise experimental determination of the slope in the time-like momentum transfer region.

  8. Numerical investigation into the failure of a micropile retaining wall


    Prat Catalán, Pere


    The paper presents a numerical investigation on the failure of a micropile wall that collapsed while excavating the adjacent ground. The main objectives are: to estimate the strength parameters of the ground; to perform a sensitivity analysis on the back slope height and to obtain the shape and position of the failure surface. Because of uncertainty of the original strength parameters, a simplified backanalysis using a range of cohesion/friction pairs has been used to estimate the most realis...

  9. Developments Related to Tourism and Their Effects in Debrecen Following the Turn of the Millennium (Northern Great Plain Region, Hungary Success Or Failure?

    Directory of Open Access Journals (Sweden)

    Mária Vasvári


    Full Text Available The present paper focuses on the developments related to tourism and their effects in Debrecen, the largest city in the Northern Great Plain Region most of all in the time period after the country joining the European Union. The tourist industrial development regarding the infrastructure and supra-structure inDebrecen is presented. These developed further the traditionally popular attractions (Great Forest of the city. Relationship between the demand and reception conditions are described reflecting statistic data and the role of Debrecen in the market is analysed in relation to several other greater towns of the country. Data reveal that the number of visitors did not increase despite the developments related to tourism in the years following the turn of the millennium, even so it decreased after 2008 similarly to other greater towns of the country. Our questionnaire survey performed among the inhabitants and visitors as well revealed that the realized investments and the produced new attractions have only a slight role in attracting the target audience. Still the traditionally popular attractions attract most of the visitors to Debrecen therefore the most important task for the leaders of the Debrecen-Hortobágy Tourism Destination Management founded in 2010 is to propagate the new attraction elements.

  10. Dorsal Root Ganglion Stimulation for Complex Regional Pain Syndrome (CRPS) Recurrence after Amputation for CRPS, and Failure of Conventional Spinal Cord Stimulation. (United States)

    Goebel, Andreas; Lewis, Sarah; Phillip, Rhodri; Sharma, Manohar


    Limb amputation is sometimes being performed in long-standing complex regional pain syndrome (CRPS), although little evidence is available guiding management decisions, including how CRPS recurrence should be managed. This report details the management of a young soldier with CRPS recurrence 2 years after midtibial amputation for CRPS. Conventional spinal cord stimulation did not achieve paraesthetic coverage, or pain relief in the stump, whereas L4 dorsal root ganglion stimulation achieved both coverage and initially modest pain relief, and over time, substantial pain relief. Current evidence does not support the use of amputation to improve either pain or function in CRPS. Before a decision is made, in exceptional cases, about referral for amputation, dorsal root ganglion stimulation should be considered as a potentially effective treatment, even where conve