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Sample records for talus slopes

  1. Talus slope development: an integrated concept based on the Eastern Alps.

    Science.gov (United States)

    Sanders, D.; Ostermann, M.

    2009-04-01

    Talus slopes are deposystems that accumulate in onlap onto the area of sediment provenance, that is, rock cliffs. 'Talus slope - rock cliff ensembles' are subject to strong internal feedback due to the direct interplay of slope accumulation with cliff degradation. Our field observations in numerous Quaternary talus-slope successions indicate an overall predictable relation between talus slope maturity, depositional geometry, and sedimentary facies: After exposure of rock cliffs by deglaciation or rocksliding, a low-dipping immature talus (dominated by debris flows and/or by rockfalls) or a rock glacier initially accumulates. Upon progressive aggradation and steepening of the proximal slope segment, prevalent processes of deposition change to grain flows and 'sorted rockfalls' in the steep-dipping (30-35°) proximal slope segment, while deposits of debris flows, ephemeral fluid flows, and rare large rockfalls prevail on the distal, lower-dipping slope segment. In successions of mature talus slopes, the proximal slope package overlies the lower-dipping, distal slope deposits along a narrow 'downlap interval'. The downlap interval is characterized by a marked upslope steepening of bedding surfaces over a short vertical and lateral distance. Immediately after cliff exposure by deglaciation or rocksliding, talus can aggrade at rates of up to a few tens of meters per 1000 years; initially high accumulation rates, however, decrease rapidly with buildup of slope and consequent burial of the rock cliff. On present carbonate-lithic talus slopes of the Eastern Alps the prevalent processes of sediment transport, final deposition, and deposit overprint in many cases change over lateral distances of a few tens to a few hundreds of meters; this gives rise to different types of talus slopes. Whereas glacial-interglacial cycles determine presence/absence of talus, as well as the altitude range of effective talus formation, minor climatic changes thus are hardly to read clearly from

  2. Reflection of climate changes in the structure and morphodynamics of talus slopes (the Tatra Mountains, Poland)

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    Gądek, Bogdan; Grabiec, Mariusz; Kędzia, Stanisław; Rączkowska, Zofia

    2016-06-01

    Talus slopes beside glaciers are among the best objects to research on climate change. In the Tatra Mountains, the highest mountains of central Europe, no glaciers remain, only glacierets and permafrost. For that reasona complex investigation of talus slopes was conducted there in the years 2009-2010. This paper presents the results of GPR and lichenometric measurements of the talus slopes in six glacial cirques located in the High and Western Tatras. The thickness and internal structure of talus slopes were identified along with the variability and conditions of their development. Maximum thickness of the talus slopes ranges from 20 to 35 m, reaching higher values in the High Tatras. The diversity of the thickness of the talus slopes within the Tatras is mostly explained by differences in the relief conditioned by lithology. The diverse altitudinal locations of the talus slopes, and the exposure and inclinations are not reflected in the size and thickness. The thickness of the studied slopes depends primarily on the activity of the processes supplying rock material and on the size and shape of the sediment supply area. The results of the lichenometric testing together with the analysis of the long-term precipitation data imply a several hundred-year-long deterioration of the climate during the Little Ice Age, which is reflected in the increased activity of morphogenetic processes on the talus slopes across the whole massif of the Tatras. In the last 200 years, the talus slopes of the Tatras were most active in three periods: at the end of the Little Ice Age, in the 1930s and 1940s, and in the early 1970s.

  3. Adolescent fracture of the talus associated with talus partitus.

    Science.gov (United States)

    Serrato, Juan; Bennett, James T

    2013-01-01

    A case report of an adolescent with a fracture of the talus with an associated talus partitus is presented. Unlike the more common os trigonum, which arises from a secondary ossification center, the talus partitus is substantially larger and may include articulation with the ankle and subtalar joint, making its preservation via osteosynthesis with the talus desirable.

  4. Paediatric talus fracture.

    LENUS (Irish Health Repository)

    Byrne, Ann-Maria

    2012-01-01

    Paediatric talus fractures are rare injuries resulting from axial loading of the talus against the anterior tibia with the foot in dorsiflexion. Skeletally immature bone is less brittle, with higher elastic resistance than adult bone, thus the paediatric talus can sustain higher forces before fractures occur. However, displaced paediatric talus fractures and those associated with high-energy trauma have been associated with complications including avascular necrosis, arthrosis, delayed union, neurapraxia and the need for revision surgery. The authors present the rare case of a talar neck fracture in a skeletally immature young girl, initially missed on radiological review. However, clinical suspicion on the part of the emergency physician, repeat examination and further radiographic imaging revealed this rare paediatric injury.

  5. Chondroblastoma of the talus.

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    Ningegowda, Ravish V; Subramanian, Karthik; Suresh, I

    2013-01-01

    We report the case of a 13-year-old male child who presented with a painful left ankle. On imaging (radiography and computed tomography scan with 3-dimensional reconstruction views), an osteolytic lesion in the body of the talus was revealed. Open biopsy, curettage, and fibular bone grafting were done, and the specimen was sent for histopathologic examination. The histopathologic report confirmed the specimen to be chondroblastoma of the talus bone. Chondroblastoma is a rare benign cartilaginous neoplasm that accounts for approximately 1% of all bone tumors and characteristically arises in the epiphysis of a long bone, particularly the humerus, tibia, and femur. Chondroblastoma can affect people of all ages. It is, however, most common in children and young adults aged 10 to 20 years. Chondroblastoma in a tarsal bone is a rare entity. Managing chondroblastoma of the talus with curettage and bone grafting has shown good outcomes.

  6. Epidemiological study on talus fractures

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    Marcos Hideyo Sakaki

    2014-08-01

    Full Text Available Objective:To analyze the characteristics of patients with talus fractures and the injuries that they present.Methods:Retrospective analysis on patients hospitalized in the Institute of Orthopedics and Traumatology, Hospital das Clínicas, School of Medicine of the University of São Paulo, between 2006 and 2011, with talus fractures. Patient profile parameters, risk factors, fracture characteristics, treatment data and acute complications were analyzed.Results:Analysis on 23 cases showed that men were more affected than women, with a ratio of 4.8:1. The most frequent trauma mechanism was traffic accidents, followed by falls from a height. The most frequent type of fracture was at the neck of the talus, with 17 cases. Among the 23 cases, seven had peritalar dislocation at the time of presentation, four had exposed fractures and 11 presented other associated fractures. The mean length of time between the trauma and the definitive treatment was six days, while the mean length of hospital stay was 11 days. Three patients presented acute postoperative complications.Conclusion:Talus fractures occurred most commonly in the region of the talar neck and most frequently in young males who suffered high-energy trauma. In almost half of the cases, there were other associated fractures. The length of hospital stay was 11 days.

  7. Nutrient Losses by Runoff and Sediment from the Taluses of Orchard Terraces

    NARCIS (Netherlands)

    Duran Zuazo, V.H.; Martinez Ray, A.; Aguilar Ruiz, J.

    2004-01-01

    The nutrient fluxes of nitrate, ammonium, phosphorus and potassium in runoff and sediments were evaluated over a two-year period (1999¿2000) on the taluses of terraces, in a zone of intense subtropical orchard cultivation (SE Spain). The erosion plots were located on a terrace of 214% (65°) slope, a

  8. Lopsakalt rahvuslik mood Pulga talus / Tanel Veenre

    Index Scriptorium Estoniae

    Veenre, Tanel, 1977-

    2009-01-01

    Eesti Moekunstnike Ühenduse näitus "Lillemotiiv moevormil" Eesti Vabaõhumuuseumi Pulga talus. Osalevad Anne Metsis, Anneliis Vabul, Diana Denissova, Monika Kisand, Juta Piirlaid, Anu Hint ja moekunsti õppejõud Yumiko Okazaki Jaapanist. Eksponeeritud rõivamudelid on kaunistatud rahvuslikest tikanditest inspireeritud stiliseeritud kujunditega

  9. Treatment of osteochondral defects of the talus

    NARCIS (Netherlands)

    C.J.A. van Bergen

    2014-01-01

    An osteochondral defect (OCD) of the talus involves the articular cartilage and subchondral bone. It most frequently appears in the second and third decade of life. A traumatic insult, usually ankle sprain, is the most frequent etiologic factor. The typical symptom is persistent or intermittent deep

  10. Spatially distributed rockfall activity inferred from talus deposits and corresponding rockwall areas in the Gradenbach catchment (Schober Mountains, Austria)

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    Götz, Joachim; Buckel, Johannes; Heckmann, Tobias

    2013-04-01

    end on a selected talus landform, the 'rockfall contributing area' is delineated; this approach takes account of the stochastic nature of rockfall trajectories and is able to identify, for example, rockfall delivery from one rockwall segment to multiple talus landforms (or from multiple rockfall segments to the same deposit, respectively). Using both approaches, a total of 290 rockwall-talus-subsystems are statistically analysed indicating a constant relationship between rockfall source areas and corresponding areas of talus deposits of almost 1:1. However, certain rockwall-talus-subsystems deviate from this correlation since sediment storage landforms of similar size originate from varying rockwall source areas and vice versa. This varying relationship is assumed to be strongly controlled by morphometric parameters, such as rockwall slope, altitudinal interval, and aspect. The impact of these parameters on the surface area ratio will be finally discussed.

  11. A RARE CARTILAGINOUS TUMOR OF THE TALUS

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    Alok Sobhan

    2014-06-01

    Full Text Available The present report describes an unusual and rare tumor originating from the talus. A 21 years old female presented with a swelling over the right ankle 4x3.5cms in size for one year. The lesion was osteolytic with surrounded peripheral rim of bone sclerosis. Subsequent pathological study confirmed the case as chondroblastoma. The lesion was curettaged and the resultant defect was filled by autogenous bone graft. Such tumors are as chondroblastoma usually originate from epiphyseal and apophyeal regions of long bones. Thorough clinical, radiological and histological assessment is required for appropriate management.

  12. Palaeoclimatic considerations of talus flatirons and aeolian deposits in Northern Fuerteventura volcanic island (Canary Islands, Spain)

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    Gutiérrez-Elorza, Mateo; Lucha, Pedro; Gracia, F.-Javier; Desir, Gloria; Marín, Cinta; Petit-Maire, Nicole

    2013-09-01

    Fuerteventura volcanic island has been subject to considerable aeolian activity since the Late Pleistocene. The aeolian record includes inactive aeolian deposits with interbedded entisols, whose age by OSL dating ranges between 46 and 26 ky BP. The Corralejo active dune field, where sand sheets, nebkhas, coppice dunes, blowouts, barchans and transverse dunes have been described, constitutes a more recent Aeolian deposit. Here the age is about 14 ky BP. On Fuerteventura Island aeolian dust has been deposited on valleys and slopes. This last type of accumulation has been affected by gully incision, producing talus flatirons. Samples taken on the apex of these palaeo-slopes indicate an OSL age of 30 and 50 ky BP. A palaeoclimatic succession has been interpreted during which a prevailing arid period took place in OIS 4, with the accumulation of aeolian dust. A humid period occurred in OIS 2, during which slopes were dissected and formed talus flatirons. An arid period about 14 ky BP gave rise to the Corralejo dune field, which has continued until present with slight climatic oscillations.

  13. Chondroblastoma of the talus: a case report and literature review.

    Science.gov (United States)

    Zhang, Kairui; Gao, Yuan; Dai, Haifei; Zhang, Sheng; Li, Gong; Yu, Bin

    2012-01-01

    Chondroblastoma is a rare, benign cartilaginous neoplasm that accounts for approximately 1% of all bone tumors, and approximately 4% of all chondroblastomas arise in the talus. Here we report a case of chondroblastoma in the left talus. The 22-year-old male patient presented with a 16-month history of ankle pain. Based on radiological and pathological examination, we diagnosed the patient with chondroblastoma. A posterolateral approach was used to allow access to the lesion. After curettage, the allogenic bone chips were packed into the talar body defect. After 2 years' follow-up, we found no recurrence or metastasis of chondroblastoma, suggesting our surgery procedure was effective.

  14. Mixed approach (numerical modeling / equilibrium analysis) for slope stability analysis: development and application to the dams and open pit mining; Une approche mixte (numerique/equilibre limite) pour le calcul de stabilite des ouvrages en terre: developpement et application aux barrages et talus miniers

    Energy Technology Data Exchange (ETDEWEB)

    Kourdey, A.

    2002-09-15

    The determination of the sliding surface of slope (dam, slope natural..) is one of the important and complicated problems in geotechnics. The Analyze of stability by the methods of Limit Equilibrium like the method of slices are the most used methods. They are able to determine a safety factor for a geometrically defined failure surface. These methods well adapted to the homogeneous mediums, have been developed a lot but they do not integrate the basic relations of mechanics (stress-strain). The numerical methods are better adapted to mediums having more complexity (effect of water, seismicity, fracturing,..). But, they are seldom used to determine a sliding surface and a safety factor. Each family offers appreciable advantages in the analysis of slope stability. For that purpose, we have developed a method that combines the advantages of the numerical methods as well as those of Limit Equilibrium allowing obtaining a slip surface determined by the calculated constraints. This slip surface may be imposed or better optimized, thus providing a minimal safety factor. Methods of operation research are used to obtain this surface. They are search methods by level, dynamic research.. or both at the same time. We integrated these developments in an existing computer code based on the method of Finite Differences known as FLAC. The stresses are determined for a linear behavior and for nonlinear. Interfaces and graphic tools are also produced to facilitate the analysis of stability. The validity of this approach was carried out for a standard case of slope, we analyzed and compared the results with the methods of Limit Equilibrium. The parametric study shows that this approach takes account of different parameters, which influences stability. We also kept a particular place for the application on real cases presenting slopes of different nature (dams, mining slops,...). (author)

  15. Development of an internally braced prosthesis for total talus replacement.

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    Regauer, Markus; Lange, Mirjam; Soldan, Kevin; Peyerl, Steffen; Baumbach, Sebastian; Böcker, Wolfgang; Polzer, Hans

    2017-03-18

    Total loss of talus due to trauma or avascular necrosis, for example, still remains to be a major challenge in foot and ankle surgery with severely limited treatment options. Implantation of a custom made total talar prosthesis has shown promising results so far. Most important factors for long time success are degree of congruence of articular surfaces and ligamentous stability of the ankle. Therefore, our aim was to develop an optimized custom made prosthesis for total talus replacement providing a high level of primary stability. A custom made hemiprosthesis was developed using computed tomography and magnetic resonance imaging data of the affected and contralateral talus considering the principles and technology for the development of the S.T.A.R. prosthesis (Stryker). Additionally, four eyelets for fixation of artificial ligaments were added at the correspondent footprints of the most important ligaments. Two modifications can be provided according to the clinical requirements: A tri-articular hemiprosthesis or a bi-articular hemiprosthesis combined with the tibial component of the S.T.A.R. total ankle replacement system. A feasibility study was performed using a fresh frozen human cadaver. Maximum range of motion of the ankle was measured and ligamentous stability was evaluated by use of standard X-rays after application of varus, valgus or sagittal stress with 150 N. Correct implantation of the prosthesis was technically possible via an anterior approach to the ankle and using standard instruments. Malleolar osteotomies were not required. Maximum ankle dorsiflexion and plantarflexion were measured as 22-0-28 degrees. Maximum anterior displacement of the talus was 6 mm, maximum varus tilt 3 degrees and maximum valgus tilt 2 degrees. Application of an internally braced prosthesis for total talus replacement in humans is technically feasible and might be a reasonable procedure in carefully selected cases with no better alternatives left.

  16. Congenital vertical talus: Treatment by reverse ponseti technique

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    Bhaskar Atul

    2008-01-01

    Full Text Available Background: The surgery for idiopathic congenital vertical talus (CVT can lead to stiffness, wound complications and under or over correction. There are sporadic literature on costing with mixed results. We describe our early experience of reverse ponseti technique. Materials and methods: Four cases (four feet of idiopathic congenital vertical talus (CVT which presented one month after birth were treated by serial manipulation and casting, tendoachilles tenotomy and percutaneous pinning of talonavicular joint. An average of 5.2 (range - four to six plaster cast applications were required to correct the forefoot deformity. Once the talus and navicular were aligned based on the radiographic talus-first metatarsal axis, percutaneous fixation of the talo-navicular joint with a Kirschner wire, and percutaneous tendoachilles tenotomy under anesthesia was performed following which a cast was applied with the foot in slight dorsiflexion. Results: The mean follow-up period for the four cases was 8.5 months (6-12 months. At the end of the treatment all feet were supple and plantigrade but still using ankle foot orthosis (AFO. The mean talocalcaneal angle was 70 degrees before treatment and this reduced to 31 degrees after casting. The mean talar axis first metatasal base angle (TAMBA angle was 60° before casting and this improved to 10.5°. Conclusion: Although our follow-up period is small, we would recommend early casting for idiopathic CVT along the same lines as the Ponseti technique for clubfoot except that the forces applied are in reverse direction. This early casting method can prevent extensive surgery in the future, however, a close vigil is required to detect any early relapse.

  17. Three-dimensional geometric analysis of the talus for designing talar prosthetics.

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    Islam, Kamrul; Dobbe, Ashlee; Duke, Kajsa; El-Rich, Marwan; Dhillon, Sukhvinder; Adeeb, Samer; Jomha, Nadr M

    2014-04-01

    Proper understanding of the complex geometric shape of the talus bone is important for the design of generic talar body prosthetics and restoration of the proper ankle joint function after surgery. To date, all talus implants have been patient-specific with the limitation that complex computer modeling is required to produce a mirrored image from the unaffected opposite side followed by machining a patient-specific prosthesis. To develop an "off-the-shelf" non-custom talar prosthesis, it is important to perform a thorough investigation of the geometric shape of the talus bone. This article addresses the applicability of a scaling approach for investigating the geometric shape and similarity of talus bones. This study used computed tomography scan images of the ankle joints of 27 different subjects to perform the analysis. Results of the deviation analyses showed that the deviation in the articulating surfaces of the talus bones was not excessive in terms of talus size. These results suggest that a proposed range of five implant sizes is possible. Finally, it is concluded that the talus bones of the ankle joints are geometrically similar, and a proposed range of five implant sizes will fit a wide range of subjects. This information may help to develop generic talus implants that might be applicable to patients with a severe talus injury.

  18. Surgical treatment of osteochondritis dissecans of the talus

    DEFF Research Database (Denmark)

    Zwingmann, Jörn; Südkamp, Norbert P; Schmal, Hagen

    2012-01-01

    PURPOSE: Osteochondritis dissecans (OCD) is an aseptic bone necrosis and represents pathology of high clinical relevance, which is frequently located on the talus. Various treatment strategies including non-surgical and surgical approaches have been described. An evidence-based treatment algorithm...... inclusion criteria (minimum follow-up 12 months, patient evaluation by standardized scoring systems, etc.), a total of 54 studies with clinical follow-up of 1,105 patients was included. Methodology of these studies was systematically analyzed by the means of the Coleman Methodology Score. Outcome......,105 patients was 47 months (SD ± 17) with a mean age of 29 (SD ± 5.6) years. The proportion of excellent and good treatment results was stage-independent in total 75 %. According to the criteria of the score applied for patient's evaluation in the individual study, the overall percentage of "good...

  19. CT for diagnosing fractures of the undersurface of the talus and mechanism of injury

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    Okamoto, Hideaki; Shibata, Yoshimori; Nishi, Genzaburo; Tago, Kyoji; Tsuchiya, Daiji; Chiba, Takehiro; Okumura, Hisashi [Aichiken Koseiren Kainan Hospital, Yatomi (Japan); Ikeda, Takeshi; Wada, Ikuo

    2000-02-01

    Talus fractures whose fracture lines extend to the subtalar joint, except fractures of the neck and the body of the talus, are defined as fractures of the lower portion of the talus. It is difficult to make a correctly diagnosis of inferior fractures of the talus by plain radiography or tomography alone. The author encountered 12 cases of inferior fractures of the talus between 1989 and 1997, and CT imaging in 2 directions, in the horizontal and frontal plane, was useful in making the diagnosis. The correct diagnosis rate was 100%, and differentiation of the site and extent of the fractures was possible. Based on the CT findings, the fractures were classified into 8 types (fractures of the lateral process of the talus, fractures of the medial tubercle, fractures of the posterior process, and combinations of the above, and comminuted fractures). The mechanism of the injuries was also investigated, and the fractures of the lateral process of the talus seemed to have been caused by excessive eversion force on the ankle joint, with the lateral process becoming trapped between the fibula and the calcaneus. Medial tubercle fractures also seemed to be caused by forcible inversion of the ankle, with the tip of the medial malleous impacting and the medial tubercle being trapped between it and the sustentaculum tali. The comminuted fractures seem to have been caused by axial compression added to various of external forces. (K.H.)

  20. Effect of anterior translation of the talus on outcomes of three-component total ankle arthroplasty

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    2013-01-01

    Background Ankle osteoarthritis commonly involves sagittal malalignment with anterior translation of the talus relative to the tibia. Total ankle arthroplasty has become an increasingly popular treatment for patients with symptomatic ankle osteoarthritis. However, no comprehensive study has been conducted on the outcomes of total ankle arthroplasty for osteoarthritis with preoperative sagittal malalignment. The purpose of this study was to evaluate the effect of anterior translation of the talus on outcomes of three-component total ankle arthroplasty. Methods One hundred and four osteoarthritic ankles in 104 patients who underwent three-component total ankle arthroplasty were included in this study. The 104 ankles were divided into 2 groups: ankles with anteriorly translated talus (50 ankles), and ankles with non-translated talus (54 ankles). Clinical and radiographic outcomes were assessed in both groups. The mean follow-up duration was 42.8 ± 17.9 months (range, 24 to 95 months). Results Forty-six (92%) of 50 ankles with anterior translation of the talus showed relocation of the talus within the mortise at 6 months, and 48 (96%) ankles were relocated at 12 months after total ankle arthroplasty. But, 2 (4%) ankles were not relocated until the final follow-up. The AOFAS scores, ankle range of motion, and radiographic outcomes showed no significant difference between the two groups at the final follow-up (p > 0.05 for each). Conclusions In majority of cases, the anteriorly translated talus in osteoarthritic ankles was restored to an anatomical position within 6 months after successful three-component total ankle arthroplasty. The clinical and radiographic outcomes in the osteoarthritic ankles with anteriorly translated talus group were comparable with those in non-translated talus group. PMID:24007555

  1. Regional Migratory Osteoporosis of the Hip and Talus

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    Mohammad Hasan Shahverdi

    2016-02-01

    Full Text Available Introduction Transient osteoporosis of the hip (TOH is a relatively rare disorder characterized by the loss of bone tissue in the proximal femur. Hip joint is the most common location of the disease, although it may also involve the knee, ankle or foot bones. Self-limited nature of the disease is characteristic with complete relief of symptoms occurring after 6 - 12 months. Case Presentation Authors report a case with transient osteoporosis of the hip and a clear migratory pattern of osteoporosis from the hip to talus bone in the ipsilateral foot. Spontaneous resolution of symptoms occurred in the patient and he was asymptomatic in the last follow-up. Conclusions It is important to consider TOH in the differential diagnosis of middle-aged males and young females with hip pain. It should be included in the differential diagnosis of patients with acute foot and ankle pain. The importance of recognizing this condition lies in its self-limiting nature, with spontaneous resolution in less than a year in the majority of cases. Consequently, invasive investigations may often be avoided in these patients.

  2. ARTHROSCOPIC TREATMENT OF OSTEOCHONDRAL LESIONS OF THE TALUS

    Science.gov (United States)

    de Araujo, Mariana Korbage; de Cillo, Mario Sergio Paulillo; Bittar, Cinthia Kelly; Zabeu, José Luis Amin; Cezar, Caroliny Nociti Moreira

    2016-01-01

    ABSTRACT Objective: To assess pain and function of the ankle in patients with injuries up to 1.5 cm diameter by the American Orthopaedic Foot and Ankle Society (AOFAS) score after arthroscopic treatment. Methods: The AOFAS scale was applied before and after arthroscopy, as well as the degree of subjective satisfaction of ambulatory patients. Patients with type I osteochondral injuries, acute trauma, using plaster, presenting lesions in other joints of the lower limbs and cognitive impairment that would prevent the application of the satisfaction questionnaire were excluded from the study. Statistical analysis was performed using unpaired t test with Welch correction, Mann Whitney test, and ANOVA, with Kruskal Wallis test and Dun test, considering p value lower than 0.05. Results: There was an increased AOFAS scores after arthroscopic treatment in 52 (94.5%) patients. The mean values of AOFAS score in 55 patients was 77.32 ± 6.67 points preoperative and 93.10± 8.24 points postoperative, with a mean variation of 15.8 points, p0.05. Conclusion: Patients with stage II, III or IV osteochondral injuries of the talus of up to 1.5 cm diameter, whether medial or lateral, showed a significant improvement after arthroscopic treatment. Level of Evidence III, Retrospective Study. PMID:26997911

  3. Congenital vertical talus in four generations of the same family

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    Levinsohn, E. Mark [Crouse Hospital, Department of Medical Imaging, Syracuse (United States); Shrimpton, Antony E. [SUNY Upstate Medical University, Department of Clinical Pathology, Syracuse (United States); Cady, Robert B. [SUNY Upstate Medical University, Department of Pediatrics, Syracuse (United States); Packard, David S. [SUNY Upstate Medical University, Department of Cell and Developmental Biology, Syracuse (United States); Hootnick, David R. [SUNY Upstate Medical University, Department of Pediatrics, Syracuse (United States); SUNY Upstate Medical University, Department of Cell and Developmental Biology, Syracuse (United States); SUNY Upstate Medical University, Department of Orthopedic Surgery, Syracuse (United States)

    2004-11-01

    This paper presents four generations of a family with radiographically demonstrated congenital vertical talus (CVT) in whom a HOXD10 gene mutation was identified. Some members of the family with this mutation exhibited cavo-varus foot deformity consistent with a Charcot-Marie-Tooth (CMT)-like disorder. Physical examination was performed on nearly all of the affected and unaffected family members. DNA was extracted from blood obtained from 14 subjects who showed radiographic and clinical features of CVT (two of whom also had CMT), from two subjects with features of CMT but not CVT, and from 20 related family members who were clinically normal. Radiographs show the appearance of uncorrected CVT in infancy, in childhood, and in adulthood. DNA analysis revealed a mutation in a HOXD10gene located on chromosome 2 in all of the affected but none of the unaffected family members. There is an autosomal-dominant-inherited mutation with complete penetrance which is found in all members of a pedigree with CVT, some of whom exhibit a CMT-like foot disorder. Radiologic findings vary depending on the severity of involvement, treatment provided and age of the patient. (orig.)

  4. Current strategies of tissue engineering in talus chondral defects.

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    Martinelli, Niccolo; Bonifacini, Carlo; Longo, Umile Giuseppe; Marinozzi, Andrea; Florio, Pino; Khan, Wasim S; Denaro, Vincenzo

    2013-05-01

    Due to the nature of articular cartilage of being poorly vascularized the capabilities of self repair are limited. Mesenchymal stem cells transplantation is a modern technique which has been developed after the high success rates obtained by microfracturing and drilling techniques which promote the release of growth factors and the infiltration of bone marrow derived cells in the lesion. In order to increase the concentration of bone marrow derived cells appropriate devices, the scaffolds, are necessary. These three dimensional constructs mimic the physiological ambient of chondrogenesis.The race for new scaffold materials, which will show high biocompatibility to prevent inflammatory response, high cellular adhesion properties with three dimensional architecture, high bioactivity to deliver growth factor appropriately and possibly high biodegrability has just begun. New studies will concentrate on the role, on the interaction and on the temporal sequence of growth factors to improve ostheocondral differentiation, but the necessity to increase the number of clinical studies with more patients and longer follow ups seems mandatory. The aim of this review is to update and summarise the evidence-based knowledge of treatment of talus chondral defect with new tissue engineering techniques.

  5. Parrotfish erosion underpins reef growth, sand talus development and island building in the Maldives

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    Morgan, Kyle M.; Kench, Paul S.

    2016-07-01

    Parrotfish play a key functional role on coral reefs as external bioerosion agents and produce large quantities of carbonate sediment as a by-product of grazing on reef surfaces. Parrotfish are therefore an important potential source of sediment for island construction and maintenance within atoll reef environments, particularly under future scenarios of sea level rise and island morphological change. Here, we present the first field-based estimates of excavating parrotfish erosion (Chlorurus sordidus and Chlorurus strongylocephalus) within the Indian Ocean and quantify the contribution of parrotfish to the carbonate and sediment budgets of an atoll interior reef platform in the Maldives. We note that parrotfish erosion rates are high (6.3 kg m- 2 y- 1), generating large amounts of new coral-based sediment (2.6 kg m- 2 y- 1) that has a comparable grain size distribution to island deposits. Mean erosion rates by individual C. strongylocephalus (405 kg individual y- 1) were higher than C. sordidus (55 kg individual y- 1), but their contribution to erosion per unit area of reef was less due to a lower relative biomass (C. strongylocephalus: 1.3 kg m- 2 y- 1; C. sordidus: 5.0 kg m- 2 y- 1). Parrotfish also facilitate sediment export from reefs (0.7 kg m- 2 y- 1), which contributes extensively to the development of the sand talus on the fore-reef slope and to the evolution of the wider atoll basin. Our results provide strong evidence that parrotfish erosion (and sediment generation) underpins island morphology on Maldivian reefs and highlight the importance of larger parrotfish as producers of island-grade sediment. Ecological processes must therefore be considered within future coastal management strategies for enhancing island stability.

  6. Assessment of gait symmetry for Talus Valgus children based on experimental kinematic analysis

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    Toth-Tascau, Mirela; Pasca, Oana; Vigaru, Cosmina; Rusu, Lucian

    2013-10-01

    The general purpose of this study was to assess the gait symmetry for Talus Valgus deformity based on experimental kinematic analysis. As this foot condition generally occurs in children, the study is focused on two children having five years old, one being healthy, as control subject, and the second one having bilateral Talus Valgus deformity. Kinematic experimental analysis was conducted using Zebris CMS-HS Measuring System. The bilateral symmetry was analyzed using two methods: index of symmetry (SI) calculated for spatio-temporal parameters (stance phase, swing phase, and step length) and kinematic parameter (maximum value of dorsiflexion - plantar flexion angle in the ankle joint), and an unpaired t-test to compare the variation of means values of dorsiflexion - plantar flexion angle in ankle joint for both left and right side. The study evidenced a good bilateral symmetry in case of the control subject and quantified the asymmetry in case of subject with Talus Valgus deformity.

  7. TREATMENT OF OSTEOCHONDRAL LESIONS OF THE TALUS BY MEANS OF THEARTHROSCOPY-ASSISTED MICROPERFORATION TECHNIQUE

    Science.gov (United States)

    de Lima, Everton; de Queiroz, Felipe; Lopes, Osmar Valadão; Spinelli, Leandro de Freitas

    2015-01-01

    Objective: To evaluate patients affected by osteochondral fractures of the talus who were treated surgically by means of arthroscopy-assisted microperforation. Methods: A retrospective study was carried out on 24 patients with osteochondral lesions of the talus who underwent microperforation assisted by videoarthroscopy of the ankle. They were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) score system before and after the operation. Results: There were 19 men and 5 women, with a mean age of 35.3 years (minimum of 17 years and maximum of 54 years). The minimum follow-up was two years (maximum of 39 months). All the patients showed an improvement in AOFAS score after surgery, with an average improvement of around 22.5 points. Conclusion: Videoarthroscopy-assisted microperforation is a good option for treating osteochondral lesions of the talus and provides good functional results. PMID:27027076

  8. Vanad sõbrad: Poola president õhtustas Ärma talus

    Index Scriptorium Estoniae

    2011-01-01

    President Toomas Hendrik Ilves võõrustas 28. märtsil 2011 Viljandimaal Ärma talus Poola presidenti Bronislaw Komorowskit. Poola riigipea abikaasa Anna Komorowska ja proua Evelin Ilves külastasid Tallinnas ka lastekirjanduse keskust, kus esitleti raamatut "Väike Chopin" ning tegid ekskursiooni Tallinna vanalinnas

  9. Finite Element Analysis of Foot and Ankle Impact Injury: Risk Evaluation of Calcaneus and Talus Fracture.

    Directory of Open Access Journals (Sweden)

    Duo Wai-Chi Wong

    Full Text Available Foot and ankle impact injury is common in geriatric trauma and often leads to fracture of rearfoot, including calcaneus and talus. The objective of this study was to assess the influence of foot impact on the risk of calcaneus and talus fracture via finite element analysis.A three-dimensional finite element model of foot and ankle was constructed based on magnetic resonance images of a female aged 28. The foot sustained a 7-kg passive impact through a foot plate. The simulated impact velocities were from 2.0 to 7.0 m/s with 1.0 m/s interval.At 5.0 m/s impact velocity, the maximum von Mises stress of the trabecular calcaneus and talus were 3.21MPa and 2.41MPa respectively, while that of the Tresca stress were 3.46MPa and 2.55MPa. About 94% and 84% of the trabecular calcaneus and talus exceeded the shear yielding stress, while 21.7% and 18.3% yielded the compressive stress. The peak stresses were distributed around the talocalcaneal articulation and the calcaneal tuberosity inferiorly, which corresponded to the common fracture sites.The prediction in this study showed that axial compressive impact at 5.0 m/s could produce considerable yielding of trabecular bone in both calcaneus and talus, dominantly by shear and compounded with compression that predispose the rearfoot in the risk of fracture. This study suggested the injury pattern and fracture mode of high energy trauma that provides insights in injury prevention and fracture management.

  10. Impact of land-use change on soil degradation by establishment of terraces with subtropical orchards in sloping areas (Granada, SE Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez Pleguezuelo, C. R.; Duran Zuzo, V. H.; Martin Peinado, F. J.; Franco Tarifa, D.

    2009-07-01

    In the coast of Granada, an intensive irrigated agriculture based on subtropical crops has been established. These trees have been planted in highly sloped areas, by the construction of terraces. In this fragile Mediterranean agroecosystem, the removal of native spontaneous vegetation cover and substitution by orchards, increase the susceptibility to soil degradation and eventually brings up the destruction of these structures by rainfall events. To study this net change, we monitored the soil loss and runoff over a two-year period in the taluses of terraces with a mature mango (Mangifera indica L.) orchard. The studied treatments were bare soil (BS) and spontaneous vegetation (NSV), each twice replicated. The erosion plots were 4 m x 4 m in area and were located in the taluses of orchard in the taluses of orchard terraces (65 degree centigrade slope). The average annual soil loss by erosion for BS and NSV was 2.5 and 0.3 Mg ha{sup -}1 yr{sup -}1, and for runoff 34.1 and 6.8 mm yr{sup -}1, respectively. Therefore, soil erosion and runoff from BS plot were 8- and 5-times higher than in NSV, showing the importance of plant covers in the taluses of terraces in reducing this impact. Thus, the removal of plant cover from the taluses under these conditions, represent a high risk of slump and collapse, causing serious environmental and economic problems for farmers of subtropical crops. (Author) 11 refs.

  11. Arthroscopic treatment for osteochondral lesions of the talus: analysis of outcome predictors

    Institute of Scientific and Technical Information of China (English)

    GUO Qin-wei; HU Yue-lin; JIAO Chen; YU Chang-long; AO Ying-fang

    2010-01-01

    Background Compared with traditional arthrotomy procedures, arthroscopic treatment for osteochondral lesions of the talus has some advantages. However, there has been considerable debate about the outcome predictors for this surgical technique. This study aimed to investigate the outcomes of arthroscopic treatment for osteochondral lesions of the talus, and analyze its outcome predictors.Methods Clinical data of 48 patients with osteochondral lesions of the talus who underwent ankle arthroscopy were studied. Arthroscopic debridement was performed on all patients, and microfracture was also performed in 36 cases. Scores on a subjective satisfaction questionnaire, visual analog scale (VAS) for pain, and the American Orthopedic Foot & Ankle Society (AOFAS) ankle and hindfoot scores were obtained before and after surgery.Results Five patients lost to follow up. The other forty-three patients, 8 of whom were athletes, were followed up for an average of 23.9 months. The average AOFAS post-operative score was 90.16±9.96, compared with 70.81±6.96 before surgery (t=9.353, P <0.001). The VAS pain score after the operation (2.51±9.45) was significantly lower than that before the operation (6.95±1.40) (t=8.647, P<0.001). Of the 43 patients, 35 (81.4%) had good or excellent results. There was no significant difference in outcome between the medial and lateral groups (z=0.205, P=0.838), while a better outcome was found with lesions smaller than 10 mm than those with larger lesions (z=2.199, P=0.028). Age, sex, athletic profession and location of the lesion did not significantly correlate with outcomes.Conclusions Arthroscopic treatment is effective and safe for osteochondral lesions of the talus. A strong correlation was found between the size of the lesion and successful outcome.

  12. Neglected lateral process of talus fracture presenting as a loose body in tarsal canal

    Institute of Scientific and Technical Information of China (English)

    Kamal Bali; Sharad Prabhakar; Nitesh Gahlot; Mandeep S Dhillon

    2011-01-01

    Lateral process fractures of talus are rare injuries with a potential to cause significant morbidity if rnisdiagnosed.The appropriate management of these fractures is still controversial and only a few reports are available on this subject.We presented a case of a 37-year-old male with neglected fracture on the lateral process of talus which was misdiagnosed at the time of injury.The patient presented to 7 months after misdiagnosis with a chronic ankle pain.Our case is unique in the sense that it is a rare case of neglected fracture on the lateral process of talus which presented as a loose body in sinus tarsi.However,a surgery with an excision of the loose body presented a satisfactory outcome along with 2 years' follow-up.To our knowledge,it ought to be the first case reported in the English literature.Through this case report,we highlight the importance of high index of suspicion for such rare bony injuries while evaluating trauma to the lateral side of ankle and discuss the principles of management of these fractures.

  13. Talus measurements as a diagnostic tool for sexual dimorphism in Egyptian population.

    Science.gov (United States)

    Abd-elaleem, Shereen Abd-elhakim; Abd-elhameed, Mostafa; Ewis, Ashraf Abd-elazeem

    2012-02-01

    Measurements of talus have been shown to be sexually dimorphic in South African blacks and whites and Prehistoric New Zealand Polynesians. Since several studies have demonstrated that discriminant function equations used to determine the sex of a skeleton are population specific, the purpose of the present study was to derive similar equation for the tali of Egyptians. The sample consisted of 110 tali (67 male & 43 female) whose age at death ranged between 20 and 60 years. The tali were obtained from Anatomy departments of Minia and Cairo Universities and also from Forensic Medicine department of Justice Office in Minia governates - Egypt. Twelve measurements were taken for every talus. Data were analyzed by SPSS version 16. All measurements showed significant sexual differences (P < 0.05) except calcaneus articular surface width and navicular articular surfaced width. Talar length was found to be the most sexual dimorphic (90.9%). Combination of talar length, talar width and neck width gave a percentage of accuracy of 85.5%. Finally, it is concluded that the talus of Egyptian population is useful for sex estimation.

  14. ElevationSlope_SLOPE1M2009

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Barre Montpelier 2009 1m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce...

  15. ElevationSlope_SLOPE2M

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Bennington County 2012 2.0m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce...

  16. ElevationSlope_SLOPE1M2005

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Essex County 2005 1m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce change in...

  17. ElevationSlope_SLOPE1M2010

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Bennington Floodplain 2010 1m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce...

  18. ElevationSlope_SLOPE1M2007

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Bennington Floodplain 2007 1m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce...

  19. Groundwater flow and storage within an alpine meadow-talus complex

    Directory of Open Access Journals (Sweden)

    A. F. McClymont

    2010-02-01

    Full Text Available The different types of geological deposits and rock formations found in alpine watersheds play key roles in regulating the rate and timing of runoff to mountain rivers. Talus and alpine meadows are dominant features in these areas, but scant data exist for their capacity to store and transmit groundwater. To gain further understanding of these processes, we have undertaken a combined geophysical and hydrological study of a small (2100 m2 alpine meadow and surrounding talus within the Lake O'Hara watershed in the Canadian Rockies. Several intersecting ground-penetrating radar (GPR and electrical resistivity tomography (ERT profiles and a seismic refraction profile were acquired to map the thickness of the talus and to image the topography of the bedrock basin that lies under the meadow. From analysis of the GPR and seismic profiles, we estimate that the talus deposits are relatively thin (<6 m. Combined interpretations from the GPR and ERT data show that the fine-grained sediment, that the meadow basin is comprised of, has a total volume of ca. 3300 m3 and has a maximum thickness of ca. 4 m. Annual snow surveys and stream gauging reveal that the total input volume of snowmelt and rainfall to the meadow basin is several times larger than its groundwater storage capacity, giving rise to low total-dissolved species concentrations (14–21 mg/L within the meadow groundwater. Observations from four piezometers established on the meadow show that the water table fluctuates rapidly in response to spring snowmelt and precipitation events but otherwise maintains a relatively stable depth of 0.3–0.4 m below the meadow surface during summer months. A slug test performed on one of the piezometers indicated that the saturated hydraulic conductivity of the shallow meadow sediments is 2.5×10−7 m/s. We suggest that a bedrock saddle imaged underneath the southern end of the meadow forms a natural constriction to subsurface

  20. Dysplasia Epiphysealis Hemimelica (Trevor Syndrome of Talus in a 21-Year Old Woman; Case Report

    Directory of Open Access Journals (Sweden)

    Amir R Sdeghifar

    2014-03-01

    Full Text Available Dysplasia epiphysealis hemimelica is a rare nonhereditary epiphyseal disease that mimics synovial chondromatosis and osteochondroma of the joints. The disease mainly involves long bones of the lower extremities and tarsal bones. Herein we report 21-year old woman who presented with pain and limited range of ankle motion, who underwent surgical excision of talus exostosis after preoperative imaging and careful planning. after that she was discharged and her problem improved and she have no problem in three year follow up .pathologic examination of specimen confirm the diagnosis.

  1. Sex determination from the talus in a contemporary Greek population using discriminant function analysis.

    Science.gov (United States)

    Peckmann, Tanya R; Orr, Kayla; Meek, Susan; Manolis, Sotiris K

    2015-07-01

    The determination of sex is an important part of building the biological profile for unknown human remains. Many of the bones traditionally used for the determination of sex are often found fragmented or incomplete in forensic and archaeological cases. The goal of the present research was to derive discriminant function equations from the talus, a preservationally favoured bone, for sexing skeletons from a contemporary Greek population. Nine parameters were measured on 182 individuals (96 males and 86 females) from the University of Athens Human Skeletal Reference Collection. The individuals ranged in age from 20 to 99 years old. The statistical analyses showed that all measured parameters were sexually dimorphic. Discriminant function score equations were generated for use in sex determination. The average accuracy of sex classification ranged from 65.2% to 93.4% for the univariate analysis, 90%-96.5% for the direct method and 86.7% for the stepwise method. Comparisons to other populations were made. Overall, the cross-validated accuracies ranged from 65.5% to 83.2% and males were most often correctly identified. The talus was shown to be useful for sex determination in the modern Greek population.

  2. Management of 1½ month old neglected talus neck fracture: A case report and review of literature

    Directory of Open Access Journals (Sweden)

    Dinesh R Kale

    2014-01-01

    Full Text Available Undisplaced talus neck fractures are uncommon and difficult to diagnose. We present a case of an 18-year-old female came with the complaints of pain and swelling in the foot following a fall from a bicycle 1½ months back. For the above complaints, she had consulted local doctors who had done X-rays of the foot and no diagnosis was made. She was treated conservatively with medications and compression bandage for swelling and the patient was allowed to walk. On presenting to us, X-ray of the foot was done and minimally displaced talus neck fracture was suspected. Magnetic resonance imaging of the foot was done and the diagnosis was confirmed. Patient was operated with percutaneous screw fixation following which below knee cast was given for 6 weeks followed by partial weight bearing. Patient returned to complete weight bearing and previous activity level without pain at the end of 3 months.

  3. Retrograde Percutaneous Drilling for Osteochondritis Dissecans of the Head of the Talus: Case Report and Review of the Literature.

    Science.gov (United States)

    Corominas, Laura; Sanpera, Ignacio; Masrouha, Karim; Sanpera-Iglesias, Julia

    2016-01-01

    Osteochondral lesions of the talus might be a more common cause of pain than previously recognized, especially among those involved in athletic activities. However, the location of an osteochondral lesion on the talar head is much less common than such lesions localized to the dome of the talus and can pose diagnostic difficulties. We present the case of a 14-year-old soccer player who complained of longstanding pain in his left foot. After unsuccessful conservative treatment consisting of rest and bracing, he was ultimately treated with retrograde percutaneous drilling of the talar head performed by a medial approach. This was followed by casting and non-weightbearing for 6 weeks, after which physical therapy was undertaken. He was able to return to full activity and remained asymptomatic during a 5-year observation period. Although rare, osteochondritis dissecans of the talar head should be considered in young athletes with persistent foot pain that is unresponsive to reasonable therapy.

  4. Snowboard, wakeboard, dashboard? Isolated fracture of the lateral process of the talus in a high-speed road traffic accident.

    Science.gov (United States)

    Ng, Evangeline Shimei; O'Neill, Barry James; Cunningham, Laurence Patrick; Quinlan, John Francis

    2013-07-10

    We present a 23-year-old man who sustained an isolated fracture of the lateral process of the talus (LPT) in a head-on vehicle collision at a combined speed of 200 km/h. The driver of the other vehicle sustained fatal injuries at the scene. The LPT was openly reduced and fixed with successful outcome at 3 months. This case is unusual in the method of injury, in particular in relation to the isolated relatively minor injury sustained.

  5. Snowboard, wakeboard, dashboard? Isolated fracture of the lateral process of the talus in a high-speed road traffic accident.

    LENUS (Irish Health Repository)

    Ng, Evangeline Shimei

    2013-01-01

    We present a 23-year-old man who sustained an isolated fracture of the lateral process of the talus (LPT) in a head-on vehicle collision at a combined speed of 200 km\\/h. The driver of the other vehicle sustained fatal injuries at the scene. The LPT was openly reduced and fixed with successful outcome at 3 months. This case is unusual in the method of injury, in particular in relation to the isolated relatively minor injury sustained.

  6. MRI-guided percutaneous retrograde drilling of osteochondritis dissecans of the talus: a feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Kerimaa, Pekka; Ojala, Risto; Markkanen, Paula; Tervonen, Osmo; Blanco Sequeiros, Roberto [Oulu University Hospital, Department of Radiology, Oulu (Finland); Sinikumpu, Juha-Jaakko; Korhonen, Jussi [Oulu University Hospital, Department of Paediatric Surgery, Oulu (Finland); Hyvoenen, Pekka [Oulu University Hospital, Department of Surgery, Oulu (Finland)

    2014-07-15

    The purpose of this study was to evaluate the feasibility of MRI guidance for percutaneous retrograde drilling in the treatment of osteochondritis dissecans of the talus (OCDT). Four patients, one juvenile and three adults, with one OCDT lesion each and persisting ankle pain after conservative treatment, were treated with MRI-guided retrograde drilling. All lesions were stable and located in the middle or posterior medial third of the talar dome. Pain relief and the ability to return to normal activities were assessed during clinical follow-up. MRI and plain film radiographs were used for imaging follow-up. Technical success was 100 % with no complications and with no damage to the overlying cartilage. All patients experienced some clinical benefit, although only one had complete resolution of pain and one had a relapse leading to surgical treatment. Changes in the pathological imaging findings were mostly very slight during the follow-up period. MRI guidance seems accurate, safe and technically feasible for retrograde drilling of OCDT. Larger series are needed to reliably assess its clinical value. (orig.)

  7. The emergency and delay management in total talus extrusion: Case report and review of literature after 24 months of follow up

    Directory of Open Access Journals (Sweden)

    Luigi Piscitelli

    2016-07-01

    Full Text Available Total talus extrusion is a rare and severe injury. It is burdened by many complications as avascular necrosis and osteomyelitis even if a proper debridement of extruded talus is performed. Few case reports or case series were published, and because of the rarity of this event, there are no guidelines for treatment. We report the first case on an octogenarian man providing a long-term follow-up performing contrast enhanced magnetic resonances. The authors report the case of an octogenarian man who fell from an olive tree reporting a total talus extrusion associated with the fracture of the medial malleolus. After an accurate debridement and washing of the wound, the talus was anatomically repositioned and the fracture was treated with an external fixator. The wound healed with difficulty after 12 months and the patient developed a chronic osteomyelitis of the talar dome and avascular necrosis of talar head. We followed the patient for 24 months performing contrast enhanced magnetic resonances and evaluating the development of the avascular necrosis. Even if we encountered these complications, the treatment allowed the patient to walk without pain, using a talus type shoe and one crutch. Although the literature suggests that an anatomic replacement of talus allows avoiding main complications, we deem that the patient's age is an important biological feature to consider in the prognostic stratification. Moreover, primary talectomy and tibio-calcaneal fusion should be reserved as a salvage procedure. Talus replacement allows an overall good outcome for the patients, retaining height, and allowing a good quality of life.

  8. The emergency and delay management in total talus extrusion:Case report and review of literature after 24 months of follow up

    Institute of Scientific and Technical Information of China (English)

    Luigi Piscitelli; Michele Bisaccia; Luigi Meccariello; Gabriele Falzarano; Antonio Medici; Daniele Maiettini; Alberto Rebonato; Giuseppe Rinonapoli; Auro Caraffa

    2016-01-01

    Total talus extrusion is a rare and severe injury. It is burdened by many complications as avascular necrosis and osteomyelitis even if a proper debridement of extruded talus is performed. Few case reports or case series were published, and because of the rarity of this event, there are no guidelines for treatment. We report the first case on an octoge-narian man providing a long-term follow-up performing contrast enhanced magnetic resonances. The authors report the case of an octogenarian man who fell from an olive tree reporting a total talus extrusion associated with the fracture of the medial malleolus. After an accurate debridement and washing of the wound, the talus was anatomically repositioned and the fracture was treated with an external fixator. The wound healed with difficulty after 12 months and the patient developed a chronic osteomyelitis of the talar dome and avascular necrosis of talar head. We followed the patient for 24 months per-forming contrast enhanced magnetic resonances and evaluating the development of the avascular necrosis. Even if we encountered these complications, the treatment allowed the patient to walk without pain, using a talus type shoe and one crutch. Although the literature suggests that an anatomic replacement of talus allows avoiding main compli-cations, we deem that the patient's age is an important biological feature to consider in the prognostic stratification. Moreover, primary talectomy and tibio-calcaneal fusion should be reserved as a salvage procedure. Talus replacement allows an overall good outcome for the patients, retaining height, and allowing a good quality of life.

  9. Staged bilateral ankle arthroplasty for the treatment of patient with severe defect of the talus (case report

    Directory of Open Access Journals (Sweden)

    K. S. Mikhaylov

    2013-01-01

    Full Text Available Ankle arthroplasty is known to become more successful procedure versus ankle fusion in patients with ankle osteoarthritis. This article represents a clinical case of performing three-staged bilateral ankle arthroplasty by means of HINTEGRA and Mobility implants in a patient with severe defect of the talus. The patient was followed up for 2 years for right ankle and 4 years - for left ankle. The correct treatment strategy gave the patient a new lease of life. He resumed sports activities, being pain-free in both the ankle joints.

  10. Snowboard, wakeboard, dashboard? Isolated fracture of the lateral process of the talus in a high-speed road traffic accident

    OpenAIRE

    2013-01-01

    We present a 23-year-old man who sustained an isolated fracture of the lateral process of the talus (LPT) in a head-on vehicle collision at a combined speed of 200 km/h. The driver of the other vehicle sustained fatal injuries at the scene. The LPT was openly reduced and fixed with successful outcome at 3 months. This case is unusual in the method of injury, in particular in relation to the isolated relatively minor injury sustained.

  11. Functional anatomy of the calcaneum and talus in Cercopithecinae (Mammalia, Primates, Cercopithecidae

    Directory of Open Access Journals (Sweden)

    Pina, M.

    2011-12-01

    Full Text Available Among the species of the order Primates exist a huge variety of forms and habitats. This heterogeneity has encouraged the evolution and development of a great number of locomotor adaptations to different environments. Thus, nowadays there are both arboreal and terrestrial groups within the order. The subfamily Cercopithecinae present taxa with both kinds of locomotor behaviours, although the most of them are adapted to a ground life-style. This group probably has an arboreal ancestor and its radiation is relatively recent. Consequently, species belonged to this group present mixed features or sometimes not too much derived ones. Likewise, it is important the fact that the evolutionary history and phylogeny of the group could influence in some characteristics. Both the calcaneum and the talus are two of the largest bones of the foot and are good for inferring the kind of locomotion. For this reason, it has been used these two tarsal bones to study the morphology of eight species of cercopithecines and then deduce functional implications of the kind of locomotion.

    Dentro del orden Primates existe una gran variedad de especies distribuidas a lo largo de hábitats muy diversos. Dicha heterogeneidad ha fomentado la evolución y desarrollo de un gran número de adaptaciones locomotoras a los diferentes ambientes en los que habitan. Así, existen en la actualidad tanto grupos arborícolas como terrestres. La subfamilia Cercopithecinae agrupa una serie de taxones que representan ambos comportamientos locomotores, aunque la mayoría de las especies están adaptadas a una vida en el suelo. Se supone que este grupo desciende de un ancestro arborícola y que su radiación es relativamente reciente. En consecuencia, las especies de este grupo presentan características mixtas o poco derivadas en algunas ocasiones. Asimismo, es importante tener en cuenta la influencia que la herencia filogenética puede tener sobre alguno de estos rasgos. El calc

  12. Alternative diagenetic models for cretaceous talus deposits, Deep Sea Drilling Project Site 536, Gulf of Mexico: Chapter 8 in Initial reports of the Deep Sea Drilling Project

    Science.gov (United States)

    Halley, Robert B.; Pierson, B. J.; Schlager, Wolfgang

    1984-01-01

    Talus deposits recovered from Site 536 show evidence of aragonite dissolution, secondary porosity development, and calcite cementation. Although freshwater diagenesis could account for the petrographic features of the altered talus deposits, it does not uniquely account for isotopic or trace-element characteristics. Also, the hydrologic setting required for freshwater alteration is not easily demonstrated for the Campeche Bank. A mixing-zone model does not account for the available trace-element data, but does require somewhat less drastic assumptions about the size of the freshwater lens. Although a seawater (bottom-water) alteration model requires no hydrologic difficulties, unusual circumstances are required to account for the geochemical characteristics of the talus deposits using this model.

  13. Hazard assessment of vegetated slopes

    NARCIS (Netherlands)

    J.E. Norris; J.R. Greenwood; A. Achim; B.A. Gardiner; B.C. Nicoll; E. Cammeraat; S.B. Mickovski

    2008-01-01

    The hazard assessment of vegetated slopes are reviewed and discussed in terms of the stability of the slope both with and without vegetation, soil erosion and the stability of the vegetated slope from windthrow and snow loading. Slope stability can be determined by using either limit equilibrium or

  14. Slope constrained Topology Optimization

    DEFF Research Database (Denmark)

    Petersson, J.; Sigmund, Ole

    1998-01-01

    pointwise bounds on the density slopes. A finite element discretization procedure is described, and a proof of convergence of finite element solutions to exact solutions is given, as well as numerical examples obtained by a continuation/SLP (sequential linear programming) method. The convergence proof...

  15. Slope earthquake stability

    CERN Document Server

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

    2017-01-01

    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.

  16. ElevationSlope_SLOPE3p2M

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): ( and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce change in elevation over the...

  17. ElevationSlope_SLOPE0p7M2013

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Rutland/GI Counties 2013 0.7m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce...

  18. ElevationSlope_SLOPE0p7M2015

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Windham County 2015 0.7m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce...

  19. ElevationSlope_SLOPE1p6M2010

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Missisquoi Upper 2010 1.6m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce...

  20. ElevationSlope_SLOPE1p6M2012

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Addison County 2012 1.6m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce...

  1. ElevationSlope_SLOPE0p7M2014

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Eastern VT 2014 0.7m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce change in...

  2. ElevationSlope_SLOPE1p6M2008

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Missisquoi Lower 2008 1.6m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce...

  3. ElevationSlope_SLOPE3p2M2004

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): ( and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce change in elevation over the...

  4. A mounded spherical storage tank at Papeete; Une sphere sous talus a Papeete

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2003-09-01

    Because demand for liquid petroleum gas (LPG) in French Polynesia is burgeoning, deliveries of the product are on the rise, in particular from New Zealand. In consideration of this, Gaz de Tahiti has had a mounded 1.800 m{sup 3} spherical propane storage tank built by the Tissot group. The new tank joins the ranks of the standard 2.500 m{sup 3} spherical butane tank that Gaz de Tahiti already has at its Papeete site. The slope consists of earth-filled gabions, which are at least one metre thick at any point of the steel structure. The project is proof once again that Gaz de Tahiti has no reason to envy European companies when it comes to technology and development. (authors)

  5. Comments on the slope function

    CERN Document Server

    Kim, Minkyoo

    2016-01-01

    The exact slope function was first proposed in $SL(2)$ sector and generalized to $SU(2)$ sector later. In this note, we consider the slope function in $SU(1|1)$ sector of ${\\cal N}=4$ SYM. We derive the quantity through the method invented by N. Gromov and discuss about its validity. Further, we give comments on the slope function in deformed SYM.

  6. MORPHOMETRY OF THE ARTICULAR FACETS ON THE SUPERIOR, MEDIAL AND LATERAL SURFACES OF THE BODY OF TALUS AND ITS CLINICAL RELEVANCE

    Directory of Open Access Journals (Sweden)

    Goda Jatin B, Patel Shailesh M, Parmar Ajay M, Agarwal GC

    2015-07-01

    Full Text Available Background: In the formation of Ankle joint, tibio-fibular mortice receives superior, medial and lateral articular surfaces of body of Talus. Because of very limited availability of the data on the Morphometry of the articular facets on the Body of the dry human tali, this study was undertaken. Aims: To prepare the database on the articular facets on the superior, medial and lateral surfaces of body of talus, to find if there is statistically significant difference between both the sides of measurements and to compare the results with the previous studies. Methods and Material: 40 Dry Human Tali (20 Right and 20 Left were measured with Digital vernier caliper for the following Measurements: On the Trochlear surface: Medial length, Central length, Lateral length, Anterior width, Central width, Posterior width. On the lateral triangular articular facet: Central height, Central width. On the coma shaped medial articular facet: Central height, Central width. Results: Mean values of Medial, Central and Lateral lengths were 31.02, 30.39 and 29.63mm on Right side and 31.79, 30.65 and 29.45mm on Left side. Mean Anterior, Central and Posterior widths were 28.87, 28.16 and 21.59mm on right side and 29.08, 27.54 and 21.78mm on left side. On the medial articular surface, mean central height was 11.93mm on the right side and 11.29mm on the left side, Mean central width was 27.94mm on the right side and 28.29mm on the left side. On the lateral articular surface, mean central height was 22.14mm on the right side and 22.63mm on the left side. Mean central width was 18.93mm on the right side and 18.99mm on the left side. There is no significant difference between right and left sides of measurements. Conclusion: The trochlear articular surface is wider in front, measurements of opposite talus bone can be used as a control during talus bone replacement surgery, it may help surgeons to plan pre-operatively the complex talar fracture surgeries, to design accurate

  7. EXTENDED MILD-SLOPE EQUATION

    Institute of Scientific and Technical Information of China (English)

    黄虎; 丁平兴; 吕秀红

    2001-01-01

    The Hamiltonian formalism for surface waves and the mild-slope approximation were empolyed in handling the case of slowly varying three-dimensional currents and an uneven bottom, thus leading to an extended mild-slope equation. The bottom topography consists of two components: the slowly varying component whose horizontal length scale is longer than the surface wave length, and the fast varying component with the amplitude being smaller than that of the surface wave. The frequency of the fast varying depth component is, however, comparable to that of the surface waves. The extended mild- slope equation is more widely applicable and contains as special cases famous mild-slope equations below: the classical mild-slope equation of Berkhoff , Kirby' s mild-slope equation with current, and Dingemans' s mild-slope equation for rippled bed. The extended shallow water equations for ambient currents and rapidly varying topography are also obtained.

  8. Estimação dos parâmetros do modelo do motor de indução usando o algoritmo Talus

    Directory of Open Access Journals (Sweden)

    Eurico Souza Filho Bezerra de

    2004-01-01

    Full Text Available In this paper, the algorithm Talus is applied to problem of parameter estimation of induction motor. The solution of the estimation problem is achieved minimizing a quadratic cost function. The data source used in the algorithm is the measured value of current end power in standard laboratory. The estimated parameters are compared with classical test (no-load and locked rotor either by simulation and experimentally

  9. Arthroscopic excision of bone fragments in a neglected fracture of the lateral process of the talus in a junior soccer player.

    Science.gov (United States)

    Funasaki, Hiroki; Kato, Soki; Hayashi, Hiroteru; Marumo, Keishi

    2014-06-01

    Fractures of the lateral process of the talus are uncommon and often overlooked. Typically, they are found in adult snowboarders. We report the case of an 11-year-old male soccer player who complained of lateral ankle pain after an inversion injury 6 months earlier. He did not respond to conservative treatment and thus underwent arthroscopic excision of fragments of the talar lateral process. The ankle was approached through standard medial and anterolateral portals. A 2.7-mm-diameter 30° arthroscope was used. Soft tissues around the talus were cleared with a motorized shaver, and the lateral aspect of the talar process was then visualized. The lateral process presented as an osseous overgrowth, and a loose body was impinged between the talus and the calcaneus. The osseous overgrowth was resected piece by piece with a punch, and the loose body was removed en block. The patient returned to soccer 5 weeks after the operation. This case exemplifies 2 important points: (1) This type of fracture can develop even in children and not only in snowboarders. (2) Arthroscopic excision of talar lateral process fragments can be accomplished easily, and return to sports can be achieved in a relatively short time.

  10. Human talus bones from the Middle Pleistocene site of Sima de los Huesos (Sierra de Atapuerca, Burgos, Spain).

    Science.gov (United States)

    Pablos, Adrián; Martínez, Ignacio; Lorenzo, Carlos; Gracia, Ana; Sala, Nohemi; Arsuaga, Juan Luis

    2013-07-01

    Here we present and describe comparatively 25 talus bones from the Middle Pleistocene site of the Sima de los Huesos (SH) (Sierra de Atapuerca, Burgos, Spain). These tali belong to 14 individuals (11 adult and three immature). Although variation among Middle and Late Pleistocene tali tends to be subtle, this study has identified unique morphological characteristics of the SH tali. They are vertically shorter than those of Late Pleistocene Homo sapiens, and show a shorter head and a broader lateral malleolar facet than all of the samples. Moreover, a few shared characters with Neanderthals are consistent with the hypothesis that the SH population and Neanderthals are sister groups. These shared characters are a broad lateral malleolar facet, a trochlear height intermediate between modern humans and Late Pleistocene H. sapiens, and a short middle calcaneal facet. It has been possible to propose sex assignment for the SH tali based on their size. Stature estimates based on these fossils give a mean stature of 174.4 cm for males and 161.9 cm for females, similar to that obtained based on the long bones from this same site.

  11. All-Arthroscopic Autologous Matrix-Induced Chondrogenesis for the Treatment of Osteochondral Lesions of the Talus

    Science.gov (United States)

    Usuelli, Federico Giuseppe; de Girolamo, Laura; Grassi, Miriam; D'Ambrosi, Riccardo; Montrasio, Umberto Alfieri; Boga, Michele

    2015-01-01

    Several surgical techniques have been described for the treatment of talar chondral lesions. Among them, microfracture is well established. Autologous matrix-induced chondrogenesis (AMIC), using microfracture and biomaterials, has shown promising results for the treatment of knee osteochondral lesions and has been proposed for the ankle as an open technique. We describe an all-arthroscopic AMIC technique. The benefits of an all-arthroscopic procedure include smaller incisions with less soft-tissue dissection, better visualization of the joint, and a quicker recovery compared with open surgery. The use of matrix to support cartilage regeneration promotes good-quality cartilage tissue with satisfactory long-term outcomes. Our all-arthroscopic AMIC technique uses a type I–type III porcine collagen matrix (Chondro-Gide; Geistlich Pharma, Wolhusen, Switzerland) and is characterized by 2 different arthroscopic surgical phases. First, adequate exposure is achieved through use of a Hintermann spreader (Integra LifeSciences, Plainsboro, NJ) with sufficient joint distraction and wet lesion preparation. The second surgical step is performed dry, involving matrix placement and fixation. The all-arthroscopic AMIC technique for the treatment of osteochondral lesions of the talus allows a very precise reconstruction in the case of cartilage defects and avoids the need for a more invasive operation associated with higher morbidity and a longer surgical time. PMID:26258040

  12. 婴幼儿距骨畸形性扁平外翻足的治疗%Experience in the treatment of infantile talus deformity lfatfoot

    Institute of Scientific and Technical Information of China (English)

    蔡豪祺; 王志刚; 蔡海清; 葛翼华

    2015-01-01

    目的:介绍引起婴幼儿扁平外翻足的距骨畸形中,垂直距骨与斜行距骨的鉴别要点及相应的治疗方案。方法本组22例28足,通过对跟腱等的体格检查,X 线片上测量跟骨倾斜角、跟距角、距骨第一跖骨角来判断疾病的类型及严重性。垂直距骨在最大跖屈位时舟状骨没有复位,而斜行距骨在最大跖屈位时舟状骨复位,以此来鉴别两者。其中垂直距骨5例6足,为僵硬性扁平足,大年龄患儿采用广泛软组织松解及跟骨延长。斜行距骨17例22足,为跟腱挛缩型柔韧性扁平足,采用延长跟腱及复位距骨治疗。随访上述 X 线片指标,并采用 Maryland 足部评分标准评估。结果患儿平均随访31个月,垂直距骨 Walker 评分均>9分;斜行距骨 Maryland 评分均达到优良。5例垂直距骨,侧位片跟距角由83.1°减小至51.3°,跟骨倾斜角由-20.1°达到1.3°,距骨第一跖骨角由85.3°减小至30.6°。采用 Maryland 足部评分标准,优2例,良1例,可2例;17例斜行距骨,侧位片跟距角由58.2°减小至35.3°,跟骨倾斜角由-5.3°达到15.6°,距骨第一跖骨角由42.3°减小至9.7°采用 Maryland 足部评分标准,优15例,良2例。结论斜行距骨是伴跟腱挛缩的柔韧性扁平足,垂直距骨是僵硬性扁平足,通过体格检查和影像学检查可鉴别,两者都需要积极的早期治疗。斜行距骨的患儿的治疗主要采用连续石膏矫形,跟腱延长术,闭合复位内固定,支具治疗。垂直距骨的治疗根据患儿的年龄而有所不同,包括连续石膏固定矫形,跟腱延长,复位内固定,广泛软组织松解,跟骨延长术。%Objective To introduce the key points to identify the vertical talus and oblique talus, and discuss the treatment.Methods According to the X-ray and clinical findings, two types of deformity were identified and corresponding treatment was given in 22

  13. ElevationSlope_SLOPE1p6M

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Addison County 2012 1.6m; Missisquoi Upper 2010 1.6m; Missisquoi Lower 2008 1.6m and related SLOPE...

  14. Biotechnical performance of vegetal species in slope conservation in Cruz Alta, RS, Brazil

    Science.gov (United States)

    Prates Bisso, Fernando; Durlo, Miguel

    2016-04-01

    The aim of this work was the evaluation of biotechnical performance of different vegetal species growth in the slope soil conservation and reforest (revegetate). The study was performed with oxic soil talus, in Cruz Alta - RS, Brazil (28°23'28.14" S and 53°22'25.61" W) and began in January 2010. The sow treatments employed were: 1) cuttings of Ateleia glazioveana; 2) cuttings of Pyrostegia venusta; 3) seedlings of Baccharis trimera; 4) Seedlings of Cynodom plectostachyus; 5) blank, no sow. The evaluated parameters were: plant survival ratio (%); vegetal covered percentage; natural revegetation (plants/m2); the slope soil level reduction (cm); and water and soil runoff. C. plectostachyus and B. trimera afforded considerable higher survival (92% and 78.5%, respectively) and vegetation cover of the slope (99.6% and 82.9%) than other species. The natural revegetation showed an increase according to the ground above the slope (146.9 plants/m2) compared with the slope ramp (22.1 plants/m2). Moreover, C. plectostachyus, A. glazioveana, P. venusta, B. trimera and C. plectostachyus treatments showed 34.9, 28.6, 23.0 and 21.0 plants/m2, respectively, when compared with the blank (2.5 plants/m2) in the slope ramp region. Furthermore, the sow line regions gave 91.2 plants/m2) whereas the regions among lines afforded 8.6 plants/m2. Additionally, C. plectostachyus showed soil average drawdown profile decrease of 12.8 mm after 360 days after planting, and A. glazioveana reached 16.9 mm after 540 days according to the blank (34.0 mm). Considering the period of 60 to 360 days, it was observed significant differences in the soil loss estimative and reduction percentage compared to blank were: Blank 127.9 ton/ha/year; A. glazioveana, 117.9 ton/ha/year (-8%); P. venusta, 116.3 ton/ha/year (-9%); B. trimera, 106.7 ton/ha/year (-17%); and C. plectostachyus, 73.2 ton/ha/year (-43%). Thus, C. plectostachyus showed the best survival and vegetal coverage producing significant reduction of

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

    Energy Technology Data Exchange (ETDEWEB)

    1994-02-01

    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.

  16. Slope stability hazard management systems

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Weather-related geo-hazards are a major concern for both natural slopes and man-made slopes and embankments.Government agencies and private companies are increasingly required to ensure that there is adequate protection of sloping surfaces in order that interaction with the climate does not produce instability. Superior theoretical formulations and computer tools are now available to address engineering design issues related to the near ground surface soil-atmospheric interactions. An example is given in this paper that illustrates the consequences of not paying adequate attention to the hazards of slope stability prior to the construction of a highway in South America. On the other hand, examples are given from Hong Kong and Mainland China where significant benefits are derived from putting in place a hazard slope stability management system. Some results from a hazard management slope stability study related to the railway system in Canada are also reported. The study took advantage of recent research on unsaturated soil behaviour and applied this information to real-time modelling of climatic conditions. The quantification of the water balance at the ground surface, and subsequent infiltration, is used as the primary tool for hazard level assessment. The suggested hazard model can be applied at either specific high risk locations or in a more general, broad-based manner over large areas. A more thorough understanding of unsaturated soil behaviour as it applies to near ground surface soils,along with the numerical computational power of the computer has made it possible for new approaches to be used in slope hazard management engineering.

  17. Environmental impact of introducing plant covers in the taluses of orchard terraces: implications for erosion and agricultural runoff control

    NARCIS (Netherlands)

    Rodriguez Pleguezuelo, C.R.; Duran Zuazo, V.H.; Francia Martinez, J.R.; Martin Peinado, F.J.; Graaff, de J.; Muriel Fernandez, J.L.

    2011-01-01

    South-eastern Spain, and in particular the coastal areas of Granada and Malaga, feature a large area under subtropical crops, with orchards established on terraces built along the slopes of the mountainous areas. The climate, characterized by periodically heavy rainfall, variable in space and time,

  18. Diagnosis and treatment for primary bone tumor of the talus%距骨原发肿瘤的诊断与治疗

    Institute of Scientific and Technical Information of China (English)

    杨发军; 刘巍峰; 牛晓辉; 丁易

    2011-01-01

    Objective To analyze the clinical feature, surgical treatment and prognosis of primary bone tumor of the talus.Methods From January 1993 to December 2008, 21 patients of primary bone tumor and tumor-like lesion in the talus were retrospectively analyzed.The feature of bone tumor of the talus was analyzed from clinical, imaging and pathological aspects.All patients underwent surgical treatment.During postoperative follow-up, the function of patients was evaluated according to the criteria of musculoskeletal tumor society (MSTS).Results In all 21 patients,there were chondroblastoma (10 cases), giant cell tumor of bone (7 cases), osteoid osteoma (1 case), aneurysmal bone cysts (1 case), simple bone cysts (1 case), and osteofibrous dysplasia (1 case).Among 10 patients with chondroblastoma,the mean age was 22 years old (range; 10-35years).All 10 patients were performed curettage.1 patient was performed curettage and filled with bone cement.9 patients were performed curettage and bone grafting.No recurrence appeared among 9 patients with complete follow-up.The follow-up lasted for 15-87 months, and the median follow-up was 36 months.The function score (MSTS) was all 30.The mean age of onset of 7 patients with giant cell tumor of bone was 24 years old (range; 20-33years).Through image text, all cases suffered osteolytic damage.No calcification existed in ground substance.4 patients were primary cases and conducted curettage.3 cases relapsed.2 cases were performed astragalectomy and fusion of calcaneus and tibia.1 patient was applied crus amputation.3 patients had complete followup, and 2 patients were primary cases.Postoperatively, no recurrence happened within 10 and 32 months respectively.Recurrence happened in 1 case.No recurrence happened in follow-up lasting for 36 months.The function scores were respectively 26, 29 and 24.For other four patients with diagnosis, 1 patient with osteoid osteoma received lesion resection and bone grafting and 3 patients received

  19. ElevationSlope_SLOPE0p7M

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Windham County 2015 0.7m; Eastern VT 2014 0.7m; Rutland/GI Counties 2013 0.7m and related SLOPE datasets....

  20. Geologic context of recurring slope lineae in Melas and Coprates Chasmata, Mars

    Science.gov (United States)

    Chojnacki, Matthew; McEwen, Alfred; Dundas, Colin M.; Ojha, Lujendra; Urso, Anna; Sutton, Sarah

    2016-01-01

    One of the major Mars discoveries of recent years is the existence of recurring slope lineae (RSL), which suggests that liquid water occurs on or near the surface of Mars today. These dark and narrow features emerge from steep, rocky exposures and incrementally grow, fade, and reform on a seasonal basis and are detected in images from the High Resolution Imaging Science Experiment camera. RSL are known to occur at scattered midlatitude and equatorial sites with little spatial connection to one another. One major exception is the steep, low-albedo slopes of Melas and Coprates Chasmata, in Valles Marineris where RSL are detected among diverse geologic surfaces (e.g., bedrock and talus) and landforms (e.g., inselbergs and landslides). New images show topographic changes including sediment deposition on active RSL slopes. Midwall locations in Coprates and Melas appear to have more areally extensively abundant RSL and related fans as compared with other RSL sites found on Mars. Water budget estimates for regional RSL are on the order of 105 to 106 m3 of fluid, for depths of 10 to 100mm, and suggest that a significant amount of near-surface watermight be present. Many RSL are concentrated near local topographic highs, such as ridge crests or peaks, which is challenging to explain via groundwater or ice without a recharge mechanism. Collectively, results provide additional support for the notion that significant amounts of near-surface water can be found on Mars today and suggest that a widespread mechanism, possibly related to the atmosphere, is recharging RSL sources.

  1. Geologic context of recurring slope lineae in Melas and Coprates Chasmata, Mars

    Science.gov (United States)

    Chojnacki, Matthew; McEwen, Alfred; Dundas, Colin; Ojha, Lujendra; Urso, Anna; Sutton, Sarah

    2016-07-01

    One of the major Mars discoveries of recent years is the existence of recurring slope lineae (RSL), which suggests that liquid water occurs on or near the surface of Mars today. These dark and narrow features emerge from steep, rocky exposures and incrementally grow, fade, and reform on a seasonal basis and are detected in images from the High Resolution Imaging Science Experiment camera. RSL are known to occur at scattered midlatitude and equatorial sites with little spatial connection to one another. One major exception is the steep, low-albedo slopes of Melas and Coprates Chasmata, in Valles Marineris where RSL are detected among diverse geologic surfaces (e.g., bedrock and talus) and landforms (e.g., inselbergs and landslides). New images show topographic changes including sediment deposition on active RSL slopes. Midwall locations in Coprates and Melas appear to have more areally extensively abundant RSL and related fans as compared with other RSL sites found on Mars. Water budget estimates for regional RSL are on the order of 105 to 106 m3 of fluid, for depths of 10 to 100 mm, and suggest that a significant amount of near-surface water might be present. Many RSL are concentrated near local topographic highs, such as ridge crests or peaks, which is challenging to explain via groundwater or ice without a recharge mechanism. Collectively, results provide additional support for the notion that significant amounts of near-surface water can be found on Mars today and suggest that a widespread mechanism, possibly related to the atmosphere, is recharging RSL sources.

  2. Treatment of ankle fracture and biomechanics of talus%踝部骨折治疗效果与距骨生物力学的关系

    Institute of Scientific and Technical Information of China (English)

    梁庆威; 范广宇; 吕刚

    2004-01-01

    BACKGROUND: The anatomical structure of ankle joint is not complicated, but its biomechanics is very important. The talus has participated in consisting of three joints and played very important role in supporting the functions of ankle. Therefore, it is very important to stabilize the position of talus in order to restore the anatomical structure of ankle.OBJECTIVE: To explore the relationship between treatment of ankle fracture and the biomechanics of the talus.DESIGN: A non-randomized case controlled study was conducted.SETTING and PARTICIPANTS: There were 95 patients with fracture of ankle joints during January 1985 to October 2000 from the First Affiliated Hospital of China Medical University. Three specimens of amputating legs due to malignant tumor were collected.INTERVENTIONS: The biomechanics of talus in ankle fracture was observed by amputated leg specimens and the clinical manifestation and Xray examinations were analyzed in the 95 fracture patients after treatment.MAIN OUTCOME MEASURES: Forces acting on different fracture types,relationship between therapeutic effects and biomechanics of talus.RESULTS: Sixty-five cases were followed up. There were 41 cases with very good therapeutic effects, 12 cases with good effects, 7 cases with fair effects and 5 cases with poor effects. Biomechanics results: the neck was compressed 0.48 cm when both ankles were broken. The lateral malleolar facet got more pressure than medial malleolar facet when vertical pressure acted in external facet fracture. When fracture happened in the lower 1/3 of fibula, the pressure acted on lateral malleolar facet was less than that on medial malleolar facet when in inversion position.CONCLUSION: It should pay more attention to the anatomical relations of talus in ankle cavity and the gap of lower tibiofibular joint no matter external fixation or internal fixation of manual reposition to ankle fracture was used. It is a very important treatment standard to restore the biomechanical

  3. Enucleación medial de astrágalo abierta: Evolución a medio plazo Medial dislocation of the talus: Medium term evolution

    Directory of Open Access Journals (Sweden)

    S. García Mata

    2009-04-01

    Full Text Available Paciente de 57 años con enucleación abierta medial del astrágalo izquierdo, con fractura suprasindesmal de peroné, por traumatismo indirecto. Se realizó lavado, limpieza del astrágalo y partes blandas, Friedrich, reducción, fijación con agujas de kirschner, sutura del ligamento deltoideo y osteosíntesis del peroné. No hubo infección superficial ni profunda postoperatoria. Permaneció seis semanas de inmovilización y tres meses en descarga. Dos años después no había signos radiológicos de necrosis avascular. En gammagrafía ósea realizada a los 18 meses de la lesión se observaba necrosis avascular parcial astragalina. Tres años después de la lesión realizaba vida normal, sin dolor en reposo pero sí a la marcha y movilidad con limitación de la dorsiflexión (-20º. Cinco años y medio después de la lesión presentaba hundimiento de cúpula astragalina por la necrosis avascular con sintomatología dolorosa a la marcha y diástasis tibio-peronea distal, que requirió realizar artrodesis tibio-astragalina.Fifty-seven year old patient with open medial dislocation of the left talus, with suprasyndesmotic fracture of the fibula, due to indirect traumatism. The following were carried out: washing, cleaning the talus and the soft parts, Friedrich, reduction, fixing with Kirschner needles, suture of the deltoid ligament, and osteosynthesis of the fibula. There were neither surface nor deep post-operational infections. The patient underwent six weeks of immobilisation and spent three months on discharge. Two years later there were no radiological signs of avascular necrosis. In the osseous gammagraphy carried out 18 months after the lesion, partial avascular necrosis of the talus was observed. Three years after the lesion, the patient was able to carry out a normal life, without pain in repose but with pain whilst moving, and mobility with limitation of dorsoinflection (-20º. Five and a half years after the lesion, the patient

  4. Is rock slope instability in high-mountain systems driven by topo-climatic, paraglacial or rock mechanical factors? - A question of scale!

    Science.gov (United States)

    Messenzehl, Karoline; Dikau, Richard

    2016-04-01

    Due to the emergent and (often non-linear) complex nature of mountain systems the key small-scale system properties responsible for rock slope instability contrast to those being dominant at larger spatial scales. This geomorphic system behaviour has major epistemological consequences for the study of rockfalls and associated form-process-relationships. As each scale requires its own scientific explanation, we cannot simply upscale bedrock-scale findings and, in turn, we cannot downscale the valley-scale knowledge to smaller phenomena. Here, we present a multi-scale study from the Turtmann Valley (Swiss Alps), that addresses rock slope properties at three different geomorphic levels: (i) regional valley scale, (ii) the hillslope scale and (iii) the bedrock scale. Using this hierarchical approach, we aim to understand the key properties of high-mountain systems responsible for rockfall initiation with respect to the resulting form-process-relationship at each scale. (i) At the valley scale (110 km2) rock slope instability was evaluated using a GIS-based modelling approach. Topo-climatic parameters, i.e. the permafrost distribution and the time since deglaciation after LGM were found to be the key variables causative for the regional-scale bedrock erosion and the storage of 62.3 - 65.3 x 106 m3 rockfall sediments in the hanging valleys (Messenzehl et al. 2015). (ii) At the hillslope scale (0.03 km2) geotechnical scanline surveys of 16 rock slopes and one-year rock temperature data of 25 ibuttons reveal that the local rockfall activity and the resulting deposition of individual talus slope landforms is mainly controlled by the specific rock mass strength with respect to the slope aspect, than being a paraglacial reaction. Permafrost might be only of secondary importance for the present-day rock mechanical state as geophysical surveys disprove the existence of frozen bedrock below 2600 m asl. (Messenzehl & Draebing 2015). (iii) At the bedrock scale (0.01 mm - 10 m) the

  5. THE EQUIVALENT SLOPE - A NEW METHOD FOR CALCULATING SOIL LOSS FROM IRREGULAR SLOPES

    Institute of Scientific and Technical Information of China (English)

    Xiaoguang ZHAO; Hui SHI; Ming'an SHAO

    2004-01-01

    The slopes in field conditions are always irregular, but the supposed uniform slopes are used in most erosion models. Some studies used several uniform slopes to approximate an irregular slope for estimating soil erosion. This approximation is both time-consuming and weak in physical insights. In this paper, the concept of equivalent slope is presented based on that runoff potential on uniform slope is equal to that of irregular slope, and the equivalent uniform slope is used to estimate soil erosion instead of the irregular slopes. The estimated results of slope-length factors for convex and concave slopes are consistent with those from the method of Foster and Wischmeier.The experiments in the southern part of the Loess Plateau in China confirmed the applicability of the present method. The method is simple and has, to some extent, clear physical meanings, and is applicable for estimating soil erosion from irregular slopes.

  6. Precision of SPECT/CT allows the diagnosis of a hidden Brodie's abscess of the talus in a patient with sickle cell disease

    Energy Technology Data Exchange (ETDEWEB)

    Al jafar, Hassan [Dept. of Hematology, Amiri Hospital, Kuwait (Kuwait); Al Shemmeri, Eman [Dept. of Nuclear Medicine, Farwaniya Hospital, Al-Farwania (Kuwait); Al Shemmeri, Jehan; Al Enizi, Saud [Faculty of Medicine, Nuclear Medicine Dept, Kuwait University, Kuwait (Kuwait); Aytglu, Leena [Molecular Imaging Center, Jaber Al-Ahmad Center, Kuwait (Kuwait); Afzai, Uzma [Dept. of Nuclear Medicine, Farwaniya Hospital, Al-Farwania (Kuwait)

    2015-06-15

    Brodie's abscess is a rare subacute osteomyelitis that can be found in sickle cell disease along with other bone complications. A 21-year-old female with sickle cell disease was presenting frequently to the medical casualty department for painful vasoocclusive crises and for persistent ankle pain and swelling. Hybrid imaging with single-photon emission computed tomography-computed tomography (SPECT-CT) incidentally revealed Brodie's abscess in the talus bone of the ankle, causing persisting long-standing pain. SPECT-CT is a modern technology used to scan bone to detect both anatomical and functional abnormalities with high specificity. Brodie's abscess is a rare bone inflammation that could be a hidden cause of pain and infection in sickle cell disease. Although rare, this lesion requires more attention in patients with sickle cell disease because their immunocompromised status renders them prone to this infection.

  7. Retrograde nail for tibiotalocalcaneal arthrodesis as a limb salvage procedure for open distal tibia and talus fractures with severe bone loss.

    Science.gov (United States)

    Ochman, Sabine; Evers, Julia; Raschke, Michael J; Vordemvenne, Thomas

    2012-01-01

    The treatment of complex fractures of the distal tibia, ankle, and talus with soft tissue damage, bone loss, and nonreconstructable joints for which the optimal timing for reduction and fixation has been missed is challenging. In such cases primary arthrodesis might be a treatment option. We report a series of multi-injured patients with severe soft tissue damage and bone loss, who were treated with a retrograde tibiotalocalcaneal arthrodesis nail as a minimally invasive treatment option for limb salvage. After a median follow-up of 5.4 years, all patients returned to their former profession. The ankle and bone fusion was complete, with moderate functional results and quality of life. Calcaneotibial arthrodesis using a retrograde nail is a good treatment option for nonreconstructable fractures of the ankle joint with severe bone loss and poor soft tissue quality in selected patients with multiple injuries, in particular, those involving both lower extremities, as a salvage procedure.

  8. 距骨骨软骨损伤手术治疗的研究进展%Research progress on operative treatment of osteochondral lesions of the talus

    Institute of Scientific and Technical Information of China (English)

    王双利; 潘政军; 江华; 黄彰

    2016-01-01

    目的:总结距骨骨软骨损伤(OLT)的手术治疗方法。方法在 PubMed、Springer link英文期刊全文数据库以“osteochondral lesions”、“talus”为关键词查阅2010年1月—2014年11月有关OLT 手术治疗方法的相关文献,进行总结分析。结果治疗 OLT 常用的手术方法包括清创、微骨折或钻孔术,自体或异体骨软骨移植术,自体软骨细胞移植术等多种方法。清创、微骨折或钻孔术一般适用于年轻、损伤面积小而浅或孤立病灶的患者。面积大、深的软骨及软骨下骨损伤可考虑自体或异体骨软骨移植术。关节镜手术因其微创、直视下操作及可同时进行诊断与治疗等优势,可做为手术治疗 OLT 的首选方式。目前,关节镜联合其他方法成为 OLT 治疗的新趋势。临床上儿童 OLT 少见,对保守治疗失败的 OLT 儿童,内固定和清创微骨折的手术治疗都是较好的手术方法。结论 OLT 有多种治疗方法,这些方法各有其适应证和优缺点,临床治疗应强调“个体化”原则,综合考虑患者的自身因素和病灶的特点,选择合适的手术方式。%Objective To summarize operative treatment of osteochondral lesions of the talus. Methods A computer-based search was conducted in PubMed and Springer link for literatures related to operative treatment of osteochondral lesions of the talus from January 2010 to November 2014 with the key words " osteochondral lesions" , " talus" in English. Analysis was conducted based on the articles. Results Surgical options are lesion excision, excision and curettage, microfracturing, antegrade ( transmalleolar) drilling, retrograde drilling, which are suitable for younger patients with small, superficial or isolated lesions, fixation and techniques such as osteochondral transplantation(autograft or allograft) and autologous chondrocyte implantation. Osteochondral transplantation is often applied if the damages are large

  9. Precision of SPECT/CT Allows the Diagnosis of a Hidden Brodie's Abscess of the Talus in a Patient with Sickle Cell Disease.

    Science.gov (United States)

    Al-Jafar, Hassan; Al-Shemmeri, Eman; Al-Shemmeri, Jehan; Aytglu, Leena; Afzal, Uzma; Al-Enizi, Saud

    2015-06-01

    Brodie's abscess is a rare subacute osteomyelitis that can be found in sickle cell disease along with other bone complications. A 21-year-old female with sickle cell disease was presenting frequently to the medical casualty department for painful vasoocclusive crises and for persistent ankle pain and swelling. Hybrid imaging with single-photon emission computed tomography-computed tomography (SPECT-CT) incidentally revealed Brodie's abscess in the talus bone of the ankle, causing persisting long-standing pain. SPECT-CT is a modern technology used to scan bone to detect both anatomical and functional abnormalities with high specificity. Brodie's abscess is a rare bone inflammation that could be a hidden cause of pain and infection in sickle cell disease. Although rare, this lesion requires more attention in patients with sickle cell disease because their immunocompromised status renders them prone to this infection.

  10. Treatment of osteochondral lesions of the talus with autologous collagen-induced chondrogenesis: clinical and magnetic resonance evaluation at one-year follow-up

    Science.gov (United States)

    USUELLI, FEDERICO GIUSEPPE; GRASSI, MIRIAM; MANZI, LUIGI; GUARRELLA, VINCENZO; BOGA, MICHELE; DE GIROLAMO, LAURA

    2016-01-01

    Purpose the aim of this study is to report the clinical and imaging results recorded by a series of patients in whom osteochondral lesions of the talus (OLTs) were repaired using the autologous collagen-induced chondrogenesis (ACIC) technique with a completely arthroscopic approach. Methods nine patients (mean age 37.4±10 years) affected by OLTs (lesion size 2.1±0.9 cm2) were treated with the ACIC technique. The patients were evaluated clinically both preoperatively and at 12 months after surgery using the American Orthopaedic Foot and Ankle Society Ankle-Hindfoot Scale (AOFAS) and a visual analog scale (VAS). For morphological evaluation, the magnetic resonance observation of cartilage repair tissue (MOCART) score was used. Results the AOFAS score improved from 51.4±11.6 preoperatively to 71.8±20.6 postoperatively, while the VAS value decreased from 6.9±1.8 to 3.2±1.9. The mean MOCART score was 51.7±16.6 at 12 months of follow-up; these scores did not directly correlate with the clinical results. Conclusion use of the ACIC technique for arthroscopic repair of OLTs allowed satisfactory clinical results to be obtained in most of the patients as soon as one year after surgery, with no major complications or delayed revision surgery. ACIC is a valid and low-invasive surgical technique for the treatment of chondral and osteochondral defects of the talus. Level of evidence therapeutic case series, level IV. PMID:27602347

  11. Slope Streaks in Terra Sabaea

    Science.gov (United States)

    2007-01-01

    [figure removed for brevity, see original site] Figure 1 Click on image for larger version This HiRISE image shows the rim of a crater in the region of Terra Sabaea in the northern hemisphere of Mars. The subimage (figure 1) is a close-up view of the crater rim revealing dark and light-toned slope streaks. Slope streak formation is among the few known processes currently active on Mars. While their mechanism of formation and triggering is debated, they are most commonly believed to form by downslope movement of extremely dry sand or very fine-grained dust in an almost fluidlike manner (analogous to a terrestrial snow avalanche) exposing darker underlying material. Other ideas include the triggering of slope streak formation by possible concentrations of near-surface ice or scouring of the surface by running water from aquifers intercepting slope faces, spring discharge (perhaps brines), and/or hydrothermal activity. Several of the slope streaks in the subimage, particularly the three longest darker streaks, show evidence that downslope movement is being diverted around obstacles such as large boulders. Several streaks also appear to originate at boulders or clumps of rocky material. In general, the slope streaks do not have large deposits of displaced material at their downslope ends and do not run out onto the crater floor suggesting that they have little reserve kinetic energy. The darkest slope streaks are youngest and can be seen to cross cut and superpose older and lighter-toned streaks. The lighter-toned streaks are believed to be dark streaks that have lightened with time as new dust is deposited on their surface. Observation Geometry Image PSP_001808_1875 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 15-Dec-2006. The complete image is centered at 7.4 degrees latitude, 47.0 degrees East longitude. The range to the target site was 272.1 km (170.1 miles). At this distance the

  12. VT Lidar Slope (1 meter) - 2005 - Essex

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Essex County 2005 1m and related SLOPE datasets. Created using ArcGIS "SLOPE" command...

  13. Gravity-induced stresses in finite slopes

    Science.gov (United States)

    Savage, W.Z.

    1994-01-01

    An exact solution for gravity-induced stresses in finite elastic slopes is presented. This solution, which is applied for gravity-induced stresses in 15, 30, 45 and 90?? finite slopes, has application in pit-slope design, compares favorably with published finite element results for this problem and satisfies the conditions that shear and normal stresses vanish on the ground surface. The solution predicts that horizontal stresses are compressive along the top of the slopes (zero in the case of the 90?? slope) and tensile away from the bottom of the slopes, effects which are caused by downward movement and near-surface horizontal extension in front of the slope in response to gravity loading caused by the additional material associated with the finite slope. ?? 1994.

  14. In-Place Randomized Slope Selection

    DEFF Research Database (Denmark)

    Blunck, Henrik; Vahrenhold, Jan

    2006-01-01

    Slope selection, i.e. selecting the slope with rank k among all 􀀀n 2lines induced by a collection P of points, results in a widely used robust estimator for linefitting. In this paper, we demonstrate that it is possible to perform slope selection in expected O(n·log2 n) time using only...

  15. Mycorrhizal aspects in slope stabilisation

    Science.gov (United States)

    Graf, Frank

    2016-04-01

    In order to re-colonise and stabilise slopes affected by superficial soil failure with plants essential requirements have to be met: the plants must grow the plants must survive sustainably plant succession must start and continuously develop These requirements, however, are anything but easy given, particularly under the often hostile environmental conditions dominating on bare and steep slopes. Mycorrhizal fungi, the symbiotic partners of almost all plants used in eco-engineering, are said to improve the plants' ability to overcome periods governed by strongly (growth) limiting factors. Subsequently, results of investigations are presented of mycorrhizal effects on different plant and soil functions related to eco-engineering in general and soil and slope stabilisation in particular. Generally, inoculation yielded higher biomass of the host plants above as well as below ground. Furthermore, the survival rate was higher for mycorrhized compared to non-mycorrhized plants, particularly under extreme environmental conditions. However, the scale of the mycorrhizal impact may be species specific of both the plant host as well as the fungal partner(s) and often becomes evident only after a certain time lag. Depending on the plant-fungus combination the root length per soil volume was found to be between 0 and 2.5 times higher for inoculated compared to non-inoculated specimens. On an alpine graded ski slope the survival of inoculated compared to non-treated Salix herbacea cuttings was significant after one vegetation period only for one of the three added mycorrhizal fungus species. However, after three years all of the inoculated plantlets performed significantly better than the non-inoculated controls. The analysis of the potential for producing and stabilising soil aggregates of five different ectomycorrhizal fungi showed high variation and, for the species Inocybe lacera, no significant difference compared to untreated soil. Furthermore, inoculation of Salix

  16. The Influence of Shales on Slope Instability

    Science.gov (United States)

    Stead, Doug

    2016-02-01

    Shales play a major role in the stability of slopes, both natural and engineered. This paper attempts to provide a review of the state-of-the-art in shale slope stability. The complexities of shale terminology and classification are first reviewed followed by a brief discussion of the important physical and mechanical properties of relevance to shale slope stability. The varied mechanisms of shale slope stability are outlined and their importance highlighted by reference to international shale slope failures. Stability analysis and modelling of anisotropic rock slope masses are briefly discussed and the potential role of brittle rock fracture and damage highlighted. A short review of shale slopes in open pits is presented.

  17. Three Practical Methods for Analyzing Slope Stability

    Institute of Scientific and Technical Information of China (English)

    XU Shiguang; ZHANG Shitao; ZHU Chuanbing; YIN Ying

    2008-01-01

    Since the environmental capacity and the arable as well as the inhabitant lands have actually reached a full balance, the slopes are becoming the more and more important options for various engineering constructions. Because of the geological complexity of the slope, the design and thedecision-making of a slope-based engineering is still not ractical to rely solely on the theoretical analysis and numerical calculation, but mainly on the experience of the experts. Therefore, it hasimportant practical significance to turn some successful experience into mathematic equations. Basedupon the abundant typical slope engineering construction cases in Yunnan, Southwestern China, 3methods for yzing the slope stability have been developed in this paper. First of all, the corresponded analogous mathematic equation for analyzing slope stability has been established through case studies. Then, artificial neural network and multivariate regression analysis have alsobeen set up when 7 main influencing factors are adopted

  18. Mathematical Model of the Identical Slope Surface

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The formation of the identical slope surface and the method of construction are discussed. Onthe basement of building the parameter equation of variable-radius circle family envelope, the frequentlyused parameter equation of the identical slope surface of the top of taper moving along column helix,horizental arc and line is built. The equation can be used to construct the identical slope surface's con-tours, gradient lines and three dimensional figures correctly.

  19. Slope Estimation from ICESat/GLAS

    Directory of Open Access Journals (Sweden)

    Craig Mahoney

    2014-10-01

    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.

  20. INFLUENCES OF SLOPE GRADIENT ON SOIL EROSION

    Institute of Scientific and Technical Information of China (English)

    刘青泉; 陈力; 李家春

    2001-01-01

    The main factors influencing soil erosion include the net rain excess, the water depth, the velocity, the shear stress of overland flows , and the erosion-resisting capacity of soil. The laws of these factors varying with the slope gradient were investigated by using the kinematic wave theory. Furthermore, the critical slope gradient of erosion was driven. The analysis shows that the critical slope gradient of soil erosion is dependent on grain size , soil bulk density , surface roughness, runoff length, net rain excess, and the friction coefficient of soil, etc. The critical slope gradient has been estimated theoretically with its range between 41. 5 °~ 50°.

  1. Fuzzy Logic System for Slope Stability Prediction

    Directory of Open Access Journals (Sweden)

    Tarig Mohamed

    2012-01-01

    Full Text Available The main goal of this research is to predict the stability of slopes using fuzzy logic system. GeoStudio, a commercially available software was used to compute safety factors for various designs of slope. The general formulation of the software could analyze slope stability using various methods of analysis i.e. Morgenstern-Price, Janbu, Bishop and Ordinary to calculate the safety factors. After analyzing, fuzzy logic was used to predict the slope stability. Fuzzy logic is based on natural language and conceptually easy to understand, flexible, tolerant of imprecise data and able to model nonlinear functions of arbitrary complexity. Several important parameters such as height of slope, unit weight of slope material, angle of slope, coefficient of cohesion and internal angle of friction were used as the input parameters, while the factor of safety was the output parameter. A model to test the stability of the slope was generated from the calculated data. This model presented a relationship between input parameters and stability of the slopes. Results showed that the prediction using fuzzy logic was accurate and close to the target data.

  2. Slope of the Slope Derivative Surface used to characterize the complexity of the seafloor around St. John, USVI

    Data.gov (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...

  3. Air pocket removal from downward sloping pipes

    NARCIS (Netherlands)

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

    2012-01-01

    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 assoc

  4. 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

  5. Gas hydrate dissociation structures in submarine slopes

    Energy Technology Data Exchange (ETDEWEB)

    Gidley, I.; Grozic, J.L.H. [Calgary Univ., AB (Canada). Dept. of Civil Engineering

    2008-07-01

    Studies have suggested that gas hydrates may play a role in submarine slope failures. However, the mechanics surrounding such failures are poorly understood. This paper discussed experimental tests conducted on a small-scale physical model of submarine soils with hydrate inclusions. The laboratory tests investigated the effects of slope angle and depth of burial of the hydrate on gas escape structures and slope stability. Laponite was used to model the soils due to its ability to swell and produce a clear, colorless thixotropic gel when dispersed in water. An R-11 refrigerant was used to form hydrate layers and nodules. The aim of the experiment was to investigate the path of the fluid escape structures and the development of a subsequent slip plane caused by the dissociation of the R-11 hydrates. Slope angles of 5, 10, and 15 degrees were examined. Slopes were examined using high-resolution, high-speed imaging techniques. Hydrate placement and slope inclinations were varied in order to obtain stability data. Results of the study showed that slope angle influenced the direction of travel of the escaping gas, and that the depth of burial affected sensitivity to slope angle. Theoretical models developed from the experimental data have accurately mapped deformations and stress states during testing. Further research is being conducted to investigate the influence of the size, shape, and placement of the hydrates. 30 refs., 15 figs.

  6. How vegetation reinforces soil on slopes

    NARCIS (Netherlands)

    Stokes, A.; Norris, J.E.; van Beek, L.P.H.; Bogaard, T.; Cammeraat, E.; Mickovski, S.B.; Jenner, A.; Di Iorio, A.; Fourcaud, T.; Norris, J.E.; Stokes, A.; Mickovski, S.B.; Cammeraat, E.; van Beek, R.; Nicoll, B.C.; Achim, A.

    2008-01-01

    Once the instability process e.g. erosion or landslides has been identified on a slope, the type of vegetation to best reinforce the soil can then be determined. Plants improve slope stability through changes in mechanical and hydrological properties of the root-soil matrix. The architecture of a pl

  7. Stability Analysing of Unsaturated Soil Slope

    Institute of Scientific and Technical Information of China (English)

    张士林; 邵龙潭

    2003-01-01

    The stability of unsaturated soil slope has been the hot point recently. Especially, the seeping rainfall makes losing stability of unsaturated soil slope, and causes enormous loss to the producation and safety of other people. The seeping rainfall makes volumetric water content of unsaturated soil slope changing, and the volumetric water content has directly relationship with matric suction. And matric suction also has directly relationship with the stability of unsaturated soil slope. So the change of matric suction influence the stability changing, that is, safety coefficient has decided relationship with volumetric water content. The profile of dangerous volumetric water content curves of unsaturated soil slope has been obtained. If a volumetric water content curve of some unsaturated soil slope belongs to one of these dongerous curves, the unsaturated soil slope could be in danger. So this is called DVWCCP(dangerous volumetric water content curves profile). By monitoring the volumetric water content curves can obtain the stability information of some soil slope to serve producing and safety.

  8. In-Place Randomized Slope Selection

    DEFF Research Database (Denmark)

    Blunck, Henrik; Vahrenhold, Jan

    2006-01-01

    Slope selection is a well-known algorithmic tool used in the context of computing robust estimators for fitting a line to a collection P of n points in the plane. We demonstrate that it is possible to perform slope selection in expected O(nlogn) time using only constant extra space in addition...

  9. Eastern slopes grizzly bear project

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-01-01

    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.

  10. [Effects of slope gradient on slope runoff and sediment yield under different single rainfall conditions].

    Science.gov (United States)

    He, Ji-Jun; Cai, Qiang-Guo; Liu, Song-Bo

    2012-05-01

    Based on the field observation data of runoff and sediment yield produced by single rainfall events in runoff plots, this paper analyzed the variation patterns of runoff and sediment yield on the slopes with different gradients under different single rainfall conditions. The differences in the rainfall conditions had little effects on the variation patterns of slope runoff with the gradient. Under the conditions of six different rainfall events in the study area, the variation patterns of slope runoff with the gradient were basically the same, i. e., the runoff increased with increasing gradient, but the increment of the runoff decreased slightly with increasing gradient, which was mainly determined by the infiltration flux of atmospheric precipitation. Rainfall condition played an important role on the slope sediment yield. Generally, there existed a critical slope gradient for slope erosion, but the critical gradient was not a fixed value, which varied with rainfall condition. The critical slope gradient for slope erosion increased with increasing slope gradient. When the critical slope gradient was greater, the variation of slope sediment yield with slope gradient always became larger.

  11. Automated sliding susceptibility mapping of rock slopes

    Directory of Open Access Journals (Sweden)

    A. Günther

    2004-01-01

    Full Text Available We present a suite of extensions for ARCVIEW GIS™ (ESRI that allows to map the spatial distribution of first-order mechanical slope-properties in hard rock terrain, e.g. for large slope areas like water reservoir slopes. Besides digital elevation data, this expert-system includes regional continuous grid-based data on geological structures that might act as potential sliding or cutoff planes for rockslides. The system allows rapid automated mapping of geometrical and kinematical slope properties in hard rock, providing the basis for spatially distributed deterministic sliding-susceptibility evaluations on a pixel base. Changing hydrostatic slope conditions and rock mechanical parameters can be implemented and used for simple predictive static stability calculations. Application is demonstrated for a study area in the Harz Mts., Germany.

  12. Micromechanical properties and mechanical parameters of talus deposit based on digital image technology%基于数字图像的大型堆积体细观力学特性及力学参数研究

    Institute of Scientific and Technical Information of China (English)

    徐安权; 徐卫亚; 石崇; 李德亮

    2012-01-01

    大型堆积体常见于西南水电工程中,其力学性质极其复杂,需从细观结构上对其加以研究,才能从本质上揭示其力学特性及变形破坏的特征和规律。将数字图像处理技术(DIPT)应用到堆积体的数值模拟中,自行开发了Photo-To-FLAC3D(PTF)自动建模程序,可实现对堆积体图像的分析处理、信息获取并自动生成细观模型文件的全过程,为堆积体力学行为的模拟提供了新的建模方法。以澜沧江古水水电站堆积体边坡为例,对实拍数码照片采用PTF实现其细观模型快速、准确的建立,运用三轴数值模拟试验对其力学特性及力学参数进行分析和研究。研究表明,堆积体变形表现出明显的“欺软怕硬”特性,受力表现出“贯穿带”的特性。提出随机统计分析法对堆积体力学参数进行研究,通过随机选取多组现场照片进行分析,由统计分析得出的力学参数与实际工程物理实验的参数非常接近,说明该力学参数研究方法的可信性,为堆积体力学参数的选取提供了一条新的路径和依据,是大型原位试验的有益补充。%Talus deposit is often seen in hydropower projects in the southwest of China. Its mechanical properties are so complex that the microstructural study is often used to reveal the essence of its deformation and damage. The digital image processing technology (DIPT) is introduced to the simulation of talus deposits. Based on the study of DIPT, a Photo-To-FLAC3D (PTF) auto-modeling program is developed. It is able to realize the whole process: analyzing and processing the digital images, acquiring the information and establishing the micro-model files. A new modeling method is developed for the mechanical behaviors of talus deposits. As an example, some talus deposit data of Gushui Hydropower Station are used. A micro-model for the talus deposit is established fast and correctly by

  13. Alaskan North Slope petroleum systems

    Science.gov (United States)

    Magoon, L.B.; Lillis, P.G.; Bird, K.J.; Lampe, C.; Peters, K.E.

    2003-01-01

    Six North Slope petroleum systems are identified, described, and mapped using oil-to-oil and oil-to-source rock correlations, pods of active source rock, and overburden rock packages. To map these systems, we assumed that: a) petroleum source rocks contain 3.2 wt. % organic carbon (TOC); b) immature oil-prone source rocks have hydrogen indices (HI) >300 (mg HC/gm TOC); c) the top and bottom of the petroleum (oil plus gas) window occur at vitrinite reflectance values of 0.6 and 1.0% Ro, respectively; and d) most hydrocarbons are expelled within the petroleum window. The six petroleum systems we have identified and mapped are: a) a southern system involving the Kuna-Lisburne source rock unit that was active during the Late Jurassic and Early Cretaceous; b) two western systems involving source rock in the Kingak-Blankenship, and GRZ-lower Torok source rock units that were active during the Albian; and c) three eastern systems involving the Shublik-Otuk, Hue Shale and Canning source rock units that were active during the Cenozoic. The GRZ-lower Torok in the west is correlative with the Hue Shale to the east. Four overburden rock packages controlled the time of expulsion and gross geometry of migration paths: a) a southern package of Early Cretaceous and older rocks structurally-thickened by early Brooks Range thrusting; b) a western package of Early Cretaceous rocks that filled the western part of the foreland basin; c) an eastern package of Late Cretaceous and Paleogene rocks that filled the eastern part of the foreland basin; and d) an offshore deltaic package of Neogene rocks deposited by the Colville, Canning, and Mackenzie rivers. This petroleum system poster is part of a series of Northern Alaska posters on modeling. The poster in this session by Saltus and Bird present gridded maps for the greater Northern Alaskan onshore and offshore that are used in the 3D modeling poster by Lampe and others. Posters on source rock units are by Keller and Bird as well as

  14. Reinforcement mechanism of slope stability method with no cutting trees

    OpenAIRE

    Yuki, Chikata; Harushige, KUSUMI; 楠見, 晴重; Katsumi, TERAOKA

    2008-01-01

    The study in this paper is the slope stability. Although many slopes are prone to collapse, countermeasures against slop failures have not been progressed yet in Japan. Most slope protection methods were to cover shotcrete on the slope in 1960’s. However, the slope covered shotcrete have been deteriorating. Therefore, the slope failures frequently occur due to the natural disaster such as heavy rainfall and earthquake. It is important to develop an effective slope stability method. Moreover, ...

  15. MECHANICAL HARVESTING OF COFFEE IN HIGH SLOPE

    Directory of Open Access Journals (Sweden)

    FELIPE SANTINATO

    2016-01-01

    Full Text Available Brazilian coffee farming is carried out both on flat and steep lands. In flat areas, mechanized operations are intensive; however, in steep slope areas, certain mechanized operations cannot be performed, such as harvesting. Based on this, the industry has developed machinery to harvest coffee in areas with up to 30% slope. However, harvesters have their efficiency and operational performance influenced by land slope. Thus, this study aimed to evaluate the operational performance and harvesting efficiency of a steep-slope harvester under different situations, using different speed settings. The experiment was carried out in the county of Santo Antônio do Amparo, state of Minas Gerais, Brazil, using five coffee stands with 10, 15, 20, 25 and 30% slope. Evaluations were performed with a self-propelled harvester (Electron, TDI®, Araguari, MG, Brazil at three rotation speeds (600, 800 and 1.000 rpm and two ground speeds (800 and 1.000 m h-1. The results showed the lower speed (800 m h-1 was suitable for 10% slope areas since the amount of fallen coffee berries. For areas of 20% slope, harvesting time was 21.6% longer than in flatter areas. Downtime varied from 10.66 to 29.18% total harvest due to a higher number of maneuvers.

  16. ElevationOther_SLOPE10M

    Data.gov (United States)

    Vermont Center for Geographic Information — Used ElevationDEM_DEM10M and the Arc/Info SLOPE command with the "PERCENT_RISE" and ".3048" Z_unit options to create this data layer. Input source dataset is...

  17. Percent Agricultural Land Cover on Steep Slopes

    Data.gov (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....

  18. North Slope, Alaska ESI: NESTS (Nest Points)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for waterfowl, seabirds, gulls and terns for the North Slope of Alaska. Vector points in this data set...

  19. North Slope, Alaska ESI: FISH (Fish Polygons)

    Data.gov (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...

  20. North Slope, Alaska ESI: FACILITY (Facility Points)

    Data.gov (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...

  1. On Front Slope Stability of Berm Breakwaters

    DEFF Research Database (Denmark)

    Burcharth, Hans F.

    2013-01-01

    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 r......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...... 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...

  2. Numerical Computation of Homogeneous Slope Stability

    Directory of Open Access Journals (Sweden)

    Shuangshuang Xiao

    2015-01-01

    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.

  3. Prediction of slope failure due to earthquake

    Institute of Scientific and Technical Information of China (English)

    CHEN XiaoLi; KATO Nobuaki; TSUNAKI Ryosuke; MUKAI Keiji

    2009-01-01

    The earthquake-triggered landslides and slope failures are common phenomena during strong earthquakes and have drawn more attention from the world because of severe hazards they induced.These hazards usually cannot be prevented by current mitigating measures,thus,it becomes more and more important to develop a precise technique for the risk assessment of earthquake-induced failures in the mountainous area.The application of discrimination analysis method is proved to be successful and effective in the prediction of earthquake-triggered landslides and slope failures in the region of Imokawa Basin in Japan.Diacriminant score can be used to assess the relative risk of slope failures,as the score increases,the possibility of slope failures occurrence increases accordingly.At the same time,the variables in the judgement formula,such as slope gradient,slope curvature and seismic peak ground acceleration,are easy to obtain.This advantage makes this method more practical and manipulable than others at present.In order to apply this method more effectively,there are still several problems to resolve.

  4. Geomorphologic mapping in the Ny Ålesund area (Svalbard Island, Norway) for the analysis of geomorphologic effects on rock slopes induced by glacier retreat in climate sensitive High Arctic regions

    Science.gov (United States)

    Miccadei, Enrico; Piacentini, Tommaso; Casacchia, Ruggero; Sparapani, Roberto

    2014-05-01

    The geomorphological effects of glacial retreat, rapidly changing Arctic environments and consequent local temporary permafrost melting are several types of glacial and periglacial landforms (pingos, solifluction, drumlins, etc.) but also debris and rock falls, alluvial fan and glacial outwash development and scarp/slopes retreat and evolution. In this work we have realized a geomorphologic map of rockfalls, landslides, alluvial fans and the slopes and scarps of steep mountainsides in the Ny Ålesund area (Svalbard Island, Norway) focused on the analysis of rock falls as geomorphological effects of glacier retreat, permafrost degradation and higher temperatures on slope processes. The investigation is based on geological and geomorphological field survey, and remote sensing and aerial photo interpretation, The Ny Ålesund area landscape is characterized by rugged non-vegetated mountains only partially covered by glaciers, with steep flanks and rock scarps; the scarps are formed by different types of rocks (intrusive and effusive igneous rocks, marine sedimentary rocks); this landscape is highly affected by debris and rock falls (from scarps and slopes) forming wide talus slopes and by alluvial fan and fluvial outwash (from glaciers), which make the surface sedimentary cover of the island together with rock glaciers and moraine deposits and locally fluvial deposits. The work is focused on the comprehension of the role of different factors in inducing rock falls, alluvial fans, slope/scarps evolution in high geomorphological sensitivity environments (i.e. glacial, periglacial or mountain) including: orography, lithology, rock fracturation, morphostructural setting, meteorological context. The conclusions focus on the possible geomorphological hazards affecting the Ny Ålesund area.

  5. Feature of resistivity response of slope from steady to unsteady

    Institute of Scientific and Technical Information of China (English)

    谢忠球; 张玉池; 温佩琳; 段靓靓

    2008-01-01

    Using resistivity as index and referring to the law about effect of slope to resistivity,the apparent resistivities of geophysical model concerned with unsteady rock type slope failure were calculated systematically by using the boundary integral equation method.After studying the feature of resistivity response of slope failure,the variety of resistivity during evolution of slope from steady to unsteady was found and the characteristics of resistivity response about slope failure was concluded.These make electrical exploring method for detecting the slip plane or structural plane of slope failure,evaluating the stability of the slope,and forecasting slope failure become true.

  6. Slope stability, triggering factors and threshold conditions. Study of debris flow activity in the Reyðarfjörður fjord, eastern Iceland.

    Science.gov (United States)

    Margeirsson, Guðbjörn; Sæmundsson, Þorsteinn; Norðdahl, Hreggviður

    2016-04-01

    Precipitation is one of the main triggering factor for debris flow activity in Eastern Iceland, but the amount needed, duration and the rainfall and its intensity to trigger the flow (e.g. the threshold condition) can vary considerably between areas. There are a few factors that have to be taken into account to determine the threshold condition and slope stability between areas, such as the slope angle and aspect, type and thickness of loose material, vegetation cover and gully distribution. Weather factors such as air and soil temperature, wind speed and wind direction is also crucial. The study area is located in the Reyðarfjörður fjord, one of the longest fjords on the east coast of Iceland. It is a 30 km long glacially eroded fjord, cut into the Tertiary bedrock. The bedrock is mostly made up of jointed basaltic lava flows, individual flows can vary in thickness from 2-30 m and usually separated by lithified sedimentary horizons often red in color. The slopes of the fjord are steep up to 900 m high, often consisting of nearly vertical cliffs, 60°-90°, in the upper parts of the slopes. The lower parts are covered with various glaciogenic landforms and consist of sediments and talus material. Several small hanging valleys and numerous small gullies and streams occur along the both sides of the fjord. The debris flow activity in the Reyðafjörður fjord is mostly constrained to the gullies and streams. Some activity has also been observed on the slopes between the gullies, but such activity is usually connected to extreme conditions, during or following heavy rain storms or a rainfall, especially of long duration. The aim of the study is to map the distribution of loose slope sediments in two areas inside the fjord, collect data about the known debris flow history, analyze various weather patterns which have contributed to these debris flows and understand how variables between the slopes react differently to different factors.

  7. Decision Guide for Roof Slope Selection

    Energy Technology Data Exchange (ETDEWEB)

    Sharp, T.R.

    1988-01-01

    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.

  8. Asteroid absolute magnitudes and slope parameters

    Science.gov (United States)

    Tedesco, Edward F.

    1991-01-01

    A new listing of absolute magnitudes (H) and slope parameters (G) has been created and published in the Minor Planet Circulars; this same listing will appear in the 1992 Ephemerides of Minor Planets. Unlike previous listings, the values of the current list were derived from fits of data at the V band. All observations were reduced in the same fashion using, where appropriate, a single basis default value of 0.15 for the slope parameter. Distances and phase angles were computed for each observation. The data for 113 asteroids was of sufficiently high quality to permit derivation of their H and G. These improved absolute magnitudes and slope parameters will be used to deduce the most reliable bias-corrected asteroid size-frequency distribution yet made.

  9. Assessment of Slope Instability and Risk Analysis of Road Cut Slopes in Lashotor Pass, Iran

    Directory of Open Access Journals (Sweden)

    Mohammad Hossein Taherynia

    2014-01-01

    Full Text Available Assessment of the stability of natural and artificial rock slopes is an important topic in the rock mechanics sciences. One of the most widely used methods for this purpose is the classification of the slope rock mass. In the recent decades, several rock slope classification systems are presented by many researchers. Each one of these rock mass classification systems uses different parameters and rating systems. These differences are due to the diversity of affecting parameters and the degree of influence on the rock slope stability. Another important point in rock slope stability is appraisal hazard and risk analysis. In the risk analysis, the degree of danger of rock slope instability is determined. The Lashotor pass is located in the Shiraz-Isfahan highway in Iran. Field surveys indicate that there are high potentialities of instability in the road cut slopes of the Lashotor pass. In the current paper, the stability of the rock slopes in the Lashotor pass is studied comprehensively with different classification methods. For risk analyses, we estimated dangerous area by use of the RocFall software. Furthermore, the dangers of falling rocks for the vehicles passing the Lashotor pass are estimated according to rockfall hazard rating system.

  10. Reliability analysis method applied in slope stability: slope prediction and forecast on stability analysis

    Institute of Scientific and Technical Information of China (English)

    Wenjuan ZHANG; Li CHEN; Ning QU; Hai'an LIANG

    2006-01-01

    Landslide is one kind of geologic hazards that often happens all over the world. It brings huge losses to human life and property; therefore, it is very important to research it. This study focused in combination between single and regional landslide, traditional slope stability analysis method and reliability analysis method. Meanwhile, methods of prediction of slopes and reliability analysis were discussed.

  11. Research on monitoring system for slope deformation

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-sheng; ZHANG Xue-zhuang; WANG Ai-gong

    2007-01-01

    The monitoring system for slope deformation which bases on Leica (TCA series)was researched and developed. This system consists of electronic total stations, high precision thermometer, digital barometer, photoelectric frequency adjustor and other related instruments and data collection and processing software. The system can monitor a series of targets automatically to obtain accurate data of distance at predetermined time, besides,it can timely display targets' coordinates and deformation value, velocity, etc. in graph as well. To compare of the results of different monitoring time, we can find the problems of mine slope deformation rapidly and accurately.

  12. The Sloping Land Conversion Program in China

    DEFF Research Database (Denmark)

    Liu, Zhen

    conversion program. Our results show that SLCP works as a valid external policy intervention on rural livelihood diversification. In addition, the findings demonstrate that there exist heterogeneous effects of SLCP implementation on livelihood diversification across different rural income groups. The lower......By overcoming the barriers that limit access to financial liquidity and human resource, the Sloping Land Conversion Program (SLCP) can promote rural livelihood diversification. This paper examines this effect using a household survey data set spanning the 1999 implementation of the Sloping land...... income group was more affected by the program in terms of income diversification....

  13. INITIAL SLOPE OF THE HYSTERESIS CURVE

    OpenAIRE

    Gerritsma, G.J.; Stam, M.T.H.C.W.; Lodder, J. C.; Popma, Th.J.A.

    1988-01-01

    An analytical expression for the initial slope T of the hysteresis curve is derived for a stripe domain structure in a thin magnetic film, giving that T-1 is proportional to t-1/2 (t = film thickness). This is confirmed by measurements on RF sputtered CoCr films with 20 nm ≤ t ≤ 950 nm.

  14. Initial slope of the hysteresis curve

    NARCIS (Netherlands)

    Gerritsma, G.J.; Stam, M.T.H.C.W.; Lodder, J.C.; Popma, Th.J.A.

    1988-01-01

    An analytical expression for the initial slope T of the hysteresis curve is derived for a stripe domain structure in a thin magnetic film, giving that T-1 is proportional to t-1/2 (t = film thickness). This is confirmed by measurements on RF sputtered CoCr films with 20 nm £ t £ 950 nm.

  15. Level-Slope-Curvature - Fact or Artefact?

    NARCIS (Netherlands)

    R. Lord (Roger); A.A.J. Pelsser (Antoon)

    2005-01-01

    textabstractThe first three factors resulting from a principal components analysis of term structure data are in the literature typically interpreted as driving the level, slope and curvature of the term structure. Using slight generalisations of theorems from total positivity, we present sufficient

  16. Measuring acoustic emissions in an avalanche slope

    Science.gov (United States)

    Reiweger, Ingrid; Schweizer, Jürg

    2014-05-01

    Measurements of acoustic emissions are a common technique for monitoring damage and predicting imminent failure of a material. Within natural hazards it has already been used to successfully predict the break-off of a hanging glacier. To explore the applicability of the acoustic emission (AE) technique for avalanche prediction, we installed two acoustic sensors (with 30 kHz and 60 kHz resonance frequency) in an avalanche prone slope at the Mittelgrat in the Parsenn ski area above Davos, Switzerland. The slope is north-east facing, frequently wind loaded, and approximately 35° steep. The AE signals - in particular the event energy and waiting time distributions - were compared with slope stability. The latter was determined by observing avalanche activity. The results of two winter's measurements yielded that the exponent β of the inverse cumulative distribution of event energy showed a significant drop (from a value of 3.5 to roughly 2.5) at very unstable conditions, i.e. on the three days during our measurement periods when spontaneous avalanches released on our study slope.

  17. Improved wavefront reconstruction algorithm from slope measurements

    Science.gov (United States)

    Phuc, Phan Huy; Manh, Nguyen The; Rhee, Hyug-Gyo; Ghim, Young-Sik; Yang, Ho-Soon; Lee, Yun-Woo

    2017-03-01

    In this paper, we propose a wavefront reconstruction algorithm from slope measurements based on a zonal method. In this algorithm, the slope measurement sampling geometry used is the Southwell geometry, in which the phase values and the slope data are measured at the same nodes. The proposed algorithm estimates the phase value at a node point using the slope measurements of eight points around the node, as doing so is believed to result in better accuracy with regard to the wavefront. For optimization of the processing time, a successive over-relaxation method is applied to iteration loops. We use a trial-and-error method to determine the best relaxation factor for each type of wavefront in order to optimize the iteration time and, thus, the processing time of the algorithm. Specifically, for a circularly symmetric wavefront, the convergence rate of the algorithm can be improved by using the result of a Fourier Transform as an initial value for the iteration. Various simulations are presented to demonstrate the improvements realized when using the proposed algorithm. Several experimental measurements of deflectometry are also processed by using the proposed algorithm.

  18. A Novel Way To Practice Slope.

    Science.gov (United States)

    Kennedy, Jane B.

    1997-01-01

    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. 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.

    2008-01-01

    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 i

  20. Effects of grapevine root density and reinforcement on slopes prone to shallow slope instability

    Science.gov (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

    2016-04-01

    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

  1. Imaging diagnosis of bone tumor and tumor-like lesion in the talus%距骨肿瘤及瘤样病变的影像学特点

    Institute of Scientific and Technical Information of China (English)

    潘涛; 王林森; 胡永成; 王淑丽; 万业达

    2014-01-01

    Objective To research the variety and the imaging features of bone tumor and tumor-like lesions in the talus.Methods The imaging features of 33 cases of tumor and tumor-like lesions in the talus were reviewed retrospectively.All cases were confirmed by operation and pathology,All of 33 cases were performed X-ray examination,23 cases were examined by CT,and 11 cases were taken by MR.Results In 33 cases,24 cases were males,9 cases were females; including 7 cases of chondroblastoma(21.2%),7 cases of giant cell tumor(21.2%)(1 case of recurrence),6 cases of osteochondroma(18.2%),2 cases of osteoid osteoma(6.1%),7 cases of adjacent joint bone cyst(21.2%,2 cases of fibrous dysplasia of bone(6.1%),1 case of bone cyst(3%),1 case of malignant fibrous histiocytoma(MFH) of bone(3%).6 cases showed pathological fractures.The X-ray and CT imaging features of chondroblastoma,giant cell tumor,adjacent joint bone cyst,fibrous dysplasia of bone,bone cyst demonstrated cystic bony destruction.The common location of chondroblastoma were the posterior of talus(57%),expanding growth slightly,margin were mild osteosclerosis.The margin were osteosclerosis irregularly and osteal ridges showed in giant cell tumor.MRI features were different on pathologic basis,isointense and hypointense signal on T1WI and hyperintense signal on T2WI usually.The osteochondroma showed osseous protuberance connecting the talus,some cases showed calcification in the cap.The imaging of MFH in the talus X-ray and CT showed ill-defined osteolytic bony destruction,soft tissue-mass,no periosteal reactions and bone formation.MRI showed isointense and hypointense signal on T1WI and isointense and hyperintense signal on T2WI.The extent of tumour invasion clearly displayed.Conclusion Tumor and tumor-like lesion in the talus were rare.But there are great varieties.The benign tumor was more common than malignant tumor.Chondroblastoma,giant cell tumor,osteochondroma,osteoid osteoma and adjacent joint bone

  2. Relief unity emulator and slope stability simulator applied to mass movement occurrence analysis in slope evolution

    Science.gov (United States)

    Colangelo, Antonio C.

    2010-05-01

    This work refers to a part of my "Fellow" thesis "Geomorphosynthesis and Geomorphocinematic applied to slope stability and evolution" (Colangelo, 2007). Relief unity emulator (rue) is a device that permits to synthesize a slope unity by means of a single generatrix profile that determine the initial conditions for application of a set of a geotechnical, hydrological and morphological models. This initial profile is considered in equilibrium with original environmental conditions, and operates in an integrated manner with these models. The aim is to induce a boundary condition on initial profile and produce a new profile: a threshold profile. For this manner and by iterations we generate a set of new profiles that represents, each one, a meta-stable profile, or a descending profile. The evolution of these profiles is in according with the central geomorphologycal concepts of slope retreat, base level change and head retreat. This set of "descending profiles" will be now sliced at topographic equivalent points, that will linked for describe a "topographic equivalence line". The crossing of this kind of isolines with descending profiles composes a 3D slope unity. This descending slope unity is represented by a mesh built for the crossing of these new slope profiles with the topographic equivalence lines and, the result is a four-dimensional meta-stable object integrated to the slope stability simulator (sss). This composite "rue-sss" device operates with 10 main models and 16 variables. The models describe effective stress, shearing resistance, soil saturation level behavior, potential rupture surface depth, critical depth, potential rupture surface critical gradient, critical soil saturation level, top of percolation flow gradient and unit weight of soil. Of this manner, is possible to evaluate effective friction angles and cohesion, critical soil saturation levels, critical gradients for potential rupture surfaces, neutral stress, shear strength, shear stress

  3. General regularity of dynamic responses of slopes under dynamic input

    Institute of Scientific and Technical Information of China (English)

    QI Shengwen; WU Faquan; SUN Jinzhong

    2003-01-01

    Through lots of numerical simulations with FLAC3D, dynamic responses of slopes are comprehensively studied in this paper and the general regularities of the isoline of the coefficient of the displacement, velocity and acceleration of the slope section are reached. Given a certain material slope, if the height of the slope is less than a certain value, the displacement, velocity and acceleration linearly enlarge with elevation in the vertical direction; if the height of the slope surpasses the certain value, the displacement,velocity and acceleration do not linearly enlarge with elevation any more, on the other hand, they fluctuate with a certain rhythm. At the same time, the rhythm appears in the horizontal direction, and the displacement, velocity and acceleration of the slope surface enlarge near the slope surface. The distribution form of the isoline of the coefficient of displacement, velocity and acceleration in the section of the slope is remarkably affected by the slope angle. In the certain area near the slope surface, the isoline of displacement,velocity and acceleration is parallel to the surface of the slope; in the mean time the strike direction of the extremum area is parallel to the surface of the slope, too. The charts of the slope dynamic responses can be depicted with two indexes, one is the strike direction of the isoline, and the other is the number of the rhythm extremum area of the direction parallel to the surface of the slope.

  4. Application of fuzzy optimal selection of similar slopes to the evaluation of slope stability

    Institute of Scientific and Technical Information of China (English)

    WANG Xu-hua; CHEN Shou-yu; TANG Lie-xian; ZHANG Hou-quan

    2007-01-01

    The numerical calculation method is widely used in the evaluation of slope stability, but it cannot take the randomness and fuzziness into account that exist in rock and soil engineering objectively. The fuzzy optimization theory is thus introduced to the evaluation of slope stability by this paper and a method of fuzzy optimal selection of similar slopes is put forward to analyze slope stability. By comparing the relative membership degrees that the evaluated object sample of slope is similar to the source samples of which the stabilities are detected clearly, the source sample with the maximal relative membership degree will be chosen as the best similar one to the object sample, and the stability of the object sample can be evaluated by that of the best similar source sample. In the process many uncertain influential factors are considered and characteristics and knowledge of the source samples are obtained. The practical calculation indicates that it can achieve good results to evaluate slope stability by using this method.

  5. Slope reinforcement design using geotextiles and geogrids

    Science.gov (United States)

    Setser, Darrell M.

    1990-08-01

    A geotextile is defined by ASTM as: any permeable textile material used with foundation, soil, rock, earth, or any other geotechnical engineering related material, as a integral part of a man-made project, structure, or system. A geogrid is defined as: any geotextile-related material used in a similar manner to geotextiles. They are usually made of plastic, but can be metal or wood. Geotextiles and geogrids are collectively referred to as geosynthetics in this paper. Geosynthetic reinforcement of slopes is a relatively new option available to the civil engineer. Slope angles can be increased and 'poor' soil can be used to construct economical soil-geosynthetic facilities. Uncertainties exist in the complex interaction between the soil and the geosynthetic but there are numerous procedures which ignore this in the design. The design procedures available may be conservative yet still may be an economical alternative when compared to more conventional options.

  6. An Extended Mild-Slope Equation

    Institute of Scientific and Technical Information of China (English)

    PAN Junning; HONG Guangwen; ZUO Qihua

    2000-01-01

    On the assumption that the vortex and the vertical velocity component of the current are small, a mild-slope equation for wave propagation on non-uniform flows is deduced from the basic hydrodynamic equations, with the terms of ( h h)2 and /2h h included in the equation. The terms of bottom friction, wind energy input and wave nonlinearity are also introduced into the equation. The wind energy input functions for wind waves and swells are separately considered by adopting Wen′s (1989) empirical formula for wind waves and Snyder′s observation results for swells. Thus, an extended mild-slope equation is obtained, in which the effects of refraction, diffraction, reflection, current, bottom friction, wind energy input and wave nonlinearity are considered synthetically.

  7. The Salpeter Slope of the IMF Explained

    CERN Document Server

    Oey, M S

    2012-01-01

    If we accept a paradigm that star formation is a self-similar, hierarchical process, then the Salpeter slope of the IMF for high-mass stars can be simply and elegantly explained as follows. If the instrinsic IMF at the smallest scales follows a simple -2 power-law slope, then the steepening to the -2.35 Salpeter value results when the most massive stars cannot form in the lowest-mass clumps of a cluster. It is stressed that this steepening MUST occur if clusters form hierarchically from clumps, and the lowest-mass clumps can form stars. This model is consistent with a variety of observations as well as theoretical simulations.

  8. 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)

    2010-07-01

    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.

  9. Transhumanism, medical technology and slippery slopes

    OpenAIRE

    McNamee, M. J.; Edwards, S D

    2006-01-01

    In this article, transhumanism is considered to be a quasi‐medical ideology that seeks to promote a variety of therapeutic and human‐enhancing aims. Moderate conceptions are distinguished from strong conceptions of transhumanism and the strong conceptions were found to be more problematic than the moderate ones. A particular critique of Boström's defence of transhumanism is presented. Various forms of slippery slope arguments that may be used for and against transhumanism are discussed and on...

  10. Ocean processes at the Antarctic continental slope.

    Science.gov (United States)

    Heywood, Karen J; Schmidtko, Sunke; Heuzé, Céline; Kaiser, Jan; Jickells, Timothy D; Queste, Bastien Y; Stevens, David P; Wadley, Martin; Thompson, Andrew F; Fielding, Sophie; Guihen, Damien; Creed, Elizabeth; Ridley, Jeff K; Smith, Walker

    2014-07-13

    The Antarctic continental shelves and slopes occupy relatively small areas, but, nevertheless, are important for global climate, biogeochemical cycling and ecosystem functioning. Processes of water mass transformation through sea ice formation/melting and ocean-atmosphere interaction are key to the formation of deep and bottom waters as well as determining the heat flux beneath ice shelves. Climate models, however, struggle to capture these physical processes and are unable to reproduce water mass properties of the region. Dynamics at the continental slope are key for correctly modelling climate, yet their small spatial scale presents challenges both for ocean modelling and for observational studies. Cross-slope exchange processes are also vital for the flux of nutrients such as iron from the continental shelf into the mixed layer of the Southern Ocean. An iron-cycling model embedded in an eddy-permitting ocean model reveals the importance of sedimentary iron in fertilizing parts of the Southern Ocean. Ocean gliders play a key role in improving our ability to observe and understand these small-scale processes at the continental shelf break. The Gliders: Excellent New Tools for Observing the Ocean (GENTOO) project deployed three Seagliders for up to two months in early 2012 to sample the water to the east of the Antarctic Peninsula in unprecedented temporal and spatial detail. The glider data resolve small-scale exchange processes across the shelf-break front (the Antarctic Slope Front) and the front's biogeochemical signature. GENTOO demonstrated the capability of ocean gliders to play a key role in a future multi-disciplinary Southern Ocean observing system.

  11. Motion of rock masses on slope

    Directory of Open Access Journals (Sweden)

    Urška Petje

    2006-12-01

    Full Text Available This paper shows the different ways of how rock masses (stones, rocks, and blocks move along slopes and for each different way of motion (free fall, bouncing, rolling, sliding, slowing down, lubrication, fluidizationadequatedynamicequationsaregiven.Knowingthe kinematics and dynamics of travelling rock masses is necessary for mathematical modeling of motion and by this an assessment of maximal possible rockfall runout distances as an example of a sudden and hazardeous natural phenomenon, threatening man and his property, especially in the natural environment.

  12. Geosynthetic clay liners - slope stability field study

    Energy Technology Data Exchange (ETDEWEB)

    Carson, D.A. [Environmental Protection Agency, Cincinnati, OH (United States); Daniel, D.E. [Univ. of Illinois, Urbana, IL (United States); Koerner, R.M. [Geosynthetic Research Institute, Philadelphia, PA (United States); Bonaparte, R. [GeoSyntec Consultants, Atlanta, GA (United States)

    1997-12-31

    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.

  13. Rock slope instabilities in Norway: First systematic hazard and risk classification of 22 unstable rock slopes

    Science.gov (United States)

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

    2016-04-01

    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

  14. APPLICATION OF DIGITAL IMAGE TECHNOLOGY TO SIMULATION OF TALUS DEPOSIT BASED ON WAVELET TRANSFORM%基于小波变换的数字图像技术在堆积体模拟中的应用

    Institute of Scientific and Technical Information of China (English)

    徐安权; 徐卫亚; 石崇

    2011-01-01

    基于小波变换与Gamma校正提出一种新的数字图像处理技术,将其应用于堆积体的离散元模拟,可实现数值模型快速、准确的建立.该技术先基于二维小波理论对数字图像进行消噪预处理,并采用自适应Gamma校正方法以消除不同光照和环境对图像的影响,最后进行色彩空间转换以实现二值化处理,针对整个数字图像处理过程自行开发Wavelet-Gamma-Conversion(WGC)自动建模程序,可实现对堆积体图像的信息获取、分析处理并自动生成细观建模文件的全过程,为堆积体力学行为的模拟提供新的建模方法.以澜沧江古水水电站堆积体边坡为例,对实拍数码照片采用WGC建立其细观模型,运用双轴压缩数值模拟实验对其力学特性进行分析和研究.研究表明,堆积体中碎块石与土体相互压密形成共同受力体承担外力作用,由于碎块石的影响,出现明显的应变硬化阶段;随着土颗粒间黏结强度的提高,堆积体的初始弹性模量和峰值强度都有所提高.数值模拟反映出的规律与室内实验结果相一致.%Based on the wavelet transform and Gamma correction, a new digital image processing technology (DIPT) is proposed. Then it is applied to the discrete element simulation of talus deposit; the numerical model can be established fast and correctly. As for the technologyt the two-dimensional wavelet theory is used for the denoising of digital image, then the adaptive Gamma correction method is adopted to eliminate the impact of different lights and environments, and finally, the color space is conversed for the binary treatment. Based on the study of DIPT, a Wavelet-Gamma-Conversion(WGC) auto-modeling program is developed. It is able to realize the whole process: acquiring the information, analyzing and processing, establishing the micro-model files. A new modeling method is developed for the mechanical behavior simulation of talus deposit. As an example, some

  15. Characterization of the collagen component of cartilage repair tissue of the talus with quantitative MRI: comparison of T2 relaxation time measurements with a diffusion-weighted double-echo steady-state sequence (dwDESS)

    Energy Technology Data Exchange (ETDEWEB)

    Kretzschmar, M.; Hainc, N.; Studler, U. [University Hospital Basel, Department of Radiology, Basel (Switzerland); Bieri, O. [University Hospital Basel, Division of Radiological Physics, Basel (Switzerland); Miska, M. [University Hospital, Department of Orthopedics, Heidelberg (Germany); Wiewiorski, M.; Valderrabano, V. [University Hospital Basel, Department of Orthopedic Surgery, Basel (Switzerland)

    2015-04-01

    The purpose of this study was to characterize the collagen component of repair tissue (RT) of the talus after autologous matrix-induced chondrogenesis (AMIC) using quantitative T2 and diffusion-weighted imaging. Mean T2 values and diffusion coefficients of AMIC-RT and normal cartilage of the talus of 25 patients with posttraumatic osteochondral lesions and AMIC repair were compared in a cross-sectional design using partially spoiled steady-state free precession (pSSFP) for T2 quantification, and diffusion-weighted double-echo steady-state (dwDESS) for diffusion measurement. RT and cartilage were graded with modified Noyes and MOCART scores on morphological sequences. An association between follow-up interval and quantitative MRI measures was assessed using multivariate regression, after stratifying the cohort according to time interval between surgery and MRI. Mean T2 of the AMIC-RT and cartilage were 43.1 ms and 39.1 ms, respectively (p = 0.26). Mean diffusivity of the RT (1.76 μm{sup 2}/ms) was significantly higher compared to normal cartilage (1.46 μm{sup 2}/ms) (p = 0.0092). No correlation was found between morphological and quantitative parameters. RT diffusivity was lowest in the subgroup with follow-up >28 months (p = 0.027). Compared to T2-mapping, dwDESS demonstrated greater sensitivity in detecting differences in the collagen matrix between AMIC-RT and cartilage. Decreased diffusivity in patients with longer follow-up times may indicate an increased matrix organization of RT. (orig.)

  16. Mechanical interaction between roots and soil mass in slope vegetation

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The most basic function of slope vegetation is to strengthen rock and soil mass through plant roots which increase the shear strength of the slope markedly and thereby increase the stability of the slope. However, the calculation of the reinforcement ability of slope vegetation still remains at the stage of judging by experience, because it is rather difficult due to the intricacy and volatility of the force condition of plant roots in rock and soil medium. Although some scholars have tried to study the interaction between plant roots and soil mass, the systemic analysis of the mechanical reinforcement mechanism and the contribution of plant roots to strengthening the rock and soil mass on the surface of the slope is untapped. In this paper, by analyzing the mechanism of slope vegetation and the corresponding reinforcement effect, the effects that slope vegetation generates on the shear strength of slope soil mass are studied, thereby a theoretical basis for plant protection designing is provided.

  17. Propagation of internal waves up continental slope and shelf

    Institute of Scientific and Technical Information of China (English)

    DAI Dejun; WANG Wei; QIAO Fangli; YUAN Yeli; XIANG Wenxi

    2008-01-01

    In a two-dimensional and linear framework, a transformation was developed to derive eigensolutions of internal waves over a subcriticai hyperbolic slope and to approximate the continental slope and shelf. The transformation converts a hyperbolic slope in physical space into a fiat bottom in transform space while the governing equations of internal waves remain hyperbolic. The eigensolutions are further used to study the evolution of linear internal waves as it propagates to subcritical continental slope and shelf. The stream function, velocity, and vertical shear of velocity induced by internal wave at the hyperbolic slope are analytically expressed by superposition of the obtained eigensolutions. The velocity and velocity shear increase as the internal wave propagates to a hyperbolic slope. They become very large especially when the slope of internal wave rays approaches the topographic slope, which is consistent with the previous studies.

  18. 距骨骨折畸形愈合及不愈合的手术治疗%Surgical treatment of malunited or nonunited talus fractures

    Institute of Scientific and Technical Information of China (English)

    俞光荣; 李兵; 杨云峰; 周家钤; 祝晓忠; 黄轶刚; 袁锋; Hans Zwipp

    2010-01-01

    Objective To explore the operative methods of malunited or nonunited talus fractures. Methods Twenty-two patients of malunions or nonunions after displaced faint fractures were treated from January 2000 to January 2008. There were 17 males and 5 females with an average age of 34 years (ranged from 15 to 52 years). According to classification of posttraumatic talar deformities (Zwipp 2003), there were 10 cases of type Ⅰ (malunion and/or joint displacement), 8 cases of type Ⅱ (nonunion with joint displacement), 4 cases of type Ⅲ ( type Ⅰ / Ⅱ with partial AVN) . The surgical treatments included open reduction, osteotomy, correction and internal fixation with plato, screw or K-wire, or the ankle, subtalar arthrodesis. Results Seventeen patients were followed up for 14 months in average (ranged from 12 to 24 months). No wound healing problems or infections were observed. Solid union was obtained without redislocation in all patients. The mean time of bone union was 14 weeks ( ranged from 12 to 18 weeks). The mean time of completely weight loading was 14 weeks (ranged from 12 to 18 weeks). The mean AOFAS ankle and hiudfcot score increased from 35.4 ( ranged from 28.0 to 41.0 ) to 86. 6 ( ranged from 78. 0 to 98. 0). Conclusions As to posttraumatic talar deformities, surgical treatment can lead to a favorable outcome. According to concrete status of malunions or nonunions after displaced talar fractures, suitable surgical treatment should be applied to obtain satisfactory outcome.%目的 探讨距骨骨折畸形愈合及不愈合的手术治疗方法.方法 2000年1月至2008年1月,手术治疗距骨骨折畸形愈合及不愈合22例,其中男性17例,女性5例,年龄15-52岁,平均34岁.根据Zwipp提出的距骨骨折畸形愈合及不愈合的分类标准,Ⅰ型(距骨骨折畸形愈合或伴有关节脱位)10例,Ⅱ型(距骨骨折不愈合伴关节脱位)8例,Ⅲ型(在Ⅰ或Ⅱ型的基础上出现部分距骨缺血性坏死)4例.采

  19. Seepage and slope stability modelling of rainfall-induced slope failures in topographic hollows

    Directory of Open Access Journals (Sweden)

    Kiran Prasad Acharya

    2016-03-01

    Full Text Available This study focuses on topographic hollows, their flow direction and flow accumulation characteristics, and highlights discharge of hillslope seepage so as to understand porewater pressure development phenomena in relation with slope failure in topographic hollows. For this purpose, a small catchment in Niihama city of Shikoku Island in western Japan, with a record of seven slope failures triggered by typhoon-caused heavy rainfall on 19–20 October 2004, was selected. After extensive fieldwork and computation of hydro-mechanical parameters in unsaturated and saturated conditions through a series of laboratory experiments, seepage and slope stability modellings of these slope failures were done in GeoStudio environment using the precipitation data of 19–20 October 2004. The results of seepage modelling showed that the porewater pressure was rapid transient in silty sand, and the maximum porewater pressure measured in an area close to the base of topographic hollows was found to be higher with bigger topographic hollows. Furthermore, a threshold relationship between the topographic hollow area and maximum porewater pressure in this study indicates that a topographic hollow of 1000 sq. m area can develop maximum porewater pressure of 1.253 kPa. However, the porewater pressures required to initiate slope instability in the upper part of the topographic hollows is relatively smaller than those in the lower part of the topographic hollows.

  20. Evaluation of Slope Assessment Systems for Predicting Landslides of Cut Slopes in Granitic and Meta-sediment Formations

    Directory of Open Access Journals (Sweden)

    Suhaimi Jamaludin

    2006-01-01

    Full Text Available In Malaysia, slope assessment systems (SAS are widely used in assessing the instability of slope or the probability of occurrence and the likely severity of landslides. These SAS can be derived based on either one particular approach or combination of several approaches of landslide assessments and prediction. This study overviews four slope assessment systems (SAS developed in Malaysia for predicting landslide at a large-scale assessments. They are the Slope Maintenance System (SMS, Slope Priority Ranking System (SPRS, Slope Information Management System (SIMS and the Slope Management and Risk Tracking System (SMART. An attempt is made to evaluate the accuracy of the SAS in predicting landslides based on slope inventory data from 139 cut slopes in granitic formation and 47 cut slopes in meta-sediment formation, which are the two most common rock/soil formations found in Malaysia. Based on this study, it was found that none of existing SAS is satisfactory in predicting landslides of cut slopes in granitic formation, for various reasons such as the use of hazard score developed from another country, insufficient data base, oversimplified approach and use of data base derived from different rock/soil formations. However for the case of cut slope in meta-sediment, the Slope Management and Risk Tracking System (SMART was found to be satisfactory with 90% prediction accuracy. The current database of SMART is largely based on meta-sediment formation.

  1. ANALYSIS METHODS ON STABILITY OF TALL AND BEDDIIG CREEP SLOPE

    Institute of Scientific and Technical Information of China (English)

    RUIYongqin; JIANGZhiming; LIUJinghui

    1995-01-01

    Based on the model of slope engineering geology,the creep and its failure mechanism of tall and bedding slope are deeply analyzed in this paper .The creep laws of weak intercalations are also discussed.The analysis om the stability of creep slope and the age forecasting of sliding slope have been conducted through mumerical simulations using Finite Element Method (FEM)and Dintimct Element Method(DEM).

  2. THE ARTIFICIAL NEURAL NETWORK OF FORECASTING OPEN MINING SLOPE STABILITY

    Institute of Scientific and Technical Information of China (English)

    魏春启; 白润才

    2000-01-01

    The artificial neural network model which forecasts Open Mining Slope stability is established by neural network theory and method. The nonlinear reflection relation between stability target of open mining slope and its influence factor is described. The method of forecasting Open Mining Slope stability is brought forward.

  3. Intertidal beach slope predictions compared to field data

    NARCIS (Netherlands)

    Madsen, A.J.; Plant, N.G.

    2001-01-01

    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 valu

  4. Transhumanism, medical technology and slippery slopes.

    Science.gov (United States)

    McNamee, M J; Edwards, S D

    2006-09-01

    In this article, transhumanism is considered to be a quasi-medical ideology that seeks to promote a variety of therapeutic and human-enhancing aims. Moderate conceptions are distinguished from strong conceptions of transhumanism and the strong conceptions were found to be more problematic than the moderate ones. A particular critique of Boström's defence of transhumanism is presented. Various forms of slippery slope arguments that may be used for and against transhumanism are discussed and one particular criticism, moral arbitrariness, that undermines both weak and strong transhumanism is highlighted.

  5. Slope equalities for genus 5 surface fibrations

    CERN Document Server

    Tenni, Elisa

    2010-01-01

    K. Konno proved a slope equality for fibred surfaces with fibres of odd genus and general fibre of maximal gonality. More precisely he found a relation between the invariants of the fibration and certain weights of special fibres (called the Horikawa numbers). We give an alternative and more geometric proof in the case of a genus 5 fibration, under generality assumptions. In our setting we are able to prove that the fibre with positive Horikawa numbers are precisely the trigonal ones, we compute their weights explicitly and thus we exhibit explicit examples of regular surfaces with assigned invariants and Horikawa numbers.

  6. Western Ross Sea continental slope gravity currents

    Science.gov (United States)

    Gordon, Arnold L.; Orsi, Alejandro H.; Muench, Robin; Huber, Bruce A.; Zambianchi, Enrico; Visbeck, Martin

    2009-06-01

    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

  7. Visible spectral slope survey of Jupiter Trojans

    Science.gov (United States)

    Erasmus, Nicolas; Rivkin, Andrew S.; Sickafoose, Amanda A.

    2016-10-01

    Jupiter's Trojans are predicted by the Nice Model [1,2] to be Trans-Neptunian Objects (TNOs) that moved from 30+ AU to 5.2 AU during the early evolution period of the Solar System. This model, predicting giant planet migration and widespread transport of material throughout the Solar System, is however still lacking important constraints. Correlations between the composition, size, and orbital geometry of Jupiter's Trojans can provide additional information to test predicted migration and evolution models.Two main colour groups have been observed, roughly equivalent to the C (plus low-albedo X) and D classes with distinguishable spectral slopes, and one interpretation is that the two groups have different compositions [3]. Independent compositions together with hints of differing orbital inclination distributions could imply separate formation locations; therefore, determining the relative fractions of C and D asteroids at different sizes would provide a key test for Solar System dynamical models. However, there is a caveat: the distinct colour groups could also arise by other means. Regolith processes or "space weathering" such as micrometeorite impacts and UV irradiation of ice are also plausible explanations for a range of spectrographic slopes from C-like to D-like [4].Here we report on our latest survey observations at Sutherland, South Africa of approximately 50 Trojan targets using the Sutherland High Speed Optical Camera (SHOC) [5] on the 74" telescope. These observations are part of a larger multi-telescope survey to determine the spectral slopes (C-like or D-like) for multiple Trojans, focusing on those of small size. These slopes can be used to determine the relative fraction of C+X and D asteroids at different sizes to determine whether what is seen is more consistent with regolith processes or different compositions.References:[1] A. Morbidelli, et al. Nature, 435, 462-465, (2005)[2] R. Gomes, et al. Nature 435, 466-469 (2005)[3] J.P. Emery, et al. The

  8. The sloping land conversion program in China

    DEFF Research Database (Denmark)

    Liu, Zhen; Lan, Jing

    2015-01-01

    Through addressing the motivations behind rural households’ livelihood diversification, this paper examines the effect of the Sloping Land Conversion Program (SLCP) on livelihood diversification using a longitudinal household survey data set spanning the overall implementation of the SLCP. Our...... results show that the SLCP works as a valid external policy intervention to increase rural livelihood diversification. In addition, the findings demonstrate that the implementation of the SLCP has had heterogeneous effects on livelihood diversification across different rural income groups. The lower...... income group was more affected by the program in terms of income diversification....

  9. NOAA TIFF Image - 4m Bathymetric Slope of Slope for Red Snapper Research Areas in the South Atlantic Bight, 2010

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains unified Bathymetric Slope of Slope GeoTiffs with 4x4 meter cell resolution describing the topography of 15 areas along the shelf edge off the...

  10. Stability analysis of the open-pit mine slope and the study on the incensement of the slope angle

    Institute of Scientific and Technical Information of China (English)

    LIU Bao-xu(刘宝许); QIAO Lan(乔兰); LAI Xing-ping(来兴平)

    2004-01-01

    Based on the exploration of the engineering geology and the rock mechanics testing, limit equilibrium analysis method was adopted to calculate the stability of the Huogeqi Copper Mine slope, the results show that the original slope angle is too conservative and the slope have the potential of more preferable slope angle. In order to discuss the possibility of slope angle enhancement, sensitivity analysis of parameters related to limit state slope was made. Quantitatively determined angle value of the adding and the optimal slope angle was obtained. The study having performed showed that it is not only useful for the safety control of open-pit mine slope but also for the open-pit mine design for the similar geological condition.

  11. Slope evolution of GRB correlations and cosmology

    CERN Document Server

    Dainotti, Maria Giovanna; Piedipalumbo, Ester; Capozziello, Salvatore

    2013-01-01

    Gamma -ray bursts (GRBs) observed up to redshifts $z>9.4$ can be used as possible probes to test cosmological models. Here we show how changes of the slope of the {\\it luminosity $L^*_X$ -break time $T^*_a$} correlation in GRB afterglows, hereafter the LT correlation, affect the determination of the cosmological parameters. With a simulated data set of 101 GRBs with a central value of the correlation slope that differs on the intrinsic one by a $5\\sigma$ factor, we find an overstimated value of the matter density parameter, $\\Omega_M$, compared to the value obtained with SNe Ia, while the Hubble constant, $H_0$, best fit value is still compatible in 1$\\sigma$ compared to other probes. We show that this compatibility of $H_0$ is due to the large intrinsic scatter associated with the simulated sample. Instead, if we consider a subsample of high luminous GRBs ($HighL$), we find that both the evaluation of $H_0$ and $\\Omega_M$ are not more compatible in 1$\\sigma$ and $\\Omega_M$ is underestimated by the $13\\%$. Ho...

  12. Assessment of highway slope failure using neural networks

    Institute of Scientific and Technical Information of China (English)

    Tsung-lin LEE; Hung-ming LIN; Yuh-pin LU

    2009-01-01

    An artificial intelligence technique of back-propagation neural networks is used to assess the slope failure. On-site slope failure data from the South Cross-Island Highway in southern Taiwan are used to test the performance of the neural network model. The numerical results demonstrate the effectiveness of artificial neural networks in the evaluation of slope failure potential based on five major factors, such as the slope gradient angle, the slope height, the cumulative precipitation, daily rainfall and strength of materials.

  13. The effect of beach slope on tidal influenced saltwater intrusion

    Science.gov (United States)

    Zhao, Z.; Shen, C.; Jin, G.; Xin, P.; Hua, G.; Tao, X.; Zhao, J.

    2015-12-01

    Beach slope changes the tidal induced saltwater-freshwater circulations in coastal aquifers. However, the effect of beach slope on tidal influenced saltwater-freshwater mixing process is far from understood. Based on sand flume experiments and numerical simulations, we investigated the intrusion process of saltwater into freshwater under tidal forcing and variable beach slopes. The sand flume experiment results show that milder slope induces larger upper saline plume (USP) and seaward salt wedge interface (SWI) under tidal forcing. While, the steady state SWI keeps stagnant with different beach slopes. Consistent with the previous research, our numerical simulations also show a lager flux exchange across the milder beach induced by the tidal fluctuations. The groundwater table fluctuates more intensify with deeper beach slope. The next step of our study will pay attention to the effect of beach slope on the instability of USP which induces the salt-fingering flow.

  14. Seismic Stability of Reinforced Soil Slopes

    DEFF Research Database (Denmark)

    Tzavara, I.; Zania, Varvara; Tsompanakis, Y.

    2012-01-01

    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...... of the most significant parameters involved, such as the flexibility of the sliding system, the mechanical properties of the soil and of the geosynthetics material, the frequency content of the excitation and the interface shear strength....

  15. ASPECTS OF DRIP IRRIGATION ON SLOPES

    Directory of Open Access Journals (Sweden)

    Oprea Radu

    2010-01-01

    Full Text Available Nowadays, water and its supply raise problems of strategic importance, of great complexity, being considered one of the keys to sustainable human development. Drip irrigation consists in the slow and controlled administration of water in the area of the root system of the plants for the purposes of fulfilling their physiological needs and is considered to be one of the variants of localized irrigation. Water is distributed in a uniform and slow manner, drop by drop, in a quantity and with a frequency that depend on the needs of the plant, thanks to the exact regulation of the water flow rate and pressure, as well as to the activation of the irrigation based on the information recorded by the tensiometer with regard to soil humidity. This method enables the exact dosage of the water quantity necessary in the various evolution stages of the plant, thus eliminating losses. By applying the irrigation with 5 liters of water per linear meter, at a 7 days interval, in the month of august, for a vine cultivated on a slope, in layers covered with black film and irrigated via dropping, soil humidity immediately after irrigation reaches its highest level, but within the limits of active humidity, on the line of the irrigation band. Three days later, the water content of the soil in the layer is relatively uniform, and, after this interval, it is higher in the points situated at the basis of the film. This technology of cultivation on slopes favors the accumulation, in the soil, of the water resulted from heavy rains and reduces soil losses as a result of erosion.

  16. New Insights into the Sedimentary Dynamics along Carbonate Slopes

    Science.gov (United States)

    Wunsch, Marco; Betzler, Christian; Lindhorst, Sebastian; Lüdmann, Thomas; Eberli, Gregor

    2016-04-01

    Hydroacoustic, sedimentological and seismic data of the leeward slope of Great Bahama Bank and the windward slope of the adjacent Cay Sal Bank provide new insights into carbonate platform slope sedimentation. Our study focuses on the diversity and complexity of the slope morphologies and sedimentary patterns which characterize the youngest high-frequency sequence, forming since the Last Glacial Maximum. It is shown that both carbonate platform slopes are dissected by furrows, gullies and channels which are genetically not related. Along the windward slope of Cay Sal Bank, toe of slope erosion, in conjunction with the local tectonic regime is responsible for channel incisions. Our data show that these channels were active during the regression after the last interglacial highstand of sea level. During this regression, downwelling transported platform sediment downslope, which was redistributed along the slope by contour currents. It is also shown that large mass transport complexes at the leeward slope of Great Bahama Bank formed during the last sea level lowstand, probably triggered by the release of pore-water pressure. These MTC created a complex slope morphology of gullies and scarps. These gullies act as a point source by confining the exported platform sediments during the present day sea level highstand.

  17. Three-dimensional analysis of slopes reinforced with piles

    Institute of Scientific and Technical Information of China (English)

    高玉峰; 叶茂; 张飞

    2015-01-01

    Based on the upper bound of limit analysis, the plane-strain analysis of the slopes reinforced with a row of piles to the 3D case was extended. A 3D rotational failure mechanism was adopted to yield the upper bound of the factor of safety. Parametric studies were carried out to explore the end effects of the slope failures and the effects of the pile location and diameter on the safety of the reinforced slopes. The results demonstrate that the end effects nearly have no effects on the most suitable location of the installed piles but have significant influence on the safety of the slopes. For a slope constrained to a narrow width, the slope becomes more stable owing to the contribution of the end effects. When the slope is reinforced with a row of piles in small space between piles, the effects of group piles are significant for evaluating the safety of slopes. The presented method is more appropriate for assessing the stability of slopes reinforced with piles and can be also utilized in the design of plies stabilizing the unstable slopes.

  18. Finite element analysis of effect of ankle ligment injury on stability of talus%踝关节周围韧带损伤对距骨稳定性影响的有限元分析

    Institute of Scientific and Technical Information of China (English)

    戴海飞; 余斌; 张凯瑞; 熊小龙; 陈志刚; 崔壮; 卢昌怀

    2012-01-01

    Objective To explore the biomechanical properties of the talus in different ankle ligament injury through finite element analysis and therefore to provide theoretical basis for the clinic treatment of ankle ligament injury. Methods CT scan data, three-dimensional anatomically detailed finite element models was used to simulate human ankle joint internal rotation, external rotation stress state of the finite element analysis. The contact pressure and Von Mises stress distribution of the talar articular surface were compared in different ankle ligament injury. Results The three-dimensional finite element model of bone, cartilage and ligaments of the normal human ankle was established. The biomechanical stability of the talus which influenced by the ankle ligament was different in the internal rotation and external rotation force. Conclusion The anterior tibio-talar ligament playes an important role in ankle stability under external rotation force while under internal rotation force, calca-neofibular ligament playes an important role.%目的 有限元法分析踝关节周围韧带损伤对距骨生物力学稳定性的影响,为临床踝关节周围韧带损伤的治疗提供理论依据.方法 基于正常男性的足踝部螺旋CT扫描数据,运用三维重建软件,建立足踝部三维几何模型,最后导人Abaqus 6.9软件中,模拟人体踝关节内旋、外旋的受力状况,分析踝关节周围韧带损伤后距骨各关节面的接触压力及Von Mises应力分布.结果 建立包括骨、软骨、韧带在内的正常人体足踝部三维有限元模型,踝关节周围韧带在踝关节内旋、外旋时对距骨的生物力学影响不同.结论 在外旋作用力下胫距后韧带对踝关节的稳定性具有重要作用,而在内旋作用力下跟腓韧带对踝关节的稳定性具有重要作用.

  19. Improvement parameters in dynamic compaction adjacent to the slopes

    Institute of Scientific and Technical Information of China (English)

    Elham Ghanbari; Amir Hamidi

    2015-01-01

    Dynamic compaction is a cost-effective method commonly used for improvement of sandy soils. A number of researchers have investigated experimentally and numerically the improvement parameters of soils using dynamic compaction, such as crater depth, improvement depth, and radial improvement, however, these parameters are not studied for improvement adjacent to the slopes or trenches. In this research, four different slopes with different inclinations are modeled numerically using the finite element code ABAQUS, and impact loads of dynamic compaction are applied. The static factors of safety are kept similar for all trenches and determined numerically by application of gravity loads to the slope using strength reduction method (SRM). The analysis focuses on crater depth and improvement region which are compared to the state of flat ground. It can be observed that compacted area adjacent to the slopes is narrower and slightly away from the slope compared to the flat state. Moreover, crater depth increases with increase in slope inclination.

  20. Earth slope reliability analysis under seismic loadings using neural network

    Institute of Scientific and Technical Information of China (English)

    PENG Huai-sheng; DENG Jian; GU De-sheng

    2005-01-01

    A new method was proposed to cope with the earth slope reliability problem under seismic loadings. The algorithm integrates the concepts of artificial neural network, the first order second moment reliability method and the deterministic stability analysis method of earth slope. The performance function and its derivatives in slope stability analysis under seismic loadings were approximated by a trained multi-layer feed-forward neural network with differentiable transfer functions. The statistical moments calculated from the performance function values and the corresponding gradients using neural network were then used in the first order second moment method for the calculation of the reliability index in slope safety analysis. Two earth slope examples were presented for illustrating the applicability of the proposed approach. The new method is effective in slope reliability analysis. And it has potential application to other reliability problems of complicated engineering structure with a considerably large number of random variables.

  1. Examination of slope design parameters and slope performance in some gneisses in Ghana

    Science.gov (United States)

    Ayetey, J. K.

    Relict joint properties are studied. Their influence on the weathered rock mass is examined in the different parts of the profile. A slope in a typical profile is monitored for 13 years and evidence is led to show that different parts of the profile have their engineering properties relevant to slope design, modified over the years. It is suggested that in the tropics where weathering is intensive and fast the engineering properties obtained at the time of site investigation would lead to over design or under design if not modified depending on whether the material concerned is self-stabilising as in some parts of the laterite horizon or decreases in strength as in the saprolite.

  2. Simulating the seismic behaviour of soil slopes and embankments

    DEFF Research Database (Denmark)

    Zania, Varvara; Tsompanakis, Yiannis; Psarropoulos, Prodromos

    2010-01-01

    In the current study the clarification of the main assumptions, related to the two most commonly used methods of seismic slope stability analysis (pseudostatic and permanent deformation) is attempted. The seismic permanent displacements and the corresponding seismic coefficients were determined via...... parametric dynamic numerical analyses taking into account not only the main parameters dominating the seismic slope stability, but also the inherent assumptions of the applied approaches that affect the obtained results. The investigation conclude to a realistic procedure for seismic slope stability...

  3. Overland flow resistances on varying slope gradients and partitioning on grassed slopes under simulated rainfall

    Science.gov (United States)

    Pan, Chengzhong; Ma, Lan; Wainwright, John; Shangguan, Zhouping

    2016-04-01

    It is still unclear how slope steepness (S) and revegetation affect resistance (f) to overland flow. A series of experiments on runoff hydraulics was conducted on granular surfaces (bare soil and sandpaper) and grassed surfaces, including grass plots (GP), GP with litter (GL), and GP without leaves (GS) under simulated rainfall and inflow (30grass plots. A greater f occurred at the gentle and steep slopes for the granular surfaces, while f decreased with increasing slopes for the grass treatments. The different f-S relations suggest that f is not a simple function of S. When Re≈1000, the sowing rye grass with level lines increased f by approximately 100 times and decreased bed shear stress to approximately 5%. The contribution of grass leaves, stems, litter, and grain surface to total resistance in the grass plots were averagely 52%, 32%, 16%, and 1%. The greater resistance from leaves may result from the leaves lying at the plot surface impacted by raindrop impact. These results are beneficial to understand the dynamics of runoff and erosion on hillslopes impacted by vegetation restoration.

  4. [Analysis of related factors of slope plant hyperspectral remote sensing].

    Science.gov (United States)

    Sun, Wei-Qi; Zhao, Yun-Sheng; Tu, Lin-Ling

    2014-09-01

    In the present paper, the slope gradient, aspect, detection zenith angle and plant types were analyzed. In order to strengthen the theoretical discussion, the research was under laboratory condition, and modeled uniform slope for slope plant. Through experiments we found that these factors indeed have influence on plant hyperspectral remote sensing. When choosing slope gradient as the variate, the blade reflection first increases and then decreases as the slope gradient changes from 0° to 36°; When keeping other factors constant, and only detection zenith angle increasing from 0° to 60°, the spectral characteristic of slope plants do not change significantly in visible light band, but decreases gradually in near infrared band; With only slope aspect changing, when the dome meets the light direction, the blade reflectance gets maximum, and when the dome meets the backlit direction, the blade reflectance gets minimum, furthermore, setting the line of vertical intersection of incidence plane and the dome as an axis, the reflectance on the axis's both sides shows symmetric distribution; In addition, spectral curves of different plant types have a lot differences between each other, which means that the plant types also affect hyperspectral remote sensing results of slope plants. This research breaks through the limitations of the traditional vertical remote sensing data collection and uses the multi-angle and hyperspectral information to analyze spectral characteristics of slope plants. So this research has theoretical significance to the development of quantitative remote sensing, and has application value to the plant remote sensing monitoring.

  5. A Hybrid FEM-ANN Approach for Slope Instability Prediction

    Science.gov (United States)

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

    2016-08-01

    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.

  6. The Role of Slope Geometry on Flowslide Occurrence

    Directory of Open Access Journals (Sweden)

    Chiara Deangeli

    2007-01-01

    Full Text Available The paper reports a study aimed to the prediction of susceptibility to flowslide of granular soil slopes as a consequence of the in situ state of stress. In particular, the slope geometry has been investigated as a factor influencing the initial state of stress. For this purpose the results of numerical models, performed by a finite different approach (FLAC, allowed the complete definition, in any point of the slope, of the stress conditions by changing slope height and inclination. By relating this state of stress to parameters used to describe potential for liquefaction of loose granular soils a chart of instability has been set up.

  7. Geotechnical methods of reinforcement of slopes near railroads

    Institute of Scientific and Technical Information of China (English)

    Vladimir D.Vereskun; Victor A.Yavna

    2015-01-01

    In order to generate well-based design decisions on reinforcement of landslide slopes and road embankment slopes, a system of combined geotechnical analysis of geological conditions is suggested which includes topographic and geo-physical survey, and laboratory studies of soils using infra-red spectroscopy methods. Calculations of slopes' deflected modes are carried out with taking into account elastic and elasto-plastic behavior of soil, and the presence of supporting man-made constructions. Results of the application of the system suggested may be used as criteria for the classification of landslide slopes along permanent ways according to the degree of danger when used for transportation.

  8. Adaptive slope compensation for high bandwidth digital current mode controller

    DEFF Research Database (Denmark)

    Taeed, Fazel; Nymand, Morten

    2015-01-01

    An adaptive slope compensation method for digital current mode control of dc-dc converters is proposed in this paper. The compensation slope is used for stabilizing the inner current loop in peak current mode control. In this method, the compensation slope is adapted with the variations...... in converter duty cycle. The adaptive slope compensation provides optimum controller operation in term of bandwidth over wide range of operating points. In this paper operation principle of the controller is discussed. The proposed controller is implemented in an FPGA to control a 100 W buck converter...

  9. AN EXAMPLE OF THREE-DIMENSIONAL PROGRESSIVE SLOPE FAILURE

    Institute of Scientific and Technical Information of China (English)

    王家臣; 骆中洲

    1995-01-01

    In fact, the failure of any slope takes place progressively, but the progressive failure mechanism has not been emphasized sufficently in the present stability analysis of slopes. This paper provides an example of the progressive slope failure which took place at Pingzhuang west surface coal mine and was numbered the 26th slide. The three-dimensional reliability model for progressive slope failure is used to study the failure process of the 26th slide. The outcomes indicate that the progressive failure is indeed the failure mechanism of the slide.

  10. Numerical simulation study of the influence on stability of slope by underground mining under opencast coal mine slope

    Institute of Scientific and Technical Information of China (English)

    LIU Ting-ting; LU Guo-bin; TONG Li-ming

    2011-01-01

    In view of the study on mining transferred from open-pit to underground,the research on the problem of the stability of slope is less.This article combined the actual situation of the Gaohai Coal Mine in Fuxin City and set up a three-dimensional model of the part of Huizhou open-pit slope by the finite difference software.Through the three-dimensional numerical simulation study of the influence on the stability of slope by underground mining,the basic characteristics of the open-pit slope deformation and the situation of basic stability were discussed.The simulation results of the mining slope of the displacement and deformation analysis of the state for mining provide a reference to the slope stability research.

  11. Assessment and mapping of slope stability based on slope units: A case study in Yan’an, China

    Indian Academy of Sciences (India)

    Jianqi Zhuang; Jianbing Peng; Yonglong Xu; Qiang Xu; Xinghua Zhu; Wei Li

    2016-10-01

    Precipitation frequently triggers shallow landslides in the Loess Plateau of Shaanxi, China, resulting in loss of life, damage to gas and oil routes, and destruction of transport infrastructure and farmland. To assess the possibility of shallow landslides at different precipitation levels, a method to draw slope units and steepest slope profiles based on ARCtools and a new method for calculating slope stability areproposed. The methods were implemented in a case study conducted in Yan’an, north-west China. High resolution DEM (Digital Elevation Model) images, soil parameters from in-situ laboratory measurements and maximum depths of precipitation infiltration were used as input parameters in the method. Next,DEM and reverse DEM were employed to map 2146 slope units in the study area, based on which the steepest profiles of the slope units were constructed. Combining analysis of the water content of loess, strength of the sliding surface, its response to precipitation and the infinite slope stability equation, a newequation to calculate infinite slope stability is proposed to assess shallow landslide stability. The slope unit stability was calculated using the equation at 10-, 20-, 50- and 100-year return periods of antecedent effective precipitation. The number of slope units experiencing failure increased in response to increasing effective antecedent rainfall. These results were validated based on the occurrence of landslides in recent decades. Finally, the applicability and limitations of the model are discussed.

  12. Teachers' Personal Agency: Making Sense of Slope through Additive Structures

    Science.gov (United States)

    Walter, Janet G.; Gerson, Hope

    2007-01-01

    In the context of a three-year professional development program in mathematics, practicing elementary teachers persistently engaged in collaborative inquiry and reflection to build connected meanings for slope. One teacher invented a compelling representation for slope as a process of repeated addition, using Cuisenaire rods, based on teachers'…

  13. Recurring slope lineae in equatorial regions of Mars

    Science.gov (United States)

    McEwen, Alfred S.; Dundas, Colin M.; Mattson, Sarah S.; Toigo, Anthony D.; Ojha, Lujendra; Wray, James J.; Chojnacki, Matthew; Byrne, Shane; Murchie, Scott L.; Thomas, Nicolas

    2014-01-01

    The presence of liquid water is a requirement of habitability on a planet. Possible indicators of liquid surface water on Mars include intermittent flow-like features observed on sloping terrains. These recurring slope lineae are narrow, dark markings on steep slopes that appear and incrementally lengthen during warm seasons on low-albedo surfaces. The lineae fade in cooler seasons and recur over multiple Mars years. Recurring slope lineae were initially reported to appear and lengthen at mid-latitudes in the late southern spring and summer and are more common on equator-facing slopes where and when the peak surface temperatures are higher. Here we report extensive activity of recurring slope lineae in equatorial regions of Mars, particularly in the deep canyons of Valles Marineris, from analysis of data acquired by the Mars Reconnaissance Orbiter. We observe the lineae to be most active in seasons when the slopes often face the sun. Expected peak temperatures suggest that activity may not depend solely on temperature. Although the origin of the recurring slope lineae remains an open question, our observations are consistent with intermittent flow of briny water. Such an origin suggests surprisingly abundant liquid water in some near-surface equatorial regions of Mars.

  14. Preliminary blasting as a means of constructing the final slopes

    Energy Technology Data Exchange (ETDEWEB)

    Lopez Jimeno, E.; Lopez Jimeno, C. (Lignitos de Meirama, La Coruna (Spain))

    1983-01-01

    In order to undertake construction of a new belt at the Meirama opencast lignite workings in the Province of Coruna it has been necessary partially to re-site the slope of the general haulage drift. Preliminary blasting was thought to be the most suitable method of blasting in order to maintain slope stability of the rock mass. (17 refs.)

  15. Slope Morphology of Twin Peaks, Mars Pathfinder Landing Site

    Science.gov (United States)

    Hobbs, Steven; Paine, Colin; Clarke, Jon; Caprarelli, Graziella

    2010-05-01

    Development of slope form over time has long been a concern of geomorphologists, although recently this concern has been moved to slope processes rather than form. There are two basic approaches. The first is theoretical, involving modeling of different types and rates of processes, and calculation of results in terms of slope evolution over time. Comparisons with real-life slopes can follow this approach [1], [2]. The second, inductive, approach involves field measurements to test ideas about slope evolution starting from the assumption that observed slopes represent different stages of an essentially similar evolution [3]. Space is substituted for time, and a number of slopes, assumed to be of increasing age, are measured and placed in an evolutionary sequence (e.g. [4], [5], [6]). [5] showed that slope angles are modally distributed, with the modal angles controlled by the materials (regolith) of which the slopes are formed, and by the processes operating on them. Data can be obtained directly from field work or from digital elevation models (DEM) derived from remote sensing investigations [7]. DEMs are particularly useful to study inaccessible planets, such as Mars, where on site observations are restricted to only a few landing sites. Here we present a study of slopes on the Twin Peaks, two small hills located 780 m north and 910 m south of the Mars Pathfinder landing site at the mouth of the Ares and Tiu flood channels. The presence of streamlined hills, jumbled surfaces and conglomerates suggested the region was modified by massive flooding 1.8 - 3.5 billion years ago [8], [9]. The streamlined forms and terraces of the Twin Peaks were taken to indicate catastrophic flood conditions that were believed to be prevalent in the area [8]. It was also suggested that the northernmost peak was topped by floodwater, causing its flatter appearance. Other researchers postulated alternative geomorphological origins for the features observed at the Pathfinder landing site

  16. Integrating concepts and skills: Slope and kinematics graphs

    Science.gov (United States)

    Tonelli, Edward P., Jr.

    The concept of force is a foundational idea in physics. To predict the results of applying forces to objects, a student must be able to interpret data representing changes in distance, time, speed, and acceleration. Comprehension of kinematics concepts requires students to interpret motion graphs, where rates of change are represented as slopes of line segments. Studies have shown that majorities of students who show proficiency with mathematical concepts fail accurately to interpret motion graphs. The primary aim of this study was to examine how students apply their knowledge of slope when interpreting kinematics graphs. To answer the research questions a mixed methods research design, which included a survey and interviews, was adopted. Ninety eight (N=98) high school students completed surveys which were quantitatively analyzed along with qualitative information collected from interviews of students (N=15) and teachers ( N=2). The study showed that students who recalled methods for calculating slopes and speeds calculated slopes accurately, but calculated speeds inaccurately. When comparing the slopes and speeds, most students resorted to calculating instead of visual inspection. Most students recalled and applied memorized rules. Students who calculated slopes and speeds inaccurately failed to recall methods of calculating slopes and speeds, but when comparing speeds, these students connected the concepts of distance and time to the line segments and the rates of change they represented. This study's findings will likely help mathematics and science educators to better assist their students to apply their knowledge of the definition of slope and skills in kinematics concepts.

  17. Analysis of hydrological processes in unstable clayey slopes

    NARCIS (Netherlands)

    Bogaard, T.A.

    2002-01-01

    In slope stability research a ground water level increase is often the critical factor for failure. High ground water levels (or more properly stated: high pore water pressures) reduce the internal strength of the slope. It is recognised for quite some time that fast infiltration of precipitation to

  18. Wave overtopping resistance of grassed dike slopes in Vietnam

    NARCIS (Netherlands)

    Trung, L.H.; Van der Meer, J.W.; Luong, N.Q.; Verhagen, H.J.; Schiereck, G.J.

    2011-01-01

    The resistance of various grassed slopes against wave overtopping has been appraised by means of the Wave Overtopping Simulator in situ for a couple of years in Viet Nam. Destructive test results show that a dike slope covered with grass could suffer a certain overtopping discharge not smaller than

  19. After the Slippery Slope: Dutch Experiences on Regulating Active Euthanasia

    NARCIS (Netherlands)

    Boer, Th.A.

    2003-01-01

    “When a country legalizes active euthanasia, it puts itself on a slippery slope from where it may well go further downward.” If true, this is a forceful argument in the battle of those who try to prevent euthanasia from becoming legal. The force of any slippery-slope argument, however, is by definit

  20. Slope spectrum variation in a simulated loess watershed

    Science.gov (United States)

    Li, Fayuan; Tang, Guoan; Wang, Chun; Cui, Lingzhou; Zhu, Rui

    2016-06-01

    A simulated loess watershed, where the loess material and relief properly represent the true loess surface, is adopted to investigate the variation in slope spectrum with loess watershed evolution. The evolution of the simulated loess watershed was driven by the exogenetic force of artificial rainfall. For a period of three months, twenty artificial rainfall events with different intensities and durations were carried out. In the process, nine DEM data sets, each with 10 mm grid resolution, were established by the method of close-range photogrammetry. The slope spectra were then extracted from these DEMs. Subsequent series of carefully designed quantitative analyses indicated a strong relationship between the slope spectrum and the evolution of the simulated loess watershed. Quantitative indices of the slope spectrum varied regularly following the evolution of the simulated loess watershed. Mean slope, slope spectrum information entropy ( H), terrain driving force ( T d ), Mean patch area ( AREA_MN), Contagion Index ( CONTAG), and Patch Cohesion Index ( COHESION) kept increasing following the evolution of the simulated watershed, while skewness ( S), Perimeter-Area Fractal Dimension ( PAFRAC), and Interspersion and Juxtaposition Index ( IJI) represented an opposite trend. All the indices changed actively in the early and active development periods, but slowly in the stable development periods. These experimental results indicate that the time series of slope spectra was able to effectively depict the slope distribution of the simulated loess watershed, thus presenting a potential method for modeling loess landforms.

  1. Influence of bedforms on the transverse bed slope effect

    NARCIS (Netherlands)

    Baar, A.W.; Kleinhans, M.G.; Smit, Jaco; Uijttewaal, Wim

    2016-01-01

    The deflection of sediment transport on a transverse slope due to gravity determines the large scale morphology by influencing bar dimensions and bifurcation dynamics. However, existing transverse bed slope predictors in morphodynamic models are based on a small range of flow conditions and sediment

  2. RMS slope of exponentially correlated surface roughness for radar applications

    DEFF Research Database (Denmark)

    Dierking, Wolfgang

    2000-01-01

    In radar signature analysis, the root mean square (RMS) surface slope is utilized to assess the relative contribution of multiple scattering effects. For an exponentially correlated surface, an effective RMS slope can be determined by truncating the high frequency tail of the roughness spectrum...

  3. A continuous seismic section across the continental slope off Ireland

    NARCIS (Netherlands)

    Lagaay, R.A.; Collette, B.J.

    1967-01-01

    Continuous seismic reflection data show that there are no unconsolidated sediments on the outer part of the Irish continental shelf west of Donegal Bay and on the upper part of the slope. Both the “basement” and the sediment cover on the lower part of the slope are heavily intersected, presumably by

  4. Study of Slope Reinforcement Force Based on FLAC

    Institute of Scientific and Technical Information of China (English)

    HUANG Xian-wu; MAO xian-biao; MIAO Xie-xing; CHEN Zhan-qing

    2006-01-01

    A slope will slide if the unbalanced force does not tend to zero when the stability of the slope is analyzed with the help of FLAC. Thus the ultimate reason of slope sliding is the unbalanced force determined by FLAC. The slope will remain stable if the unbalanced force is counterbalanced by a reinforcement force which is produced by a suitable reinforcement method. In this paper, the stability of the slope was analyzed by using FLAC, and the unbalanced force of the slope was obtained through the FISH function in FLAC. According to the equilibrium conditions, the relationship between the reinforcement force and unbalanced force was derived and accordingly the reinforcement force was determined. The reinforcement design was adopted by using pre-stressed anchor bars on the basis of the reinforcement force. An example is used to show that the effect of slope reinforcement based on the reinforcement force is safe and economical. The method doesn't need to suppose a sliding surface to obtain the reinforcement force, and it is also clear in physical meaning. So this method realized the organic unification of the stability analysis and the slope reinforcement

  5. Strength of the landward slopes of sea dikes in Vietnam

    NARCIS (Netherlands)

    Trung, L.H.; Verhagen, H.J.; Van der Meer, J.W.; Cat, V.M.

    2012-01-01

    The landware slopes of sea dikes in the north of Vietnam are steep and solely constructed by soil covered with grass due to the budget constraints and also the out-of-date design guidelines.The resistance against erosion due to wave overtopping of several grass covered slopes were tested with the Wa

  6. Deformation Mechanism and Stability of a Rocky Slope

    Institute of Scientific and Technical Information of China (English)

    Huang Runqiu; Xiao Huabo; Ju Nengpan; Zhao Jianjun

    2007-01-01

    A high slope is located on the side of the spillway at a hydropower station in Southwest China, which has some weak inter-layers inclining outwards. Parts of the slope show heavy weathering and unloading. There appeared deformation and tensile crack either on the surface or on the afteredge of the slope during excavation, and under a platform (elev. 488 m), two levels of slopes collapsed on the downriver side. Based on the investigation in situ and the analysis of the geological structure, the conceptual model of deformation and failure mechanism was erected for this slope. Furthermore, the deformation characteristics were studied with FLAC3D numerical simulation. Comprehensive analysis shows that the whole deformation of the slope is unloading rebound in certain depth scope and the whole body does not slide along any weak interlayer. In addition, two parts with prominent local deformation in the shallow layer of the slope show the models of "creep sliding-tensile cracking" and "sliding-tensile cracking", respectively. Based on the above analysis, the corresponding project of support and reinforcement is proposed to make the slope more stable.

  7. INFLUENCE OF LEAF AREA INDEX (LAI ON SLOPE STABILITY

    Directory of Open Access Journals (Sweden)

    Tymoteusz Adam Zydroń

    2016-09-01

    Full Text Available Determination of effect of the leaf area ratio on the results of slope stability calculation of one of the landslide's prone slope of in the Pogórze Wiśnickie was presented in the paper. The calculations were carried out in modules Vadose/W and SLOPE/W of package GeoStudio 2012. The calculations involved the integration of rainfall infiltration process and slope stability calculations. As a result, the calculations allow to determinate precipitation conditions (time and accumulated precipitation height causing slope failure (i.e. rainfall threshold. The calculation results showed significant impact of LAI on the results of modeling. It was revealed, that LAI values in range 1-3, corresponding to the grass vegetation, contribute in long-term to accumulation of precipitation within slope, which limits its retention ability when intense rainfalls occur. In turn, the leaf are index LAI = 5, corresponding to the coverage of trees, increase the retentive capacity of the soil, which resulting in delayed response of slope on rainfall with in comparison to an area covered with grass plants. It was also found significant impact of moisture content conditions on rainfall threshold. It was revealed that in case of analyzed slope threshold rainfall can be comprised from 90 mm to over 700 mm.

  8. Eastern slopes grizzly bear project : project update

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-01-01

    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.

  9. US North Slope gas and Asian LNG markets

    Science.gov (United States)

    Attanasi, E.D.

    1994-01-01

    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.

  10. Determination Of Slope Instability Using Spatially Integrated Mapping Framework

    Science.gov (United States)

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

    2016-11-01

    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.

  11. Effects of rainfall infiltration on deep slope failure

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    With the finite element method and the limit equilibrium method, a numerical model has been established for examining the effects of rainfall infiltration on the stability of slopes. This model is able to availably reflect the variations in pore pressure field in slopes, dead weight of soil, and the softening of soil strength caused by rainfall infiltration. As a case study, an actual landslide located at the Nongji Jixiao in Chongqing is studied to analyze the effects of rainfall infiltration on the seepage field and the slope stability. The simulated results show that a deep slope failure is prone to occur when rainfall infiltration will lead to a remarkable variation in the seepage field, in particular, for large range pore water pressure increase in slopes.

  12. Effects of rainfall infiltration on deep slope failure

    Institute of Scientific and Technical Information of China (English)

    SUN JianPing; LIU QingQuan; LI JiaChun; AN Yi

    2009-01-01

    With the finite element method and the limit equilibrium method, a numerical model has been estab-lished for examining the effects of rainfall infiltration on the stability of slopes. This model is able to availably reflect the variations in pore pressure field in slopes, dead weight of soil, and the softening of soil strength caused by rainfall infiltration. As a case study, an actual landslide located at the Nongji Jixiao in Chongqing is studied to analyze the effects of rainfall infiltration on the seepage field and the slope stability. The simulated results show that a deep slope failure is prone to occur when rainfall infiltration will lead to a remarkable variation in the seepage field, in particular, for large range pore water pressure increase in slopes.

  13. Long Wave Reflection and Transmission over A Sloping Step

    Institute of Scientific and Technical Information of China (English)

    Hsien-Kuo CHANG; Jin-Cheng LIOU

    2004-01-01

    This investigation examines long wave reflection and transmission induced by a sloping step. Bellman and Kalaba's(1959) invariant imbedding is introduced to find wave reflection. An alternative method matching both the surface elevation and its surface slope of each region at the junction is applied to the determination of wave reflection and transmission.The proposed methods are compared with the accurate numerical results of Porter and Porter (2000) and those of Mei(1983) for a vertical step. The wave reflection obtained for a mildly sloping step differs significantly from the result of Mei. The wave reflection is found to fluctuate owing to wave trapping for the mild sloping step. The height and the face slope of the step are important for determining wave reflection and transmission coefficients.

  14. Slope mass rating and kinematic analysis of slopes along the national highway-58 near Jonk, Rishikesh, India

    Institute of Scientific and Technical Information of China (English)

    Tariq Siddique; M. Masroor Alam; M.E.A. Mondal; V. Vishal

    2015-01-01

    The road network in the Himalayan terrain, connecting remote areas either in the valleys or on the hill slopes, plays a pivotal role in socio-economic development of India. The planning, development and even maintenance of road and rail networks in such precarious terrains are always a challenging task because of complexities posed by topography, geological structures, varied lithology and neotectonics. Increasing population and construction of roads have led to destabilisation of slopes, thus leading to mass wasting and movement, further aggravation due to recent events of cloud bursts and unprecedented flash floods. Vulnerability analysis of slopes is an important component for the“Landslide Hazard Assessment”and“Slope Mass Characterisation” guide planners to predict and choose suitable ways for construction of roads and other engineering structures. The problem of landslides along the national highway-58 (NH-58) from Rishikesh to Devprayag is a common scene. The slopes along the NH-58 between Jonk and Rishikesh were investigated, which experienced very heavy traffic especially from March to August due to pilgrimage to Kedarnath shrine. On the basis of slope mass rating (SMR) investigation, the area falls in stable class, and landslide susceptibility score (LSS) values also indicate that the slopes under investi-gation fall in low to moderate vulnerability to landslide. More attentions should be paid to the slopes to achieve greater safe and economic benefits along the highway.

  15. Effect of slope height and horizontal forces on the bearing capacity of strip footings near slopes in cohesionless soil

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Damkilde, Lars; Krabbenhøft, Kristian

    2016-01-01

    The problem of determining the bearing capacity of a strip foundation located near a slope of infinite height has been dealt with by several authors. Very often in practical problems the slope is of limited height, and furthermore the resulting load may be inclined at an angle to the horizontal, ...

  16. Slope mass rating and kinematic analysis of slopes along the national highway-58 near Jonk, Rishikesh, India

    Directory of Open Access Journals (Sweden)

    Tariq Siddique

    2015-10-01

    Full Text Available The road network in the Himalayan terrain, connecting remote areas either in the valleys or on the hill slopes, plays a pivotal role in socio-economic development of India. The planning, development and even maintenance of road and rail networks in such precarious terrains are always a challenging task because of complexities posed by topography, geological structures, varied lithology and neotectonics. Increasing population and construction of roads have led to destabilisation of slopes, thus leading to mass wasting and movement, further aggravation due to recent events of cloud bursts and unprecedented flash floods. Vulnerability analysis of slopes is an important component for the “Landslide Hazard Assessment” and “Slope Mass Characterisation” guide planners to predict and choose suitable ways for construction of roads and other engineering structures. The problem of landslides along the national highway-58 (NH-58 from Rishikesh to Devprayag is a common scene. The slopes along the NH-58 between Jonk and Rishikesh were investigated, which experienced very heavy traffic especially from March to August due to pilgrimage to Kedarnath shrine. On the basis of slope mass rating (SMR investigation, the area falls in stable class, and landslide susceptibility score (LSS values also indicate that the slopes under investigation fall in low to moderate vulnerability to landslide. More attentions should be paid to the slopes to achieve greater safe and economic benefits along the highway.

  17. The effects of plant density of Melastoma malabathricum on the erosion rate of slope soil at different slope orientations

    Institute of Scientific and Technical Information of China (English)

    Aimee Halim n; Osman Normaniza

    2015-01-01

    abstract Malaysia's cut slopes, especially for road lines accommodation, are prone to erosions and landslides. These problems mainly occur due to lack of vegetation cover and strong erosive forces. In addition, the topography factors have also become a major factor affecting soil degradation. Thus, this study is aimed at determining the effects of planting density of a selected species, namely Melastoma malabathricum;one, two, and three seedlings per box, on the erosion rate at selected slopes of different orientation (morning and evening sun) at the Guthrie Corridor Expressway, Selangor. In six months of observation, treatment with three seedlings/box on the morning sun slope showed a lower erosion rate by 69.2%than those with the same treatment on the evening sun slope. In addition, the treatment of the three seedlings recorded at month six (final observation) had the highest reduction of soil saturation level (STL), by 23.6%. Furthermore, the physiological values of the species studied, grown on the morning sun slope, were higher in terms of stomatal conductance and photosynthetic rate by 12.1%and15.8%(three seedlings/box), respectively. The overall results showed that plant density was inversely related to the STL and erosion rate on the slope. In conclusion, a planting density of three seedlings/box and morning sun orientation gave positive effects on the plant's physiological performance of the slope, reducing the STL, as well as alleviating the erosion rate of slope soils.

  18. Biomechanics and Physiology for Propelling Wheelchair Uphill Slope.

    Science.gov (United States)

    Hashizume, Tsutomu; Kitagawa, Hiroshi; Lee, Hokyoo; Ueda, Hisatoshi; Yoneda, Ikuo; Booka, Masayuki

    2015-01-01

    A vertical slope of sidewalks significantly inhibits to the mobility of manual wheelchair users in their daily life. International guidelines of the vertical slope are specified approximately 4% or 5% (1:20) gradient or less as preferred, and allow 8.3% (1:12) as its maximum when it is impossible. Relevant research of the physical strain for wheelchair users with pushing on slopes, and the validity assessment of slope guidelines have been investigated. However, the analysis for the effect of a slope distance and their transient performance are still remained. The purpose of this study is to clarify the physiological and biomechanical characteristics of manual wheelchair users that propelling a wheelchair on an uphill slope. We measured these data by a metabolic analysis system, a heart rate monitor system and an instrumented wheelchair wheel. Sixteen unimpaired subjects (non-wheelchair users) were examined to investigate the effect of a long slope with 120m distance and 8% gradient. And five wheelchair users with cervical cord injury were examined to evaluate the influence of different gradients (5%, 6.7%, 8.3%, 10% and 12.5%) with 3m length in laboratory. Our experimental results of the long slope showed that wheelchair propulsion velocity and power increased considerably at the beginning of the slope where the peak mean value of them were 0.96 m/s and 70.8W and they decreased linearly to 0.55m/s and 33.6W at final interval. A mean oxygen uptake and heart rate were increased as the distance increased and their results indicated the extremely high exercise intensity at a final interval that were 1.2liter /min and 152bpm. While wheelchair pushing cadence reduced after an initial interval, mean of strokes per10m increased to compensate the decrease of upper limb's power. The results of different gradients indicated that the normalized power of subjects with cervical cord injury was significant difference between each subject in the ability to climb a slope. Mean

  19. Anisotropy of Soil Hydraulic Properties Along Arable Slopes

    Institute of Scientific and Technical Information of China (English)

    JING Yuan-Shu; ZHANG Bin; A.THIMM; H.ZEPP

    2008-01-01

    The spatial variations of the soil hydraulic properties were mainly considered in vertical direction.The objectives of this study were to measure water-retention curves,θ(ψ),and unsaturated hydraulic conductivity functions,K(ψ),of the soils sampled at different slope positions in three directions,namely,in vertical direction,along the slope and along the contour,and to determine the effects of sampling direction and slope position of two soil catenas.At the upper slope positions,the surface soils (0-10 cm) sampled in the vertical direction had a lower soil water content,θ,at a certain soil water potential (-1500 kPa <ψ<-10 kPa) and had the greatest unsaturated hydraulic conductivity,K,at ψ> -10kPa.At the lower slope positions,K at ψ>-10 kPa was smaller in the vertical direction than in the direction along the slope.The deep soils (100-110 cm) had similar soil hydraulic properties in all the three directions.The anisotropic variations of the hydraulic properties of the surface soils were ascribed to the effects of natural wetting and drying cycles on the structural heterogeneity.These results suggested that the anisotropy of soil hydraulic properties might be significant in influencing soil water movement along the slope and need to be considered in modeling.

  20. Surface Macrofabric of Boulder Dominated Desert Mountain Slopes, California, USA

    Institute of Scientific and Technical Information of China (English)

    Donald A. FRIEND

    2005-01-01

    Rhyolite domes formed over a million year continuum in eastern California are used to study boulder dominated slopes. Slopes in this study are steep (~25° to ~35°) and are made of coarse boulder sized blocks. These slopes include well varnished vertically oriented eolluvial deposits that have been likened to relict periglacial stone stripes, or as indicated in this study, are the result of ongoing desert slope processes. The deposits are common throughout the arid southwestern US, but their morphometric character, fabric, and rates of formation have not been assessed systematically.Results indicate that boulder deposits examined here are remnant from the original surface formed during volcanic eruption and that these boulder slope deposits evolve slowly. Grain size, grain shape and grain angularity do not change significantly from genesis to ~0.6 Ma; trends in the data change markedly after that time. Mean eigenvectors indicate a fabric oriented downhill, parallel to the slope,consistent with the visual impression that long thin to plate-like rocks orient themselves similarly; however,fabric is actually randomly dispersed, similar to that at slope genesis, as indicated by the eigenvalue analysis resultants of C and K. Interestingly, grains remain or become more angular over the million-year time scale of the study as they decrease in size,indicating active in situ weathering processes on individual grains; this result is counter to the common assumption that as grains weather they become more rounded over time.

  1. Slope gradient and shape effects on soil profiles in the northern mountainous forests of Iran

    Science.gov (United States)

    Fazlollahi Mohammadi, M.; Jalali, S. G. H.; Kooch, Y.; Said-Pullicino, D.

    2016-12-01

    In order to evaluate the variability of the soil profiles at two shapes (concave and convex) and five positions (summit, shoulder, back slope, footslope and toeslope) of a slope, a study of a virgin area was made in a Beech stand of mountain forests, northern Iran. Across the slope positions, the soil profiles demonstrated significant changes due to topography for two shape slopes. The solum depth of the convex slope was higher than the concave one in all five positions, and it decreased from the summit to shoulder and increased from the mid to lower slope positions for both convex and concave slopes. The thin solum at the upper positions and concave slope demonstrated that pedogenetic development is least at upper slope positions and concave slope where leaching and biomass productivity are less than at lower slopes and concave slope. A large decrease in the thickness of O and A horizons from the summit to back slope was noted for both concave and convex slopes, but it increased from back slope toward down slope for both of them. The average thickness of B horizons increased from summit to down slopes in the case of the concave slope, but in the case of convex slope it decreased from summit to shoulder and afterwards it increased to the down slope. The thicknesses of the different horizons varied in part in the different positions and shape slopes because they had different plant species cover and soil features, which were related to topography.

  2. Research on the slope spectrum of the Loess Plateau

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new concept dealing with digital analysis of loess terrain,slope spectrum,is presented and discussed in this paper,by introducing its characteristic,represen-tation and extracting method from DEMs. Using 48 geomorphological units in dif-ferent parts of the loess as test areas and 5 m-resolution DEMs as original test data,the quantitative depiction and spatial distribution of slope spectrum in China’s Loess Plateau have been studied on the basis of a series of carefully-designed experiments. In addition,initial experiment indicates a strong relationship between the slope spectrum and the loess landform types,displaying a potential importance of the slope spectrum in geomorphological studies. Based on the slope spectrums derived from the 25 m-resolution DEM data in whole loess terrain in northern part of Shaanxi,13 slope spectrum indices were extracted and integrated into a compre-hensive layer with image integration method. Based on that,a series of unsuper-vised classifications was applied in order to make a landform classification in northern Shaanxi Loess Plateau. Experimental results show that the slope spec-trum analysis is an effective method in revealing the macro landform features. A continuous change of slope spectrum from south to north in northern Shaanxi Loess Plateau shows an obvious spatial distribution of different loess landforms. This also proves the great significance of the slope spectrum method in describing the terrain roughness and landform evolution as well as a further understanding on landform genesis and spatial distribution rule of different landforms in the Loess Plateau.

  3. Water content distribution in the surface layer of Maoping slope

    Institute of Scientific and Technical Information of China (English)

    LIU Yuewu; CHEN Huixin; LIU Qingquan; GONG Xin; ZHANG Dawei; LI Lianxiang

    2005-01-01

    The water content distribution in the surface layer of Maoping slope has been studied by testing the water content at 31 control sites. The water content profiles at these sites have also been determined. The water content distributions at different segments have been obtained by using the Kriging method of geostatistics. By comparing the water content distributions with the landform of the slope, it was shown that the water content is closely dependent on the landform of the slope. The water content distribution in the surface layer provided a fundamental basis for landslide predication and treatment.

  4. Heliostat field cost reduction by `slope drive' optimization

    Science.gov (United States)

    Arbes, Florian; Weinrebe, Gerhard; Wöhrbach, Markus

    2016-05-01

    An algorithm to optimize power tower heliostat fields employing heliostats with so-called slope drives is presented. It is shown that a field using heliostats with the slope drive axes configuration has the same performance as a field with conventional azimuth-elevation tracking heliostats. Even though heliostats with the slope drive configuration have a limited tracking range, field groups of heliostats with different axes or different drives are not needed for different positions in the heliostat field. The impacts of selected parameters on a benchmark power plant (PS10 near Seville, Spain) are analyzed.

  5. Mass movement slope streaks imaged by the Mars Orbiter Camera

    Science.gov (United States)

    Sullivan, Robert; Thomas, Peter; Veverka, Joseph; Malin, Michael; Edgett, Kenneth S.

    2001-10-01

    Narrow, fan-shaped dark streaks on steep Martian slopes were originally observed in Viking Orbiter images, but a definitive explanation was not possible because of resolution limitations. Pictures acquired by the Mars Orbiter Camera (MOC) aboard the Mars Global Surveyor (MGS) spacecraft show innumerable examples of dark slope streaks distributed widely, but not uniformly, across the brighter equatorial regions, as well as individual details of these features that were not visible in Viking Orbiter data. Dark slope streaks (as well as much rarer bright slope streaks) represent one of the most widespread and easily recognized styles of mass movement currently affecting the Martian surface. New dark streaks have formed since Viking and even during the MGS mission, confirming earlier suppositions that higher contrast dark streaks are younger, and fade (brighten) with time. The darkest slope streaks represent ~10% contrast with surrounding slope materials. No small outcrops supplying dark material (or bright material, for bright streaks) have been found at streak apexes. Digitate downslope ends indicate slope streak formation involves a ground-hugging flow subject to deflection by minor topographic obstacles. The model we favor explains most dark slope streaks as scars from dust avalanches following oversteepening of air fall deposits. This process is analogous to terrestrial avalanches of oversteepened dry, loose snow which produce shallow avalanche scars with similar morphologies. Low angles of internal friction typically 10-30¡ for terrestrial loess and clay materials suggest that mass movement of (low-cohesion) Martian dusty air fall is possible on a wide range of gradients. Martian gravity, presumed low density of the air fall deposits, and thin (unresolved by MOC) failed layer depths imply extremely low cohesive strength at time of failure, consistent with expectations for an air fall deposit of dust particles. As speed increases during a dust avalanche, a

  6. Cut slope reinforcement technique in open-pit mines

    Institute of Scientific and Technical Information of China (English)

    Yongtao Gao; Jianbo Sun; Shunchuan Wu; Aibing Jin

    2004-01-01

    The design and practice in supporting the cut slope of an open-pit mine were introduced, in which the high pressure grouting method was used in reinforcing the weak formation in the slopes. Based on a detailed geological survey of the slope, a theoretical analysis was carried out, and the design parameters were proposed, where the Tresca or Mohr-Coulomb yield criteria was employed. A patent technology, named "Technology of high pressure and multiple grouting in different levels within a single hole", was employed in the construction. Anchor bars were also installed as grouting proceeds. This method combines anchoring and grouting comprehensively and was found successful in practice.

  7. Slope Deformation Prediction Based on Support Vector Machine

    Directory of Open Access Journals (Sweden)

    Lei JIA

    2013-07-01

    Full Text Available This paper principally studies the prediction of slope deformation based on Support Vector Machine (SVM. In the prediction process,explore how to reconstruct the phase space. The geological body’s displacement data obtained from chaotic time series are used as SVM’s training samples. Slope displacement caused by multivariable coupling is predicted by means of single variable. Results show that this model is of high fitting accuracy and generalization, and provides reference for deformation prediction in slope engineering.

  8. Stability analysis of slopes of expansive soils considering rainfall effect

    Institute of Scientific and Technical Information of China (English)

    ZHU Fang-cai

    2007-01-01

    Typical failure types of slopes of expansive soils are divided to two kinds: slip in surface layer and slip in shallow layer. Based on total strength law of expansive soils, the relationship between its water content and shear strength inculding cohesion and friction angle, was studied in detail. Acoording to change of water content and depth effect during rainfall, distribution of shear strength in slopes of expansive soils was analyzed. Finally,with a slope of expansive soils in Nanning city of Guangxi Autonomous Region of China as a case, safety factor and slip surface was studied.

  9. Dynamic characteristics and simulation of traffic flow with slope

    Institute of Scientific and Technical Information of China (English)

    He Hong-Di; Lu Wei-Zhen; Xue Yu; Dong Li-Yun

    2009-01-01

    This paper proposes a new traffic model to describe traffic flow with slope under consideration of the gravity effect. Based on the model, stability analysis is conducted and a numerical simulation is performed to explore the characteristics of the traffic flow with slope. The result shows that the perturbation of the system is an inherent one,which is induced by the slope. In addition, the hysteresis loop is represented through plotting the figure of velocity against headway and highly depends on the slope angle. The kinematic wave at high density is also obtained through reproducing the phenomenon of stop-and-go traffic, which is significant to explore the phase transition of traffic flow and the evolution of traffic congestion.

  10. Hadronic Cross Sections, Elastic Slope and Physical Bounds

    CERN Document Server

    Fagundes, D A

    2012-01-01

    An almost model-independent parametrization for the ratio of the total hadronic cross section to elastic slope is discussed. Its applicability in studies of asymptotia and analyses of extensive air shower in cosmic-ray physics is also outlined.

  11. North Slope, Alaska ESI: M_MAMMAL (Marine Mammal Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for whales, seals, walruses, and polar bears for the North Slope of Alaska. Vector polygons in this data...

  12. Percent Agricultural Land Cover on Steep Slopes (Future)

    Data.gov (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....

  13. North Slope, Alaska ESI: T_MAMMAL (Terrestrial Mammal Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for brown bears, caribou, and muskoxen for the North Slope, Alaska. Vector polygons in this data set...

  14. Submarine landslides along the eastern Mediterranean Israeli continental slope

    Science.gov (United States)

    Reuven, Einav; Katz, Oded; Aharonov, Einat

    2013-04-01

    Numerous shallow submarine slope failures (scars and deposits) are observed in recent high resolution bathymetric grids of the continental slope off the Israeli eastern Mediterranean coast. The nature of these slope failures is currently not comprehensively understood as well as the question of whether the eastern Mediterranean continental slope is continuously or episodically unstable. We report here first steps towards understanding the present state of this submarine landslide system, which include mapping and analyzing the geology of the landslides and the hosting slopes. The continental slope extends from water depths of about 150 to more than 1000 meters with a slope of less than 5 degrees in general. Bathymetric grids with pixel resolution of 15 m till water depth of 700 m and 50 m till water depth of 1700 m were used. Analyzing the bathymetry revealed three main submarine surface features: (a) numerous shallow landslides, within the upper sequence of the post-Messenian sediments. Landslide widths range between hundreds to thousand of meters at the scar, with scar heights up to hundred meters. The toes of the landslides are not always mapable and lay up to a few kilometers down slope from the scar. Slope angles within the scars are 5 to more than15 degrees. At least two types of landslides were detected: presumably young slides with sharp scars, and presumably old slides with secondary slides and secondary drainage systems developed within the scar area; (b) a few kilometers long, north striking step-like lineaments. Step heights are up to 100 meters and the slopes are up to 20 degrees. The offset between parallel steps is less than a kilometer to a few kilometers. The steps are interpreted as surface expressions of growth faults rooted at the Messinian evaporates up to 1.5 kilometers below surface; (c) a few north striking channels were also detected with steep walls of more than 15 degrees, up to two kilometers width and a few kilometers length. The nature

  15. Research on the Slope Protection Mechanism of Roots

    Directory of Open Access Journals (Sweden)

    Juan Wan

    2013-08-01

    Full Text Available This study aims to investigate the slope protection mechanism of roots. In ecological slope protection, plant roots can fix soil and protect slop through biological and mechanical action. However, previous studies on the slope protection mechanism are still not deep enough and inadequate. By taking four kinds of typical plant roots along Wu-Shen Expressway as the research object, through the indoor tensile test and root morphology observation analysis, the tensile strength and ultimate tension were studied and the influence to the stability of the slope was discussed in this study. The results show that the mean ultimate tension of roots is 7.19~29.96 N. The mean tension of shrub roots is 2~4 times greater than that of herb roots. The ultimate tension of the same plant roots increases with the diameter significantly. To the range of improvement, Shrub roots exceed herb ones. It also indicates that the mean tensile strength of roots are 24.48~74.25 MPa. Compared with the steel HRB235, the tensile strength of herb roots is as great as 1/5~1/3, while Shrub roots is about 1/10~1/5. The slope stability coefficient with plant growing is a positive correlation with roots tension and root number through the sliding surface and is a negative correlation with plants weight. In addition, the slope stability coefficient is related to plant density and root morphology. The test results demonstrate that the roots tension with acute angle or right angle to the landslide surface and the roots shear stiffness with obtuse angle can improve the performance of slope’s anti-slide. Four kinds of plants can improve the stability coefficient of shallow soil. As for the slope protection effect, herbage is superior to shrub. In general, grass-shrub mixed community is the ideal system for slope protection.

  16. Reliability Analysis of Slope Stability by Central Point Method

    OpenAIRE

    Li, Chunge; WU Congliang

    2015-01-01

    Given uncertainty and variability of the slope stability analysis parameter, the paper proceed from the perspective of probability theory and statistics based on the reliability theory. Through the central point method of reliability analysis, performance function about the reliability of slope stability analysis is established. What’s more, the central point method and conventional limit equilibrium methods do comparative analysis by calculation example. The approach’s numerical ...

  17. Recurring Slope Lineae in Mid-Latitude and Equatorial Mars

    Science.gov (United States)

    McEwen, A. S.; Dundas, C. M.; Mattson, S.; Toigo, A. D.; Ojha, L.; Wray, J. J.; Chojnacki, M.; Byrne, S.; Murchie, S. L.; Thomas, N.

    2013-12-01

    A key to potential present-day habitability of Mars is the presence of liquid H2O (water). Recurring slope lineae (RSL) could be evidence for the seasonal flow of water on relatively warm slopes. RSL are narrow (250 K to >300 K. In the past year we have monitored active RSL in equatorial (0°-15°S) regions of Mars, especially in the deep canyons of Valles Marineris. They are especially active on north-facing slopes in northern summer and spring and on south-facing slopes in southern spring and summer, following the most normal solar incidence angles on these steep slopes. However, predicted peak temperatures for north-facing slopes are nearly constant throughout the Martian year because orbital periapse occurs near the southern summer solstice. Although warm temperatures and steep low-albedo slopes are required, some additional effect besides temperature may serve to trigger and stop RSL activity. Seasonal variation in the atmospheric column abundance of water does not match the RSL activity. Although seasonal melting of shallow ice could explain the mid-latitude RSL, the equatorial activity requires a different explanation, perhaps migration of briny groundwater. To explain RSL flow lengths, exceeding 1 km in Valles Marineris, the water is likely to be salty. Several RSL attributes are not yet understood: (1) the relation between apparent RSL activity and dustiness of the atmosphere; (2) salt composition and concentration; (3) variability in RSL activity from year to year; (4) seasonal activity on north-facing equatorial slopes in spite of little change in temperature; and (5) temporal changes in the color properties of fans where RSL terminate. Continued orbital monitoring, laboratory experiments, and future orbital and landed exploration with new measurement types are needed. Equatorial water activity, if confirmed, creates new exploration opportunities and challenges. RSL >1 km long near boundary between Eos and Capri Chasmata of Valles Marineris, Mars.

  18. Reliability analysis method for slope stability based on sample weight

    Directory of Open Access Journals (Sweden)

    Zhi-gang YANG

    2009-09-01

    Full Text Available The single safety factor criteria for slope stability evaluation, derived from the rigid limit equilibrium method or finite element method (FEM, may not include some important information, especially for steep slopes with complex geological conditions. This paper presents a new reliability method that uses sample weight analysis. Based on the distribution characteristics of random variables, the minimal sample size of every random variable is extracted according to a small sample t-distribution under a certain expected value, and the weight coefficient of each extracted sample is considered to be its contribution to the random variables. Then, the weight coefficients of the random sample combinations are determined using the Bayes formula, and different sample combinations are taken as the input for slope stability analysis. According to one-to-one mapping between the input sample combination and the output safety coefficient, the reliability index of slope stability can be obtained with the multiplication principle. Slope stability analysis of the left bank of the Baihetan Project is used as an example, and the analysis results show that the present method is reasonable and practicable for the reliability analysis of steep slopes with complex geological conditions.

  19. Alternative method for direct measurement of tibial slope

    Directory of Open Access Journals (Sweden)

    Stijak Lazar

    2014-01-01

    Full Text Available Background/Aim. The tibial slope is one of the most frequently cited anatomical causes of anterior cruciate ligament trauma. The aim of this study was to determine the possibility of direct measuring of the tibial slope of the knee without prior soft tissue dissection in cadavers. Methods. Measurement was performed on the two groups of samples: osteological and cadaveric. The osteological group consisted of 102 matured tibiae and measurement was performed: indirectly by sagittal photographing of the tibia, and directly by a set of parallel bars. The cadaveric group consisted of 50 cadaveric knees and measurement was performed directly by a set of parallel bars. The difference and correlation between indirect and the direct measurements were observed, which included also measuring of the difference and correlation of the tibial slope on the medial and lateral condyles. Results. A statistically significant difference between the direct and indirect method of measuring (p 0.05. However, the slope on the medial condyle, as well as indirect measurement showed a statistically significant difference (p < 0.01. Conclusion. By the use of a set of parallel bars it is possible to measure the tibial slope directly without removal of the soft tissue. The results of indirect, photographic measurement did not statistically differ from the results of direct measurement of the tibial slope.

  20. Relating weak layer and slab properties to snow slope stability

    Directory of Open Access Journals (Sweden)

    J. Schweizer

    2014-07-01

    Full Text Available Snow slope stability evaluation requires considering weak layer as well as slab properties – and in particular their interaction. We developed a stability index from snow micro-penetrometer measurements and compared it to 129 concurrent point observations with the compression test (CT. The index considers the SMP-derived micro-structural strength and the additional load which depends on the hardness of the surface layers. The new quantitative measure of stability discriminated well between point observations rated as either "poor" or "fair" (CT < 19 and those rated as "good" (CT ≥ 19. However, discrimination power within the intermediate range was low. We then applied the index to gridded snow micro-penetrometer measurements from 11 snow slopes to explore the spatial structure and possibly relate it to slope stability. Stability distributions on the 11 slopes reflected various possible strength and load (stress distributions that naturally can occur. Their relation to slope stability was poor possibly because the index does not consider crack propagation. Hence, the relation between spatial patterns of point stability and slope stability remains elusive. Whereas this is the first attempt of a truly quantitative measure of stability, future developments should consider a better reference of stability and incorporate a measure of crack propagation.

  1. Quantifying Slopes with Digital Elevation Models of the Verdugo Hills, California: Effects of Resolution

    Science.gov (United States)

    Fielding, E. J.; Burbank, D. W.; Duncan, C. C.

    1996-01-01

    Quantification of surface slope angles is valuable in a wide variety of earth sciences. Slopes measured from digital elevation models (DEMs) or other topographic data sets depend strongly on the length scale or window size used in the slope calculations.

  2. Slope Derivative Surface used to characterize the complexity of the seafloor around St. John, USVI

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Slope was calculated from the bathymetry surface for each raster cell using ArcGIS's Spatial Analyst 'Slope' Tool. Slope describes the maximum steepness of a terrain...

  3. Soil properties in high-elevation ski slopes

    Science.gov (United States)

    Filippa, Gianluca; Freppaz, Michele; Letey, Stéphanie; Corti, Giuseppe; Cocco, Stefania; Zanini, Ermanno

    2010-05-01

    The development of winter sports determines an increasing impact on the high altitude ecosystems, as a consequence of increased participation and an increasing demand of high quality standards for skiable areas. The construction of a ski slope is associated with a certain impact on soil, which varies as a function of the degree of human-induced disturbance to the native substrata. In this work, we provide a description of the characteristics of alpine tundra ski-slope soils and their nutrient status, contrasted with undisturbed areas. The study site is located in the Monterosaski Resort, Aosta Valley, NW Italy (45°51' N; 7°48' E). We chose 5 sites along an altitudinal gradient between 2700 and 2200 m a.s.l.. Per each site, one plot was established on the ski slope, while a control plot was chosen under comparable topographic conditions a few meters apart. Soils were described and samples were collected and analysed for main chemical-physical properties. In addition an evaluation of N forms, organic matter fractionation and microbial biomass was carried out. Soil depth ranged between 10 to more than 70 cm, both on the ski slope and in the undisturbed areas. A true organo-mineral (A) horizon was firstly identified at 2500 m a.s.l., while a weathering horizon (Bw) was detected at 2400 m a.s.l.. However, a Bw horizon thick enough to be recognised as diagnostic for shifting soil classification order from Entisols to Inceptisols (USDA-Soil Taxonomy) was detected only below 2400 m a.s.l.. Lithic Cryorthents were predominant in the upper part of the sequence (above 2500 m a.s.l.), both in the ski slope and the undisturbed areas; Typic Cryorthents were identified between 2500 and 2400 m a.s.l., while Inceptisols were predominant between 2400 and 2200 m a.s.l.. Chemical-physical properties will be discussed focusing on the main differences between ski slope and undisturbed soils, as determined by the ski slope construction. Pedogenetic processes at high altitude are

  4. Landslides induced by heavy rainfall in July 2012 in Northern Kyushu District, Japan and the influence of long term rainfall increase comparing with the slope destabilization due to strong seismic shaking

    Science.gov (United States)

    Kubota, Tetsuya; Shinohara, Yoshinori; Aditian, Aril

    2013-04-01

    soil strength reduction by seismic shaking. The target areas are located in northern Kyushu district, western Japan where they often have severe landslide disasters. The geology in research areas consists of Paleozoic and Mesozoic rocks (mainly schist, slate) and Quaternary volcanic sediment such as Aso volcano body. The vegetation consists of mainly Japanese cypress, cedar or bamboo. 3. Result and consideration Consequently, the long term rainfall increase in the region such as increment of approximately 20 mm/hr for rain intensity Ri in 36 years is confirmed statistically using Kendall's rank correlation, and it is found that its impact on slope stability is considerable and critical in other cases. In the sample landslide slopes, even the increase in rain of duration for only 10 years has impact to a certain extent on their stabilities in terms of Fs. The Fs calculated with rains in previous decade is higher than 1.0 that corresponds to stable state, whereas the Fs with present rains is lower than 1.0 such as 0.99 which means unstable state. Extremely heavy rainfall with this impact is generally cause extreme ground water pressure in the slope. It is also obvious that the extreme ground water content rendered even small landslides liquefied to be source of destructive debris flows. In this disaster, especially in the Aso volcanic region, tremendous number of debris flow occurred and even the talus cone slopes which are usually stable collapsed to flow down. However, the influence of the long term rainfall increase on the slopes (such as 1% decrease in Fs) is not relatively small compared with the destabilization of the slopes due to the reduction of soil strength by seismic shaking (8~9 % reduction in Fs after seismic shaking of even 490gal). 4. Conclusion In the disaster in July 2012, many landslides and debris flows originated from landslides induced by concentrated underground water supplied by the heavy rainfall occurred. The increase of rainfall due to climate

  5. Prótese do tornozelo híbrida em um caso de necrose avascular pós-traumática do tálus Hybrid ankle prosthesis in a case of post-traumatic avascular necrosis of the talus

    Directory of Open Access Journals (Sweden)

    Ricardo Jorge Gomes de Sousa

    2011-01-01

    Full Text Available As fraturas do astrágalo originam frequentemente artrose pós-traumática tardia. Nestes casos, a utilização de próteses do tornozelo não cimentadas de última geração tem sido evitada pela presença de necrose avascular. Relatamos o caso de um paciente com 65 anos que se apresenta quatro anos após uma fratura do colo do astrágalo. Apresentava uma artrose do tornozelo dolorosa (escala AOFAS do retropé e tornozelo 19 e necrose avascular com colapso de toda a cúpula astragalina. Dada a extensão da necrose, foi decidido cimentar o componente protésico astragalino. Um ano após a cirurgia, o paciente apresenta bom resultado clínico e radiológico (escala AOFAS do retropé e tornozelo 87 e está satisfeito com o procedimento. Não temos conhecimento de nenhum relato semelhante na literatura.Talus fractures often lead to late post-traumatic arthrosis. In such cases, the use of latest generation, cementless prostheses has been hindered by the presence of avascular necrosis. We report the case of a 65-year-old patient who presented four years after a talus neck fracture. He had painful ankle arthrosis (AOFAS ankle-hindfoot score 19 and avascular necrosis, with collapse of the entire talar dome. Given the extent of the necrosis, it was decided to cement the talus prosthetic component. One year after the surgery, the patient shows good clinical and radiological results (AOFAS ankle-hindfoot score 87 and is satisfied with the procedure. We are not aware of any similar reports in the literature.

  6. Comprehensive evaluation of high-steep slope stability and optimal high-steep slope design by 3D physical modeling

    Science.gov (United States)

    Lai, Xing-ping; Shan, Peng-fei; Cai, Mei-feng; Ren, Fen-hua; Tan, Wen-hui

    2015-01-01

    High-steep slope stability and its optimal excavation design in Shuichang open pit iron mine were analyzed based on a large 3D physical simulation technique. An optimal excavation scheme with a relatively steeper slope angle was successfully implemented at the northwest wall between Nos. 4 and 5 exploration lines of Shuichang Iron Mine, taking into account the 3D scale effect. The physico-mechanical properties of rock materials were obtained by laboratory tests conducted on sample cores from exploration drilling directly from the iron mine. A porous rock-like composite material was formed for the model, and the mechanical parameters of the material were assessed experimentally; specifically, the effect of water on the sample was quantitatively determined. We adopted an experimental setup using stiff modular applied static loading to carry out a visual excavation of the slope at a random depth. The setup was equipped with acoustic emission (AE) sensors, and the experiments were monitored by crack optical acquirement, ground penetrating radar, and close-field photogrammetry to investigate the mechanisms of rock-mass destabilization in the high-steep slope. For the complex study area, the model results indicated a clear correlation between the model's destabilization resulting from slope excavation and the collected monitoring information. During the model simulation, the overall angle of the slope increased by 1-6 degrees in different sections. Dramatically, the modeled excavation scheme saved over 80 million tons of rock from extraction, generating enormous economic and ecological benefits.

  7. Dynamic Response and Dynamic Failure Mode of a Weak Intercalated Rock Slope Using a Shaking Table

    Science.gov (United States)

    Fan, Gang; Zhang, Jianjing; Wu, Jinbiao; Yan, Kongming

    2016-08-01

    A large-scale shaking table test was performed to study the dynamic response of slopes parallel to geological bedding (bedding slopes) and slopes that cross-cut geological bedding (counter-bedding slopes). The test results show that the acceleration amplification coefficients increase with increasing elevation and, when the input earthquake amplitude is greater than 0.3 g, both bedding and counter-bedding slopes begin to show nonlinear dynamic response characteristics. With increasing elevation, the displacement of the bedding slope surface increases greatly. Conversely, the displacement of the counter-bedding slope surface increases first and then decreases; the slope develops a bulge at the relative elevation of 0.85. The displacement of the bedding slope surface is greater than that of the counter-bedding slope. The counter-bedding slope is more seismically stable compared with the bedding slope. Based on the Hilbert-Huang transform and marginal spectrum theories, the processes that develop dynamic damage of the bedding and counter-bedding slopes are identified. It is shown that the dynamic failure mode of the bedding slope is mainly represented by vertical tensile cracks at the rear of the slope, bedding slide of the strata along the weak intercalation, and rock collapse from the slope crest. However, the dynamic failure mode of the counter-bedding slope is mainly represented by staggered horizontal and vertical fissures, extrusion of the weak intercalation, and breakage at the slope crest.

  8. Debris flows in a young mid-latitude crater on Mars: Evidence for recent water-bearing mass wasting and efficient insolation-controlled slope modification within the last

    Science.gov (United States)

    Johnsson, Andreas; Reiss, Dennis; Hauber, Ernst; Hiesinger, Harald; Zanetti, Michael

    2013-04-01

    Debris flows are moving masses of loose debris of varying grain sizes, water and air that travels down a slope under the influence of gravity. Terrestrial debris flows are mainly studied and monitored because of their hazardous nature. On Mars they may serve as important geomorphologic indicators of transient liquid water. The discovery of well-developed debris flow deposits within a very young southern mid-latitude crater (~0.2 Ma) highlights the impact of periglacial slope processes during recent climate conditions on Mars. We compared the morphology of debris flows on Svalbard as possible analogues to the observed deposits on Mars in order to infer possible formation mechanisms. Within our study crater on Mars, high-resolution imagery obtained by the HiRISE instrument (High Resolution Imaging Science Experiment) revealed typical debris-flow attributes such as overlapping terminal lobes, debris tongues, debris-flow fans, scoured channels with medial deposits (debris plugs), and well-defined lateral deposits (levées). Collectively, these attributes are found on studied debris flows on Svalbard. Additionally, our study crater's interior walls display mass-wasting with strong aspect-dependence, ranging from debris-flow dominated pole-facing slopes, to east-and-west-facing single channel gullies, and north-facing talus cones (grain flow). Our findings suggest that the debris flows are neither related to impact induced heating and release of meltwater or melting of an ice-rich mantling deposit since the latter is absent in the study crater. Instead, we propose that the debris flows are formed by melting of very recent snow deposits after the termination of the last Martian ice-age. As such it may represent one of the most recent geomorphological indicators of transient liquid water in the Martian mid-latitudes. Our study crater further illustrates the importance of regolith differences and micro-climate variability (e.g., insolation) in debris flow initiation on Mars

  9. The Influence of Slope Breaks on Lava Flow Surface Disruption

    Science.gov (United States)

    Glaze, Lori S.; Baloga, Stephen M.; Fagents, Sarah A.; Wright, Robert

    2014-01-01

    Changes in the underlying slope of a lava flow impart a significant fraction of rotational energy beyond the slope break. The eddies, circulation and vortices caused by this rotational energy can disrupt the flow surface, having a significant impact on heat loss and thus the distance the flow can travel. A basic mechanics model is used to compute the rotational energy caused by a slope change. The gain in rotational energy is deposited into an eddy of radius R whose energy is dissipated as it travels downstream. A model of eddy friction with the ambient lava is used to compute the time-rate of energy dissipation. The key parameter of the dissipation rate is shown to be rho R(sup 2/)mu, where ? is the lava density and mu is the viscosity, which can vary by orders of magnitude for different flows. The potential spatial disruption of the lava flow surface is investigated by introducing steady-state models for the main flow beyond the steepening slope break. One model applies to slow-moving flows with both gravity and pressure as the driving forces. The other model applies to fast-moving, low-viscosity, turbulent flows. These models provide the flow velocity that establishes the downstream transport distance of disrupting eddies before they dissipate. The potential influence of slope breaks is discussed in connection with field studies of lava flows from the 1801 Hualalai and 1823 Keaiwa Kilauea, Hawaii, and 2004 Etna eruptions.

  10. Slope Error Measurement Tool for Solar Parabolic Trough Collectors: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Stynes, J. K.; Ihas, B.

    2012-04-01

    The National Renewable Energy Laboratory (NREL) has developed an optical measurement tool for parabolic solar collectors that measures the combined errors due to absorber misalignment and reflector slope error. The combined absorber alignment and reflector slope errors are measured using a digital camera to photograph the reflected image of the absorber in the collector. Previous work using the image of the reflection of the absorber finds the reflector slope errors from the reflection of the absorber and an independent measurement of the absorber location. The accuracy of the reflector slope error measurement is thus dependent on the accuracy of the absorber location measurement. By measuring the combined reflector-absorber errors, the uncertainty in the absorber location measurement is eliminated. The related performance merit, the intercept factor, depends on the combined effects of the absorber alignment and reflector slope errors. Measuring the combined effect provides a simpler measurement and a more accurate input to the intercept factor estimate. The minimal equipment and setup required for this measurement technique make it ideal for field measurements.

  11. Semisolid metal forming by novel sloping plate process

    Institute of Scientific and Technical Information of China (English)

    GUAN Ren-guo; WANG Chao; SHANG Jian-hong; XING Zhen-huan

    2006-01-01

    Semisolid metal forming by a novel sloping plate process was studied. A sloping plate with wavelike surface was used to prepare semisolid alloy. Semisolid billets and slurries with good microstructures and excellent property were prepared by cooling or preheating the sloping plate. During preparing semisolid alloy by the proposed process, the co-action of burst nucleation and dendrite fragmentation causes fine spherical microstructure formation, and casting temperature, cooling strength and sloping angle are the main factors influencing the alloy microstructure. Under the current experimental conditions, in order to prepare good quality semisolid billets, proper casting temperature ranges of 660-690 ℃ for AlMg3 alloy and 660-680 ℃ for AlSi6Mg2 alloy are suggested. A small car hub wheel of AlSi6Mg2 alloy was thixoformed, and its pattern and inner microstructure are fine. The reasonable technological conditions for preparing AlSi6Mg2 slurry are also proposed: the sloping plate preheating temperature is 300 ℃, and the casting temperature is 680 ℃.

  12. Spectral slope and Kolmogorov constant of MHD turbulence.

    Science.gov (United States)

    Beresnyak, A

    2011-02-18

    The spectral slope of strong MHD turbulence has recently been a matter of controversy. While the Goldreich-Sridhar model predicts a -5/3 slope, shallower slopes have been observed in numerics. We argue that earlier numerics were affected by driving due to a diffuse locality of energy transfer. Our highest-resolution simulation (3072(2)×1024) exhibited the asymptotic -5/3 scaling. We also discover that the dynamic alignment, proposed in models with -3/2 slope, saturates and cannot modify the asymptotic, high Reynolds number slope. From the observed -5/3 scaling we measure the Kolmogorov constant C(KA)=3.27±0.07 for Alfvénic turbulence and C(K)=4.2±0.2 for full MHD turbulence, which is higher than the hydrodynamic value of 1.64. This larger C(K) indicates inefficient energy transfer in MHD turbulence, which is in agreement with diffuse locality.

  13. On the role of topographic amplification in seismic slope instabilities

    Institute of Scientific and Technical Information of China (English)

    Fardin Jafarzadeh; Mohammad Mahdi Shahrabi; Hadi Farahi Jahromi

    2015-01-01

    Surface wave generation due to body wave propagation near ground surface has been discussed in the literature. This phenomenon, typically occurring in topographic changing areas, along with its interaction with body waves (SV), decreases precision of formulas for evaluation of slope displacement. This sig-nificant fact caused the researchers not only to investigate the combined surface and SV waves motion pattern, but also to consider its effect on structures built on the slopes. In order to reveal the phe-nomenon, several finite element numerical studies have been performed by ABAQUS programme. Be-sides, two physical model slopes simulating the landslide occurrence have been constructed and tested by shaking table device. The results of induced and calculated accelerations obtained by two approaches have been compared and Rayleigh wave generation has been proved. Furthermore, the slope displace-ments have been calculated by various empirical methods and the results were compared with nu-merical ones. The results proved that in order to increase the precision of empirical formulas for displacement prediction, surface wave effect should be taken into account. Finally, a concept of“effective depth of surficial amplification”is introduced and its effect on dynamic slope stability is analysed.

  14. Soil Erodibility of Slope Farmland in Guizhou Mountain Areas

    Institute of Scientific and Technical Information of China (English)

    Jian; LI; Li; CHENG; Zhenggang; CHEN; Qing; ZHU

    2014-01-01

    This paper studied soil erodibility of slope farmland in Guizhou mountain areas by the plot runoff method,analysis and test. Results show that the variation coefficient of erodibility K value calculated according to formula introduced by Sharply is low and relatively stable and accurate,so it is a suitable method for calculating erodibility K value of slope farmland in Guizhou mountain areas. K value of layer A slope farmland decreases with increase of years. The erodibility of entire soil layer is high,and the erosion resistance is weak. From the influence of different planting system and use types in 4 years,K values of different soil layers decrease,average reduction of A,B and C layers reaches 3. 17%- 11. 64%( 1. 26%- 12. 34% for layer A,1. 29%- 13. 80% for layer B,and 1. 26%- 10. 80% for layer C). Except engineering terraced treatment,the decline of K value of grassland,zoning crop rotation,economic fruit forest,grain and grass intercropping,plant hedge, and mixed forest treatment is higher than farmers’ treatment,and the decline level is grassland > zoning crop rotation > economic fruit forest > grain and grass intercropping > plant hedge > and mixed forest treatment. Planting grass and trees is favorable for lowering erodibility of slope farmland and improving farmland quality. Interplanting of corns with other plants can increase plant coverage and species,so it is favorable for improving erodibility of slope farmland.

  15. Landform Degradation and Slope Processes on Io: The Galileo View

    Science.gov (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.; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    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.

  16. Infinite slope stability under steady unsaturated seepage conditions

    Science.gov (United States)

    Lu, N.; Godt, J.

    2008-01-01

    [1] 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. Copyright 2008 by the American Geophysical Union.

  17. Linking Slope Sedimentation, Gradient, Morphology, and Active Faulting: An Integrated Example from the Palos Verdes Slope, Southern California Borderland

    Science.gov (United States)

    Maier, K. L.; Brothers, D. S.; Paull, C. K.; McGann, M.; Caress, D. W.; Conrad, J. E.

    2015-12-01

    Seafloor gradient variations associated with restraining and releasing bends along the active (1.6-1.9 mm/yr) right-lateral Palos Verdes Fault appear to control Holocene sediment thickness, depositional environment, and morphodynamic processes along a section of the continental slope offshore Los Angeles, California. Autonomous underwater mapping vehicle (AUV), remotely operated vehicle (ROV), and shipboard methods were used to acquire a dense grid of high-resolution chirp profiles (150 m line spacing; 11 cm vertical resolution), multibeam bathymetry (2 m grid), and targeted sediment core samples (<2 m length). Detailed interpretation of Holocene deposits in the chirp profiles combined with radiocarbon dating and laser particle-size analyses allow correlation of Holocene sediment thickness and seafloor gradient with sediment gravity flow deposits. Holocene down-slope flows appear to have been generated by mass wasting processes, primarily on the upper slope (~100-200 m water depth) where shipboard multibeam bathymetry reveals submarine landslide headwall scarps in a region that has been isolated from terrigenous sediment sources throughout the Holocene. Submarine landslides appear to have transformed into sandy and organic-rich turbidity currents that created up-slope migrating sediment waves, a low relief (<5 m) fault-bounded channel, and a series of depocenters. A down-slope gradient profile and a Holocene isopach down-slope profile show that the primary depocenter occurs within a small pull-apart basin associated with a decrease in seafloor gradient of ~1.5°. Holocene sediment-flow deposits vary in number, thickness, and character with subtle changes in seabed gradient (<0.5°) and depositional environment. These results help quantify morphodynamic sensitivity to seafloor gradients and have implications for down-slope flow dynamics, deep-water depositional architecture, Holocene sediment, nutrient, and contaminant transport, and turbidite paleoseismology along

  18. Experimental Study of Wave Breaking on Gentle Slope

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    -An experimental study of regular wave and irregular wave breaking is performed on a gentle slope of 1:200. In the experiment, asymmetry of wave profile is analyzed to determine its effect on wave breaker indices and to explain the difference between Goda and Nelson about the breaker indices of regular waves on very mild slopes. The study shows that the breaker index of irregular waves is under less influence of bottom slope i, relative water depth d/ L0 and the asymmetry of wave profile than that of regular waves. The breaker index of regular waves from Goda may be used in the case of irregular waves, while the coefficient A should be 0.15. The ratio of irregular wavelength to the length calculated by linear wave theory is 0.74. Analysis is also made on the waveheight damping coefficient of regular waves after breaking and on the breaking probability of large irregular waves.

  19. ABRUPT DEFLECTED SUPERCRITICAL WATER FLOW IN SLOPED CHANNELS

    Institute of Scientific and Technical Information of China (English)

    LIU Ya-kun; NI Han-gen

    2008-01-01

    The effect of the bottom slope on abrupt deflected supercritical water flow was experimentally and theoretically studied. Model tests were conducted in a flume of 1.2 m wide and 2.6 m long with sloped bottom at an angle 35.54o, its length of deflector was 0.2 m and the deflection angles were 15o and 30o. An approximate method for calculatjng the shock wave angle and depth ratio of the abrupt deflected supercritical water flow was suggested, and a correction coefficient for the hydrodynamic pressure was introduced to generalize the momentum equation in the direction perpendicular to the shock front. It must be noticed that in the sloped channel the shock wave angle and the depth ratio are no longer constant as those in the horizontal channels, but slowly change along the shock front. The calculated results are in good agreement with measured data.

  20. Constitutive models in stability analysis of rock slope

    Institute of Scientific and Technical Information of China (English)

    言志信; 段建; 王后裕

    2008-01-01

    Equivalent Mohr-Coulomb yield criterion was established,and the relationship between different constitutive models was studied.The application of equivalent Mohr-Coulomb yield criterion in Ansys was achieved by means of transforming material parameters.The stability research aiming at the most common rock slope without conspicuous slide surface was accomplished,the methods of measurably assessing the stability of rock slope without conspicuous slide surface were explored,and the disadvantages of method of minimum slide-resisted reserve as dangerous slide path were pointed out.The results show that through the calculation and analysis of cases,the conception that measurable assessment of the stability of rock slope without conspicuous slide surface can be achieved under condition that equivalent Mohr-Coulomb yield criterion is validated.Its safety parameter formula is explicit in theory and credible in results.The results obtained are approximate to those obtained by using finite element intensity reducing method.

  1. Forest harvesting influence on slope erosion in Baikal Basin Mountains

    Science.gov (United States)

    Onuchin, A. A.; Borisov, A. N.; Burenina, T. A.

    2009-04-01

    Post-logging recovery of forest water protection and erosion prevention functions can occur different ways on slopes and in big river catchments. While erosion decreases several times during only three to five years after logging on slopes, as compared to its immediate post-logging rate, water silt load in big rivers can remain high for decades after forest logging in their catchments. Among other factors, this can be attributable to erosion of timber transportation roads and skidding trails, which become extremely eroded 10-15 years following forest logging. One should not underestimate a probable sediment load increase resulting from post-logging channel runoff changes. Disregarding this increase leads to contradictory conclusions about post-logging recovery of forest water protecting capability. Investigating this issue requires to clearly determine the type of the forest site of interest (a certain slope, an elementary or a complex catchments) and to consider the experience gained so far in estimating erosion rate changes depending on changing forest areas of continents. Therefore, hierarchical river catchments ranking should be recognized effective and useful for forest hydrology. This approach will allow systematizing the existing information and facilitating the development of fruitful analysis of water protection and erosion prevention functions of forest in areas of different ranks. This study used an approach that enabled a single-model description of the rate of soil erosion previously estimated by different models for areas of various ranks, from a micro slope to elementary catchments. An elementary catchments is defined as the smallest drainage area characterized by uniform surface, ground, and vegetation structures and having a single well-pronounced channel, with hydro network being practically absent. Using runoff slope length as the argument and introducing a dummy variable that describes specific investigation methodologies ensured high generality

  2. A new vision of carbonate slopes: the Little Bahama Bank

    Science.gov (United States)

    Mulder, Thierry; Gillet, Hervé; Hanquiez, Vincent; Reijmer, John J.; Tournadour, Elsa; Chabaud, Ludivine; Principaud, Mélanie; Schnyder, Jara; Borgomano, Jean; Fauquembergue, Kelly; Ducassou, Emmanuelle

    2016-04-01

    Recent high-quality multibeam and seismic data allow to image a large part of the uppermost slope of Northeastern Little Bahama Bank between 30 and 400 m water depth and to characterize the uppermost slope (Rankey and Doolitle, 1992) over a surface of 170 km2. The new data set includes multibeam bathymetry and acoustic imagery, 3.5 kHz very-high resolution (VHR) seismic reflexion lines (1120 km), 21 gravity cores and 11 Van Veen grabs. This dataset completes the recent surveys of the slope adjacent to LBB (Carambar cruise, Mulder et al, 2012). The data provide insight into sediment transfer from the shallow carbonate bank to the adjacent slope. Four major terraces and escarpments dominate the morphology of the slope. The terraces are located at 22 m, 27-33 m, 40-46 and 55-64 m below present water depth (mpwd). They could either be related to periods of stagnating sea-level and therefore increased erosion by waves, or periods of accelerated sea-level rise since the Last Glacial Maximum. Escarpments bound the terraces. The deepest one (64-56 mpwd) is also the steepest 35-50°). It corresponds to the marginal scarp of Rankey and Doolitle (1992). The lower part of the uppermost slope shows a discontinuous Holocene sediment wedge with varying thickness between 0 and 35 m. It forms a blind or very crudely stratified echo facies. This Holocene unit can be thicker than 20 m and consists of mud that forms most of the present sediment export. This unit fills small depressions in the substratum and thickens in front of gullies that cut the carbonate platform edge. It forms by off-bank export initiated when a cold front passes by, resulting in density cascading currents. The associated sediment fall-out and convective sedimentation can generate density currents that flow through linear structures on the upper slope. The survey reveals the presence of recently active channels that extend laterally over the entire uppermost slope and interrupt the density cascading fall

  3. Development of a new generation of optical slope measuring profiler

    Energy Technology Data Exchange (ETDEWEB)

    Yashchuk, Valeriy V.; Takacs, Peter Z.; McKinney, Wayne R.; Assoufid, Lahsen; Siewert, Frank; Zeschke, Thomas

    2010-09-16

    A collaboration, including all DOE synchrotron labs, industrial vendors of x-ray optics, and with active participation of the HBZ-BESSY-II optics group has been established to work together on a new slope measuring profiler -- the optical slope measuring system (OSMS). The slope measurement accuracy of the instrument is expected to be<50 nrad for the current and future metrology of x-ray optics for the next generation of light sources. The goals were to solidify a design that meets the needs of mirror specifications and also be affordable; and to create a common specification for fabrication of a multi-functional translation/scanning (MFTS) system for the OSMS. This was accomplished by two collaborative meetings at the ALS (March 26, 2010) and at the APS (May 6, 2010).

  4. VARIABILITY OF ARABLE AND FOREST SOILS PROPERTIES ON ERODED SLOPES

    Directory of Open Access Journals (Sweden)

    Paweł Wiśniewski

    2014-10-01

    Full Text Available The basic method of reducing soil and land erosion is a change of land use, for example, from arable to forest. Particularly effective as a protective role – according to the Polish law – soil-protecting forests. The thesis presents differences in the deformation of the basic soil properties on moraine slopes, depending on land use. There has been presented the function and the efficiency of the soil-protecting forests in erosion control. The soil cross section transects and soil analysis displayed that soil-protecting forests are making an essential soil cover protection from degradation, inter alia, limiting the decrease of humus content, reduction of upper soil horizons and soil pedons layer. On the afforested slopes it was stated some clear changes of grain size and chemical properties of soils in relation to adjacent slopes agriculturally used.

  5. The Socioeconomic Assessment of Sloping Land Conversion Program in China

    DEFF Research Database (Denmark)

    Liu, Zhen

    , reduction of compensation payment rate lowers the treatment effect of the SLCP on participating households from both River basins. Lastly, the third paper, ― The effect of the Sloping Land Conversion Program on farm household productivity in rural China, investigates the treatment effect (the causal effect......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 household survey data, this study aims to improve our understanding of the treatment effect of the SLCP on farm households, which is split into three parts. The first paper ― The Sloping Land Conversion Program in China: Effects on Rural Households’ Livelihood Diversification, evaluates the effects...

  6. Newton slopes for Artin-Schreier-Witt towers

    DEFF Research Database (Denmark)

    Davis, Christopher James; Wan, Daqing; Xiao, Liang

    2016-01-01

    We fix a monic polynomial f(x)∈Fq[x] over a finite field and consider the Artin-Schreier-Witt tower defined by f(x); this is a tower of curves ⋯→Cm→Cm−1→⋯→C0=A1, with total Galois group Zp. We study the Newton slopes of zeta functions of this tower of curves. This reduces to the study of the Newton...... slopes of L-functions associated to characters of the Galois group of this tower. We prove that, when the conductor of the character is large enough, the Newton slopes of the L-function form arithmetic progressions which are independent of the conductor of the character. As a corollary, we obtain...

  7. Rock mass characterisation and stability analyses of excavated slopes

    Science.gov (United States)

    Zangerl, Christian; Lechner, Heidrun

    2016-04-01

    Excavated slopes in fractured rock masses are frequently designed for open pit mining, quarries, buildings, highways, railway lines, and canals. These slopes can reach heights of several hundreds of metres and in cases concerning open pit mines slopes larger than 1000 m are not uncommon. Given that deep-seated slope failures can cause large damage or even loss of life, the slope design needs to incorporate sufficient stability. Thus, slope design methods based on comprehensive approaches need to be applied. Excavation changes slope angle, groundwater flow, and blasting increases the degree of rock mass fracturing as well as rock mass disturbance. As such, excavation leads to considerable stress changes in the slopes. Generally, slope design rely on the concept of factor of safety (FOS), often a requirement by international or national standards. A limitation of the factor of safety is that time dependent failure processes, stress-strain relationships, and the impact of rock mass strain and displacement are not considered. Usually, there is a difficulty to estimate the strength of the rock mass, which in turn is controlled by an interaction of intact rock and discontinuity strength. In addition, knowledge about in-situ stresses for the failure criterion is essential. Thus, the estimation of the state of stress of the slope and the strength parameters of the rock mass is still challenging. Given that, large-scale in-situ testing is difficult and costly, back-calculations of case studies in similar rock types or rock mass classification systems are usually the methods of choice. Concerning back-calculations, often a detailed and standardised documentation is missing, and a direct applicability to new projects is not always given. Concerning rock mass classification systems, it is difficult to consider rock mass anisotropy and thus the empirical estimation of the strength properties possesses high uncertainty. In the framework of this study an approach based on

  8. Probabilistic approaches for geotechnical site characterization and slope stability analysis

    CERN Document Server

    Cao, Zijun; Li, Dianqing

    2017-01-01

    This is the first book to revisit geotechnical site characterization from a probabilistic point of view and provide rational tools to probabilistically characterize geotechnical properties and underground stratigraphy using limited information obtained from a specific site. This book not only provides new probabilistic approaches for geotechnical site characterization and slope stability analysis, but also tackles the difficulties in practical implementation of these approaches. In addition, this book also develops efficient Monte Carlo simulation approaches for slope stability analysis and implements these approaches in a commonly available spreadsheet environment. These approaches and the software package are readily available to geotechnical practitioners and alleviate them from reliability computational algorithms. The readers will find useful information for a non-specialist to determine project-specific statistics of geotechnical properties and to perform probabilistic analysis of slope stability.

  9. Slope tunable Fano resonances in asymmetric embedded microring resonators

    Science.gov (United States)

    Wang, Gencheng; Dai, Tingge; Jiang, Jianfei; Yu, Hui; Hao, Yinlei; Wang, Yuehai; Li, Yubo; Jiang, Xiaoqing; Yang, Jianyi

    2017-02-01

    An asymmetric embedded microring resonant system is proposed and fabricated on a silicon-on-insulator (SOI) to achieve slope tunable Fano resonances. The Fano resonances originate from the nonlinear phase shift produced by adding an inner ring coupling with the outer ring. The slope of the Fano resonance can be well tuned to be ultra-high by controlling the microheaters to adjust the phase condition. Experimentally, we observe Fano resonance with a maximum extinction ratio of about 40 dB, and the slope can be tuned from -35 dB nm-1 to -93 dB nm-1, which shows good agreement with the theoretical analysis. This device could find potential applications in ultra-high sensitivity sensing systems.

  10. Slope streaks in the Antarctic Dry Valleys: Characteristics, candidate formation mechanisms, and implications for slope streak formation on Mars

    Science.gov (United States)

    Head, J. W.

    2007-12-01

    Slope streaks on Mars are typically dark, extend downslope for up to ~2 km, are relief, and have been observed to form and change over less than decadal time periods. Mars slope streaks occur exclusively in regions of low thermal inertia, steep slopes, and only where peak temperatures exceed 275 K; changes are observed only if the interval includes the warm season. Mechanisms proposed for Mars slope streaks include dry dust avalanches, dust avalanches controlled by wind, wet debris flows, both wet and dry debris flows, and erosive fluvial processes from spring discharge, where melting is aided by hydrothermal activity or hypersaline aquifers. Although the ADV represent one of the most Mars-like terrestrial environments, there are also substantial differences (e.g., atmospheric pressure and composition; abundance of water, etc.) and thus analogs must be assessed cautiously. We investigated very similar slope streaks in upper Wright Valley of the Antarctic Dry Valleys and interpret their formation to be due to snowpack and near-surface melting-derived saline water traveling downslope along the top of the ice table, wicking upward, and dampening the surface to cause the streak. Among the observations of Mars streaks that suggest that this mechanism should be seriously considered are: 1) similarities in characteristics, brightness, scales, slopes, aspect ratio, temporal behavior, and modes of occurrence; 2) distribution and geometry of occurrence suggesting a relation to solar insolation (low latitudes and northernmost streaks occur preferentially on warmer south-facing slopes); 3) the observation that they occur only where peak temperatures exceed 275 K, and that changes occur only where there has been an intervening warm season, suggesting a potential role for the melting of surface snow and ice. We thus conclude that the saline-assisted surface-near surface melting and water migration origin of slope streaks interpreted from the ADV should be further assessed as a

  11. Wind-driven export of Weddell Sea slope water

    Science.gov (United States)

    Meijers, A. J. S.; Meredith, M. P.; Abrahamsen, E. P.; Morales Maqueda, M. A.; Jones, D. C.; Naveira Garabato, A. C.

    2016-10-01

    The export of waters from the Weddell Gyre to lower latitudes is an integral component of the southern subpolar contribution to the three-dimensional oceanic circulation. Here we use more than 20 years of repeat hydrographic data on the continental slope on the northern tip of the Antarctic Peninsula and 5 years of bottom lander data on the slope at 1000 m to show the intermittent presence of a relatively cold, fresh, westward flowing current. This is often bottom-intensified between 600 and 2000 dbar with velocities of over 20 cm s-1, transporting an average of 1.5 ± 1.5 Sv. By comparison with hydrography on the continental slope within the Weddell Sea and modeled tracer release experiments we show that this slope current is an extension of the Antarctic Slope Current that has crossed the South Scotia Ridge west of Orkney Plateau. On monthly to interannual time scales the density of the slope current is negatively correlated (r > 0.6 with a significance of over 95%) with eastward wind stress over the northern Weddell Sea, but lagging it by 6-13 months. This relationship holds in both the high temporal resolution bottom lander time series and the 20+ year annual hydrographic occupations and agrees with Weddell Sea export variability observed further east. We compare several alternative hypotheses for this wind stress/export relationship and find that it is most consistent with wind-driven acceleration of the gyre boundary current, possibly modulated by eddy dynamics, and represents a mechanism by which climatic perturbations can be rapidly transmitted as fluctuations in the supply of intermediate-level waters to lower latitudes.

  12. Recurring Slope Lineae and Future Exploration of Mars

    Science.gov (United States)

    McEwen, Alfred; Byrne, Shane; Chevrier, Vincent; Chojnacki, Matt; Dundas, Colin; Masse, Marion; Mattson, Sarah; Ojha, Lujendra; Pommerol, Antoine; Toigo, Anthony; Wray, James

    2014-05-01

    Recurring slope lineae (RSL) on Mars may be evidence for the seasonal flow or seepage of water on relatively warm slopes. RSL are narrow (250 K to >300 K. Over the past Martian year we have monitored active RSL in equatorial (0°-15°S) regions of Mars, especially in the deep canyons of Valles Marineris [McEwen et al., 2014, Nature Geoscience]. These equatorial RSL are especially active on north-facing slopes in northern summer and spring and on south-facing slopes in southern spring and summer, following the most normal solar incidence angles on these steep slopes. More recently we have confirmed RSL near 35°N in the low-albedo and low-altitude Acidalia Planitia. All RSL locations have warm peak daily temperatures (typically >273 K at the surface) in the seasons when RSL are active, and occur on steep, rocky, low-albedo slopes. However, most times and places with these properties lack apparent RSL, so there are additional, unseen requirements. We do not know what time of day RSL are actively flowing. Seasonal variation in the atmospheric column abundance of water vapor does not match the RSL activity. Seasonal melting of shallow ice best explains the RSL observations, but the origin and replenishment of such ice is not understood, especially in the tropics. Laboratory experiments are consistent with two key MRO observations: (1) that seeping water darkens basaltic soils but may only produce weak water absorption bands undetectable in ratio spectra after partial dehydration during the low-humidity middle afternoon conditions when MRO observes; and (2) the flows are more linear than under terrestrial conditions and do not erode channels under Martian atmospheric pressures [Masse et al., 2014, LPSC]. No dry process is known to create such slowly creeping seasonal flows. The potential for equatorial water activity creates new exploration opportunities, to search for extant life, as well as challenges such as the definition of special regions for planetary protection.

  13. Morphodynamics and slope stability at Mergui Ridge, off western Thailand

    Science.gov (United States)

    Schwab, J.; Gross, F.; Krastel, S.; Jintasaeranee, P.; Bunsomboonsakul, S.; Winkelmann, D.; Weinrebe, W.

    2012-04-01

    2D seismic data from the top and the western slope of the Mergui Ridge (200 km off the Thai west coast) have been acquired during MASS cruise III in January 2011 in water depths between 300 and 2200 m. The Mergui Ridge is a part of the outer shelf slope off the Thai-Malay Peninsula and forms the eastern boundary of the East Andaman Basin. Structural features in the working area include faulted older slope sediments at the transition from Mergui Ridge to East Andaman Basin that are onlapping on the (acoustic) basement of Mergui Ridge. At their top these sediments are bordered by a pronounced erosive unconformity. Younger sedimentary units on top include three E-W elongated carbonate platforms. Moreover, drift sediments are deposited on top of the ridge, comprising features such as large scale sediment waves and moats around the platforms indicating transport and reworking of the sediments. These sediments are thinning towards the edge of the ridge where a zone of non-sedimentation prevails. In the East Andaman Basin younger sediments comprise disturbed and partially faulted units that are overlain by plastered drifts with increasing thickness towards south, where pronounced sediment waves within the drifts may indicate slope normal sediment transport by bottom currents. At the basin ridge transition, within the drift sediments on top of Mergui Ridge, and at the edge of the ridge several smaller scale mass transport deposits were identified. These MTDs indicate a general instability of the slope. Instability and general morphology of the slope may result from long-term tectonic processes such as extension due to backarc basin formation in the Andaman Sea basin. Moreover, phases of uplift, erosion and subsidence may have contributed to faulting and deformation of older units in our working area. Ongoing tectonics might still cause deformation and instability. In addition, bottom currents may presently play an important role concerning morphodynamic development by

  14. Comparison between characteristics of mild slope equations and Boussinesq equations

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Boussinesq-type equations and mild-slope equations are compared in terms of their basic forms and characteristics. It is concluded that linear mild-slope equations on dispersion relation are better than non-linear Boussinesq equations. In addition, Berkhoff experiments are computed and compared by the two models, and agreement between model results and available experimental data is found to be quite reasonable, which demonstrates the two models' capacity to simulate wave transformation. However they can deal with different physical processes respectively, and they have their own characteristics.

  15. Stability analysis for natural slope by kinematical approach

    Institute of Scientific and Technical Information of China (English)

    孙志彬; 覃长兵

    2014-01-01

    The stability of natural slope was analyzed on the basis of limit analysis. The sliding model of a kind of natural slope was presented. A new kinematically admissible velocity field for the new sliding model was constructed. The stability factor formulation by the upper bound theorem leads to a classical nonlinear programming problem, when the external work rate and internal energy dissipation were solved, and the constraint condition of the programming problem was given. The upper bound optimization problem can be solved efficiently by applying a nonlinear SQP algorithm, and stability factor was obtained, which agrees well with previous achievements.

  16. VEHICLE SIMULATION MODEL FOR DEVELOPING AN INTELLIGENT SLOPE SHIFT STRATEGY

    Institute of Scientific and Technical Information of China (English)

    Jin Hui; Ge Anlin

    2004-01-01

    With the rapid development of electronics and the growing demand for higher vehicle performance,intelligent shift technology is becoming increasingly important,and it promises to be a developing trend in vehicle automatic transmissions.A new simulation model is presented,which includes engine,powertrain,tire and vehicle dynamics models.Based on the model,simulation experiments are conducted to investigate the slope shift strategy.The data and conclusions obtained from the simulations are valuable contributions to the development of an intelligent slope shift strategy.

  17. A gravity similitude model for studying steep rock slopes

    Institute of Scientific and Technical Information of China (English)

    张永兴; FAN; Zebao

    2002-01-01

    A method of a large experimental model coupled with a smaller one and an equivalent replacement method are adopted to study the deformation and the failure mechanism of a steep rock slope,in order to solve the difficult problems in space gravity similitude of the experimental model on steep rock slope with weak layers.The experimental results on the Lianziya Precipice of the Yangtze Three Gorges are in general agreement with the field observations.The experimental method adopted is proved to be successful in molding the complex geological condition especially with the weak layers.

  18. Breaking of Waves over a Steep Bottom Slope

    DEFF Research Database (Denmark)

    Jensen, Morten S.

    The thesis deals with the wave breaking process of waves propagating over a steep submerged bottom slope. The amount of energy dissipated in the wave breaking process is focused upon. An extensive number of experimental tests (>400) using regular and irregular waves breaking over a simulated reef...... in the hydraulic laboratory are performed. Based on the experimental tests several formulae developed. Formulae  are capable of predicting the transmitted wave height and wave energy flux, respectively. Futhermore, a numerical wave model based on the extended Mild-Slope equation has been developed. The model...

  19. A New Formula for Front Slope Recession of Berm Breakwaters

    DEFF Research Database (Denmark)

    Andersen, Thomas Lykke; Burcharth, Hans F.

    2010-01-01

    The front slope stability of breakwaters with a homogeneous berm was studied in a large number of two dimensional model tests at Aalborg University, Denmark. The results are presented together with a new formula for prediction of the berm recession which is the most important parameter for descri......The front slope stability of breakwaters with a homogeneous berm was studied in a large number of two dimensional model tests at Aalborg University, Denmark. The results are presented together with a new formula for prediction of the berm recession which is the most important parameter...

  20. Oscillating Nocturnal Slope Flow in a Coastal Valley

    DEFF Research Database (Denmark)

    Gryning, Sven-Erik; Larsen, Søren Ejling; Mahrt, Larry

    1985-01-01

    Observations of slope flows in a coastal valley are analyzed. The diurnal variation of upslope and downslope flows depends on season in a systematic way which appears to be related to the high latitude of the observational site and the presence of a nearby layer of marine air. Summer nocturnal flow...... over the sloping valley floor was studied during a special observing campaign. A downslope gravity flow interacts with even colder surface air at the valley floor. The latter originates as cold marine air or previous drainage of cold air. Regular oscillations which appear to be trapped, terrain...

  1. Crawling versus Walking Infants' Perception of Affordances for Locomotion over Sloping Surfaces.

    Science.gov (United States)

    Adolph, Karen E.; And Others

    1993-01-01

    Examined the behavior of 8.5-month-old crawling infants and 14-month-old walking toddlers in ascending and descending sloping walkways. Both groups overestimated their ability to ascend slopes. Toddlers hesitated most before descending 10 and 20 degree slopes, whereas infants hesitated most before descending 30 and 40 degree slopes. (MDM)

  2. Comprehensive evaluation of high-steep slope stability and optimal high-steep slope design by 3D physical modeling

    Institute of Scientific and Technical Information of China (English)

    Xing-ping Lai; Peng-fei Shan; Mei-feng Cai; Fen-hua Ren; Wen-hui Tan

    2015-01-01

    High-steep slope stability and its optimal excavation design in Shuichang open pit iron mine were analyzed based on a large 3D physical simulation technique. An optimal excavation scheme with a relatively steeper slope angle was successfully implemented at the northwest wall between Nos. 4 and 5 exploration lines of Shuichang Iron Mine, taking into account the 3D scale effect. The phys-ico-mechanical properties of rock materials were obtained by laboratory tests conducted on sample cores from exploration drilling directly from the iron mine. A porous rock-like composite material was formed for the model, and the mechanical parameters of the material were assessed experimentally;specifically, the effect of water on the sample was quantitatively determined. We adopted an experimental setup using stiff modular applied static loading to carry out a visual excavation of the slope at a random depth. The setup was equipped with acous-tic emission (AE) sensors, and the experiments were monitored by crack optical acquirement, ground penetrating radar, and close-field pho-togrammetry to investigate the mechanisms of rock-mass destabilization in the high-steep slope. For the complex study area, the model re-sults indicated a clear correlation between the model’s destabilization resulting from slope excavation and the collected monitoring informa-tion. During the model simulation, the overall angle of the slope increased by 1–6 degrees in different sections. Dramatically, the modeled excavation scheme saved over 80 million tons of rock from extraction, generating enormous economic and ecological benefits.

  3. Challenging conservation agriculture on marginal slopes in Sehoul, Morocco

    NARCIS (Netherlands)

    Schwilch, G.; Laouina, A.; Chaker, M.; Machouri, N.; Sfa, M.; Stroosnijder, L.

    2015-01-01

    In Sehoul, Morocco, the use of marginal land for agriculture became a necessity for the local population due to increased poverty and the occupation of the best land by new owners. Desertification poses an additional threat to agricultural production on marginal slopes, which are often stony and deg

  4. Facets of Uncertainty in Digital Elevation and Slope Modeling

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jingxiong; LI Deren

    2005-01-01

    This paper investigates the differences that result from applying different approaches to uncertainty modeling and reports an experimental examining error estimation and propagation in elevation and slope,with the latter derived from the former. It is confirmed that significant differences exist between uncertainty descriptors, and propagation of uncertainty to end products is immensely affected by the specification of source uncertainty.

  5. Soil Strength Characteristics Along an Arable Eroded Slope

    Institute of Scientific and Technical Information of China (English)

    PENG Xin-Hua; ZHANG Bin; ZHAO Qi-Guo; R. HORN

    2005-01-01

    Undisturbed soil cores were taken from different slope positions (upslope, backslope and footslope) and soil depths (0-15, 20-35 and 100-115 cm) in a soil catena derived from Quaternary red clay to determine the spatial changes in soil strength along the eroded slope and to evaluate an indicator to determine soil strength during compaction. Precompression stress, as an indicator of soil strength, significantly increased from topsoil layer to subsoil layer (P<0.05) and was affected by slope position. In the subsoil layer (20-35 cm), the precompression stress at the footslope position was significantly greater than at the backslope and upslope positions (P<0.05), while there were no significant differences at 0-15 and 100-115 cm. Precompression stress followed the spatial variation of soil clay content with soil depth and had a significant linear relationship with soil porosity (r2 = 0.40, P<0.01). Also, soil cohesion increased with increasing soil clay content.The precompression stress was significantly related to the applied stress corresponding to the highest change of pore water pressure (r2 = 0.69, P<0.01). These results suggested that soil strength induced by soil erosion and soil management varied spatially along the slope and the maximum change in pore water pressure during compaction could be an easy indicator to describe soil strength.

  6. Stability Analysis of Nonlinear Systems with Slope Restricted Nonlinearities

    Directory of Open Access Journals (Sweden)

    Xian Liu

    2014-01-01

    Full Text Available The problem of absolute stability of Lur’e systems with sector and slope restricted nonlinearities is revisited. Novel time-domain and frequency-domain criteria are established by using the Lyapunov method and the well-known Kalman-Yakubovich-Popov (KYP lemma. The criteria strengthen some existing results. Simulations are given to illustrate the efficiency of the results.

  7. 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

    2008-08-15

    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.

  8. Wave overtopping resistance of grassed slopes in Viet Nam

    NARCIS (Netherlands)

    Trung, L.H.; Verhagen, H.J.; Van der Meer, J.W.

    2011-01-01

    The Simulator was applied to test the resistance against wave overtopping of grass covered dike slopes in Viet Nam. Observation and measurement during destructive tests were performed to investigate the development process of damage induced by overtopping flow. Damages were likely to be initiated at

  9. 30 CFR 77.1911 - Ventilation of slopes and shafts.

    Science.gov (United States)

    2010-07-01

    ... connected to the slope or shaft opening with fireproof air ducts; (3) Designed to permit the reversal of the... from the shaft; and (6) Equipped with air ducts which are fire resistant and maintained so as to... exhausting or blowing methods and when metal air ducts are used, they shall be grounded effectively to...

  10. Wave Run-Up on Sloping Coastal Structures

    DEFF Research Database (Denmark)

    Rouck, J. De; Troch, P.; Ronde, J. De;

    2001-01-01

    Wave run-up is one of the main physical processes which are taken into account in the design of the crest level of sloping coastal structures. The crest level design of these structures is mainly based on physical scale model results....

  11. Geomorphological control on variably saturated hillslope hydrology and slope instability

    Science.gov (United States)

    Giuseppe, Formetta; Simoni, Silvia; Godt, Jonathan W.; Lu, Ning; Rigon, Riccardo

    2016-06-01

    In steep topography, the processes governing variably saturated subsurface hydrologic response and the interparticle stresses leading to shallow landslide initiation are physically linked. However, these processes are usually analyzed separately. Here, we take a combined approach, simultaneously analyzing the influence of topography on both hillslope hydrology and the effective stress fields within the hillslope itself. Clearly, runoff and saturated groundwater flow are dominated by gravity and, ultimately, by topography. Less clear is how landscape morphology influences flows in the vadose zone, where transient fluxes are usually taken to be vertical. We aim to assess and quantify the impact of topography on both saturated and unsaturated hillslope hydrology and its effects on shallow slope stability. Three real hillslope morphologies (concave, convex, and planar) are analyzed using a 3-D, physically based, distributed model coupled with a module for computation of the probability of failure, based on the infinite slope assumption. The results of the analyses, which included parameter uncertainty analysis of the results themselves, show that convex and planar slopes are more stable than concave slopes. Specifically, under the same initial, boundary, and infiltration conditions, the percentage of unstable areas ranges from 1.3% for the planar hillslope, 21% for convex, to a maximum value of 33% for the concave morphology. The results are supported by a sensitivity analysis carried out to examine the effect of initial conditions and rainfall intensity.

  12. Internal wave-turbulence pressure above sloping sea bottoms

    NARCIS (Netherlands)

    van Haren, H.

    2011-01-01

    An accurate bottom pressure sensor has been moored at different sites varying from a shallow sea strait via open ocean guyots to a 1900 m deep Gulf of Mexico. All sites show more or less sloping bottom topography. Focusing on frequencies (sigma) higher than tidal, the pressure records are remarkably

  13. Wave Reflection on a Two-Slope Steep Beach

    Science.gov (United States)

    2012-03-01

    surveys taken during cross-shore transport study experiment. .....................................12  Figure 7.  Sea kayak with echo sounder and...Suhayda, 1974) Natural beaches are composed of complicated slopes and encounter a wide spectrum of wave frequencies, amplitudes, and directions. Suhayda...1974) conducted a field experiment investigating standing waves on a natural beach. He expanded on the theoretical results of Lamb (1932

  14. On slope genera of knotted tori in the 4-space

    CERN Document Server

    Liu, Yi; Sun, Hongbin; Wang, Shicheng

    2011-01-01

    In this note, we investigate genera for the slopes of a knotted torus in the 4-sphere analogous to the genus of a classical knot. We compare various formulations of this notion, and use this notion to study the extendable subgroup of the mapping class group of the knotted torus.

  15. Phase transition on speed limit traffic with slope

    Institute of Scientific and Technical Information of China (English)

    Li Xing-Li; Song Tao; Kuang Hua; Dai Shi-Qiang

    2008-01-01

    Through introducing a generalized optimal speed function to consider spatial position, slope grade and variable safe headway, the effect of slope in a single-lane highway on the traffic flow is investigated with the extended optimal speed model. The theoretical analysis and simulation results show that the flux of the whole road with the upgrade (or downgrade) increases linearly with density, saturates at a critical density, then maintains this saturated value in a certain density range and finally decreases with density. The value of saturated flux is equal to the maximum flux of the upgrade (or downgrade) without considering the slight influence of the driver's sensitivity. And the fundamental diagrams also depend on sensitivity, slope grade and slope length. The spatiotemporal pattern gives the segregation of different traffic phases caused by the rarefaction wave and the shock wave under a certain initial vehicle number.A comparison between the upgrade and the downgrade indicates that the value of saturated flux of the downgrade is larger than that of the upgrade under the same condition. This result is in accordance with the real traffic.

  16. Overtopping And Rear Slope Stabillity Of Reshaping Breakwaters

    DEFF Research Database (Denmark)

    Burcharth, Hans Falk; Lykke Andersen, Thomas

    2003-01-01

    An experimental study of overtopping and rear slope stability of reshaping breakwaters has been carried out. The variation of those two parameters with crest width, crest freeboard and sea state was investigated. The tests showed that the variation in overtopping discharge with crest freeboard...

  17. 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...

  18. Granular flow behavior at sharp changes in slope

    Science.gov (United States)

    Crosta, Giovanni; De Blasio, Fabio; Locatelli, Michele

    2015-04-01

    This study extends some recent experiments and analyses performed by the authors to examine the behavior of granular flows along path characterised by sharp changes in slope. In particular, various series of experiments along a bi-linear broken slope (an inclined initial sector followed by a horizontal one) have been completed using a uniform (Hostun, 0.32 mm) sand and a uniform fine gravel (2 mm grains). 60 new have been performed by releasing different volumes (1.5, 2.1 and 5.1 L) on surfaces characterized by different slope angles (35-60°), type of materials (wood and plexiglass), with or without an erodible layer (sand), or in presence of a shallow water pond (0.5 cm). These geometrical features are typical of many large rock and snow avalanches, rock falls and of chalk flows. The latter are usually typical of coastal cliffs where a shallow water environment is typical. The evolution of the flow has been monitored through a laser profilometer at 120 Hz sampling frequency and high speed camera, and in this way it has been possible to follow the evolution of the flow and deposition, and to analyse the change in deposition mode at varying the slope angle, the material and the basal friction. This is an extremely interesting development in the study of the evolution of the deposition and of the final morphology typical of such phenomena, and can support the testing of numerical models. Propagation and deposition occur forward or backward accordingly to the slope angle and the basal friction. Forward movement and deposition occur at high slope angles and with low basal friction. The opposite is true for the backward deposition. The internal "layering" within the deposit is also strongly controlled by the combination of such parameters. The time evolution of the flow allowed to determine the velocity of flow and the mode of deposition through the analysis of the change in thickness, position of the front and of the flow tail. Presence of water reduces the runout of

  19. Study of slope topple mechanism on belt express way around Jilin City

    Institute of Scientific and Technical Information of China (English)

    Aref M.O. Al-Jabali; Lei NIE; Shiwei SHEN

    2006-01-01

    The Slope Program is a complex problem, and the constructive mechanics is the emphasis and difficult point of the slope researching. The research on the slope constructive mechanics takes an important theory and experience role of the stability analysis and preventive methods. On the basis of the field survey of the overturn-slope on the Jilin Belt Highway, the authors analyzed its constructive mechanics, valuated its stability, and showed the treatments of the slope.

  20. HIRESSS: a physically based slope stability simulator for HPC applications

    Directory of Open Access Journals (Sweden)

    G. Rossi

    2013-01-01

    Full Text Available HIRESSS (HIgh REsolution Slope Stability Simulator is a physically based distributed slope stability simulator for analyzing shallow landslide triggering conditions in real time and on large areas using parallel computational techniques. The physical model proposed is composed of two parts: hydrological and geotechnical. The hydrological model receives the rainfall data as dynamical input and provides the pressure head as perturbation to the geotechnical stability model that computes the factor of safety (FS in probabilistic terms. The hydrological model is based on an analytical solution of an approximated form of the Richards equation under the wet condition hypothesis and it is introduced as a modeled form of hydraulic diffusivity to improve the hydrological response. The geotechnical stability model is based on an infinite slope model that takes into account the unsaturated soil condition. During the slope stability analysis the proposed model takes into account the increase in strength and cohesion due to matric suction in unsaturated soil, where the pressure head is negative. Moreover, the soil mass variation on partially saturated soil caused by water infiltration is modeled.

    The model is then inserted into a Monte Carlo simulation, to manage the typical uncertainty in the values of the input geotechnical and hydrological parameters, which is a common weak point of deterministic models. The Monte Carlo simulation manages a probability distribution of input parameters providing results in terms of slope failure probability. The developed software uses the computational power offered by multicore and multiprocessor hardware, from modern workstations to supercomputing facilities (HPC, to achieve the simulation in reasonable runtimes, compatible with civil protection real time monitoring.

    A first test of HIRESSS in three different areas is presented to evaluate the reliability of the results and the runtime performance on

  1. Some new pre-warning criteria for creep slope failure

    Institute of Scientific and Technical Information of China (English)

    HACK; Robert

    2011-01-01

    The forecasting of the failure time of a slope remains a worldwide problem because of many different possibilities of geological conditions in combination with many varying external factors such as climate and vegetation,and not well-defined or unknown time effects in deformation and failure models.The aim of this paper is to suggest a new method to carry out the phase division and to explore tangential angular features of the displacement-time curve of creep slopes as well as the acceleration characteristics in the process of slope deformation and the pre-warning criteria for critical failure.An imminent failure is pro-ceeded with usually three basic deformation phases,namely primary creep("decelerated") ,secondary creep("steadystate") and tertiary creep("accelerated") .Mostly,only during the accelerated phase the imminence of a possible slope failure is rec-ognized.The analysis of displacement data from a series of landslides allowed to recognize different evolutionary patterns of displacement.A quantitative approach was proposed to describe the tangential angle of the displacement-time curve and a new criterion based on the angle was put forward to divide the accelerated phase into three sub-phases:initial acceleration,medium acceleration,and the critical failure.A pre-warning criterion for critical failure is also proposed consequently. Changes of acceleration showed completely different characteristics from those of cumulative displacement and displacement in the process of slope deformation.The values of acceleration usually oscillate around 0 prior to the critical failure phase,whereas the acceleration increases abruptly when the deformation moves into the critical failure phase.This allows,therefore,for a method to forecast the time of the failure.So it is possible to define different alert acceleration threshold values to be used for emergency management.

  2. The dependence of sheet erosion velocity on slope angle

    Directory of Open Access Journals (Sweden)

    Chernyshev Sergey Nikolaevich

    2014-09-01

    Full Text Available The article presents a method for estimating the erosion velocity on forested natural area. As a research object for testing the methodology the authors selected Neskuchny Garden - a city Park on the Moskva river embankment, named after the cognominal Palace of Catherine's age. Here, an almost horizontal surface III of the Moskva river terrace above the flood-plain is especially remarkable, accentuated by the steep sides of the ravine parallel to St. Andrew's, but short and nameless. The crests of the ravine sides are sharp, which is the evidence of its recent formation, but the old trees on the slopes indicate that it has not been growing for at least 100 years. Earlier Russian researchers defined vertical velocity of sheet erosion for different regions and slopes with different parent (in relation to the soil rocks. The comparison of the velocities shows that climatic conditions, in the first approximation, do not have a decisive influence on the erosion velocity of silt loam soils. The velocities on the shores of Issyk-Kul lake and in Moscow proved to be the same. But the composition of the parent rocks strongly affects the sheet erosion velocity. Even low-strength rock material reduces the velocity by times. Phytoindication method gives a real, physically explainable sheet erosion velocities. The speed is rather small but it should be considered when designing long-term structures on the slopes composed of dispersive soils. On the slopes composed of rocky soils sheet erosion velocity is so insignificant that it shouldn't be taken into account when designing. However, there may be other geological processes, significantly disturbing the stability of slopes connected with cracks.

  3. Parallel processing for efficient 3D slope stability modelling

    Science.gov (United States)

    Marchesini, Ivan; Mergili, Martin; Alvioli, Massimiliano; Metz, Markus; Schneider-Muntau, Barbara; Rossi, Mauro; Guzzetti, Fausto

    2014-05-01

    We test the performance of the GIS-based, three-dimensional slope stability model r.slope.stability. The model was developed as a C- and python-based raster module of the GRASS GIS software. It considers the three-dimensional geometry of the sliding surface, adopting a modification of the model proposed by Hovland (1977), and revised and extended by Xie and co-workers (2006). Given a terrain elevation map and a set of relevant thematic layers, the model evaluates the stability of slopes for a large number of randomly selected potential slip surfaces, ellipsoidal or truncated in shape. Any single raster cell may be intersected by multiple sliding surfaces, each associated with a value of the factor of safety, FS. For each pixel, the minimum value of FS and the depth of the associated slip surface are stored. This information is used to obtain a spatial overview of the potentially unstable slopes in the study area. We test the model in the Collazzone area, Umbria, central Italy, an area known to be susceptible to landslides of different type and size. Availability of a comprehensive and detailed landslide inventory map allowed for a critical evaluation of the model results. The r.slope.stability code automatically splits the study area into a defined number of tiles, with proper overlap in order to provide the same statistical significance for the entire study area. The tiles are then processed in parallel by a given number of processors, exploiting a multi-purpose computing environment at CNR IRPI, Perugia. The map of the FS is obtained collecting the individual results, taking the minimum values on the overlapping cells. This procedure significantly reduces the processing time. We show how the gain in terms of processing time depends on the tile dimensions and on the number of cores.

  4. Multi-factor sensitivity analysis of shallow unsaturated clay slope stability

    Institute of Scientific and Technical Information of China (English)

    Zhuoying Tan; Meifeng Cai

    2005-01-01

    An unsaturated clay slope, with various sloping angles and a thickness of 14 m, consists of backfill, slope soil and residual soil. Slide interfaces were determined by geophysical approaches and the original slope was reconstructed. Sub-slope masses were classified based on the varieties of sloping angle. A force recursive principle was proposed to calculate the stability coefficient of the sub-slope masses. The influencing factors such as sloping angle, water content, hydrostatic pressure, seismic force as well as train load were analyzed. The range and correlation of the above-mentioned factors were discussed and coupled wave equations were established to reflect the relationships between unit weight, cohesion, internal frictional angle, and water content, as well as between internal frictional angle and cohesion. The sensitivity analysis of slope stability was carried out and susceptive factors were determined when the factors were taken as independent and dependent variables respectively. The results show that sloping angle, water content and earthquake are the principal susceptive factors influencing slope stability. The impact of hydrostatic pressure on slope stability is similar to the seismic force in quantity. Train load plays a small role in slope stability and its influencing only reaches the roadbed and its neighboring slope segment. If the factors are taken as independent variables, the influencing extent of water content and cohesion on slope stability can be weakened and train load can be magnified.

  5. Effect of slope height and horizontal forces on the bearing capacity of strip footings near slopes in cohesionless soil

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Damkilde, Lars; Krabbenhøft, Kristian

    2016-01-01

    , and in such cases the bearing capacity of the footing cannot be found using the existing methods. The present work comprises finite element based upper- and lower-bound calculations, using the geotechnical software OptumG2 to investigate the effect of the slope height and horizontal forces on the total bearing...

  6. A method for determining average beach slope and beach slope variability for U.S. sandy coastlines

    Science.gov (United States)

    Doran, Kara S.; Long, Joseph W.; Overbeck, Jacquelyn R.

    2015-01-01

    The U.S. Geological Survey (USGS) National Assessment of Hurricane-Induced Coastal Erosion Hazards compares measurements of beach morphology with storm-induced total water levels to produce forecasts of coastal change for storms impacting the Gulf of Mexico and Atlantic coastlines of the United States. The wave-induced water level component (wave setup and swash) is estimated by using modeled offshore wave height and period and measured beach slope (from dune toe to shoreline) through the empirical parameterization of Stockdon and others (2006). Spatial and temporal variability in beach slope leads to corresponding variability in predicted wave setup and swash. For instance, seasonal and storm-induced changes in beach slope can lead to differences on the order of 1 meter (m) in wave-induced water level elevation, making accurate specification of this parameter and its associated uncertainty essential to skillful forecasts of coastal change. A method for calculating spatially and temporally averaged beach slopes is presented here along with a method for determining total uncertainty for each 200-m alongshore section of coastline.

  7. [Responses of plant functional traits and soil factors to slope aspect in alpine meadow of South Gansu, Northwest China].

    Science.gov (United States)

    Min-Xi, Liu; Jian-Zu, Ma

    2012-12-01

    This paper studied the plant functional traits, soil factors, and their relationships at different slope aspects in the alpine meadow of South Gansu. On the sunny slope, grasses were the dominant functional groups; while on the shady slope, forbs and shrubs dominated. The plant community biomass was significantly higher on shady slope than on sunny slope, while the leaf N/P ratio was in adverse. The leaf phosphorus content, specific leaf area, and plant average height at different slope aspects were in the order of shady slope > partial shady slope > sunny slope, whereas the leaf nitrogen content on different slopes had less difference. The survival strategies of the vegetations on sunny and shady slopes had great changes, reflecting in the differences in the plant leaf traits and dominant functional groups. Soil temperature was in the order of sunny slope > partial shady slope > shady slope, while soil water content was in the order of shady slope > partial shady slope > sunny slope. Soil total phosphorus content increased from the sunny slope to the shady slope, while the other soil nutrients contents showed the sequence of shady slope > sunny slope > partial shady slope. The specific leaf area and plant average height were significantly positively correlated to the soil organic carbon, total phosphorous, and water contents, and significantly negatively correlated to soil pH. Soil water content and soil pH co-affected the distribution patterns of plant functional traits and soil nutrients at different slope aspects of alpine meadow.

  8. Model slope infiltration experiments for shallow landslides early warning

    Science.gov (United States)

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

    2009-04-01

    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. 空心钉结合带筋膜跗外侧血管蒂骰骨骨膜瓣移位治疗距骨颈骨折%Cannulated screws combined with transposition of cuboid periosteal flap pedicled with fascia and lateral tarsal artery in the treatment of talus neck fractures

    Institute of Scientific and Technical Information of China (English)

    周炎; 刘世清; 瞿新丛; 廖琦; 余铃; 黄涛

    2014-01-01

    目的 探讨空心钉结合带筋膜跗外侧血管蒂骰骨骨膜瓣移位治疗距骨颈骨折的手术方法及临床疗效. 方法 2008年3月至2011年6月,对收治的12例距骨颈骨折采用空心钉结合带筋膜跗外侧血管蒂骰骨骨膜瓣移位治疗.术后非负重功能位外固定12~14周,并根据X线片显示骨折愈合情况确定负重时间.末次随访时根据美国足与踝关节外科协会踝与后足功能评分系统评价术后功能. 结果 12例术后随访12 ~ 48个月,平均24个月.1例出现切口皮缘坏死,经换药处理后愈合.距骨颈骨折均获愈合,愈合时间为16~ 24周,平均20周.末次随访时AOFAS踝与后足功能评分为55~ 96分,平均82.5分,其中优4例,良5例,可3例.2例发生距下关节轻度创伤性关节炎,口服消炎镇痛药后疼痛缓解;1例发生距骨体缺血性坏死,X线片显示距骨体骨质硬化,但未塌陷,嘱患者减少负重并定期随访观察. 结论 应用空心钉结合带筋膜跗外侧血管蒂骰骨骨膜瓣移位治疗距骨颈骨折,能改善距骨体血供,降低距骨缺血性坏死的发生,是有效的治疗手段.%Objective To investigate the surgical techniques and clinical efficacy of cannulated screws combined with transposition of cuboid periosteal flap pedicled with fascia and lateral tarsal artery in the treatment of talus neck fractures.Methods From March 2008 to June 2011,12 cases with talus neck fractures were treated with cannulated screws combined with transposition of cuboid periosteal flap pedicled with fascia and lateral tarsal artery.External fixation in functional position for 12-14 weeks,and the load time was determined by X-ray fracture healing.Functional results were assessed according to AOFAS (American Orthopaedic Foot and Ankle Society) score at last follow-up.Results Twelve cases were followed up for an average of 24 months (12 to 48 months).One case of skin flap necrosis healed by dressing.All the fractures healed

  10. Area utilization efficiency of a sloping heliostat system for solar concentration.

    Science.gov (United States)

    Wei, L Y

    1983-02-15

    Area utilization efficiency (AUE) is formulated for a sloping heliostat system facing any direction. The effects of slope shading, incidence factor, sun shading, and tower blocking by the mirrors are all taken into account. Our results show that annually averaged AUEs calculated for heliostat systems (1) increase with tower height at low slope angles but less rapidly at high slopes, (2) increase monotonically with slope angle and saturate at large slopes for systems facing due south, (3) reach a maximum at a certain slope for systems facing other directions than due south, and (4) drop sharply at slopes greater than a certain value for systems facing due east or west due to slope shading effect. The results are useful for solar energy collection on nonflat terrains.

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

    Directory of Open Access Journals (Sweden)

    Liang Lu

    2014-01-01

    Full Text Available 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 geosynthetics is proposed to evaluate the seismic slope stability. In the proposed procedure, the failure of slope is defined when the cumulative plastic displacement calculated by a dynamic response analysis using actual seismic wave exceeds the critical value of displacement estimated by a static stability analysis considering seismic coefficient. The proposed procedure is applied to the laboratory model tests and an actual failure of slope in earthquake. The case study shows the possibility that the proposed procedure gives the realistic evaluation of seismic slope stability.

  12. Reliability Evaluation of Slopes Using Particle Swarm Optimization

    Directory of Open Access Journals (Sweden)

    Mohammad Khajehzadeh

    2011-01-01

    Full Text Available The objective of this research is to develop a numerical procedure to reliability evaluation of earth slope and locating the critical probabilistic slip surface. The performance function is  formulated using simplified Bishop’s limit equilibrium method  to calculate the reliability index. The reliability index defined by Hasofer and Lind is used as an index of safety measure. Searching the critical probabilistic surface that is associated with the lowest reliability index will be formulated as an optimization problem. In this paper, particle swarm optimization is applied to calculate the minimum Hasofer and Lind reliability index and critical probabilistic failure surface. To demonstrate the applicability and to investigate the effectiveness of the algorithm, two numerical examples from literature are illustrated. Results show that the proposed method is capable to achieve better solutions for reliability analysis of slope if compared with those reported in the literature.

  13. Surface Slope Metrology on Deformable Soft X-ray Mirrors

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Sheng; Yashchuk, Valeriy V.; Goldberg, Kenneth A.; Celestre, Rich; Church, Matthew; McKinney, Wayne R.; Morrison, Greg; Warwick, Tony

    2010-01-31

    We report on the current state of surface slope metrology on deformable mirrors for soft x-rays at the Advanced Light Source (ALS). While we are developing techniques for in situ at-wavelength tuning, we are refining methods of ex situ visible-light optical metrology to achieve sub-100-nrad accuracy. This paper reports on laboratory studies, measurements and tuning of a deformable test-KB mirror prior to its use. The test mirror was bent to a much different optical configuration than its original design, achieving a 0.38 micro-radian residual slope error. Modeling shows that in some cases, by including the image conjugate distance as an additional free parameter in the alignment, along with the two force couples, fourth-order tangential shape errors (the so-called bird shape) can be reduced or eliminated.

  14. Surface Slope Metrology on Deformable Soft X-ray Mirrors

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, S.; Yashchuk, V.V.; Goldberg, K.A.; Celestre, R.; Church, M.; McKinney, W.R.; Morrison, G.; Warwick, T.

    2009-09-18

    We report on the current state of surface slope metrology on deformable mirrors for soft x-rays at the Advanced Light Source (ALS). While we are developing techniques for in situ at-wavelength tuning, we are refining methods of ex situvisible-light optical metrology to achieve sub-100-nrad accuracy. This paper reports on laboratory studies, measurements and tuning of a deformable test-KB mirror prior to its use. The test mirror was bent to a much different optical configuration than its original design, achieving a 0.38 micro-radian residual slope error. Modeling shows that in some cases, by including the image conjugate distance as an additional free parameter in the alignment, along with the two force couples, fourth-order tangential shape errors (the so-called bird shape) can be reduced or eliminated.

  15. COMPARISON BETWEEN BOUSSINESQ EQUATIONS AND MILD-SLOPE EQUATIONS MODEL

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this paper, the Boussinesq equations and mild-slope equation of wave transformation in near-shore shallow water were introduced and the characteristics of the two forms of equations were compared and analyzed. Meanwhile, a Boussinesq wave model which includes effects of bottom friction, wave breaking and subgrid turbulent mixing is established, slot technique dealing with moving boundary and damping layer dealing with absorbing boundary were established. By adopting empirical nonlinear dispersion relation and including nonlinear term, the mild-slope equation model was modified to take nonlinear effects into account. The two types of models were validated with the experiment results given by Berkhoff and their accuracy was analysed and compared with that of correlated methods.

  16. HIGH FIELD Q-SLOPE AND THE BAKING EFFECT

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, Gianluigi [JLAB

    2009-11-01

    The performance of SRF cavities made of bulk Nb at high fields (peak surface magnetic field greater than about 90 mT) is characterized by exponentially increasing RF losses (high-field Q-slope), in the absence of field emission, which are often mitigated by a low temperature (100-140 °C, 12-48h) baking. In this contribution, recent experimental results and phenomenological models to explain this effect will be briefly reviewed. New experimental results on the high-field Q-slope will be presented for cavities that had been heat treated at high temperature in the presence of a small partial pressure of nitrogen. Improvement of the cavity performances have been obtained, while surface analysis measurements on Nb samples treated with the cavities revealed significantly lower hydrogen concentration than for samples that followed standard cavity treatments.

  17. Characteristic of involute slope modification of asymmetric spur gear

    Institute of Scientific and Technical Information of China (English)

    DENG Xiao-he; HUA Lin; HAN Xing-hui

    2015-01-01

    The meshing characteristic of asymmetric involute spur gear was studied, the equations of the geometric shape of the asymmetric gear for both sides were deduced, and the equations of contact ratio and the key points of contact were also obtained. Meanwhile, an involute slope modification method considering the effects of static transmission errors was proposed based on the meshing properties. The characteristic of the involute slope modification was analyzed by changing different modification parameters. The mesh stiffness and synthetic mesh stiffness of unmodified and modified asymmetric spur gears were investigated. Furthermore, the spectrums of synthetic mesh stiffness under different modification parameters were compared. Research results showed that the modification parameters influence the meshing performance of gear pairs, and the proposed modification method was feasible to improve the transmission performance of gear pairs with appropriate modification parameters.

  18. Evaluating thermal performance of a single slope solar still

    Science.gov (United States)

    Badran, Omar O.; Abu-Khader, Mazen M.

    2007-08-01

    The distillation is one of the important methods of getting clean water from brackish and sea water using the free energy supply from the sun. An experimental work is conducted on a single slope solar still. The thermal performance of the single slope solar still is examined and evaluated through implementing the following effective parameters: (a) different insulation thicknesses of 1, 2.5 and 5 cm; (b) water depth of 2 and 3.5 cm; (c) solar intensity; (d) Overall heat loss coefficient (e) effective absorbtivity and transmissivity; and (f) ambient, water and vapor temperatures. Different effective parameters should be taken into account to increase the still productivity. A mathematical model is presented and compared with experimental results. The model gives a good match with experimental values.

  19. Inverse problem of bottom slope design for aerator devices

    Institute of Scientific and Technical Information of China (English)

    吴建华; 樊博; 许唯临

    2013-01-01

    Air entrainment is an effective approach to protect release works from cavitation damage. The traditional method of aera-tor device designs is that, for given flow conditions, the geometries of the aerator device are designed and then the effects are experi-mentally tested for cavitation damage control. The present paper proposes an inverse problem method of determining the bottom slopes in front of and behind an aerator if the requirements of air entrainment, flow conditions and some of aerator geometric para-meters are given. An RBF neural network model is developed and the relevant bottom slopes are calculated in different conditions of flow and geometry on the basis of the data of 19 aerator devices from different discharge tunnels with safe operation. The case study shows that the methodology provides an effective way to design aerator devices under given target conditions.

  20. Influence of groundwater level to slope displacement by geodetic method

    Science.gov (United States)

    Sadarviana, Vera; Abidin, Hasanuddin Z.; Santoso, Djoko; Kahar, Joenil; Achmad R., T.

    2016-05-01

    In the rainy season, Indonesia often experience landslide disasters. Rainwater flows on the surface of the ground and partially into the ground, and changing the groundwater level (GWL) which can cause pressure on surrounding material. Water becomes the main factor that triggered landslides because water causes pressure force on the slopes that are prone to move. With the geometric approach, slope material displacement vectors can be known, including the origin of the material pressure using dynamic mathematical model that considers GWL. The data was used 5 campaigns of GPS observations. The results are obtained the correlation coefficients between coefficient changes in groundwater levels to the vector position as a representative of correlation between the physical and geometric parameters. There is relatively strong because of the value of the average correlation coefficient is 0.91997. Further, curves between changes in groundwater levels and the displacement position shows that the greater the groundwater levels, the greater the material position shift occurs.

  1. Wave Run-Up on Sloping Coastal Structures

    DEFF Research Database (Denmark)

    Rouck, J. De; Troch, P.; Ronde, J. De;

    Wave run-up is one of the main physical processes which is taken into account in the design of the crest level of sloping coastal structures. Until recently, solely physical model results were used for the crest level design. However, prototype measurements have indicated that scale models...... underestimate wave run-up. Therefore wave run-up is studied in detail comparing prototype measurements and physical modelling....

  2. Aerial Photogrammetric Analysis of a Scree Slope and Cliff

    Science.gov (United States)

    Saunders, Greg; Galland, Olivier; Mair, Karen

    2014-05-01

    Mapping the physical features of landslide tracks provides information about factors controlling landslide movement. The increasing availability of unmanned aerial vehicles (UAV) provides the opportunity to efficiently and cost effectively map terrain. The main goal of this field study is to create a streamlined work-flow from acquisition to interpretation for the photogrammetric analysis of landslide tracks. Here an open source software package MicMac is used for ortho-image and point-cloud creation. A series of two flights were conducted over a scree (rockfall) slope in Kolsas, Norway. The slope runs roughly 500 m north-south with a maximum width of 60 m. A cliff to the west is the source area for the scree. The cliff consists of conglomerate, basalt, and porphyry from bottom to top respectively. The grain size of boulders in the scree slope apparently varies due to lateral differences in the cliff composition. The flights were completed under cloud cover and consisted of multiple lengthwise passes over the scree field. There was a minimum of 75% overlap between images. During the first flight the altitude was roughly 100 m, the camera was positioned normal to the scree (60 degrees from horizontal), and the resolution was 2.7 cm per pixel. The second flight had an altitude of 200 m, the camera orientation was 30 degrees from horizontal, and the resolution was 4.0 cm per pixel. Using the Micmac engine, Ortho-photos and Digital Elevation Models (DEM) were created for both the scree and the cliff. This data will allow for analysis of grain-size, surface roughness, grain-shape, fracture plane orientation, as well as geological mapping. Further work will focus the quantitative assessment of the significance different camera altitudes and angles have on the results. The work-flow used in this study provides a repeatable method for aerial photogrammetric surveys of scree slopes.

  3. ASTRONOMICAL ALGORITHMS OF EGYPTIAN PYRAMIDS SLOPES AND THEIR MODULES DIVIDER

    OpenAIRE

    Aboulfotouh, Hossam M. K.

    2015-01-01

    This paper is an attempt to show the astronomical design principles that are encoded in the geometrical forms of the largest five pyramids of the fourth Egyptian dynasty, in Giza and Dahshur plateaus, based on using the pyramids’ design-modules that are mentioned in the so-called Rhind Mathematical Papyrus. It shows the astronomical algorithms for quantifying the slopes of pyramids, with reference to specific range of earth’s axial tilt, within spherical co-ordinates system. Besid...

  4. Random Intercept and Random Slope 2-Level Multilevel Models

    Directory of Open Access Journals (Sweden)

    Rehan Ahmad Khan

    2012-11-01

    Full Text Available Random intercept model and random intercept & random slope model carrying two-levels of hierarchy in the population are presented and compared with the traditional regression approach. The impact of students’ satisfaction on their grade point average (GPA was explored with and without controlling teachers influence. The variation at level-1 can be controlled by introducing the higher levels of hierarchy in the model. The fanny movement of the fitted lines proves variation of student grades around teachers.

  5. Time shift of pulses due to dispersion slope and nonlinearity

    Energy Technology Data Exchange (ETDEWEB)

    Marcuse, D.; Menyuk, C.R.; Holzloehner, R.

    1999-12-01

    The authors show that the time delay of optical pulses traveling in long fibers is influenced by the dispersion slope and the fiber nonlinearity. Consequently, one or more new pulses that are inserted by add-drop operations into a pulse train that has already traveled a long distance may shift relative to the old pulses. This time shift delays the initial pulses more than the newly inserted ones, so that the newly inserted pulses can leave their time frames, leading to errors.

  6. Characterization and calibration of 2nd generation slope measuring profiler

    Science.gov (United States)

    Siewert, Frank; Buchheim, Jana; Zeschke, Thomas

    2010-05-01

    High spectral resolution and nanometer sized foci of 3rd generation SR beamlines can only be achieved by means of ultra precise optical elements. The improved brilliance and the coherence of free electron lasers (FEL) even push the accuracy limits and make the development of a new generation of ultra precise reflective optical elements mandatory. Typical elements are wave front preserving plane mirrors (lengths of up to 1 m, residual slope errors ˜0.05 μrad (rms) and values of 0.1 nm (rms) for the micro-roughness) and curved optical elements like spheres, toroids or elliptical cylinder (residual slope error ˜0.25 μrad (rms) and better). These challenging specifications and the ongoing progress in finishing technology need to be matched by improved accuracy metrology instruments. We will discuss the results of recent developments in the field of metrology made in the BESSY-II-optics laboratory (BOL) at the Helmholtz Zentrum Berlin (HZB), by the use of vertical angle comparator (VAC) in use to calibrate the nanometer optical component measuring machine (NOM). The BESSY-NOM represents an ultra accurate type of slope measuring instruments characterized by an accuracy of 0.05 μrad (rms) for plane substrates and 0.2 μrad (rms) for significant curved surfaces.

  7. Simulation analysis of construction process of high rock slope's stabilization

    Institute of Scientific and Technical Information of China (English)

    ZHU Zhan-yuan; LING Xian-zhang; WANG Xuan-qing; ZOU Zu-yin

    2008-01-01

    A self-developed elasto-plastic finite element program was used to analyze the construction sequence of high rock slope' s stabilization in a coal-coking plant, and the result was compared with that employing the ultimate equilibrium method. Based on the results of finite element analysis, the stress contour graphs and dis-placement vector graphs at different construction steps were obtained, and the behavior of the slope during stabi-lization construction process was analyzed quantitatively. Based on the analysis of safety factors of three different schemes of stabilization and two different construction schemes, the assessment of stability and bracing design of the construction process were performed. The results show that the original reinforcement design is improper;the stability of the rock slope is controlled by a developed structural plane, the stability factor after excavation is less than 1, and the free surface should be braced in time ; for stability, the construction sequence should adopt that bracing follows excavation step by step up to down; the local slide occurred during the construction process agrees with the dangerous slide determined by the numerical analysis, which proves the validity and rationality of the adopted method.

  8. North Slope Decision Support for Water Resource Planning and Management

    Energy Technology Data Exchange (ETDEWEB)

    Schnabel, William; Brumbelow, Kelly

    2013-03-31

    The objective of this project was to enhance the water resource decision-making process with respect to oil and gas exploration/production activities on Alaska’s North Slope. To this end, a web-based software tool was developed to allow stakeholders to assemble, evaluate, and communicate relevant information between and amongst themselves. The software, termed North Slope Decision Support System (NSDSS), is a visually-referenced database that provides a platform for running complex natural system, planning, and optimization models. The NSDSS design was based upon community input garnered during a series of stakeholder workshops, and the end product software is freely available to all stakeholders via the project website. The tool now resides on servers hosted by the UAF Water and Environmental Research Center, and will remain accessible and free-of-charge for all interested stakeholders. The development of the tool fostered new advances in the area of data evaluation and decision support technologies, and the finished product is envisioned to enhance water resource planning activities on Alaska’s North Slope.

  9. Lichenometric dating of slope movements, Nant Ffrancon, North Wales

    Science.gov (United States)

    Winchester, Vanessa; Chaujar, Ravinder K.

    2002-09-01

    Over the last 50 years, frequent debris flows on the oversteepened slopes crossed by the main A5 road in Nant Ffrancon, North Wales, have presented a significant traffic hazard. This study uses two approaches to lichenometry to date earlier debris flows. The first approach provides dating estimates based on size/age correlations of the lichen Rhizocarpon geographicum subspecies prospectans growing in two local churchyards. The correlations supplied a growth rate of 1.47 mm year -1 for the species over a 140-year period, with a delay before colonization of 18 years. Remeasurement of the same lichens after a 4.25-year interval confirmed the growth and colonization rates in the churchyards. The second lichenometric approach, based on population size frequency distributions with size increments dated using the churchyard growth rate, provided controls for the Nant Ffrancon study site, with peaks in Rhizocarpon population size frequency distributions correlating with debris flow dates recorded by Gwynedd Council Highways Department. Circumstantial evidence supporting adoption of the growth rate on the Nant Ffrancon slopes was also supplied by data from archival and meteorological sources. The lichenometric dating estimates suggest that these slopes have a history of periodic debris flows covering at least the last 110 years, with major flows occurring in the 1890s followed by further flows in the early decades of the twentieth century.

  10. Meteorological, elevation, and slope effects on surface hoar formation

    Science.gov (United States)

    Horton, S.; Schirmer, M.; Jamieson, B.

    2015-08-01

    Failure in layers of buried surface hoar crystals (frost) can cause hazardous snow slab avalanches. Surface hoar crystals form on the snow surface and are sensitive to micro-meteorological conditions. In this study, the role of meteorological and terrain factors was investigated for three layers of surface hoar in the Columbia Mountains of Canada. The distribution of crystals over different elevations and aspects was observed on 20 days of field observations during a period of high pressure. The same layers were modelled over simplified terrain on a 2.5 km horizontal grid by forcing the snow cover model SNOWPACK with forecast weather data from a numerical weather prediction model. Modelled surface hoar growth was associated with warm air temperatures, high humidity, cold surface temperatures, and low wind speeds. Surface hoar was most developed in regions and elevation bands where these conditions existed, although strong winds at high elevations caused some model discrepancies. SNOWPACK simulations on virtual slopes systematically predicted smaller surface hoar on south-facing slopes. In the field, a complex combination of surface hoar and sun crusts were observed, suggesting the simplified model did not adequately resolve the surface energy balance on slopes. Overall, a coupled weather-snow cover model could benefit avalanche forecasters by predicting surface hoar layers on a regional scale over different elevation bands.

  11. Effects of Topographic Slopes on Hydrological Proecsses and Climate

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based on previous research results on river re-distribution models, a modification on the effects of topographic slopes for a runoff parameterization was proposed and implemented to the NCAR's land sur face model (LSM). This modification has two aspects: firstly, the topographic slopes cause outflows from higher topography and inflows into the lower topography points; secondly, topographic slopes also cause decrease of infiltration at higher topography and increases of infiltration at lower topography. Then changes in infiltration result in changes in soil moisture, surface fluxes and then in surface temperature, and eventual ly in the upper atmosphere and the climate. This mechanism is very clearly demonstrated in the point bud gets analysis at the Andes Mountains vicinities. Analysis from a regional scale perspective in the Mackenzie GEWEX Study (MAGS) area, the focus of the ongoing Canadian GEWEX program, shows that the modi fied runoff parameterization does bring significant changes in the regional surface climate. More important ly, detailed analysis from a global perspective shows many encouraging improvements introduced by the modified LSM over the original model in simulating basic atmospheric climate properties such as thermodynamic features (temperature and humidity). All of these improvements in the atmospheric climate simulation illustrate that the inclusion of topographic effects in the LSM can force the AGCM to produce a more realistic model climate.

  12. Native plants for erosion control in urban river slopes

    Directory of Open Access Journals (Sweden)

    Virginia Alvarado

    2014-03-01

    Full Text Available Mechanical and structural erosion of soils is produced by the loss of the vegetal cover and the action of rain on unprotected surfaces. Raindrop impact, transport and sediment deposition leads to landslides and slope instability and soil loss. In Costa Rica, water bodies have been negatively impacted by urban development and both water resources and soils have become more vulnerable. This is the case of the Pirro river micro watershed where riverbed vegetation has been replaced by constructions producing erosion problems in its slopes. In order to evaluate how native plants favor sediment control and prevent this sediment from been deposited in the river, eight experimental plots were installed. Four treatments were established: A (Costus pulverulentus Presl, B (Heliconia tortuosa (Griggs Standl., C (Vetiveria zizanioides (L. Nash and D (control. Sediments were collected weekly during the rainy and transitional seasons. A clear relation between rainfall intensity and sediment production was determined, particularly for intensities higher than 50 mm h-1. Significant differences were also determined between the treatments and the efficiency order was B >A > C >D, with the native plants being the most efficient in terms of sediment control. The use of native plants is recommended for the management and rehabilitation of slopes near urban rivers due to their ecological value and their capability for sediment control.

  13. Soil-water interaction in unsaturated expansive soil slopes

    Institute of Scientific and Technical Information of China (English)

    ZHAN Liangtong

    2007-01-01

    The intensive soil-water interaction in unsatura- ted expansive soil is one of the major reasons for slope fail- ures. In this paper, the soil-water interaction is investigated with the full-scale field inspection of rainwater infiltration and comprehensive experiments, including wetting-induced softening tests, swelling, and shrinkage tests. It is demonstrat- ed that the soil-water interaction induced by seasonal wetting- drying cycles is very complex, and it involves coupled effects among the changes in water content, suction, stress, deforma- tion and shear strength. In addition, the abundant cracks in the expansive soil play an important role in the soil-water interaction. The cracks disintegrate the soil mass, and more importantly, provide easy pathways for rainfall infiltration. Infiltration of rainwater not only results in wetting-induced softening of the shallow unsaturated soil layers, but also leads to the increase of horizontal stress. The increase of horizontal stress may lead to a local passive failure. The seasonal wetting-drying cycles tend to result in a down-slope creeping of the shallow soil layer, which leads to progressive slope failure.

  14. Absolute surface reconstruction by slope metrology and photogrammetry

    Science.gov (United States)

    Dong, Yue

    Developing the manufacture of aspheric and freeform optical elements requires an advanced metrology method which is capable of inspecting these elements with arbitrary freeform surfaces. In this dissertation, a new surface measurement scheme is investigated for such a purpose, which is to measure the absolute surface shape of an object under test through its surface slope information obtained by photogrammetric measurement. A laser beam propagating toward the object reflects on its surface while the vectors of the incident and reflected beams are evaluated from the four spots they leave on the two parallel transparent windows in front of the object. The spots' spatial coordinates are determined by photogrammetry. With the knowledge of the incident and reflected beam vectors, the local slope information of the object surface is obtained through vector calculus and finally yields the absolute object surface profile by a reconstruction algorithm. An experimental setup is designed and the proposed measuring principle is experimentally demonstrated by measuring the absolute surface shape of a spherical mirror. The measurement uncertainty is analyzed, and efforts for improvement are made accordingly. In particular, structured windows are designed and fabricated to generate uniform scattering spots left by the transmitted laser beams. Calibration of the fringe reflection instrument, another typical surface slope measurement method, is also reported in the dissertation. Finally, a method for uncertainty analysis of a photogrammetry measurement system by optical simulation is investigated.

  15. Posterior Slope of the Tibia Plateau in Malaysian Patients Undergoing Total Knee Replacement

    Directory of Open Access Journals (Sweden)

    R Yoga

    2009-05-01

    Full Text Available The posterior slope of the tibial plateau is an important feature to preserve during knee replacement. The correct slope aids in the amount of flexion and determines if the knee will be loose on flexion. This is a study on the posterior tibial plateau slope based on preoperative and postoperative radiographs of 100 consecutive patients who had total knee replacements. The average posterior slope of the tibia plateau was 10.1 degrees. There is a tendency for patients with higher pre-operative posterior tibial plateau slope to have higher post-operative posterior tibial plate slope.

  16. Artificial neural network based inverse design method for circular sliding slopes

    Institute of Scientific and Technical Information of China (English)

    丁德馨; 张志军

    2004-01-01

    Current design method for circular sliding slopes is not so reasonable that it often results in slope sliding. As a result, artificial neural network (ANN) is used to establish an artificial neural network based inverse design method for circular sliding slopes. A sample set containing 21 successful circular sliding slopes excavated in the past is used to train the network. A test sample of 3 successful circular sliding slopes excavated in the past is used to test the trained network. The test results show that the ANN based inverse design method is valid and can be applied to the design of circular sliding slopes.

  17. Large slope failures in the La Paz basin, Bolivian Andes

    Science.gov (United States)

    Roberts, N. J.; Hermanns, R. L.; Rabus, B.; Guzmán, M. A.; Minaya, E.; Clague, J. J.

    2014-12-01

    The La Paz basin in the eastern Bolivian Andes has been a hotspot for large-scale, deep-seated gravitational slope deformation during the Holocene. In less than 2 Ma, a network of steep-sided valleys up to 800 m deep formed in sediments of the Altiplano Plateau and underlying basement rocks. We characterize the distribution, extent, mechanisms, and modern activity of large-scale failures within this landscape using optical image interpretation, existing geologic maps, synthetic RADAR interferometry (InSAR), and field investigation. Deposits of nearly 20 landslides larger than 100 Mm3 occur within the basin. Most failures have occurred in weakly lithified Late Miocene to Pliocene sedimentary rocks and include earth flows, translational and rotational landslides, and plug flows. Failures in underlying tectonized Paleozoic sedimentary rocks include bedding-parallel rockslides. The largest failure is the 3 km3 Achcocalla earth flow (ca. 11 ka BP), which ran out ~20 km. Other dated events span the period from the early Holocene to nearly the Colonial historic period. InSAR results show that many large slope failures, including the Achocalla earth flow, are currently moving at rates of a few centimeters to a few decimeters per year. Rapid deposition, shallow burial, and rapid incision of the basin fills produced steep slopes in weak geologic materials that, coupled with groundwater discharge from the valley walls, are the primary controls on instability. In contrast, the Altiplano surface has changed little in 2 Ma and the adjacent slopes of the Cordilleran Real, although steep, are relatively stable. Of the over 100 landslides that have occurred in the city of La Paz since the early twentieth century, most are at the margins of large, deep-seated prehistoric failures, and two of the most damaging historic landslides (Hanko-Hanko, 1582; Pampahasi, 2011) were large-scale reactivations of previously failed slopes. Improved understanding of large, deep-seated landslides in

  18. Agricultural terraces and slope instability at Cinque Terre (NW Italy)

    Science.gov (United States)

    Brandolini, Pierluigi; Cevasco, Andrea

    2015-04-01

    Cinque Terre, located in the eastern Liguria, are one of the most representative examples of terraced coastal landscape within the Mediterranean region. They are the result of a century-old agricultural practice and constitute an outstanding example of human integration with the natural landscape. For this highly unusual man-made coastal landscape, the Cinque Terre have been recognized as a World Heritage Site by UNESCO since 1997 and became National Park in 1999. The complex network of retaining dry stone walls and drainage networks ensured through times the control of shallow water erosion and therefore, indirectly, favoured debris cover stability. The lack of maintenance of terracing due to farmer abandonment since the 1950s led to widespread slope erosion phenomena. The effects of such phenomena culminated during the 25 October 2011 storm rainfall event, when slope debris materials charged by streams gave rise to debris floods affecting both Monterosso and Vernazza villages. As the analysis of the relationships between geo-hydrological processes and land use in the Vernazza catchment highlighted, abandoned and not well maintained terraces were the most susceptible areas to shallow landsliding and erosion triggered by intense rainfall. As a consequence, the thousands of kilometres of dry stone walls retaining millions of cubic metres of debris cover at Cinque Terre currently constitute a potential menace for both villages, that are mainly located at the floor of deep cut valleys, and tourists. Given the increasing human pressure due to tourist activities, geo-hydrological risk mitigation measures are urgently needed. At the same time, restoration policies are necessary to preserve this extraordinary example of terraced coastal landscape. In this framework, the detailed knowledge of the response of terraced areas to intense rainfall in terms of slope instability is a topic issue in order to identify adequate land planning strategies as well as the areas where

  19. Quasi-stable Slope-Failure Dams in High Asia

    Science.gov (United States)

    Shroder, J. F.

    2010-12-01

    Collapses of steep mountain slopes in the Himalaya, Karakoram, Pamir, Hindu Kush, and Tibetan Plateau are well known as a result of:(1) generally high seismicity in active tectonic areas; (2) prior deglaciation leaving undercut, unstable cliffs; (3) present-day debuttressing of rock cliffs by glacial down-wasting in conditions of global warming; and (4) degradation of permafrost cohesion and water-ice cementation in high mountain slopes. Landslide dams across mountain rivers are also well known worldwide and generally do not endure for long because of the common landslide-lake outburst floods (LLOF) whose discharge is commonly sufficiently large to remove much of the dam in a short time. A number of massive slope-failure dams in south High Asia, however, have endured for centuries and require explanations for the length of duration, whereas recent examples require robust assessment for better predictive hazard analysis. Three main factors contribute to longevity of slope-failure dams: (1) mega-rocks >15-30 m that inhibit dam failure in overflow breaches; (2) mega-porosity wherein incoming discharge to the landslide lake is balanced by subterranean water through-flow within the landslide dam; (3) impermeable clay fills caused by remobilization of prior lacustrine-dammed sediment that impart dam strength to allow lasting integrity for a time, and (4) climate-change induced lake-level lowering. Several examples of long-lived or unusually stable, slope-failure dams associated with pronounced structural/tectonic associations include: (1) Pangong Tso, Ladakh and Tibet; (2) Lake Shewa, Afghanistan; (3) Sarez Lake, Tajikistan; and (4) Lake Hunza, Pakistan. Pangong Tso and Lake Shewa were emplaced thousands of years ago and only Lake Shewa shows some instability of the dam front where percolating water maintains lake level but may be causing new slumping. Sarez Lake behind the Usoi landslide dam was emplaced by an earthquake in 1911 and maintains its level by seepage. Lake

  20. Nonlinear reflection of internal gravity wave onto a slope

    Science.gov (United States)

    Raja, Keshav; Sommeria, Joel; Staquet, Chantal; Leclair, Matthieu; Grisouard, Nicolas; Gostiaux, Louis

    2016-04-01

    The interaction of internal waves on sloping topography is one of the processes that cause mixing and transport in oceans. The mixing caused by internal waves is considered to be an important source of energy that is needed to bring back deep, dense water from the abyss to the surface of the ocean, across constant density surfaces. Apart from the vertical transport of heat (downwards) and mass (upwards), internal waves are also observed to irreversibly induce a mean horizontal flow. Mixing and wave induced mean flow may be considered as the processes that transfer wave induced energy to smaller and larger scales respectively. The process of mixing has been a subject of intense research lately. However, the process of wave induced mean flow and their dynamic impact await thorough study. The present study involves this wave induced mean flow, its generation and energetics. The nonlinear subcritical reflection of internal waves from a sloping boundary is studied using laboratory experiments carried out on the Coriolis Platform at Grenoble and, 2D and 3D numerical simulations done using a non-hydrostatic code. In the experiment, a plane wave is produced using a wave generator and is made to reflect normally on a sloping bottom in a uniformly stratified fluid. We consider both rotating and non-rotating cases. The numerical simulation mimicks the laboratory setup with an initial condition of an analytical plane wave solution in a vertical plane limited by a smooth envelope to simulate the finite wave generator. The interaction of the incident and reflected waves produce, apart from higher harmonics, an irreversible wave induced mean flow which grows in time and is localised in the interacting region. The finite extent of the wave generator allows the mean flow to recirculate in the horizontal plane, resulting in a dipolar potential vorticity field. Moreover, the generation of mean flow and higher harmonics, along with dissipative effects, diminishes the amplitude of

  1. Lacustrine Basin Slope Break — A New Domain of Strata and Lithological Trap Exploration

    Institute of Scientific and Technical Information of China (English)

    WangYingmin; LiuHao; XinRenchen; JinWudi; WangYuan; LiWeiguo

    2004-01-01

    Based on the studies of the Songliao Basin characterized by Cretaceous down-warping, of the Jurassic compressional flexural Junggar basin and of the Bohai Bay Basin characterized by Paleogene rifting, the multiple-grades slope break has developed in lacustrine basins of different origins. Their genetic types can be divided into tectonic slope break, depositional slope break and erodent slope break. The dominant agent of the slope break is tectogenesis, and the scale of slope breaks relates with the size of tectogenesis. The results of the study show that control of mutual grades slope breaks on atectonic traps mainly represent: 1) Atectonic traps develop close to mutual grades slope breaks, with beads-shaped distribution along the slope breaks. 2) In the longitudinal direction, the development of atectonic traps is characterized by the inheritance. 3) Different slope breaks and their different geographical positions can lead to different development types of atectonic traps. 4) A slope break can form different kinds of atectonic traps because of its great lateral variation. 5) The existence of mutual-grade slope breaks leads to different responses of erosion and deposition at different geographical positions in the basin. The oil source bed, reservoir and cap rock combination of atectonic traps is fine. 6) The oil-bearing condition of atectonic traps controlled by slope breaks is very favorable.

  2. Consequence assessment of large rock slope failures in Norway

    Science.gov (United States)

    Oppikofer, Thierry; Hermanns, Reginald L.; Horton, Pascal; Sandøy, Gro; Roberts, Nicholas J.; Jaboyedoff, Michel; Böhme, Martina; Yugsi Molina, Freddy X.

    2014-05-01

    Steep glacially carved valleys and fjords in Norway are prone to many landslide types, including large rockslides, rockfalls, and debris flows. Large rockslides and their secondary effects (rockslide-triggered displacement waves, inundation behind landslide dams and outburst floods from failure of landslide dams) pose a significant hazard to the population living in the valleys and along the fjords shoreline. The Geological Survey of Norway performs systematic mapping of unstable rock slopes in Norway and has detected more than 230 unstable slopes with significant postglacial deformation. This large number necessitates prioritisation of follow-up activities, such as more detailed investigations, periodic displacement measurements, continuous monitoring and early-warning systems. Prioritisation is achieved through a hazard and risk classification system, which has been developed by a panel of international and Norwegian experts (www.ngu.no/en-gb/hm/Publications/Reports/2012/2012-029). The risk classification system combines a qualitative hazard assessment with a consequences assessment focusing on potential life losses. The hazard assessment is based on a series of nine geomorphological, engineering geological and structural criteria, as well as displacement rates, past events and other signs of activity. We present a method for consequence assessment comprising four main steps: 1. computation of the volume of the unstable rock slope; 2. run-out assessment based on the volume-dependent angle of reach (Fahrböschung) or detailed numerical run-out modelling; 3. assessment of possible displacement wave propagation and run-up based on empirical relations or modelling in 2D or 3D; and 4. estimation of the number of persons exposed to rock avalanches or displacement waves. Volume computation of an unstable rock slope is based on the sloping local base level technique, which uses a digital elevation model to create a second-order curved surface between the mapped extent of

  3. A Novel Multi-Channel Dispersion Slope Compensator Using Sampled FBG

    Institute of Scientific and Technical Information of China (English)

    J.; J.; Pan; Claire; Gu; Albert; Li

    2003-01-01

    A novel dispersion slope compensator is proposed and fabricated using a sampled fiber grating. The dispersion slope of this compensator is demonstrated to match that of Coming LS fiber for a multi-channel 50GHz WDM system.

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

    OpenAIRE

    Sandra G. Catane; Mark Albert H. Zarco; Cathleen Joyce N. Cordero; Roy Albert N. Kaimo; Ricarido M. Saturay, Jr.

    2011-01-01

    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 sens...

  5. Numerical simulation of roadbed slope under seismic action in permafrost regions

    Institute of Scientific and Technical Information of China (English)

    JingYu Liu; JianKun Liu; ZhongQin Su; Li Liu; Min Xie

    2013-01-01

    The deformation and strength characteristics of roadbed slope under seismic loading in permafrost regions are simulated numerically. The seismic response of roadbed at different positions and inclinations of a slope section was analyzed. Results show that, roadbed slope damage is mainly led by lateral displacement, and the deformation gradually decreases with increasing depth;roadbed and foundation displacement and plastic strain increases with the magnitude of slope angle, hence the roadbed safety factor will be reduced.

  6. Slope wavenumber spectrum models of capillary and capillary-gravity waves

    Institute of Scientific and Technical Information of China (English)

    贾永君; 张杰; 王岩峰

    2010-01-01

    Capillary and capillary-gravity waves possess a random character, and the slope wavenumber spectra of them can be used to represent mean distributions of wave energy with respect to spatial scale of variability. But simple and practical models of the slope wavenumber spectra have not been put forward so far. In this article, we address the accurate definition of the slope wavenumber spectra of water surface capillary and capillary-gravity waves. By combining the existing slope wavenumber models and using th...

  7. Soil Erosion Spatial Distribution Character of Sloping Field in the Sichuan Hilly Basin: Taking a Cultivated Slope in Neijiang as Example

    Institute of Scientific and Technical Information of China (English)

    ZHENG Jinjun; QI Yongqing; HUA Lizhong; HE Xiubin; ZHANG Xinbao

    2006-01-01

    137Cs nuclear tracing technique was used to estimate rates of soil redistribution on a sloping field with traditional erosion control measures located near Shangqiao Village, Neijiang City, in the Sichuan Hilly Basin of China. The downslope changes of 137Cs inventory and its corresponding soil erosion rates in the sloping field show a rolling trend and have two peak values in two inflexions of the sloping field, these result reflects that the changes of microphysiognomy play a key role on the spatial soil redistribution of the sloping field.

  8. Slope angle studies from multibeam sonar data on three seamounts in Central Indian Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Kodagali, V.N.

    is presented here. The slope angle grid can be used to create the slope angle map. Morphology of three seamounts from Central Indian Basin and the slope angle data on them are described. The seamounts are of the heights 1000-1200 m and occupy area up to 300 sq...

  9. Procedural and Conceptual Difficulties with Slope: An Analysis of Students' Mistakes on Routine Tasks

    Science.gov (United States)

    Cho, Peter; Nagle, Courtney

    2017-01-01

    This study extends past research on students' understanding of slope by analyzing college students' mistakes on routine tasks involving slope. We conduct both quantitative and qualitative analysis of students' mistakes on common slope tasks to extract information regarding procedural proficiencies and conceptual underpinnings required in order for…

  10. Calcium carbonate production of the mare incognitum, the upper windward reef slope, at enewetak atoll.

    Science.gov (United States)

    Smith, S V; Harrison, J T

    1977-08-05

    Corals and algal pavement produce calcium carbonate more slowly on the windward reef slope of Enewetak Atoll than on the reef flat despite the high standing crop of reef-building organisms on the slope. The capacity of reefs to remain at or near sea level is therefore not determined primarily by growth on the seaward slope.

  11. How does slope form affect erosion in CATFLOW-SED?

    Science.gov (United States)

    Gabelmann, Petra; Wienhöfer, Jan; Zehe, Erwin

    2016-04-01

    Erosion is a severe environmental problem in agro-ecosystems with highly erodible loess soils. It is controlled by various factors, e.g. rainfall intensity, initial wetness conditions, soil type, land use and tillage practice. Furthermore slope form and gradient have been shown to influence erosion amounts to a large extent. Within the last fifty years, various erosion models have been developed to describe the erosion process, estimate erosion amounts and identify erosion-prone areas. These models differ in terms of complexity, the processes which are considered, and the data required for model calibration and they can be categorised into empirical or statistical, conceptual, and physically-based models. CATFLOW-SED is a process-based hydrology and erosion model that can operate on catchment and hillslope scales. Soil water dynamics are described by the Richards equation including effective approaches for preferential flow. Evapotranspiration is simulated using an approach based on the Penman-Monteith equation. The model simulates overland flow using the diffusion wave equation. Soil detachment is related to the attacking forces of rainfall and overland flow, and the erosion resistance of soil. Sediment transport capacity and sediment deposition are related to overland flow velocity using the equation of Engelund and Hansen and the sinking velocity of grain sizes respectively. We performed a study to analyse the erosion process on different virtual hillslopes, with varying slope gradient and slope form, using the CATFLOW-SED model. We explored the role of landform on erosion and sedimentation, particularly we look for forms that either maximise or minimise erosion. Results indicate the importance to performing the process implementation within physically meaningful limits and choose appropriate model parameters respectively.

  12. AMS radiocarbon dating on Campos Basin, Southeast Brazilian Continental Slope

    Energy Technology Data Exchange (ETDEWEB)

    Macario, K.D.; Anjos, R.M.; Gomes, P.R.S. E-mail: paulogom@if.uff.br; Figueiredo, A.G.; Lacerda de Souza, C.; Barbosa, C.F.; Coimbra, M.M.; Elmore, D

    2004-08-01

    We present results on radiocarbon dating of foraminifera shell samples, collected on the upper slope of Campos Basin, in Southern Brazil. This is the first time that the sedimentation rate of this area is measured with a fine scale (cm) stratigraphy. {sup 14}C ages vary from (2560 {+-} 80) years. BP at the top to (7260 {+-} 80) years. BP at the bottom of the sediment column. The mean accumulation ratio for the whole column is (6.2 {+-} 0.7) cm/kyears.

  13. Numerical modeling to investigate slopes and mass flow phenomena

    Institute of Scientific and Technical Information of China (English)

    Heinz Konietzky; Lei NIE; Youhong SUN

    2006-01-01

    An overview is given about up-to-date techniques for slope stability and deformation analysis as well as mass flow phenomena simulation. The paper concentrates on a few aspects in respect to the use of numerical modeling techniques, especially in relation to the shear strength reduction techniques, discontinuum modeling, probabilistic concepts, the combination of GIS and numerical modeling as well as sophisticated hydro-mechanical coupling with time-dependent material behavior. At present these topics are preferred topics of scientific and technical research.

  14. HDMR methods to assess reliability in slope stability analyses

    Science.gov (United States)

    Kozubal, Janusz; Pula, Wojciech; Vessia, Giovanna

    2014-05-01

    Stability analyses of complex rock-soil deposits shall be tackled considering the complex structure of discontinuities within rock mass and embedded soil layers. These materials are characterized by a high variability in physical and mechanical properties. Thus, to calculate the slope safety factor in stability analyses two issues must be taken into account: 1) the uncertainties related to structural setting of the rock-slope mass and 2) the variability in mechanical properties of soils and rocks. High Dimensional Model Representation (HDMR) (Chowdhury et al. 2009; Chowdhury and Rao 2010) can be used to carry out the reliability index within complex rock-soil slopes when numerous random variables with high coefficient of variations are considered. HDMR implements the inverse reliability analysis, meaning that the unknown design parameters are sought provided that prescribed reliability index values are attained. Such approach uses implicit response functions according to the Response Surface Method (RSM). The simple RSM can be efficiently applied when less than four random variables are considered; as the number of variables increases, the efficiency in reliability index estimation decreases due to the great amount of calculations. Therefore, HDMR method is used to improve the computational accuracy. In this study, the sliding mechanism in Polish Flysch Carpathian Mountains have been studied by means of HDMR. The Southern part of Poland where Carpathian Mountains are placed is characterized by a rather complicated sedimentary pattern of flysh rocky-soil deposits that can be simplified into three main categories: (1) normal flysch, consisting of adjacent sandstone and shale beds of approximately equal thickness, (2) shale flysch, where shale beds are thicker than adjacent sandstone beds, and (3) sandstone flysch, where the opposite holds. Landslides occur in all flysch deposit types thus some configurations of possible unstable settings (within fractured rocky

  15. Cooperative Three-Robot System for Traversing Steep Slopes

    Science.gov (United States)

    Stroupe, Ashley; Huntsberger, Terrance; Aghazarian, Hrand; Younse, Paulo; Garrett, Michael

    2009-01-01

    Teamed Robots for Exploration and Science in Steep Areas (TRESSA) is a system of three autonomous mobile robots that cooperate with each other to enable scientific exploration of steep terrain (slope angles up to 90 ). Originally intended for use in exploring steep slopes on Mars that are not accessible to lone wheeled robots (Mars Exploration Rovers), TRESSA and systems like TRESSA could also be used on Earth for performing rescues on steep slopes and for exploring steep slopes that are too remote or too dangerous to be explored by humans. TRESSA is modeled on safe human climbing of steep slopes, two key features of which are teamwork and safety tethers. Two of the autonomous robots, denoted Anchorbots, remain at the top of a slope; the third robot, denoted the Cliffbot, traverses the slope. The Cliffbot drives over the cliff edge supported by tethers, which are payed out from the Anchorbots (see figure). The Anchorbots autonomously control the tension in the tethers to counter the gravitational force on the Cliffbot. The tethers are payed out and reeled in as needed, keeping the body of the Cliffbot oriented approximately parallel to the local terrain surface and preventing wheel slip by controlling the speed of descent or ascent, thereby enabling the Cliffbot to drive freely up, down, or across the slope. Due to the interactive nature of the three-robot system, the robots must be very tightly coupled. To provide for this tight coupling, the TRESSA software architecture is built on a combination of (1) the multi-robot layered behavior-coordination architecture reported in "An Architecture for Controlling Multiple Robots" (NPO-30345), NASA Tech Briefs, Vol. 28, No. 10 (October 2004), page 65, and (2) the real-time control architecture reported in "Robot Electronics Architecture" (NPO-41784), NASA Tech Briefs, Vol. 32, No. 1 (January 2008), page 28. The combination architecture makes it possible to keep the three robots synchronized and coordinated, to use data

  16. Interaction between transverse isotropy rock slope and supporting structure

    Institute of Scientific and Technical Information of China (English)

    段靓靓; 方理刚

    2008-01-01

    In order to study the interaction between transverse isotropy rock mass and supporting structure,the laboratory tests for rock sampled from the slope at expressway project were carried out,and the parameters of elasticity for transverse isotropic rock were determined by the uniaxial compression tests for rock sample with different strike of stratification plane.Then,based on the relationship of stress-stain for transverse isotropic rock mass,the analytical model was established for the interaction between transverse isotropic rock mass and frame beam with pre-stressed anchor cable.Furthermore,the conception of the best anchorage-angle in pre-stressed anchor cable was proposed.At last,the parameters of the interaction between transverse isotropy rock mass and frame beam with pre-stressed anchor cable were investigated by finite element method,and the best anchorage-angle in pre-stressed anchor cable was obtained.The rules of the influence of the directivity of stratification plane on supporting structure were determined.The results show that the analytical model and numerical method on the design of pre-stressed anchor cable with frame beam supporting for transverse isotropy rock slope are reasonable and reliable in practical engineering design.

  17. Bioengineering case studies sustainable stream bank and slope stabilization

    CERN Document Server

    Goldsmith, Wendi; McCullah, John

    2014-01-01

    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. Seismic ultimate bearing capacity of strip footings on slope

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The influence of earthquake forces on ultimate bearing capacity of foundations on sloping ground was studied. A solution to seismic ultimate bearing capacity of strip footings on slope was obtained by utilizing pseudo-static analysis method and taking the effect of intermediate principal stress into consideration. Based on limit equilibrium theory, the formulae for computing static bearing capacity factors, Nq, Nc, Nγ, and dynamic bearing capacity factors, Nqd, Ncd, Nγd, which are associated with surcharge, cohesion and self-weight of soils respectively, were presented. A great number of analysis calculations were carried out to obtain the relationship curves of the static and dynamic bearing capacity factors versus various calculation parameters. The curves can serve as the practical engineering design. The calculation results also show that when the values of horizontal and vertical seismic coefficients are 0.2, the dynamic bearing capacity factors Nqd, Ncd and Nγd, in which the effects of intermediate principal stress are taken into consideration, increase by 4%-42%, 3%-27% and 34%-57%, respectively.

  19. Tolerable Time-Varying Overflow on Grass-Covered Slopes

    Directory of Open Access Journals (Sweden)

    Steven A. Hughes

    2015-03-01

    Full Text Available Engineers require estimates of tolerable overtopping limits for grass-covered levees, dikes, and embankments that might experience steady overflow. Realistic tolerance estimates can be used for both resilient design and risk assessment. A simple framework is developed for estimating tolerable overtopping on grass-covered slopes caused by slowly-varying (in time overtopping discharge (e.g., events like storm surges or river flood waves. The framework adapts the well-known Hewlett curves of tolerable limiting velocity as a function of overflow duration. It has been hypothesized that the form of the Hewlett curves suggests that the grass erosion process is governed by the flow work on the slope above a critical threshold velocity (referred to as excess work, and the tolerable erosional limit is reached when the cumulative excess work exceeds a given value determined from the time-dependent Hewlett curves. The cumulative excess work is expressed in terms of overflow discharge above a critical discharge that slowly varies in time, similar to a discharge hydrograph. The methodology is easily applied using forecast storm surge hydrographs at specific locations where wave action is minimal. For preliminary planning purposes, when storm surge hydrographs are unavailable, hypothetical equations for the water level and overflow discharge hydrographs are proposed in terms of the values at maximum overflow and the total duration of overflow. An example application is given to illustrate use of the methodology.

  20. Intensity measures for seismic liquefaction hazard evaluation of sloping site

    Institute of Scientific and Technical Information of China (English)

    陈志雄; 程印; 肖杨; 卢谅; 阳洋

    2015-01-01

    This work investigates the correlation between a large number of widely used ground motion intensity measures (IMs) and the corresponding liquefaction potential of a soil deposit during earthquake loading. In order to accomplish this purpose the seismic responses of 32 sloping liquefiable site models consisting of layered cohesionless soil were subjected to 139 earthquake ground motions. Two sets of ground motions, consisting of 80 ordinary records and 59 pulse-like near-fault records are used in the dynamic analyses. The liquefaction potential of the site is expressed in terms of the the mean pore pressure ratio, the maximum ground settlement, the maximum ground horizontal displacement and the maximum ground horizontal acceleration. For each individual accelerogram, the values of the aforementioned liquefaction potential measures are determined. Then, the correlation between the liquefaction potential measures and the IMs is evaluated. The results reveal that the velocity spectrum intensity (VSI) shows the strongest correlation with the liquefaction potential of sloping site. VSI is also proven to be a sufficient intensity measure with respect to earthquake magnitude and source-to-site distance, and has a good predictability, thus making it a prime candidate for the seismic liquefaction hazard evaluation.

  1. Precision Tiltmeter as a Reference for Slope MeasuringInstruments

    Energy Technology Data Exchange (ETDEWEB)

    Kirschman, Jonathan L.; Domning, Edward E.; Morrison, Gregory Y.; Smith, Brian V.; Yashchuk, Valeriy V.

    2007-08-01

    The next generation of synchrotrons and free electron lasers require extremely high-performance x-ray optical systems for proper focusing. The necessary optics cannot be fabricated without the use of precise optical metrology instrumentation. In particular, the Long Trace Profiler (LTP) based on the pencil-beam interferometer is a valuable tool for low-spatial-frequency slope measurement with x-ray optics. The limitations of such a device are set by the amount of systematic errors and noise. A significant improvement of LTP performance was the addition of an optical reference channel, which allowed to partially account for systematic errors associated with wiggling and wobbling of the LTP carriage. However, the optical reference is affected by changing optical path length, non-homogeneous optics, and air turbulence. In the present work, we experimentally investigate the questions related to the use of a precision tiltmeter as a reference channel. Dependence of the tiltmeter performance on horizontal acceleration, temperature drift, motion regime, and kinematical scheme of the translation stage has been investigated. It is shown that at an appropriate experimental arrangement, the tiltmeter provides a slope reference for the LTP system with accuracy on the level of 0.1 {micro}rad (rms).

  2. Erosion characteristic of slope sandstone soaking in acid mine drainage

    Institute of Scientific and Technical Information of China (English)

    JIANG Li-chun; CHEN Jia-sheng; WU Ai-xiang

    2007-01-01

    Acid mine drainage(AMD) is one of the main reasons of slope instability in chemical mines with high sulfide. The pH values of the solution inside the mining pit decrease with the increasing of distance from ore body and vary from 1.2 to 4.6,according to the results of the water environmental investigation and the composition test of the slope sandstone in Xinqiao Pyrite Mine. Comparative experiments between original sandstone and AMD eroded sandstone samples show that after AMD erosion the uniaxial compressive strength and elastic modulus decrease by 30%-50% and 25%-45%, respectively, the cohesion and internal friction angle decrease obviously, and the Poisson ratio fluctuates between 0.20-0.29. The greater joints development, the higher residual stress after peak value, and the longer time to damage. Besides above, the reaction mechanism analysis of AMD eroded sandstone shows that the fillings in joints and fissures of sandstone are frequently decomposed and polyreacted, resulting in changes of interior molecule structure and framework composition, and decreases of cohesion and angle of internal friction between rock structure interfaces.

  3. Estimating significances of differences between slopes: A new methodology and software

    Directory of Open Access Journals (Sweden)

    Vasco M. N. C. S. Vieira

    2013-09-01

    Full Text Available Determining the significance of slope differences is a common requirement in studies of self-thinning, ontogeny and sexual dimorphism, among others. This has long been carried out testing for the overlap of the bootstrapped 95% confidence intervals of the slopes. However, the numerical random re-sampling with repetition favours the occurrence of re-combinations yielding largely diverging slopes, widening the confidence intervals and thus increasing the chances of overlooking significant differences. To overcome this problem a permutation test simulating the null hypothesis of no differences between slopes is proposed. This new methodology, when applied both to artificial and factual data, showed an enhanced ability to differentiate slopes.

  4. Variance-in-Mean Effects of the Long Forward-Rate Slope

    DEFF Research Database (Denmark)

    Christiansen, Charlotte

    2005-01-01

    This paper contains an empirical analysis of the dependence of the long forward-rate slope on the long-rate variance. The long forward-rate slope and the long rate are described by a bivariate GARCH-in-mean model. In accordance with theory, a negative long-rate variance-in-mean effect for the long...... forward-rate slope is documented. Thus, the greater the long-rate variance, the steeper the long forward-rate curve slopes downward (the long forward-rate slope is negative). The variance-in-mean effect is both statistically and economically significant....

  5. Effect of Different Groundwater Levels on Seismic Dynamic Response and Failure Mode of Sandy Slope.

    Science.gov (United States)

    Huang, Shuai; Lv, Yuejun; Peng, Yanju; Zhang, Lifang; Xiu, Liwei

    2015-01-01

    Heavy seismic damage tends to occur in slopes when groundwater is present. The main objectives of this paper are to determine the dynamic response and failure mode of sandy slope subjected simultaneously to seismic forces and variable groundwater conditions. This paper applies the finite element method, which is a fast and efficient design tool in modern engineering analysis, to evaluate dynamic response of the slope subjected simultaneously to seismic forces and variable groundwater conditions. Shaking table test is conducted to analyze the failure mode and verify the accuracy of the finite element method results. The research results show that dynamic response values of the slope have different variation rules under near and far field earthquakes. And the damage location and pattern of the slope are different in varying groundwater conditions. The destruction starts at the top of the slope when the slope is in no groundwater, which shows that the slope appears obvious whipping effect under the earthquake. The destruction starts at the toe of the slope when the slope is in the high groundwater levels. Meanwhile, the top of the slope shows obvious seismic subsidence phenomenon after earthquake. Furthermore, the existence of the groundwater has a certain effect of damping.

  6. Effect of Different Groundwater Levels on Seismic Dynamic Response and Failure Mode of Sandy Slope.

    Directory of Open Access Journals (Sweden)

    Shuai Huang

    Full Text Available Heavy seismic damage tends to occur in slopes when groundwater is present. The main objectives of this paper are to determine the dynamic response and failure mode of sandy slope subjected simultaneously to seismic forces and variable groundwater conditions. This paper applies the finite element method, which is a fast and efficient design tool in modern engineering analysis, to evaluate dynamic response of the slope subjected simultaneously to seismic forces and variable groundwater conditions. Shaking table test is conducted to analyze the failure mode and verify the accuracy of the finite element method results. The research results show that dynamic response values of the slope have different variation rules under near and far field earthquakes. And the damage location and pattern of the slope are different in varying groundwater conditions. The destruction starts at the top of the slope when the slope is in no groundwater, which shows that the slope appears obvious whipping effect under the earthquake. The destruction starts at the toe of the slope when the slope is in the high groundwater levels. Meanwhile, the top of the slope shows obvious seismic subsidence phenomenon after earthquake. Furthermore, the existence of the groundwater has a certain effect of damping.

  7. Methods to Analyze Flexural Buckling of the Consequent Slabbed Rock Slope under Top Loading

    Directory of Open Access Journals (Sweden)

    Hongyan Liu

    2016-01-01

    Full Text Available The consequent slabbed rock slope is prone to flexural buckling failure under its self-weight and top loading. However, nearly none of the existing studies consider the effect of the top loading on the slope flexural critical buckling height (CBH. Therefore, on the basis of Euler’s Method and the flexural buckling failure mode of the consequent slabbed rock slope, the calculation method of the CBH of the vertical slabbed rock slope under the self-weight is firstly proposed, and then it is extended to that of the consequent slabbed rock slope. The effect of slope dip angle, friction angle, and cohesion between the neighboring rock slabs and rock elastic modulus on the slope CBH is discussed. Secondly, the calculation method of the CBH of the consequent slabbed rock slope under its self-weight and top loading is proposed according to the superposition principle. Finally, on the basis of the hypothesis that the rock mechanical behavior obeys the statistical damage model, the effect of the rock mechanical parameters n and ε0 on the slope CBH is studied. The results show that the rock strength has much effect on the slope CBH. If the rock is supposed to be a linear elastic body without failure in Euler’s Method, the result from it is the maximum of the slope CBH.

  8. Stability Analysis for Loosened Rock Slope of Jinyang Grand Buddha in Taiyuan, China

    Science.gov (United States)

    SUN, Jinzhong; TIAN, Xiaofu; GUAN, Xudong; YU, Yonggui; YANG, Xiusheng

    On the basis of the status quo of Jinyang Grand Buddha in Taiyuan, some factors such as topography, geological structures, climate, hydrology, and engineering geology that influence the stability of the Buddha slope are considered, and several working situations of the slope that possibly suffered are presented in this article. The Buddha slope stands upright and the rock masses are composed of thick Permian sandstone, which dips slightly inward to the slope. Affected by both the incision of regional joints and the load relief to the free surface, the rock mass of the Buddha slope has turned into loosened blocks. Numerical stability analysis by FLAC-2D on the basis of the strength reduction method reveals that the localized deformation of the rock masses near the vertical surface of the slope may trigger reversing of rock beddings making the back dip slope convert into a dip slope with the possibility of plane sliding failure. Furthermore, the pseudostatic method for the dynamic process and limit equilibrium method for the static process are applied to different working situations of the Buddha slope. The analytical results illustrate that plane sliding failure will not occur when the slope is affected only by seism. However, water filling in the cracks of the loosened rock mass may greatly contribute to the potential plane sliding failure. When horizontal seism-force and hydrostatic pressure are coupled, the Buddha slope can hardly keep stable. Additionally, the loosened rock masses are prone to block toppling failure when influenced by the seism force.

  9. Laws and mechanisms of slope movement due to shallowly buried coal seam mining under ground gully

    Institute of Scientific and Technical Information of China (English)

    FAN Gang-wei; ZHANG Dong-sheng; ZHAI De-yuan; WANG Xu-feng; LU Xin

    2009-01-01

    Based on the results of similar material simulation, the laws of slope movement due to mining under a gully were analyzed. Selected a slope rock as objective, the mechanisms of slope movement influence upon underground mining were proposed, and respective structural models were built by means of numerical modeling and physical simulation. It holds the point that the influence of slope movement on underground mining could be controlled to some extent by appropriate measures. The results indicate that, for gully-ward mining, which mines toward a gully, the slope rock slides horizontally and rotates in layers; for gully-away mining, which mines away from the gully, the slope rock rotates in a reversed polygon. The slope movement associated with mining under a gully is attributed to pre-existing free faces in the ground gully and underground mining-induced free faces.

  10. Optimum Design of Highway Excavation Slope Angle: Evidence from Dawu Section of Jingzhu Highway

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The optimum design of the highway excavation slope angle is one of the most important problems to the highway construction and to the slope improvement. The Dawu Section of Jingzhu (Beijing-Zhuhai) Highway is taken as an example to illustrate the study method for excavation slope angle design.The analysis of the engineering condition from different angles with different factors shows that the stability of the slope is calculated by using residual pushing force and the Sarma method. Then the sensitive analysis of the slope stability is conducted by using residual pushing force method. Finally, the optimum angle of design is presented on the precondition of ensuring the whole stability of slope and the economic reasonability. The study results show that the most sensitive factors are the shear strength parameter and t he seismic force, and that the optimum excavation slope angle is 60°.``

  11. Thresholds for the slope ratio in determining transition time and quantifying diffuser performance in situ

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho; Jacobsen, Finn; Brunskog, Jonas

    2012-01-01

    This study is concerned with an objective measure called the slope ratio that can detect acoustic defects due to unexpected pressure increases such as strong reflections and coincidental constructive interference. The slope ratio is the ratio of the instantaneous slope to the mean slope in a decay...... curve. The slope ratio was suggested for determining the room acoustic transition time experimentally, but its threshold criteria have not been thoroughly investigated. The thresholds for the slope ratio, particularly for applications such as determining the room acoustic transition time and quantifying...... in situ diffuseness, are examined for various room impulse responses. For the tested rooms, a slope ratio threshold of 11 gives the most consistent and systematic results....

  12. Primary Investigations on Yangtze River Bank Slope Stability in Wanzhou for the Three Gorges Reservoir Project

    Institute of Scientific and Technical Information of China (English)

    Jian Wenxing; Yin Kunlong; Xu Yixian

    2005-01-01

    This paper investigates the main factors contributing to bank slope failures, such as the structure of rock and soil, water level change, bank slope gradient, vegetation, weathering and human activities. Based on these investigations, the bank slope failure models are analyzed. The stability of bank slopes in Wanzhou is investigated using geological surveying, 2D resistivity imaging surveying, excavated trenches and other methods. Finally, the disasters of bank slope failures in Wanzhou were investigated in detail. The results show that instability problems might occur in 60.38 km of bank slopes when the water level rises to 175 m. It is suggested that 37.8 km of unstable bank slopes should be stabilized, and 14.2 km of unstable banks should be moved or avoided after further geological surveying and reconnaissance. These results provide scientific basis and reliable data for the government to develop the third geodisaster prevention plan for the Three Gorges reservoir.

  13. A study on dynamic response of slopes under wave action using simulation tests

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    After the erection of the Three Gorges Dam, the water level of Yangtze River will reach 175 m, and the average wave crest will be up to 1 m. Therefore the wave action cannot be neglected for the slope stability. Through simulation tests, the waveinduced dynamic response of the slope is analyzed. The soil body is taken as linear elastic body when it has a small deformation under the small wave action. Based on tests, the excess pore pressure and slope displacement under the loading in different wave period are analyzed. The ratio of dynamic strength and static strength to the breaking process of the slope is discussed. It is demonstrated that smaller wave period gives rise to a larger strain of the slope under the same stress. At different depth of water, different weakness effect on the stability of the soil slope is observed and the slope has an adaptability to the wave action to some extent.

  14. Mechanism analysis of landslide of a layered slope induced by drawdown of water level

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Junfeng; LI; Zhengguo; QI; Tao

    2005-01-01

    The frequent drawdown of water level of Yangtze River will greatly influence the stability of the widely existing slopes in the Three Gorges reservoir zone, especially those layered ones. Apart from the fluctuating speed of water level, the different geological materials will also play important roles in the failure of slopes. Thus, it must be first to study the mechanism of such a landslide caused by drawdown of water level.A new experimental setup is designed to study the performance of a layered slope under the drawdown of water level. The pattern of landslide of a layered slope induced by drawdown of water level has been explored by means of simulating experiments. The influence of fluctuating speed of water level on the stability of the layered slope is probed,especially the whole process of deformation and development of landslide of the slope versus time. The experimental results show that the slope is stable during the water level rising, and the sliding body occurs in the upper layer of the slope under a certain drawdown speed of water level. In the process of slope failure, some new small sliding body will develop on the main sliding body, and the result is that they speed up the disassembly of the whole slope.Based on the simulating experiment on landslide of a layered slope induced by drawdown of water level, the stress and displacement field of the slope are calculated.The seepage velocity, the pore water pressure, and the gradient of pore water head are also calculated for the whole process of drawdown of water level. The computing results are in good agreement with the experimental results. Accordingly, the mechanism of deformation and landslide of the layered slope induced by drawdown of water level is analyzed. It may provide basis for treating this kind of layered slopes in practical engineering.

  15. Stability of submarine slopes in the northern South China Sea: a numerical approach

    Institute of Scientific and Technical Information of China (English)

    ZHANG Liang; LUAN Xiwu

    2013-01-01

    Submarine landslides occur frequently on most continental margins.They are effective mechanisms of sediment transfer but also a geological hazard to seafloor installations.In this paper,submarine slope stability is evaluated using a 2D limit equilibrium method.Considerations of slope,sediment,and triggering force on the factor of safety (FOS) were calculated in drained and undrained (φ=0) cases.Results show that submarine slopes are stable when the slope is <16° under static conditions and without a weak interlayer.With a weak interlayer,slopes are stable at <18° in the drained case and at <9° in the undrained case.Earthquake loading can drastically reduce the shear strength of sediment with increased pore water pressure.The slope became unstable at >13° with earthquake peak ground acceleration (PGA) of 0.5 g;whereas with a weak layer,a PGA of 0.2 g could trigger instability at slopes > 10°,and >3 ° for PGA of 0.5 g.The northern slope of the South China Sea is geomorphologically stable under static conditions.However,because of the possibility of high PGA at the eastern margin of the South China Sea,submarine slides are likely on the Taiwan Bank slope and eastern part of the Dongsha slope.Therefore,submarine slides recognized in seismic profiles on the Taiwan Bank slope would be triggered by an earthquake,the most important factor for triggering submarine slides on the northern slope of the South China Sea.Considering the distribution of PGA,we consider the northern slope of the South China Sea to be stable,excluding the Taiwan Bank slope,which is tectonically active.

  16. Denudational slope processes and slope response to global climate changes and other disturbances: insights from the Nepal Himalayas.

    Science.gov (United States)

    Fort, Monique

    2016-04-01

    Hillslope geomorphology results from a large range of denudational processes mainly controlled by relief, structure, lithology, climate, land-cover and land use. In most areas of the world, the "critical zone" concept is a good integrator of denudation that operates on a long-term scale. However, in large and high mountain areas, short-time scale factors often play a significant role in the denudational pattern, accelerating and/or delaying the transfer of denudation products and fluxes, and creating specific, spatially limited disturbances. We focus on the Nepal Himalayas, where the wide altitudinal range of bio-climatic zones and the intense geodynamic activity create a complex mosaic of landforms, as expressed by the present geomorphology of mountain slopes. On the basis of examples selected in the different Himalayan mountain belts (Siwaliks hills, middle mountains, High Himalaya), we illustrate different types of slopes and disturbances induced by active tectonics, climate extremes, and climate warming trends. Special attention is paid to recent events, such as landslide damming, triggered by either intense rainfalls (Kali Gandaki and Sun Kosi valleys) or the last April-May 2015 Gorkha seismic sequence (southern Khumbu). Lastly, references to older, larger events show that despite the highly dynamic environment, landforms caused by large magnitude disturbances may persist in the landscape in the long term.

  17. Predicting Modes and Displacements of Seismic Rock Slope Failures

    Science.gov (United States)

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

    2013-12-01

    Seismically induced rock slope failures have resulted in billions of dollars of economic damage and enormous loss of life throughout the world. Accurate prediction of the triggering and run out of these failures is elusive for a variety of reasons, including knowledge of the physical modes of failure. Our research explores the potential failure modes of an idealized rigid rock block and expands the modes typically considered to include not only sliding but also toppling (pure forward rotation) and slumping (combined backward rotation and translation). The yield acceleration (or minimum inertial acceleration to cause block movement) for slumping, similar to toppling, is found to be lower than for pure translational sliding. These yield accelerations indicate the initial modes of rock block failure; however, they do not always predict the ultimate failure mode. To predict the final failure modes, the results of discrete element numerical analyses were compared to pseudo static yield acceleration to develop a seismic failure mode decision-making chart based on block geometry and interface friction. With regard to seismic displacement predictions, current simplified models predicting ultimate displacement of a mass under seismic conditions are limited to purely translating, sliding blocks (i.e. Newmark's sliding block method). Our modeling introduces additional simplified analyses to predict ultimate displacement in toppling and slumping modes as well. Important findings from these new methods are that the magnitude of seismically-induced displacement is dependent on the size of the block (or failure mass) and that as the yield acceleration decreases the seismically induced displacements increase. We plan to map these tools into analyses that evaluate rock slope systems with complex geology and geotechnical characteristics. It is envisioned that the decision chart, which predicts the initial and ultimate modes of failure based on block geometry and interface friction

  18. Check dams effects on sediment transport in steep slope flume

    Science.gov (United States)

    Piton, Guillaume; Recking, Alain

    2014-05-01

    Depending on many influences (geology, relief, hydrology, land use, etc.) some mountainous watershed are prone to cause casualties and facilities damages. Large amounts of sediments episodically released by torrents are often the biggest problem in torrent related hazard mitigation. Series of transversal structures as check dams and ground sills are often used in the panel of risk mitigation technics. A large literature exits on check dams and it mainly concerns engineering design, e.g. toe scouring, stability stress diagram, changes in upper and lower reaches equilibrium slopes. Check dams in steep slope rivers constitute fixed points in the bed profile and prevent general bed incision. However their influence on sediment transport once they are filled is not yet clear. Two flume test campaigns, synthetize in Table 1, were performed to investigate this question: Table 1 : experiment plan Run (duration) Ref1 (50h)CD1a (30h)CD1b (30h)Ref2 (92h)CD2 (18h) Solid feeding discharge (g.s^-1) 44 44 44 60 60 Number of check dams none 1 3 none 2 A nearly 5-m-long, 10-cm-wide and 12%-steep flume was used. The water discharge was set to 0,55 l/s in all runs. A mixture of poorly sorted natural sediments with diameters between 0.8 and 40 mm was used. An open solid-discharge-feeding circuit kept the inlet sediment flux constant during all experiments. As both feeding rates did not present variation, changes in outlet solid discharge were assumed to be due to bed variations in the bed storage. We observed strong fluctuations of solid flux and slope in each reaches of all runs between: (i) steep aggradating armoured bed and (ii) less steep and finer bed releasing bedload sheets during erosion events and inducing bedload pulses. All experiments showed consistent results: transported volume associated with erosion event decreased with the length between two subsequent check dams. Solid transversal structures shorten the upstream erosion-propagation and avoid downstream change in the

  19. Linking hydrological, infinite slope stability and land-use change models through GIS for assessing the impact of deforestation on slope stability in high Andean watersheds

    Science.gov (United States)

    Vanacker, Veerle; Vanderschaeghe, Michiel; Govers, Gerard; Willems, Edith; Poesen, Jean; Deckers, Jozef; De Bievre, Bert

    2003-06-01

    In the Ecuadorian Andes, episodic slope movements comprising shallow rotational and translational slides and rapid flows of debris and soil material are common. Consequently, not only considerable financial costs are experienced, but also major ecological and environmental problems arise in a larger geographical area. Sediment production by slope movement on hillslopes directly affects sediment transport and deposition in downstream rivers and dams and morphological changes in the stream channels. In developing countries world-wide, slope movement hazards are growing: increasing population pressure and economic development force more people to move to potentially hazardous areas, which are less suitable for agriculture and rangelands. This paper describes the methods used to determine the controlling factors of slope failure and to build upon the results of the statistical analysis a process-based slope stability model, which includes a dynamic soil wetness index using a simple subsurface flow model. The model provides a time-varying estimate of slope movement susceptibility, by linking land-use data with spatially varying hydrologic (soil conductivity, evapotranspiration, soil wetness) and soil strength properties. The slope stability model was applied to a high Andean watershed (Gordeleg Catchment, 250 ha, southern Ecuadorian Andes) and was validated by calculating the association coefficients between the slope movement susceptibility map of 2000 and the spatial pattern of active slope movements, as measured in the field with GPS. The proposed methodology allows assessment of the effects of past and future land-use change on slope stability. A realistic deforestation scenario was presented: past land-use change includes a gradual fragmentation and clear cut of the secondary forests, as observed over the last four decades (1963-2000), future land-use change is simulated based on a binary logistic deforestation model, whereby it was assumed that future land

  20. Biocorrosive Thermophilic Microbial Communities in Alaskan North Slope Oil Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Duncan, Kathleen E.; Gieg, Lisa M.; Parisi, Victoria A.; Tanner, Ralph S.; Green Tringe, Susannah; Bristow, Jim; Suflita, Joseph M.

    2009-09-16

    Corrosion of metallic oilfield pipelines by microorganisms is a costly but poorly understood phenomenon, with standard treatment methods targeting mesophilic sulfatereducing bacteria. In assessing biocorrosion potential at an Alaskan North Slope oil field, we identified thermophilic hydrogen-using methanogens, syntrophic bacteria, peptideand amino acid-fermenting bacteria, iron reducers, sulfur/thiosulfate-reducing bacteria and sulfate-reducing archaea. These microbes can stimulate metal corrosion through production of organic acids, CO2, sulfur species, and via hydrogen oxidation and iron reduction, implicating many more types of organisms than are currently targeted. Micromolar quantities of putative anaerobic metabolites of C1-C4 n-alkanes in pipeline fluids were detected, implying that these low molecular weight hydrocarbons, routinely injected into reservoirs for oil recovery purposes, are biodegraded and provide biocorrosive microbial communities with an important source of nutrients.

  1. REVIEW OF HIGH FIELD Q SLOPE, CAVITY MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Gianluigi Ciovati

    2008-01-23

    One of the most interesting phenomenon occurring in superconducting radio-frequency (SRF) cavities made of bulk niobium is represented by a sharp decrease of the quality factor above peak surface magnetic field of about 90 mT and is referred to as "high field Q-slope" or "Q-drop". This phenomenon was observed first in 1997 and since then some effort was devoted to the understanding of the causes behind it. Still, no clear physical interpretation of the Q-drop has emerged, despite several attempts. In this contribution, I will review the experimental results for various cavities measured in many laboratories and I will try to identify common features and differences related to the Q-drop.

  2. Evaluation of Surface Slope Irregularity in Linear Parabolic Solar Collectors

    Directory of Open Access Journals (Sweden)

    F. Francini

    2012-01-01

    Full Text Available The paper describes a methodology, very simple in its application, for measuring surface irregularities of linear parabolic collectors. This technique was principally developed to be applied in cases where it is difficult to use cumbersome instruments and to facilitate logistic management. The instruments to be employed are a digital camera and a grating. If the reflector surface is defective, the image of the grating, reflected on the solar collector, appears distorted. Analyzing the reflected image, we can obtain the local slope of the defective surface. These profilometric tests are useful to identify and monitor the mirror portions under mechanical stress and to estimate the losses caused by the light rays deflected outside the absorber.

  3. DISSIPATION OF WAVE ENERGY ON VERY MILD SLOPE

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper presents the analysis and calculation of wave attenuation when waves travel on sand bed, sand ripple bed and muddy bed, respectively. The study shows that (1) The dissipation of wave energy due to bottom percolation may be neglected on sand bed; (2) The wave attenuation due to the friction of sand ripples is one order higher than that of flat sand bed and (3) The energy loss of waves propagating on muddy bed is the largest. Then, the equivalent coefficients of friction are calculated in order to compare with the solution by the bottom-friction model. Wave attenuation are also computed by the Bingham-model and the principle of conservation of wave energy flux on very mild muddy slope. The results coincide well with the wave information from the Lianyungang Wave Observation Station. Theoretical prediction proves that the equivalent coefficients of friction strongly rely on water depth, which inerease with decreasing depth.

  4. Slope Hazard and Risk Assessment in the Tropics: Malaysia' Experience

    Science.gov (United States)

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

    2015-04-01

    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

  5. End depth in steeply sloping rough rectangular channels

    Indian Academy of Sciences (India)

    Subhasish Dey

    2000-02-01

    The paper presents a theoretical model to compute the end depth of a free overfall in steeply sloping rough rectangular channels. A momentum equation based on the Boussinesq approximation is applied to obtain the equation of the end depth. The effect ofstreamline curvature at the free surface is utilized to develop the differential equation for the flow profile upstream of the free overfall of a wide rectangular channel. As direct solutions for the end depth and flow profile cannot be obtained owing to implicit forms of the developed equations, an auto-recursive search scheme is evolved to solve these equations simultaneously. A method for estimation of discharge from the known end depth and Nikuradse equivalent sand roughness is also presented. Results from the present model correspond satisfactorily with experimental observations except for some higher roughnesses.

  6. Pursuing optimal electric machines transient diagnosis: The adaptive slope transform

    Science.gov (United States)

    Pons-Llinares, Joan; Riera-Guasp, Martín; Antonino-Daviu, Jose A.; Habetler, Thomas G.

    2016-12-01

    The aim of this paper is to introduce a new linear time-frequency transform to improve the detection of fault components in electric machines transient currents. Linear transforms are analysed from the perspective of the atoms used. A criterion to select the atoms at every point of the time-frequency plane is proposed, taking into account the characteristics of the searched component at each point. This criterion leads to the definition of the Adaptive Slope Transform, which enables a complete and optimal capture of the different components evolutions in a transient current. A comparison with conventional linear transforms (Short-Time Fourier Transform and Wavelet Transform) is carried out, showing their inherent limitations. The approach is tested with laboratory and field motors, and the Lower Sideband Harmonic is captured for the first time during an induction motor startup and subsequent load oscillations, accurately tracking its evolution.

  7. Air-cushion tankers for Alaskan North Slope oil

    Science.gov (United States)

    Anderson, J. L.

    1973-01-01

    A concept is described for transporting oil from the Arctic to southern markets in 10,000-ton, chemically fueled air-cushion vehicles (ACV's) configured as tankers. Based on preliminary cost estimates the conceptual ACV tanker system as tailored to the transportation of Alaskan North Slope oil could deliver the oil for about the same price per barrel as the proposed trans-Alaska pipeline with only one-third of the capital investment. The report includes the description of the conceptual system and its operation; preliminary cost estimates; an appraisal of ACV tanker development; and a comparison of system costs, versatility, vulnerability, and ecological effect with those of the trans-Alaska pipeline.

  8. Global analysis on slope stability and its engineering application

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In hydraulic engineering, sometimes it is necessary to consider the stability of sliding bodies with lateral frictional boundaries. Neither the existing three dimensional limit equilibrium methods nor the commercial software products are able to treat such situations. The three dimensional factor of safety is accordingly underestimated; while the shearing strength based on the three dimensional back analysis is overestimated. In this study, the lateral boundaries are regarded as the part of the slip surface. Based on the expression of the normal pressure on the slip surface and the patch interpolation, a rigorous solution for the three dimensional limit equilibrium analysis is realized. Meanwhile, the proposed procedure is applied to the stability analysis of the slope with a cable platform on the right bank in Da Gang Shan hydraulic project under construction.

  9. Predictive Index for slope instabilities in open pit mining

    CERN Document Server

    Ortega, J H; Lecaros, R; Medel, F; Padilla, F; García, A

    2016-01-01

    In this paper we study the stability and deformation of structures, in particular the wall of an open pit mine is studied by using information obtained from a variety of remote sensors and some extra data, with a novelty approach considering the use of mathematical models and data mining techniques. In particular we present two models to help the study the slope stability of pit and the possible occurrence of movements. Primarily we present an static model for slow movements, which will help us identify areas of possible risks areas with time horizons of several months or years, depends on the available information, before the wall start moving, and secondly a dynamic short-term model, which help us to determine risks of collapse zones with several days in advance. We remark that this methodology can be a powerful tool to plain future actions in order to simulate possible scenarios considering the production plans.

  10. Flow characteristics above a very low and gently sloping hill

    Science.gov (United States)

    Smedman, Ann-Sofi; Bergström, Hans

    1984-05-01

    Tower measurements of wind and turbulence in near neutral conditions at the top of a very low and gently sloping hill (height ~ 20 m, with a length scale ~ 1000 m) are analysed in terms of current flow-over-hill theory. Measurements of wind maximum height and the change of the variances of the three wind components from the inner to the outer region are found to be in agreement with predictions from the theory. Spectra of the longitudinal and vertical wind components in the inner region, scaled according to Panofsky et al. (1982), come close to the corresponding Kansas curves in the high frequency range. They have higher energy in the low frequency region, probably a spectral lag effect caused by rougher upwind terrain. In the outer region, the spectra coincide with the corresponding Kansas curves if normalized by their respective variances and plotted against f/f m.

  11. Aspect-Driven Changes in Slope Stability Due to Ecohydrologic Feedbacks

    Science.gov (United States)

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

    2009-12-01

    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

  12. Debris flow runup on vertical barriers and adverse slopes

    Science.gov (United States)

    Iverson, Richard M.; George, David L.; Logan, Matthew

    2016-12-01

    Runup of debris flows against obstacles in their paths is a complex process that involves profound flow deceleration and redirection. We investigate the dynamics and predictability of runup by comparing results from large-scale laboratory experiments, four simple analytical models, and a depth-integrated numerical model (D-Claw). The experiments and numerical simulations reveal the important influence of unsteady, multidimensional flow on runup, and the analytical models highlight key aspects of the underlying physics. Runup against a vertical barrier normal to the flow path is dominated by rapid development of a shock, or jump in flow height, associated with abrupt deceleration of the flow front. By contrast, runup on sloping obstacles is initially dominated by a smooth flux of mass and momentum from the flow body to the flow front, which precedes shock development and commonly increases the runup height. D-Claw simulations that account for the emergence of shocks show that predicted runup heights vary systematically with the adverse slope angle and also with the Froude number and degree of liquefaction (or effective basal friction) of incoming flows. They additionally clarify the strengths and limitations of simplified analytical models. Numerical simulations based on a priori knowledge of the evolving dynamics of incoming flows yield quite accurate runup predictions. Less predictive accuracy is attained in ab initio simulations that compute runup based solely on knowledge of static debris properties in a distant debris flow source area. Nevertheless, the paucity of inputs required in ab initio simulations enhances their prospective value in runup forecasting.

  13. Short-term vegetation recovery after a spring grassland fire in Lithuania. Effect of time and slope position

    Directory of Open Access Journals (Sweden)

    P. Pereira

    2013-01-01

    Full Text Available The aim of this work is study the effects of a grassland fire in vegetation recuperation according to fire severity, slope exposition and position. We designed two experimental plots, one located in an east faced slope (Slope A and other in a west faced (Slope B. Vegetation recuperation was assessed 10, 17, 31 and 46 days after the fire. The results showed that fire severity was higher in slope B, than in slope A. In both slopes vegetation recuperation was different according position. Bottom positions recovered faster than slope and upslope positions, that it is attributed to fire severity (higher in slope and upslope areas and ash and soil transport and deposition in bottom areas. The vegetation recuperated faster in slope B and 46 days after the fire, 100% of the plot was covered. This was attributed to higher severity, more complex topography, and inclination of Slope A, that delayed the vegetation recover.

  14. Large slope instabilities in Northern Chile and Southern Peru

    Science.gov (United States)

    Crosta, Giovanni B.; Hermanns, Reginald L.; Valbuzzi, Elena; Frattini, Paolo; Valagussa, Andrea

    2014-05-01

    Deep canyon incision into Tertiary paleosurfaces and large slope instabilities along the canyon flanks characterize the landscape of western slope of the Andes of northern Chile and South Peru. This area belongs to the Coastal Escarpment and Precordillera and is formed by coarse-grained clastic and volcanoclastic formations. The area is characterized by intense seismicity and long-term hyperaridity (Atacama Desert). Landslides along the canyon flanks affect volumes generally up to 1 km3 and locally evolved in large rock avalanches. We prepared a landslide inventory covering an area of about 30,000 km2, extending from Iquique (Chile) to the South and Tacna (Peru) to the North. A total of 606 landslides have been mapped in the area by use of satellite images and direct field surveys, prevalently including large phenomena. The landslides range from 1 10-3 km2 to 464 km2 (Lluta landslide). The total landslide area, inclusive of the landslide scarp and of the deposit, amounts to about 2,130 km2 (about 7% of the area). The mega landslides can be classified as large block slides that can evolve in large rock avalanches (e.g. Minimini landslide). Their initiation seems to be strongly associated to the presence of secondary faults and large fractures transversal to the slope. These landslides show evidence suggesting a re-incision by the main canyon network. This seems particularly true for the Lluta collapse where the main 'landslide' mass is masked or deleted by the successive erosion. Other landslides have been mapped along the Coastal Escarpment and some of the major tectonic escarpments with an E-W trend. We examined area-frequency distributions of landslides by developing logarithmically binned, non-cumulative size frequency distributions that report frequency density as a function of landslide planar area A. The size frequency distribution presents a strong undersampling for smaller landslides, due to the extremely old age of the inventory. For landslides larger than

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

    Directory of Open Access Journals (Sweden)

    Ji-kun ZHAO

    2015-01-01

    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.

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

    Institute of Scientific and Technical Information of China (English)

    Ji-kun Zhao; Dan Wang; Jia-hong Chen

    2015-01-01

    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.

  17. Weathering Characteristics of Sloping Fields in the Three Gorges Reservoir Area, China

    Institute of Scientific and Technical Information of China (English)

    JIANG Hong-Tao; XU Fei-Fei; CAI Yi; YANG Da-Yuan

    2006-01-01

    For the purpose of understanding the weathering characteristics of surface layers in purple mudstone sloping fields of the Three Gorges Reservoir area of China, oxide content of major elements, composition of clay minerals, magnetic susceptibility, and difference in weathering characteristics of surface layers under different slope gradients were determined.The results showed that the oxide content of Si, Al, and Fe ranged from 60% to 75% and the weathering coefficient with depth showed no trend along the slope gradient. Also, for gentle (10° and 15°) and intermediate (25° and 40°) slopes the clay relative diffraction peak for kaolinite at the surface between 0-10 cm and 10-20 cm declined with an increase in slope gradient, while the relative diffraction peak for kaolinite in weathered layers on steep slopes (50° and 60°) disappeared altogether. Magnetic susceptibility decreased with increasing depth and, for a given depth layer, decreased with an increase in slope gradient. Analysis of the oxide content, weathering coefficients, clay minerals, and magnetic susceptibility showed that in the Three Gorges Reservoir area, the pedogenesis of the weathering layer in purple mudstone sloping fields was weak with weaker soil formation going from gentle slope to steep slope.

  18. Increased seed set in down slope-facing flowers of Lilium duchartrei

    Institute of Scientific and Technical Information of China (English)

    Shi-Guo SUN; Chi-Yuan YAO

    2013-01-01

    Flower orientation has been considered one aspect of floral attraction.Plants growing on slopes should orientate their flowers facing down slope towards greater open space to enhance reproduction by attracting more pollinators.Flower angle and floral symmetry may affect this pattern; for example,this trend would be overshadowed in vertical/pendent flowers with radial symmetry because the flowers can attract pollinators and provide landing platforms from many directions.We investigated this hypothesis in Lilium duchartrei,a herb with pendent and actinomorphic flowers,in the Hengduan Mountains region of China by measuring flower direction for individuals growing on fiat ground and on slopes.We also changed flower direction from facing down to up slope to test the effects on pollinator visitation frequency and subsequent plant reproduction.Plants growing on flat ground orientate their flowers equally towards the four geomagnetic directions,whereas the flowers on individuals growing on slopes preferentially face down slope.This pattern was more pronounced for individuals growing on steeper slopes.There was a positive correlation between slope angle and the seed set of flowers facing down slope (control),but a negative correlation between seed set and flowers facing up slope.The visitation frequency also tended to be higher for control flowers on steeper slopes and lower for those flowers changed to face up slope.Unexpectedly,floral direction was not affected by flower angle or floral symmetry.The results suggest that a down slope orientation of flowers could function to improve pollination in heterogeneous pollination environments.

  19. The slope-background for the near-peak regimen of photoemission spectra

    Energy Technology Data Exchange (ETDEWEB)

    Herrera-Gomez, A., E-mail: aherrera@qro.cinvestav.mx [CINVESTAV-Unidad Queretaro, Queretaro 76230 (Mexico); Bravo-Sanchez, M. [CINVESTAV-Unidad Queretaro, Queretaro 76230 (Mexico); Aguirre-Tostado, F.S. [Centro de Investigación en Materiales Avanzados, Chihuahua, Chihuahua 31109 (Mexico); Vazquez-Lepe, M.O. [Departamento de Ingeniería de Proyectos, Universidad de Guadalajara, Jalisco 44430 (Mexico)

    2013-08-15

    Highlights: •We propose a method that accounts for the change in the background slope of XPS data. •The slope-background can be derived from Tougaard–Sigmund's transport theory. •The total background is composed by Shirley–Sherwood and Tougaard type backgrounds. •The slope-background employs one parameter that can be related to REELS spectra. •The slope, in conjunction with the Shirley–Sherwood background, provides better fits. -- Abstract: Photoemission data typically exhibits a change on the intensity of the background between the two sides of the peaks. This step is usually very well reproduced by the Shirley–Sherwood background. Yet, the change on the slope of the background in the near-peak regime, although usually present, is not always as obvious to the eye. However, the intensity of the background signal associated with the evolution of its slope can be appreciable. The slope-background is designed to empirically reproduce the change on the slope. Resembling the non-iterative Shirley method, the proposed functional form relates the slope of the background to the integrated signal at higher electron kinetic energies. This form can be predicted under Tougaard–Sigmund's electron transport theory in the near-peak regime. To reproduce both the step and slope changes on the background, it is necessary to employ the slope-background in conjunction with the Shirley–Sherwood background under the active-background method. As it is shown for a series of materials, the application of the slope-background provides excellent fits, is transparent to the operator, and is much more independent of the fitting range than other background methods. The total area assessed through the combination of the slope and the Shirley–Sherwood backgrounds is larger than when only the Shirley–Sherwood background is employed, and smaller than when the Tougaard background is employed.

  20. Comprehensive analysis of slope stability and determination of stable slopes in the Chador-Malu iron ore mine using numerical and limit equilibrium methods

    Institute of Scientific and Technical Information of China (English)

    ATAEIM; BODAGHABADIS

    2008-01-01

    One of the critical aspects in mine design is slope stability analysis and the determination of stable slopes. In the Chador Malu iron ore mine, one of the most important iron ore mines in central Iran, it was considered vital to perform a comprehensive slope stability analysis. At first, we divided the existing rock hosting pit into six zones and a geotechnical map was prepared. Then,the value of MRMR (Mining Rock Mass Rating) was determined for each zone. Owing to the fact that the Chador-Malu iron ore mine is located in a highly tectonic area and the rock mass completely crushed, the Hock-Brown failure criterion was found suitable to estimate geo-mechanical parameters. After that, the value of cohesion (c) and friction angle (e) were calculated for different geotechnical zones and relative graphs and equations were derived as a function of slope height. The stability analyses using numerical and limit equilibrium methods showed that some instability problems might occur by increasing the slope height.Therefore, stable slopes for each geotechnical zone and prepared sections were calculated and presented as a function of slope height.

  1. Interplay between down-slope and along-slope sedimentary processes during the late Quaternary along the Capo Vaticano margin (southern Tyrrhenian Sea, Italy)

    Science.gov (United States)

    Martorelli, Eleonora; Bosman, Alessandro; Casalbore, Daniele; Falcini, Federico

    2016-04-01

    Late Quaternary along-slope and down-slope sedimentary processes and structures in the upper slope-shelf sector of the Calabro-Tyrrhenian continental margin off Capo Vaticano have been investigated using very high-resolution single-channel seismic profiles and multibeam bathymetric data. The results show that a competition among along-slope bottom currents-vs down-slope mass-wasting mostly contributed in shaping the seafloor and controlling deposition of sedimentary units during the Late Quaternary. Along-slope processes mostly formed elongated drifts located on the upper continental slope and outer shelf, between -90 and -300 m. The contourite deposits and associated erosive elements indicate the presence of a northwestward geostrophic flow that can be related to the modified-LIW issued by the Messina Strait. According to the proposed stratigraphic reconstruction it is likely that the activity of bottom-currents off Capo Vaticano was intensified around the LGM period and during the post-glacial sea-level rise, whereas they were less intense during the Holocene. Gravity-driven down-slope processes formed mass-transport deposits and turbidite systems with erosive channels, locally indenting the present-day shelf. Several slide events affected the upper 10-20 m of the stratigraphic record, dismantling considerable volume of contourite sediment. High-resolution seismic profiles indicate that failure processes appear to be dominated by translational sliding with glide plains mainly developed within contourite deposits. The most striking feature is the Capo Vaticano slide complex, which displays a large spatial coverage (area of about 18 km2) and is composed by several intersecting slide scars and overlapping deposits; these characteristics are peculiar for the Tyrrhenian continental margins, where slide events developed in open-slope areas are usually less complex and smaller in size. The presence of high-amplitude reflectors within contourite deposits (representing

  2. 基于用户相似度加权的Slope One算法%Slope One Algorithm Weighted by User Similarity

    Institute of Scientific and Technical Information of China (English)

    田松瑞

    2016-01-01

    Slope One algorithm based on a simple linear regression model. Reducing the response time and mainte-nance difficulty, it significantly improve the recommended performance. However, Slope One algorithm does not con-sider the internal relevance of users. Using data of all users without distinction is likely to cause deviation and effect the recommendation quality. In this paper we propose an improved Slope One algorithm which takes user similarity into account and modifies the rating deviation calculation formula. Combing item-based Slope One algorithm and user-based collaborative filtering algorithm, a new hybrid recommendation algorithm US-Slope One is proposed. The experimental results on Movielens data set show that the proposed algorithm has better prediction accuracy and rec-ommendation quality compared with the original Slope One algorithms.%Slope One算法基于简单的线性回归模型,通过减少响应时间和维护难度,显著提高了推荐性能。然而Slope One算法没有考虑用户内部的关联,同等地使用各个用户数据进行预测,容易造成偏差,影响推荐质量。本文提出了一种改进的Slope One算法,它将用户相似度纳入考虑并且对评分偏差计算公式进行了修正。基于项目的Slope One算法结合基于用户的协同过滤算法,提出新的混合推荐算法US-Slope One。在MovieLens数据集上的实验结果表明,该算法与原Slope One算法相比具有更好的预测准确度和推荐质量。

  3. Fault Diagnosis in Transformer Based on Weighted Degree of Grey Slope Incidence of Optimized Entropy

    Directory of Open Access Journals (Sweden)

    Zhang Anping

    2016-01-01

    Full Text Available Dissolved gas analysis (DGA is an important method to find the hidden or incipient insulation faults of oil-immersed power transformer. However, code deficiency exists in the gas ratio methods specified by the IEC standard and complexity of fault diagnosis for power transformer. Hence a new model based on optimized weighted degree of grey slope incidence was put forward. Firstly, the entropy weight is used to determine objective weight of indices; then the model fault types are obtained by weighted degree of grey slope incidence. The combination of entropy weight with grey slope incidence analysis can fully utilize over all information of DGA and give full play to the superiority of grey slope incidence, which overcomes shortcomings of original grey slope incidence analysis. The experimental results also demonstrate that the improved method has higher accuracy compared with three-ratio method and general grey slope incidence analysis method. The diagnosis accuracy is 92.8%.

  4. Determination of the Stable Slope Configuration of Oval-Shaped Furrow Pits

    Institute of Scientific and Technical Information of China (English)

    ZHU Nai-long; ZHANG Shi-xiong

    2004-01-01

    The space effects of oval-shaped furrow pit slopes were analyzed by the elastic mechanics principle. The interaction of limit equilibrium slope angle, friction coefficient, cohesion and horizontal radius of oval-shaped furrow pits has been derived. The oval trumpet-like rock mass is homogeneous and elastic while only loadedby its dead weight. The interaction indicates that the deeper an oval-shaped furrow pit is excavated, the greater thelimit equilibrium slope angle. Both the theory base for reducing stripping waste rock in an oval- shaped furrow pitand the basic way to determine the configuration of a stable slope were developed from the mentioned interaction.The theory includes the preceding principles of stability analysis of slopes. Compared with the configuration deter-mined by traditional theory of slope stability, a great quantity of stripping waste rock can be reduced by that deter-mined in this paper under stable conditions.

  5. Effects of rye grass coverage on soil loss from loess slopes

    Directory of Open Access Journals (Sweden)

    Yuequn Dong

    2015-09-01

    Full Text Available Vegetative coverage is commonly used to reduce urban slope soil erosion. Laboratory experimental study on soil erosion under grass covered slopes is conventionally time and space consuming. In this study, a new method is suggested to study the influences of vegetation coverage on soil erosion from a sloped loess surface under three slope gradients of 5°, 15°, and 25°; four rye grass coverages of 0%, 25%, 50%, and 75%; and three rainfall intensities of 60, 90, and 120 mm/h with a silt-loamy loess soil. Rye grasses were planted in the field with the studied soil before being transplanted into a laboratory flume. Grass was allowed to resume growth for a period before the rain simulation experiment. Results showed that the grass cover reduced soil erosion by 63.90% to 92.75% and sediment transport rate by 80.59% to 96.17% under different slope gradients and rainfall intensities. The sediment concentration/sediment transport rate from bare slope was significantly higher than from a grass-covered slope. The sediment concentration/transport rate from grass-covered slopes decreased linearly with grass coverage and increased with rainfall intensity. The sediment concentration/transport rate from the bare slope increased as a power function of slope and reached the maximum value at the gradient of about 25°, whereas that from grass-covered slope increased linearly and at much lower levels. The results of this study can be used to estimate the effect of vegetation on soil erosion from loess slopes.

  6. Phenomenology and Statistics of the Upper Slope sand Dunes in the Northeastern South China Sea

    Science.gov (United States)

    2014-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Phenomenology and Statistics of the Upper Slope sand Dunes...an ONR-sponsored, multi-year, interdisciplinary, international field program was launched to characterize the large sand dunes on the upper slope of...large submarine sand dunes on the upper slope. • To study the impact of the sand dunes, and the combined impact of sand dunes and nonlinear internal

  7. Landscape evolution in relation with occurrence of gravitational slope deformation and catastrophic landslides

    Science.gov (United States)

    Tsou, Ching-Ying; Chigira, Masahiro; Matsushi, Yuki; Chen, Su-Chin

    2013-04-01

    The Central Range of Taiwan is an example of a tectonically active orogen. The topography of a mountainous catchment of the Dahan River in northern side of the Central Range exhibits V-shaped inner valleys where landsliding is the dominant process of hillslope erosion and bedrock rivers are incising into the landscape. We take two approaches including (i) the study of present day morphostructural features of gravitationally deformed slopes and (ii) the study of the relationship between the gravitational slope deformation and fluvial incision to research the linkage of gravitational slope deformations, catastrophic landslides, and landscape evolution for the prediction of potential sites of future landslides. Mapped deep-seated gravitational slope deformations and scars of rainfall-induced rock/debris avalanches imply that their distributions are closely related to three series of convex slope breaks relating to the rejuvenation of topography by a three-phase fluvial incision leaded by three series of knickpoints migration. Many shallow rock/debris avalanches have occurred below the lowest slope break. By contrast, majority of gravitational slope deformations have occurred at the margins of the highest slope break around the paleosurface remnants, suggesting that the rejuvenation caused debuttressing of hillslopes and subsequent stress-release led to large scale slope destabilization, resulting in gravitational slope deformations. Catastrophic landslides in many locations deem to be preceded by gravitational slope deformation of rocks with adverse geological structures, many of which are buckling of alternating beds of sandstone and mudstone, and toppling of argillite and slate. The gravitationally deformed slopes change the topography and remain for a long time, and commonly accompany with some other types of mass movements (e.g. debris flows, rock/debris avalanches, and rockfalls). The results suggest that landslides are strongly controlled by geomorphology and

  8. Seismic response of rock slopes: Numerical investigations on the role of internal structure

    Science.gov (United States)

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

    2013-12-01

    The stability of rock slopes is significantly influenced and often controlled by the internal structure of the slope created by such discontinuities as joints, shear zones, and faults. Under seismic conditions, these discontinuities influence both the resistance of a slope to failure and its response to dynamic loading. The dynamic response, which can be characterized by the slope's natural frequency and amplification of ground motion, governs the loading experienced by the slope in a seismic event and, therefore, influences the slope's stability. In support of the Network for Earthquake Engineering Simulation (NEES) project Seismically-Induced Rock Slope Failure: Mechanisms and Prediction (NEESROCK), we conducted a 2D numerical investigation using the discrete element method (DEM) coupled with simple discrete fracture networks (DFNs). The intact rock mass is simulated with a bonded assembly of discrete particles, commonly referred to as the bonded-particle model (BPM) for rock. Discontinuities in the BPM are formed by the insertion of smooth, unbonded contacts along specified planes. The influence of discontinuity spacing, orientation, and stiffness on slope natural frequency and amplification was investigated with the commercially available Particle Flow Code (PFC2D). Numerical results indicate that increased discontinuity spacing has a non-linear effect in decreasing the amplification and increasing the natural frequency of the slope. As discontinuity dip changes from sub-horizontal to sub-vertical, the slope's level of amplification increases while the natural frequency of the slope decreases. Increased joint stiffness decreases amplification and increases natural frequency. The results reveal that internal structure has a strong influence on rock slope dynamics that can significantly change the system's dynamic response and stability during seismic loading. Financial support for this research was provided by the United States National Science Foundation (NSF

  9. Slope analysis for elastic proton-proton and proton-antiproton scattering

    OpenAIRE

    Okorokov, V. A.

    2008-01-01

    The diffraction slope parameter is investigated for elastic proton-proton and proton-antiproton scattering based on the all available experimental data at intermediate square of momentum transfer in the main. Energy dependence of the elastic diffraction slope is approximated by various analytic functions in a model-independent fashion. The expanded standard logarithmic approximations allow to describe experimental slopes in all available energy range at qualitative level reasonably. Various f...

  10. Buoyant Turbulent Kinetic Energy Production in Steep-Slope Katabatic Flow

    Science.gov (United States)

    Oldroyd, Holly J.; Pardyjak, Eric R.; Higgins, Chad W.; Parlange, Marc B.

    2016-12-01

    We develop several critical concepts that should be considered when interpreting, modelling and designing future experiments for flows over sloping terrain. Vertical buoyancy fluxes in katabatic flows can be positive and a source of turbulent kinetic energy (TKE) despite the statically stable, thermal stratification that drives these flows. This phenomenon occurs when the ratio of along-slope to slope-normal kinematic heat fluxes is greater than the cotangent of the slope angle, suggesting a critical value of slope-angle steepness found in earlier studies. We provide field-data-based evidence that the along-slope heat flux may dominate the variables in this inequality, and therefore in generating buoyant TKE production or suppression over a steep slope. These data show the along-slope heat flux can be more variable and significantly larger in magnitude than the slope-normal component. The gradient Richardson number does not include the effects of the along-slope buoyancy; furthermore, none of the canonical stability parameters can properly reflect the TKE redistribution from turbulent transport divergence and the sink of TKE in cases of counter-gradient momentum fluxes, which we frequently observe near the peak of the katabatic jet. In such cases, canonical stability parameters inadequately represent the physical mechanisms associated with stability. These results have broad implications related to accurately modelling turbulence and surface exchanges over sloping terrain and illustrate the need to more thoroughly investigate the along-slope heat flux and its drivers, the meaning and definitions of stability, and the effects of non-local turbulent transport.

  11. DEVELOPMENT OF SHALLOW VISCOUS OIL RESERVES IN NORTH SLOPE

    Energy Technology Data Exchange (ETDEWEB)

    Kishore K. Mohanty

    2004-12-01

    North Slope of Alaska has huge oil deposits in heavy oil reservoirs such as Ugnu, West Sak and Shrader Bluff etc. The viscosity of the last two reservoir oils vary from {approx}30 cp to {approx}3000 cp and the amount in the range of 10-20 billion barrels. High oil viscosity and low formation strength impose problems to high recovery and well productivity. Water-alternate-gas injection processes can be effective for the lower viscosity end of these deposits in West Sak and Shrader Bluff. Several gas streams are available in the North Slope containing NGL and CO{sub 2} (a greenhouse gas). The goal of this research is to develop tools to find optimum solvent, injection schedule and well-architecture for a WAG process in North Slope shallow sand viscous oil reservoirs. Coreflood, quarter 5-spot study, compositional simulation, wettability, relative permeability study and streamline-based simulation were conducted in this project. 1D compositional simulation results agree reasonably well with those of the slim tube experiments. Injection of CO{sub 2}-NGL is preferable over that of PBG-NGL. MME is sensitive to pressure (in the range of 1300-1800 psi) for the injection of PBG-NGL, but not for CO{sub 2}-NGL. Three hydrocarbon phases form in this pressure range. As the mean thickness of the adsorbed organic layer on minerals increases, the oil-water contact angle increases. The adsorbed organic films left behind after extraction of oil by common aromatic solvents used in core studies, such as toluene and decalin, are thinner than those left behind by non-aromatic solvents, such as cyclohexane. The force of adhesion for minerals aged with just the asphaltene fraction is similar to that of the whole oil implying that asphaltenes are responsible for the mixed-wettability in this reservoir. A new relative permeability model for a four-phase, mixed-wet system has been proposed. A streamline module is developed which can be incorporated in an existing finite-difference based

  12. Alaska North Slope regional gas hydrate production modeling forecasts

    Science.gov (United States)

    Wilson, S.J.; Hunter, R.B.; Collett, T.S.; Hancock, S.; Boswell, R.; Anderson, B.J.

    2011-01-01

    A series of gas hydrate development scenarios were created to assess the range of outcomes predicted for the possible development of the "Eileen" gas hydrate accumulation, North Slope, Alaska. Production forecasts for the "reference case" were built using the 2002 Mallik production tests, mechanistic simulation, and geologic studies conducted by the US Geological Survey. Three additional scenarios were considered: A "downside-scenario" which fails to identify viable production, an "upside-scenario" describes results that are better than expected. To capture the full range of possible outcomes and balance the downside case, an "extreme upside scenario" assumes each well is exceptionally productive.Starting with a representative type-well simulation forecasts, field development timing is applied and the sum of individual well forecasts creating the field-wide production forecast. This technique is commonly used to schedule large-scale resource plays where drilling schedules are complex and production forecasts must account for many changing parameters. The complementary forecasts of rig count, capital investment, and cash flow can be used in a pre-appraisal assessment of potential commercial viability.Since no significant gas sales are currently possible on the North Slope of Alaska, typical parameters were used to create downside, reference, and upside case forecasts that predict from 0 to 71??BM3 (2.5??tcf) of gas may be produced in 20 years and nearly 283??BM3 (10??tcf) ultimate recovery after 100 years.Outlining a range of possible outcomes enables decision makers to visualize the pace and milestones that will be required to evaluate gas hydrate resource development in the Eileen accumulation. Critical values of peak production rate, time to meaningful production volumes, and investments required to rule out a downside case are provided. Upside cases identify potential if both depressurization and thermal stimulation yield positive results. An "extreme upside

  13. Long term monitoring of landslide: observation gravitational slope cycles

    Science.gov (United States)

    Palis, Edouard; Lebourg, Thomas; Vidal, Maurin

    2016-04-01

    Since several years of studies on landslides, we realized the role and subtle interactions that existed between the structural complexity, masses dynamics and complex internal circulation of fluids. Thus, to gain a better understanding of the processes taking place during the evolution of an unstable slope, an observational study is necessary. In this perspective, our team currently monitors slow moving landslide zones. The aim of such a monitoring is to gain a better knowledge of the links between external forcing (meteorological, seismological) and signals going out of the slope (kinematic, vibrations, electrical resistivity). In December 2000, a dramatic event affected the sandy/clayey landslide in the Southern Alpes Maritimes (France). A 10 meters high scarp appeared at the foot of the landslide and affected private yards nearby. This area then became a major concern for local authorities and understand the processes taking place, a scientific challenge. In order to understand the land-sliding reactivations and to quantify the natural cycles of deformations, we analyse the main factors of this complex system. After 10 years of observation we are now able to highlight some of the complex behaviours by the measurement of physical parameters (geophysical monitoring). A permanent 115 m ERT line (5 meters electrode spacing) has been installed and provides an acquisition daily since 2006. The daily acquisitions are now accompanied by continuous measurements from boreholes (thermometers, piezometers, tiltmeters) and pluviometry. We are able to control the whole monitoring from the lab, and all these data are transmitted in real time. The analysis of these large amounts of data over large time series allows the detection of seasonal cycles of surface activity. The deformation taking place can be assimilated to a near-elastic deformation and show a lateral decoupling on both sides of the fault cutting the landslide. These deformation cycles can be associated with the

  14. Landslide trigger factors on populated, unstable slopes, Tusion, Tajikistan.

    Science.gov (United States)

    Domej, Gisela

    2015-04-01

    The Pamir region close to the Tajik-Afghan border is regularly affected by severe landslides threatening local population, their livelihood and infrastructure. In addition to landslides appearing as immediate consequence of earthquake, a high number of ground movements without previous seismic activity are also observed. The number of reported events and problem areas has strongly increased within the last ten to fifteen years. Consequently, a study was conducted to determine the triggering factors of these landslides without seismic cause. For accessibility reasons, the community of Tusion, southeast of Khorog, Gorno-Badakhshan, southern Tajikistan, where the capital township is located on a slowly moving slope, was chosen for the pilot project, and geologic mapping as well as seismic refraction and Schlumberger geoelectrics were applied. The geologic survey showed that the valley flanks around Tusion are covered with large amounts of postglacial and fluvial debris as well as moraine deposits. The absence of glacial ice and the retreat of remaining glaciers caused unstable valley flanks at many sites and, in consequence, extensive gravitational mass movements in the past, which are responsible for the today's layered ground structure as well as many secondary slumps. The latter often damage irrigation lines, which tends to further destabilize the slope. To obtain an accurate image of the superposed layers, the geophysical survey was conducted on three inhabited flanks. Arguments in favour for those three locations were not only the possibility of direct risk estimation for the region, but also the fact that the number of landslides increases constantly with population growth. Seismic and electric methods were applied in parallel to distinguish soil types and structural properties as well as to estimate the degree of water saturation. Despite of the methods' simplicity, they revealed precise explanations on triggering factors of landslides. The geophysical survey

  15. Effects of basin bottom slope on jet hydrodynamics and river mouth bar formation

    Science.gov (United States)

    Jiménez-Robles, A. M.; Ortega-Sánchez, M.; Losada, M. A.

    2016-06-01

    River mouth bars are strategic morphological units primarily responsible for the development of entire deltaic systems. This paper addresses the role of receiving basin slope in the hydrodynamics of an exiting sediment-laden turbulent jet and in resulting mouth bar morphodynamics. We use Delft3D, a coupled hydrodynamic and morphodynamic numerical model, along with a theoretical formulation to reproduce the physics of the problem, characterized by a fluvially dominated inlet free of waves and tides. We propose an updated theoretical model with a slope-dependent entrainment coefficient, showing that the rate at which ambient fluid is incorporated into a jet increases with higher basin slopes. Transient results reveal that the magnitude of a basin slope can alter the stability of a jet, favoring the formation of an unstable meandering jet. While a stable jet gives rise to "middle-ground" bars accompanied by diverging channels, a "lunate" mouth bar results from unstable jets. Additional morphodynamic simulations demonstrate that the time required for mouth bar stagnation in its final position increases linearly with the basin slope. In contrast, the distance at which the mouth bar eventually forms decreases until reaching an asymptotic value for slopes higher than 2%. Moreover, the basin slope highly influences sedimentary processes responsible for bar formation: for milder slopes, progradation processes prevail, while in steeper basins aggradation is more relevant. Finally, the minimum relative water depth over a bar crest that forces the flow to bifurcate around a fully developed bar decreases with the basin slope.

  16. Sub-microradian Surface Slope Metrology with the ALS Developmental Long Trace Profiler

    Energy Technology Data Exchange (ETDEWEB)

    Yashchuk, Valeriy V; Barber, Samuel; Domning, Edward E.; Kirschman, Jonathan L.; Morrison, Gregory Y.; Smith, Brian V; Siewert, Frank; Zeschke, Thomas; Geckeler, Ralf; Just, Andreas

    2009-09-11

    A new low budget slope measuring instrument, the Developmental Long Trace Profiler (DLTP), was recently brought to operation at the ALS Optical Metrology Laboratory. The design, instrumental control and data acquisition system, initial alignment and calibration procedures, as well as the developed experimental precautions and procedures are described in detail. The capability of the DLTP to achieve sub-microradian surface slope metrology is verified via cross-comparison measurements with other high performance slope measuring instruments when measuring the same high quality test optics. The directions of future work to develop a surface slope measuring profiler with nano-radian performance are also discussed.

  17. Slope orientation assessment for open-pit mines, using GIS-based algorithms

    Science.gov (United States)

    Grenon, Martin; Laflamme, Amélie-Julie

    2011-09-01

    Standard stability analysis in geomechanical rock slope engineering for open-pit mines relies on a simplified representation of slope geometry, which does not take full advantage of available topographical data in the early design stages of a mining project; consequently, this may lead to nonoptimal slope design. The primary objective of this paper is to present a methodology that allows for the rigorous determination of interramp and bench face slope orientations on a digital elevation model (DEM) of a designed open pit. Common GIS slope algorithms were tested to assess slope orientations on the DEM of the Meadowbank mining project's Portage pit. Planar regression algorithms based on principal component analysis provided the best results at both the interramp and the bench face levels. The optimal sampling window for interramp was 21×21 cells, while a 9×9-cell window was best at the bench level. Subsequent slope stability analysis relying on those assessed slope orientations would provide a more realistic geometry for potential slope instabilities in the design pit. The presented methodology is flexible, and can be adapted depending on a given mine's block sizes and pit geometry.

  18. Case-Based Reasoning for Slope Stability Evaluation and Its Application

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Slope is a non-linear and uncertain kinetic system affected by many factors. In view of the incompleteness and uncertainty of the information of slope stability evaluation, a new method of slope stability evaluation by using case-based reasoning is presented. Considering the sensitivity of attribute weights to the environment, the algorithm of attribute weights is set up on the basis of the concept of changeable weights. Calculating the similarity between target case of the slope and base case, the stability of target case is evaluated. It is shown from examples that the method is simple, visual, practical, and convenient for use.

  19. Wave Energy Dissipation of Waves Breaking on a Reef with a Steep Front Slope

    DEFF Research Database (Denmark)

    Jensen, M.S.; Burcharth, Hans F.; Brorsen, Michael

    2005-01-01

    The Transformation of waves propagating over a steep bottom slope is of great importance regarding the coastal processes in the near-shore area.This study will contribute with tools to predict the dissipated wave energy for irregular waves passing a steep submerged slope. An extensive number...... of test with regular and irregular waves breaking over a steep bottom slope have been performed in the Hydraulics & Coastal Engineering Laboratory, Aalborg University. Based on these experimental data formulae have been developed capable of predicting he transmitted wave energy over steep slopes....

  20. On the Density profile slope of Clusters of Galaxies

    CERN Document Server

    Del Popolo, A

    2012-01-01

    The present paper extends to clusters of galaxies the study of Del Popolo (2012), concerning how the baryon-dark matter (DM) interplay shapes the density profile of dwarf galaxies. Cluster density profiles are determined taking into account dynamical friction, random and ordered angular momentum and the response of dark matter halos to condensation of baryons. We find that halos containing only DM are characterized by Einasto's profiles, and that the profile flattens with increasing content of baryons, and increasing values of random angular momentum. The analytical results obtained in the first part of the paper were applied to well studied clusters whose inner profiles have slopes flatter than NFW predictions (A611, A383) or are characterized by profiles in agreement with the NFW model (MACS J1423.8+2404, RXJ1133). By using independently-measured baryonic fraction, a typical spin parameter value $\\lambda \\simeq 0.03$, and adjusting the random angular momentum, we re-obtain the mass and density profiles of t...

  1. Defining hyperinflation as 'dynamic': moving toward the slope.

    Science.gov (United States)

    Dolmage, Thomas E; Evans, Rachael A; Goldstein, Roger S

    2013-07-01

    Measuring the severity of dynamic hyperinflation is a useful clinical approach to assess the effect of therapeutic interventions and explain their impact on exercise tolerance. Dynamic hyperinflation is typically quantified by the change in end expiratory lung volume from rest to the end of exercise. The result may be inconsistent with disease severity and does not clearly explain how exercise tolerance improves with therapy. Using a re-examination of selected studies, we suggest an operational definition of dynamic hyperinflation using the slope derived from serial measures of inspiratory capacity expressed as a linear function of ventilation that clearly differentiates whether therapies affect static or dynamic hyperinflation or affect lung volume only as a consequence of reducing ventilation. With this approach, the magnitude of the result is consistent with disease severity and is a more reliable outcome as it uses serial measures rather than a single time point estimate. The therapies re-evaluated are breathing helium or hyperoxic gas mixtures, bronchodilation and exercise training. A clear definition of dynamic hyperinflation will assist clinicians in assessing the impact of therapeutic interventions.

  2. The water content of recurring slope lineae on Mars

    Science.gov (United States)

    Edwards, Christopher S.; Piqueux, Sylvain

    2016-09-01

    Observations of recurring slope lineae (RSL) from the High-Resolution Imaging Science Experiment have been interpreted as present-day, seasonally variable liquid water flows; however, orbital spectroscopy has not confirmed the presence of liquid H2O, only hydrated salts. Thermal Emission Imaging System (THEMIS) temperature data and a numerical heat transfer model definitively constrain the amount of water associated with RSL. Surface temperature differences between RSL-bearing and dry RSL-free terrains are consistent with no water associated with RSL and, based on measurement uncertainties, limit the water content of RSL to at most 0.5-3 wt %. In addition, distinct high thermal inertia regolith signatures expected with crust-forming evaporitic salt deposits from cyclical briny water flows are not observed, indicating low water salinity (if any) and/or low enough volumes to prevent their formation. Alternatively, observed salts may be preexisting in soils at low abundances (i.e., near or below detection limits) and largely immobile. These RSL-rich surfaces experience ~100 K diurnal temperature oscillations, possible freeze/thaw cycles and/or complete evaporation on time scales that challenge their habitability potential. The unique surface temperature measurements provided by THEMIS are consistent with a dry RSL hypothesis or at least significantly limit the water content of Martian RSL.

  3. Commercial possibilities for stranded conventional gas from Alaska's North Slope

    Science.gov (United States)

    Attanasi, E.D.; Freeman, P.A.

    2014-01-01

    Stranded gas resources are defined for this study as gas resources in discrete accumulations that are not currently commercially producible, or producible at full potential, for either physical or economic reasons. Approximately 35 trillion cubic feet (TCF) of stranded gas was identified on Alaska’s North Slope. The commercialization of this resource requires facilities to transport gas to markets where sales revenue will be sufficient to offset the cost of constructing and operating a gas delivery system. With the advent of the shale gas revolution, plans for a gas pipeline to the conterminous US have been shelved (at least temporarily) and the State and resource owners are considering a liquefied natural gas (LNG) export project that targets Asian markets. This paper focuses on competitive conditions for Asian gas import markets by estimating delivered costs of competing supplies from central Asia, Russia, Indonesia, Malaysia, and Australia in the context of a range of import gas demand projections for the period from 2020 to 2040. These suppliers’ costs are based on the cost of developing, producing, and delivering to markets tranches of the nearly 600 TCF of recoverable gas from their own conventional stranded gas fields. The results of these analyses imply that Alaska’s gas exports to Asia will likely encounter substantial competitive challenges. The sustainability of Asia’s oil-indexed LNG pricing is also discussed in light of a potentially intense level of competition.

  4. Temperature statistics above a deep-ocean sloping boundary

    CERN Document Server

    Cimatoribus, Andrea A

    2015-01-01

    We present a detailed analysis of the statistics of temperature in an oceanographic observational dataset. The data is collected using a moored array of thermistors, 100m tall and starting 5m above the bottom, deployed during four months above the slopes of a seamount in the North Eastern Atlantic Ocean. Turbulence at this location is strongly affected by the semidiurnal tidal wave. Mean stratification is stable in the entire dataset. We compute structure functions, of order up to 10, of the distributions of temperature increments. Strong intermittency is observed in particular during the downslope phase of the tide, and farther from the solid bottom. In the lower half of the mooring during the upslope phase, the statistics of temperature are consistent with those of a passive scalar. In the upper half of the mooring, the statistics of temperature deviate from those of a passive scalar, and evidence of turbulent convective activity is found. The downslope phase is generally thought to be more shear dominated,...

  5. Site Scientist for the North Slope of Alaska Site

    Energy Technology Data Exchange (ETDEWEB)

    Verlinde, Johannes [Pennsylvania State Univ., State College, PA (United States)

    2016-03-11

    Under this grant our team contributed scientific support to the Department of Energy Atmospheric Radiation Program’s (DOE-ARM) Infrastructure team to maintain high quality research data at the DOE-ARM North Slope of Alaska with special emphasis on the radars. Under our guidance two major field campaigns focusing on mixed-phase Arctic clouds were conducted that greatly increased the community’s understanding of the many processes working together to control the evolution of single-layer cloud mixed-phase clouds. A series of modeling and observational studies revealed that the longevity of the radiatively important liquid phase is strongly dependent on how the ice phase develops in mixed-phase clouds. A new ice microphysics parameterization was developed to capture better the natural evolution of ice particle growth in evolving environments. An ice particle scattering database was developed for all ARM radar frequencies. This database was used in a radar simulator (Doppler spectrum and polarimetric variables) to aid in the interpretation of the advanced ARM radars. At the conclusion of this project our team was poised to develop a complete radar simulator consistent with the new microphysical parameterization, taking advantage of parameterization’s advanced characterization of the ice shape and ice density.

  6. Root architecture characteristics of plant inlay in live slope grating

    Institute of Scientific and Technical Information of China (English)

    Gao Jia-rong; Wang Fang; Gao Yang; Rosemarie Stangl

    2007-01-01

    In the experimental garden of the Department of Soil Bioengineering and Landscape Construction, University of Applied Life Sciences in Vienna, Austria, coarse root systems of three different brush species were completely excavated and semi-automatically digitized. The species were Lonicera xylosteum, Ligustrum vulgare and Euonymus europaeus. The 3-D root architectures reveal different growth strategies between species, which are related to ecological characteristics and physical soil properties. The root architecture of Lonicera xylosteum and Ligustrum vulgare, planted in the under layer of the live slope grading, where the soil is very tight and the soil water content and fertility are relatively low, is shallow. However, the root distribution of E. europaeus, planted in the middle layer, where environmental conditions are better, is deeper. Most of the root biomass of the three species is concentrated in the 0-30 cm soil layer. A quarter of the root biomass ofLigustrum vulgare is distributed in the upper layer of the plant inlay. E. europaeus has a relatively even distribution in the 30-60 cm and 60-90 cm soil layer.

  7. Photogrammetric analysis of slope failures feeding the head of the Illgraben debris flow channel

    Science.gov (United States)

    Bennett, G. L.; Molnar, P.; Eisenbeiss, H.; McArdell, B. W.

    2012-04-01

    Our understanding of slope failure is restricted by a lack of inventories of sufficient size and directly measured volumes. We used digital photogrammetry to produce a multi-temporal record of erosion of a rock slope in the Illgraben. From this we extracted an inventory of ~2500 slope failures for 3 epochs of 6/7 years between 1986 and 2005 ranging over 6 orders of magnitude in volume. Through analysis of their magnitude-frequency, volume-area and depth-slope gradient relations we aimed to understand the characteristics of slope failure at the head of this active alpine debris-flow catchment. The slope failure volumes follow a characteristic magnitude-frequency distribution with a roll-over at 50m3 and a power-law tail between ~200m3 and 1.6x106m3 with an exponent of 1.65. We compared different methods to estimate the power law scaling exponent and found the maximum likelihood estimator to be the most accurate. Conversely, least squares regression on the probability density function consistently underestimated the exponent. Slope failure volume scales with failure area as a power law with an exponent of 1.1. This exponent is low for the bedrock nature of the slope in comparison with worldwide studies of bedrock and soil landslides and likely results from the highly fractured and incohesive nature of the quartzitic bedrock of the study slope. Comparing the results for different epochs we find that the magnitude-frequency and volume-area relationships are reasonably time-invariant demonstrating their general nature for the setting. We interpret the magnitude-frequency distribution of slope failure volumes as the result of two separate slope failure processes. Type (1) failures are frequent, small slides and slumps within the weathered layer of highly fractured rock and loose sediment. These make up the roll-over of the distribution. Type (2) failures are less frequent rockslides and rockfalls within the internal bedded and fractured slope along pre

  8. Parameterization experiments performed via synthetic mass movements prototypes generated by 3D slope stability simulator

    Science.gov (United States)

    Colangelo, Antonio C.

    2010-05-01

    The central purpose of this work is to perform a reverse procedure in the mass movement conventional parameterization approach. The idea is to generate a number of synthetic mass movements by means of the "slope stability simulator" (Colangelo, 2007), and compeer their morphological and physical properties with "real" conditions of effective mass movements. This device is an integrated part of "relief unity emulator" (rue), that permits generate synthetic mass movements in a synthetic slope environment. The "rue" was build upon fundamental geomorphological concepts. These devices operate with an integrated set of mechanical, geomorphic and hydrological models. The "slope stability simulator" device (sss) permits to perform a detailed slope stability analysis in a theoretical three dimensional space, by means of evaluation the spatial behavior of critical depths, gradients and saturation levels in the "potential rupture surfaces" inferred along a set of slope profiles, that compounds a synthetic slope unity. It's a meta-stable 4-dimensional object generated by means of "rue", that represents a sequence evolution of a generator profile applied here, was adapted the infinite slope model for slope. Any slope profiles were sliced by means of finite element solution like in Bishop method. For the synthetic slope systems generated, we assume that the potential rupture surface occurs at soil-regolith or soil-rock boundary in slope material. Sixteen variables were included in the "rue-sss" device that operates in an integrated manner. For each cell, the factor of safety was calculated considering the value of shear strength (cohesion and friction) of material, soil-regolith boundary depth, soil moisture level content, potential rupture surface gradient, slope surface gradient, top of subsurface flow gradient, apparent soil bulk density and vegetation surcharge. The slope soil was considered as cohesive material. The 16 variables incorporated in the models were analyzed for

  9. [Mechanisms of grass in slope erosion control in Loess sandy soil region of Northwest China].

    Science.gov (United States)

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

    2013-01-01

    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

  10. Static Linear and Nonlinear Analysis of R.C Building on Sloping Ground with Varying Hill Slopes

    Directory of Open Access Journals (Sweden)

    K.S.L.Nikhila

    2014-11-01

    Full Text Available Earthquake field investigations repeatedly confirm that irregular structures suffer more damage than their regular counterparts. This is recognized in seismic design codes, and restrictions on abrupt changes in mass and stiffness are imposed. Irregularities in dimensions affect the distribution of stiffness, and in turn affect capacity, while mass irregularities tend to influence the imposed demand. Elevation irregularities have been observed to cause story failures due to non-uniform distribution of demand-to-supply ratios along the height. Plan irregularities, on the other hand, cause non-uniform demand-to-capacity ratios amongst the columns. In this paper the structure chosen for study is a 4, 5 storied commercial complex building. The building is located in seismic zone IV on a rock soil site. Three dimensional mathematical models for the same are generated in ETABS software. The structural elements, M40 grade of concrete, floor diaphragms are assumed to be rigid. Seismic loads were considered acting in the horizontal direction along either of the two principal directions and the ground slope choosen in between 0° and 25° and building that which produce less torsion effect for setback - stepback with irregular configuration in horizontal and vertical direction is modeled and analyzed.

  11. Measurement of tibial slope angle after medial opening wedge high tibial osteotomy: case series

    Directory of Open Access Journals (Sweden)

    Ricardo Hideki Yanasse

    Full Text Available CONTEXT AND OBJECTIVE: In the past, changes in tibial slope were not considered when planning or evaluating osteotomies, and success in high tibial osteotomy was related to the alignment and amount of femorotibial angular correction. The aim here was to measure changes in tibial slope after medial opening wedge tibial osteotomy and investigate the effect of tibial slope angle on the clinical results. DESIGN AND SETTING: Retrospective review study on a series of cases, at the Department of Orthopedics and Traumatology, Faculdade de Medicina de Marília (Famema, Marília, Brazil. METHODS: Twenty-eight patients were studied, and a total of thirty-one knees. Lateral roentgenograms of the tibia were used pre and postoperatively to measure the tibial slope based on the proximal tibial anatomical axis. The clinical results were measured using the Lysholm knee score. RESULTS: There was an average increase in tibial slope angle after surgery of 2.38° (95% confidence interval: ± 0.73°. There was no correlation (r = -0.28 between the postoperative Lysholm knee score and the difference in tibial slope angle from before to after surgery (P = 0.13. CONCLUSION: Medial opening wedge tibial osteotomy led to a small increase in tibial slope. No significant correlation was found between increased tibial slope and short-term clinical results after high tibial osteotomy. Other clinical studies are needed in order to establish whether extension or flexion osteotomy could benefit patients with medial compartment gonarthrosis.

  12. 76 FR 10388 - Notice of Public Meeting, North Slope Science Initiative-Science Technical Advisory Panel

    Science.gov (United States)

    2011-02-24

    ... decisions. This meeting will include a workshop entitled ``Science, Natural Resources, and Subsistence in... Panel through the Executive Director, North Slope Science Initiative. Each formal meeting will also have... Bureau of Land Management Notice of Public Meeting, North Slope Science Initiative--Science...

  13. The hillslope-storage Boussinesq model for non-constant bedrock slope

    NARCIS (Netherlands)

    Hilberts, A.G.J.; Loon, van E.E.; Troch, P.A.A.; Paniconi, C.

    2004-01-01

    In this study the recently introduced hill slope-storage Boussinesq (hsB) model is cast in a generalized formulation enabling the model to handle non-constant bedrock slopes (i.e. bedrock profile curvature). This generalization extends the analysis of hydrological behavior to hillslopes of arbitrary

  14. A new GTD slope diffraction coefficient for plane wave illumination of a wedge

    DEFF Research Database (Denmark)

    Lumholt, Michael; Breinbjerg, Olav

    1997-01-01

    Two wedge problems including slope diffraction are solved: one in which the incident field is a non-uniform plane wave, and one in which it is an inhomogeneous plane wave. The two solutions lead to the same GTD slope diffraction coefficient. This coefficient reveals the existence of a coupling ef...

  15. How to Use COMSOL Multiphysics for coupled dual-permeability hydrological and slope stability modeling

    NARCIS (Netherlands)

    Shao, W.; Bogaard, T.A.; Bakker, M.

    2014-01-01

    Preferential flow paths, such as cracks, macropores, fissures, pipes etc. are common features of highly heterogeneous slopes. During intense rainstorms, preferential flow has a significant influence on subsurface flow and slope stability. Dual-permeability models are widely used to simulate preferen

  16. Slides and debris flows on the high-latitude continental slopes of Baffin Bay

    Science.gov (United States)

    Aksu, A. E.; Hiscott, R. N.

    1989-10-01

    The eastern continental margin of Baffin Island around Ocean Drilling Program (ODP) Site 645 was surveyed by using single-channel airgun, high-resolution boomer systems and piston cores. The data show that much of the upper slope between the 300 and ˜1200 m isobaths is erosional. Major sliding and rotational slumping has removed several hundred metres of sediment from the upper slope, giving the sea bed a steplike morphology. From ˜1200 m to the 2300 m isobath, the slope is constructional and is characterized by abundant acoustically transparent lenses, some of which are traced upslope into acoustically transparent to internally deformed wedge-shaped bodies. These lenses are interpreted to be debris-flow deposits and their abundance in the lower slope indicates frequent upper slope failures. The wedge-shaped bodies are much less common and are interpreted to be larger slides and/or slumps. Near the base of the slope, fields of diapiric structures pierce the acoustically well stratified section and locally produce small mounds on the sea floor. On the basis of correlation with ODP Site 645, they are interpreted as mud diapirs. The combined data show that the lower slope of Baffin Island is constructed predominantly of shingled lenses of debris-flow deposits and rotated slump blocks that originated from major erosion of the upper slope.

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

    Directory of Open Access Journals (Sweden)

    Sandra G. Catane

    2011-06-01

    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.

  18. 76 FR 69736 - Primus Solutions, Inc., and Arctic Slope Regional Corp.; Transfer of Data

    Science.gov (United States)

    2011-11-09

    ... AGENCY Primus Solutions, Inc., and Arctic Slope Regional Corp.; Transfer of Data AGENCY: Environmental... Primus Solutions, Inc., and its subcontractor, Arctic Slope Regional Corporation (ASRC) in ] accordance... from the Agency; and requires that each official and employee of the contractor sign an agreement...

  19. Payment for Environmental Services: The Sloping Land Conversion Program in Ningxia Autonomous Region of China

    NARCIS (Netherlands)

    Zhang, L.; Tu, Q.; Mol, A.P.J.

    2008-01-01

    China's Sloping Land Conversion Program has been implemented since 2002. It aims to achieve goals of ecological recovery and poverty alleviation, by retiring steeply sloping land from crop production and freeing surplus agricultural labor for off-farm activities. Given the huge investment that has b

  20. Synergism Analysis of Bedding Slope with Piles and Anchor Cable Support under Sine Wave Vehicle Load

    Directory of Open Access Journals (Sweden)

    Li Dan-Feng

    2016-01-01

    Full Text Available Slope instability under dynamic load is the technical difficulty in the engineering; the evaluation of slope stability under dynamic load and the control of dynamic load is particularly important. In this paper, taking the right side slope of K27+140 m~380 m typical section (K27 slope for short in Chongqing Fuling-Fengdu-Shizhu expresses highway as an example to calculate and analyze. The K27 slope is under sinusoidal vehicle load and supported by anchor cable and antislide pile to resist downslide strength; at the same time, the combined effect of them is studied. Three-dimensional finite element methodology (FEM is used to simulate the bedding slope with piles and anchor cable support; furthermore, the eigenvalue can be obtained. In order to reduce error of the elastic boundary conditions caused by the reflection effect of wavelengths, the combination of Lysmer surface viscous boundary and traditional ground support boundaries is utilized to analyze and calculate the time-histories during bedding slope under dynamic load. The dynamic response of pile anchor support to resist sliding force is obtained. The concept of the pile anchor supporting coordinate interval is put forward. Furthermore, it is verified that the pile anchor supporting coordinate interval can be used to evaluate the stability of the slope under dynamic load and provide a new method for the control of the dynamic load.

  1. Developing restoration planting mixes for active ski slopes: a multi-site reference community approach.

    Science.gov (United States)

    Burt, Jennifer Williamson

    2012-03-01

    Downhill ski areas occupy large expanses of mountainous lands where restoration of ecosystem function is of increasing importance and interest. Establishing diverse native plant communities on ski runs should enhance sediment and water retention, wildlife habitat, biodiversity and aesthetics. Because ski slopes are managed for recreation, ski slope revegetation mixes must consist of low-stature or herbaceous plants that can tolerate typical environmental conditions on ski slopes (high elevation, disturbed soils, open, steep slopes). The most appropriate reference communities for selecting ski slope revegetation species are thus successional, or seral plant communities in similar environments (i.e., other ski slopes). Using results from a broad-scale reference community analysis, I evaluated plant communities naturally occurring on ski slopes from 21 active and abandoned ski areas throughout the northern Sierra Nevada to identify native plant species suitable for use in ski slope restoration. I constructed a baseline planting palette of regionally appropriate plant species (for restoration of either newly created or already existing ski runs) that is functionally diverse and is likely to succeed across a broad range of environments. I also identify a more comprehensive list of species for more specialized planting mixes based on site-specific goals and particular environmental settings. Establishing seral plant communities may be an appropriate restoration goal for many other types of managed lands, including roadsides, firebreaks and utility rights-of-way. This study describes an ecological (and potentially cost-effective) approach to developing restoration planting palettes for such managed lands.

  2. Comparison of Student Understanding of Line Graph Slope in Physics and Mathematics

    Science.gov (United States)

    Planinic, Maja; Milin-Sipus, Zeljka; Katic, Helena; Susac, Ana; Ivanjek, Lana

    2012-01-01

    This study gives an insight into the differences between student understanding of line graph slope in the context of physics (kinematics) and mathematics. Two pairs of parallel physics and mathematics questions that involved estimation and interpretation of line graph slope were constructed and administered to 114 Croatian second year high school…

  3. Laboratory and 3-D-distinct element analysis of failure mechanism of slope under external surcharge

    Directory of Open Access Journals (Sweden)

    N. Li

    2014-09-01

    Full Text Available 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.

  4. Phosphorus Loss from Dry Sloping Lands of Three Gorges Reservoir Area, China

    Institute of Scientific and Technical Information of China (English)

    HU Zheng-Feng; GAO Ming; XIE De-Ti; WANG Zi-Fang

    2013-01-01

    Eutrophication in the Three Gorges Reservoir has become a serious issue,and phosphorus (P) is the nutrient thought to be primarily responsible although there are few studies about P loss from the mostly sloping farmlands of the area.This work investigated the amounts and forms of P loss from 9 farmlands with the slopes of 4°,9°,and 17° in a small watershed,Wangjiagou in Fuling District,Chongqing of China.The slope of the relationship between runoff and rainfall increased with field slope; i.e.,there was a significant interaction between the effects of rainfall and field slope on water export.For sediment export by surface runoff,there was no interaction between field slope and rainfall,and the intercept of the relationship between rainfall and sediment loss was significantly different for the 3 slopes.The main P loss was from sediments,regardless of slope.In the runoff water,particulate P was the largest P fraction,and its loss was greatest from the steepest land and least from the flattest.The release of total P and available P from sediments followed the same trend.The P loss during May to July in Wangjiagou was more than 60% of the annual total.

  5. The Relationship Between Lithology and Slope Morphology in the Tucson Mountains, Arizona.

    Directory of Open Access Journals (Sweden)

    Kamel Khanchoul

    2008-05-01

    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.

  6. Toe clearance and velocity profiles of young and elderly during walking on sloped surfaces

    Directory of Open Access Journals (Sweden)

    Begg Rezaul K

    2010-04-01

    Full Text Available Abstract Background Most falls in older adults are reported during locomotion and tripping has been identified as a major cause of falls. Challenging environments (e.g., walking on slopes are potential interventions for maintaining balance and gait skills. The aims of this study were: 1 to investigate whether or not distributions of two important gait variables [minimum toe clearance (MTC and foot velocity at MTC (VelMTC] and locomotor control strategies are altered during walking on sloped surfaces, and 2 if altered, are they maintained at two groups (young and elderly female groups. Methods MTC and VelMTC data during walking on a treadmill at sloped surfaces (+3°, 0° and -3° were analysed for 9 young (Y and 8 elderly (E female subjects. Results MTC distributions were found to be positively skewed whereas VelMTC distributions were negatively skewed for both groups on all slopes. Median MTC values increased (Y = 33%, E = 7% at negative slope but decreased (Y = 25%, E = 15% while walking on the positive slope surface compared to their MTC values at the flat surface (0°. Analysis of VelMTC distributions also indicated significantly (p th percentile (Q1 values in the elderly at all slopes. Conclusion The young displayed a strong positive correlation between MTC median changes and IQR (interquartile range changes due to walking on both slopes; however, such correlation was weak in the older adults suggesting differences in control strategies being employed to minimize the risk of tripping.

  7. Slope across the Curriculum: Principles and Standards for School Mathematics and Common Core State Standards

    Science.gov (United States)

    Nagle, Courtney; Moore-Russo, Deborah

    2014-01-01

    This article provides an initial comparison of the Principles and Standards for School Mathematics and the Common Core State Standards for Mathematics by examining the fundamental notion of slope. Each set of standards is analyzed using eleven previously identified conceptualizations of slope. Both sets of standards emphasize Functional Property,…

  8. Conservation scenarios for olive farming on sloping land in de Mediterranean

    NARCIS (Netherlands)

    Fleskens, L.

    2007-01-01

    The future of olive farming on sloping land in the Mediterranean is uncertain. Sloping and Mountainous Olive Production Systems (SMOPS) that have been sustainable for ages have in a relatively short time frame witnessed major changes. Although remnants of many of these traditional landscapes still e

  9. Formation Mechanism and Stability Assessment of the Colluvial Deposit Slope in Zuoyituo

    Institute of Scientific and Technical Information of China (English)

    Jian Wenxing; Zhang Yihu; Yin Hongmei

    2004-01-01

    The basic features of the colluvial deposit slope in Zuoyituo such as geological conditions, dimensions, slip surfaces and groundwater conditions are described concisely in this paper. The formation mechanism of the slope is discussed. It is considered that the formation of the colluvial deposit slope in Zuoyituo has undergone accumulation, slip, load, deformation and failure. The effects of rainfall on slope stability are categorized systematically based on existing methodology, and ways to determine the effects quantitatively are presented. The remained slip force method is improved by the addition of quantitative relations to the existing formulae and programs. The parameters of the colluvial deposit slope are determined through experimentation and the method of back-analysis. The safety factors of the slope are calculated with the improved remained slip force method and the Sarma method. The results show that rainfall and water level in the Yangtze River have a significant effect on the stability of the colluvial deposit slope in Zuoyituo. The hazards caused by the instability of the slope are assessed, and prevention methods are put forward.

  10. EXPERIMENTAL STUDY ON INCIPIENT MOTION OF SEDIMENT PARTICLES ON GENERALIZED SLOPING FLUVIAL BEDS

    Institute of Scientific and Technical Information of China (English)

    Subhasish DEY

    2001-01-01

    This paper presents an experimental investigation on incipient motion of non-cohesive uniform sediment under a steady-uniform stream flow on generalized sloping fluvial beds (combined lateral and stream-wise slope). The characteristic parameters affecting the incipient motion of sediment particles, identified based on the physical reasoning and dimensional analysis, are the threshold shear stress ratio (ratio of threshold shear stress for sloping bed to that for horizontal bed), lateral slope,stream-wise slope and angle of repose of sediment particles. Experiments were carried out in two ducts (closed-conduit flow) having section of semicircular invert with three types of sediments. In an open channel flow (laboratory flume study), the uniform flow is a difficult, if not impossible,proposition for a steeply sloping channel and is impossible to obtain in an adversely sloping channel.To avoid this problem, the tests were conducted with a closed-conduit flow. Equation of critical bed shear stress for the initial movement of sediment particles on generalized sloping beds was obtained using the experimental data.

  11. Efficiency of scalar and vector intensity measures for seismic slope displacements

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Ground motion intensity measures are usually used to predict the earthquake-induced displacements in earth dams,soil slopes and soil structures.In this study,the efficiency of various single ground motion intensity measures (scalar IMs) or a combination of them (vector IMs) are investigated using the PEER-NGA strong motion database and an equivalent-linear sliding-mass model.Although no single intensity measure is efficient enough for all slope conditions,the spectral acceleration at 1.5 times of the initial slope period and Arias intensity of the input motion are found to be the most efficient scalar IMs for flexible slopes and stiff slopes respectively.Vector IMs can incorporate different characteristics of the ground motion and thus significantly improve the efficiency over a wide range of slope conditions.Among various vector IMs considered,the spectral accelerations at multiple spectral periods achieve high efficiency for a wide range of slope conditions.This study provides useful guidance to the development of more efficient empirical prediction models as well as the ground motion selection criteria for time domain analysis of seismic slope displacements.

  12. Static and dynamic aspects of the rms local slope of growing random surfaces

    NARCIS (Netherlands)

    Palasantzas, George

    1997-01-01

    In this work, we investigated static and dynamic aspects of the rms local surface slope ‘‘ρ’’ for self-affine random surfaces. The rms local slope is expressed as a function of the rms roughness amplitude σ, the in-plane correlation length ξ, and the roughness exponent H (0 0).

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

    DEFF Research Database (Denmark)

    Clausen, Johan; Damkilde, Lars

    2005-01-01

    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...

  14. Slope stability improvement using low intensity field electrosmosis

    Science.gov (United States)

    Armillotta, Pasquale

    2014-05-01

    The electrosmosis technique has been introduced in the past for slope stabilization. However, its application to real cases has been scarce due to several drawbacks mostly related to the high intensity electric field needed (1.0 V/cm or higher): the rapid degradation of the electrodes, the high system management cost, the heating and cracking of the soil and the reduction of its colloidal fraction. Thanks to the introduction of new materials, the technique is currently applied to decrease the consolidation time of saturated clay soils (forcing the elimination of water), consequently improving its mechanical strength. In clay soils, the volume variation is influenced by the presence of smectites. The clay compressibility decreases with the increasing of electrolytes concentration. Soil containing smectites that have interacted with calcium showed a reduction or the absence of swelling during hydration with distilled water and a positive increase of their shear strength. The different values of pH between the anode (acid) and the cathode (basic), induced by the electrosmosis create the conditions for the precipitation of CaCO3 near the cathode. The injection of solutions containing calcium in soils and their diffusion induced by the electrosmosis, lead to calcium precipitation and consequential increase of the shear strength. The material technological advances and the laboratory experiences described in this paper, demonstrate that the use low electric field (0.1 V/cm or lower) intensity electrosmosis (LEFE in acronym) can be effective for soil dewatering and shear strength increase while reducing its adverse effect. The LEFE can be used to: reduce the potential for swelling of active clay minerals through the introduction of ions and the precipitation of hardening substances; induce the "dewatering" in cohesive soils. Several Lab activities were carried out, using custom made electrosmosis equipment. These activities can be divided in two phases: Phase 1

  15. Economics of Alaska North Slope gas utilization options

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, C.P.; Doughty, T.C.; Hackworth, J.H.; North, W.B.; Robertson, E.P.

    1996-08-01

    The recoverable natural gas available for sale in the developed and known undeveloped fields on the Alaskan North Slope (ANS) total about 26 trillion cubic feet (TCF), including 22 TCF in the Prudhoe Bay Unit (PBU) and 3 TCF in the undeveloped Point Thomson Unit (PTU). No significant commercial use has been made of this large natural gas resource because there are no facilities in place to transport this gas to current markets. To date the economics have not been favorable to support development of a gas transportation system. However, with the declining trend in ANS oil production, interest in development of this huge gas resource is rising, making it important for the U.S. Department of Energy, industry, and the State of Alaska to evaluate and assess the options for development of this vast gas resource. The purpose of this study was to assess whether gas-to-liquids (GTL) conversion technology would be an economic alternative for the development and sale of the large, remote, and currently unmarketable ANS natural gas resource, and to compare the long term economic impact of a GTL conversion option to that of the more frequently discussed natural gas pipeline/liquefied natural gas (LNG) option. The major components of the study are: an assessment of the ANS oil and gas resources; an analysis of conversion and transportation options; a review of natural gas, LNG, and selected oil product markets; and an economic analysis of the LNG and GTL gas sales options based on publicly available input needed for assumptions of the economic variables. Uncertainties in assumptions are evaluated by determining the sensitivity of project economics to changes in baseline economic variables.

  16. Large gravitational rock slope deformation in Romsdalen Valley (Western Norway

    Directory of Open Access Journals (Sweden)

    Aline Saintot

    2012-09-01

    Full Text Available Large gravitational rock slope deformation affects Precambrian gneisses at four localities of the Romsdalen valley of Western Norway. At each locality, detailed studies have allowed to determine the mechanism of deformation and to assess the degree of susceptibility for failure. 1 Svarttinden is a 4.3 Mm³ translational rockslide. Its single basal detachment developed along a foliation-parallel cataclastic fault. Although a rockslide occurred along the same detachment and the deposits reached the edge of the plateau, no displacement of the current instability is detected. 2 At Flatmark distinct 2-25 Mm³ blocks detached from the edge of the plateau by an opening along the steep foliation. The collapse of the blocks is explained by a complex mechanism of sliding and toppling. No displacement is actually detected on the instabilities. 3 At Børa blocks located at the edge of the plateau deformed by the same mechanism as at Flatmark. They have a maximum volume of 0.5 Mm3 and displacement rates of 0.2-2 cm/year. The deformation at Børa has affected a large part of the plateau and the entire deformed volume would be of 50-200 Mm³ but it is currently inactive. 4 A wedge failure at the edge of Mannen plateau is inferred to allow the 4-5 cm/year downward displacement of a 2-3.5 Mm³ instability. The high susceptibility of failure led to a permanent monitoring of the site since 2009.

  17. Application of FBG Sensing Technology in Stability Analysis of Geogrid-Reinforced Slope

    Science.gov (United States)

    Sun, Yijie; Xu, Hongzhong; Gu, Peng; Hu, Wenjie

    2017-01-01

    By installing FBG sensors on the geogrids, smart geogrids can both reinforce and monitor the stability for geogrid-reinforced slopes. In this paper, a geogrid-reinforced sand slope model test is conducted in the laboratory and fiber Bragg grating (FBG) sensing technology is used to measure the strain distribution of the geogrid. Based on the model test, the performance of the reinforced soil slope is simulated by finite element software Midas-GTS, and the stability of the reinforced soil slope is analyzed by strength reduction method. The relationship between the geogrid strain and the factor of safety is set up. The results indicate that the measured strain and calculated results agree very well. The geogrid strain measured by FBG sensor can be applied to evaluate the stability of geogrid-reinforced sand slopes. PMID:28294995

  18. Temperature regime of agrosoddy-podzolic soils on slopes of different steepness

    Science.gov (United States)

    Shein, E. V.; Bannikov, M. V.; Savoskina, O. A.; Mazirov, M. A.

    2011-02-01

    Soil temperature regime at the depth of 20 cm may vary considerably on different parts of a given slope. This variation may be related to the position of the particular site on the slope and to the geomorphic features of the slope, including its surface inclination. The soils of the upper steep part of the slope of southern aspect are subjected to more active warming in the spring. They are characterized by higher cumulative temperatures above 10°C. The degree of this difference depends on the particular weather conditions. The differences in the soil temperature regimes may be the reason for the unequal crop yields on the different parts of the slope.

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

    Directory of Open Access Journals (Sweden)

    Muhammad Suradi

    2014-04-01

    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.

  20. Meter-Scale Slopes of Candidate InSight Landing Sites from Point Photoclinometry

    Science.gov (United States)

    Beyer, Ross A.

    2016-09-01

    Photoclinometry was used to analyze the small-scale roughness of areas within the proposed Mars InSight landing ellipse. The landing ellipse presented in this study is in Elysium Planitia. This study was able to constrain surface slopes on length scales comparable to the HiRISE image resolution (0.25 meters/pixel and coarser). The InSight mission has various engineering constraints that each candidate landing ellipse must satisfy. These constraints indicate that the statistical value of the slopes at one, two, and five meter baselines are an important criterion. This technique estimates surface slopes across large swaths of each image, and builds up slope statistics for the images in the landing ellipse. The slopes I derived for the InSight landing site ellipse in this study are within the small-scale roughness constraints put forth by the InSight project. These results have provided input into the landing hazard assessment process.

  1. Optimal design of anchor cables for slope reinforcement based on stress and displacement fields

    Institute of Scientific and Technical Information of China (English)

    Guanghua Yang; Zhihui Zhong; Yucheng Zhang; Xudong Fu

    2015-01-01

    How to determine reasonable position and length of anchor cable is a frequently encountered but not well addressed problem in slope reinforcement projects. In this paper, the variable-modulus elastoplastic strength reduction method (SRM) is used to obtain the stress field, displacement field, and factor of safety of slope. Slope reinforcement using anchor cables is modeled by surface loading, i.e. different distributions of surface loading represent various reinforcement schemes. Optimal reinforcement scheme of anchor cables can be determined based on slope stress and displacement fields. By comparing the factor of safety and stress field before and after slope reinforcement, it is found that better rein-forcement results can be achieved if strong reinforcement is applied upon the regions with high stress and large displacement. This method can well optimize the arrangement of anchor cables. In addition, several cases are employed to verify the proposed method.

  2. Stability analysis of sandy slope considering anisotropy effect in friction angle

    Indian Academy of Sciences (India)

    Hamed Farshbaf Aghajani; Hossein Salehzadeh; Habib Shahnazari

    2015-09-01

    This paper aims to investigate the effect of anisotropy of shear strength parameter on the stability of a sandy slope by performing the limit equilibrium analysis. Because of scarcity of mathematical equation for anisotropic friction angle of sand, at first, all results of principal stress rotation tests are processed by artificial neural network and a computational procedure is developed for determining sand friction angle subjected to various loading directions. By implementing this procedure, slope stability analysis is performed in both isotropic and anisotropic conditions. The results indicate that while isotropic slope stability overestimates the factor of safety between 5 and 25% which the deviation is more for flatter slope, the location of critical slip surface is coincident in both conditions. Also in specific slip surface, the parameters of face angle, geometry of slip surface and soil properties relating to anisotropy are the main factors governing the result of anisotropic slope stability.

  3. Pre-stressed anchoring beam technique applicable in the reinforcement of high-steep slopes

    Institute of Scientific and Technical Information of China (English)

    Zhifa YANG; Luqing ZHANG; Jiewang ZHU

    2006-01-01

    During the construction of some large-scale rock engineering, high-steep slopes and insufficient slope stability induced by unloading fissures are often encountered. For the reinforcement of these slopes, some techniques (including conventional pre-stressed anchoring cable and unconventional anchoring hole) are usually utilized, however, having several obvious defects. Thus, it is very difficult for a designer to design an efficient reinforcement scheme for the high-steep slopes. For this reason, the authors develop the pre-stressed anchoring beam technique, in which tensile capacity of pre-stressed structures are fully utilized. It is analyzed that the new technique is characterized by multi-functions, including engineering investigation, efficient reinforcement, drainage, monitoring and urgent strength supplement, and hoped to be extensively applicable in the reinforcement of high-steep slopes.

  4. Hydrological heterogeneity in Mediterranean reclaimed slopes: runoff and sediment yield at the patch and slope scales along a gradient of overland flow

    Directory of Open Access Journals (Sweden)

    L. Merino-Martín

    2012-05-01

    Full Text Available Hydrological heterogeneity is recognized as a fundamental ecosystem attribute in drylands controlling the flux of water and energy through landscapes. Therefore, mosaics of runoff and sediment source patches and sinks are frequently identified in these dry environments. There is a remarkable scarcity of studies about hydrological spatial heterogeneity in restored slopes, where ecological succession and overland flow are interacting. We conducted field research to study the hydrological role of patches and slopes along an "overland flow gradient" (gradient of overland flow routing through the slopes caused by different amounts of run-on coming from upslope in three reclaimed mining slopes of Mediterranean-continental climate. We found that runoff generation and routing in non-rilled slopes showed a pattern of source and sink areas of runoff. Such hydrological microenvironments were associated with seven vegetation patches (characterized by plant community types and cover. Two types of sink patches were identified: shrub Genista scorpius patches could be considered as "deep sinks", while patches where the graminoids Brachypodium retusum and Lolium perenne dominate were classified as "surface sinks" or "runoff splays". A variety of source patches were also identified spanning from "extreme sources" (Medicago sativa patches; equivalent to bare soil to "poor sources" (areas scattered by dwarf-shrubs of Thymus vulgaris or herbaceous tussocks of Dactylis glomerata. Finally, we identified the volume of overland flow routing along the slope as a major controlling factor of "hydrological diversity" (heterogeneity of hydrological behaviours quantified as Shannon diversity index: when overland flow increases at the slope scale hydrological diversity diminishes.

  5. Hydrological heterogeneity in Mediterranean reclaimed slopes: runoff and sediment yield at the patch and slope scales along a gradient of overland flow

    Science.gov (United States)

    Merino-Martín, L.; Moreno-de las Heras, M.; Pérez-Domingo, S.; Espigares, T.; Nicolau, J. M.

    2012-05-01

    Hydrological heterogeneity is recognized as a fundamental ecosystem attribute in drylands controlling the flux of water and energy through landscapes. Therefore, mosaics of runoff and sediment source patches and sinks are frequently identified in these dry environments. There is a remarkable scarcity of studies about hydrological spatial heterogeneity in restored slopes, where ecological succession and overland flow are interacting. We conducted field research to study the hydrological role of patches and slopes along an "overland flow gradient" (gradient of overland flow routing through the slopes caused by different amounts of run-on coming from upslope) in three reclaimed mining slopes of Mediterranean-continental climate. We found that runoff generation and routing in non-rilled slopes showed a pattern of source and sink areas of runoff. Such hydrological microenvironments were associated with seven vegetation patches (characterized by plant community types and cover). Two types of sink patches were identified: shrub Genista scorpius patches could be considered as "deep sinks", while patches where the graminoids Brachypodium retusum and Lolium perenne dominate were classified as "surface sinks" or "runoff splays". A variety of source patches were also identified spanning from "extreme sources" (Medicago sativa patches; equivalent to bare soil) to "poor sources" (areas scattered by dwarf-shrubs of Thymus vulgaris or herbaceous tussocks of Dactylis glomerata). Finally, we identified the volume of overland flow routing along the slope as a major controlling factor of "hydrological diversity" (heterogeneity of hydrological behaviours quantified as Shannon diversity index): when overland flow increases at the slope scale hydrological diversity diminishes.

  6. Comparison of the Effects of the Different Methods for Computing the Slope Length Factor at a Watershed Scale

    Directory of Open Access Journals (Sweden)

    Fu Suhua

    2013-09-01

    Full Text Available The slope length factor is one of the parameters of the Universal Soil Loss Equation (USLE and the Revised Universal Soil Loss Equation (RUSLE and is sometimes calculated based on a digital elevation model (DEM. The methods for calculating the slope length factor are important because the values obtained may depend on the methods used for calculation. The purpose of this study was to compare the difference in spatial distribution of the slope length factor between the different methods at a watershed scale. One method used the uniform slope length factor equation (USLFE where the effects of slope irregularities (such as slope gradient, etc. on soil erosion by water were not considered. The other method used segmented slope length factor equation(SSLFE which considered the effects of slope irregularities on soil erosion by water. The Arc Macro Language (AML Version 4 program for the revised universal soil loss equation(RUSLE.which uses the USLFE, was chosen to calculate the slope length factor. In a parallel analysis, the AML code of RUSLE Version 4 was modified according to the SSLFE to calculate the slope length factor. Two watersheds with different slope and gully densities were chosen. The results show that the slope length factor and soil loss using the USLFE method were lower than those using the SSLFE method, especially on downslopes watershed with more frequent steep slopes and higher gully densities. In addition, the slope length factor and soil loss calculated by the USLFE showed less spatial variation.

  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

    2015-11-01

    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. Links among Slope Morphology, Canyon Types and Tectonics on Passive and Active Margins in the Northernmost South China Sea

    Institute of Scientific and Technical Information of China (English)

    Ho-Shing Yu; Emmy T Y Chang

    2009-01-01

    We examine slope profile types and variations in slope gradient and slope relief with depth for both passive and active margins in the northern most South China Sea.The passive South China margin is characterized by an exponential slope profile,mainly assodated with clustered slope-confined canyons.The active Taiwan margin shows a linear-like shape with great variations along the lower slope.Fewer eanyom occur on the Taiwau margin,and hence the influence of canyon incision on slope morphology is relatively less significant.Quantitative analyses of slope curvature,slope gradleut and square root of relief variance are useful statistical parameters to explain characteristics and variability of morphology of the slope of the South China margin,but not for the Kaoping slope on the Talwan side.On the active Taiwan margin,tectonic activities are dominant over sediment deposition and surface erosion,producing a slope profile quite different from those of passive margins of the Middle Atlantic,KwaZulu-Natal,South Africa where failure on slope and accompanying canyon incision are the dominant processes shaping the slope morphology.

  9. Significance of the actual nonlinear slope geometry for catastrophic failure in submarine landslides.

    Science.gov (United States)

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

    2015-03-08

    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.

  10. The Probable Whole of Slope Submarine Landslides of Southeast Queensland, Australia.

    Science.gov (United States)

    Hubble, T.

    2015-12-01

    A research cruise aboard the RV Southern Surveyor (SS2013-V01) conducted in January 2013 offshore east Australia collected regional bathymetric data for the seabed of the continental margin of southern Queensland for the seabed bounded by Noosa Heads in the south and Indian Head, Fraser Island in the north. This newly mapped area presents a particularly steep portion of continental slope (5o to 10 o) that presents numerous submarine landslides, including two 'whole-of-slope' features (The Wide Bay Canyon, and Inskip Slides. The slope is also dissected by three large submarine canyons offshore northern Fraser Island, Wide Bay and Noosa Heads (i.e. the Fraser Canyons, the Wide Bay Canyon and the Noosa Canyon). Dredge and core samples were collected from slide scars in the northern, central and southern areas of the bathymetric survey area. The initial examination of the area's bathymetry, the core and dredge sample sedimentology, and determination of biostratigraphic ages for these sediment samples indicates that the larger, submarine slides present in this study area have probably been shed from the slope since the late Pliocene and that canyon incision is currently active on this portion of the slope. In one case, canyon incision is partly responsible for generating slides due to undercutting and removal of the toe of the slope. Slope sediments are dominantly comprised of hemipelagic muds but the presence of massive coarse sands and graded sands in some cores above erosion surfaces that cut into slope mud units is interpreted to indicate that areas of the southern Queensland continental slope are probably subjected to abrasion by grain-flows and turbidites comprised of shelf-derived sands and upper slope sediment. The results from this voyage confirms and extends previous work on the southeastern Australian continental margin that indicates that sediment transport from the shelf to deep water on this margin is dominated by gravity mass transport and that the margin

  11. Unraveling uncertainties of water table slope assessment with DGPS in lowland floodplain wetlands.

    Science.gov (United States)

    Mirosław-Świątek, Dorota; Michałowski, Robert; Szporak-Wasilewska, Sylwia; Ignar, Stefan; Grygoruk, Mateusz

    2016-11-01

    In our study, we analyzed the combined standard uncertainty of water table slope assessment done using differential global positioning system (DGPS)-based measurements of water table elevation and distances between measurement locations. We compared and discussed uncertainties in water table slope assessments done in various hypothetical environments of lowland floodplains (water table slopes typically ranged from 1.25 · 10(-4) to 1 · 10(-3)). Our analyses referred to elevation measurements done with the static GPS and DGPS real-time kinematic (RTK) approaches, which are currently among the most frequently used elevation measurement techniques worldwide. Calculations of the combined standard uncertainty of water table slope allowed us to conclude that the DGPS-RTK approach used in water table slope assessment can result in assessment errors as high as 50 % at short (<200 m) distances. Acceptable water table slope measurement errors (lower than 5 %) occur at distances longer than 11,320 m in the case of DGPS-RTK measurements, while, in the case of static GPS measurements, acceptable measurement errors at the same level occur at distances as low as 1350 m. Errors in water table slope assessment as high as 50 % occur at distances of 1130 m and 140 m for DGPS-RTK and static GPS measurements, respectively. We conclude that, although the DGPS-RTK methodology-due to its ease of use and time-saving capabilities is very often applied to water level measurements in lowland riparian wetlands, the application of the DGPS-RTK methodology for water table slope assessment at distances shorter than a few couples of meters results in very low accuracy (errors greater than 50 %) and should not be used for calculating local slopes in low slope areas such as lowland riparian zones.

  12. A laboratory investigation into the effects of slope on lava flow morphology

    Science.gov (United States)

    Gregg, Tracy K. P.; Fink, Jonathan H.

    2000-03-01

    In an attempt to model the effect of slope on the dynamics of lava flow emplacement, four distinct morphologies were repeatedly produced in a series of laboratory simulations where polyethylene glycol (PEG) was extruded at a constant rate beneath cold sucrose solution onto a uniform slope which could be varied from 1° through 60°. The lowest extrusion rates and slopes, and highest cooling rates, produced flows that rapidly crusted over and advanced through bulbous toes, or pillows (similar to subaerial "toey" pahoehoe flows and to submarine pillowed flows). As extrusion rate and slope increased, and cooling rate decreased, pillowed flows gave way to rifted flows (linear zones of liquid wax separated by plates of solid crust, similar to what is observed on the surface of convecting lava lakes), then to folded flows with surface crusts buckled transversely to the flow direction, and, at the highest extrusion rates and slopes, and lowest cooling rates, to leveed flows, which solidified only at their margins. A dimensionless parameter, Ψ, primarily controlled by effusion rate, cooling rate and flow viscosity, quantifies these flow types. Increasing the underlying slope up to 30° allows the liquid wax to advance further before solidifying, with an effect similar to that of increasing the effusion rate. For example, conditions that produce rifted flows on a 10° slope result in folded flows on a 30° slope. For underlying slopes of 40°, however, this trend reverses, slightly owing to increased gravitational forces relative to the strength of the solid wax. Because of its significant influence on heat advection and the disruption of a solid crust, slope must be incorporated into any quantitative attempt to correlate eruption parameters and lava flow morphologies. These experiments and subsequent scaling incorporate key physical parameters of both an extrusion and its environment, allowing their results to be used to interpret lava flow morphologies on land, on the

  13. A continental slope stability evaluation in the Zhujiang River Mouth Basin in the South China Sea

    Institute of Scientific and Technical Information of China (English)

    LIU Ke; WANG Jianhua

    2014-01-01

    In nature, a slope stability is determined by the ratio of a sliding resistance to a slide force. The slide force of a marine deep-water continental slope is mainly affected by sediment mechanics properties, a topography, and a marine seismic. However, the sliding resistance is mainly affected by sedimentary patterns and a sedi-mentary stress history. Both of these are different from case to case, and their impact can be addressed when the data are organized in a geographic information system (GIS). The study area on the continental slope in Zhujiang River Mouth Basin in South China Sea provides an excellent opportunity to apply GIS spatial analysis technology for the evaluation of the slope stability. In this area, a continental slope topography and a three-dimension (3-D) topography mapping show a sea-floor morphology and the distribution of a slope steepness in good detail, and the sediment analysis of seabed samples and an indoor appraisal reveals the variability of a sediment density near the sea-floor surface. On the basis of the results of nine geotechnical studies of submarine study areas, it has worked out that an equivalent cyclic shear stress ratio is roughly between 0.158 and 0.933, which is mainly depending on the initial water content of sediment. A regional density, slope and level of anticipated seismic shaking information are combined in a GIS framework to yield a map that illustrates a continental slope stability zoning under the influencing factors in Zhujiang River Mouth Basin in the South China Sea. The continental slope stability evaluation can contribute to north resources development in the South China Sea, the marine functional zoning, the marine engineering con-struction and adjust measures to local conditions, at the same time also can provide references for other deep-water slope stability analysis.

  14. Automating slope monitoring in mines with terrestrial lidar scanners

    Science.gov (United States)

    Conforti, Dario

    2014-05-01

    Static terrestrial laser scanners (TLS) have been an important component of slope monitoring for some time, and many solutions for monitoring the progress of a slide have been devised over the years. However, all of these solutions have required users to operate the lidar equipment in the field, creating a high cost in time and resources, especially if the surveys must be performed very frequently. This paper presents a new solution for monitoring slides, developed using a TLS and an automated data acquisition, processing and analysis system. In this solution, a TLS is permanently mounted within sight of the target surface and connected to a control computer. The control software on the computer automatically triggers surveys according to a user-defined schedule, parses data into point clouds, and compares data against a baseline. The software can base the comparison against either the original survey of the site or the most recent survey, depending on whether the operator needs to measure the total or recent movement of the slide. If the displacement exceeds a user-defined safety threshold, the control computer transmits alerts via SMS text messaging and/or email, including graphs and tables describing the nature and size of the displacement. The solution can also be configured to trigger the external visual/audio alarm systems. If the survey areas contain high-traffic areas such as roads, the operator can mark them for exclusion in the comparison to prevent false alarms. To improve usability and safety, the control computer can connect to a local intranet and allow remote access through the software's web portal. This enables operators to perform most tasks with the TLS from their office, including reviewing displacement reports, downloading survey data, and adjusting the scan schedule. This solution has proved invaluable in automatically detecting and alerting users to potential danger within the monitored areas while lowering the cost and work required for

  15. Minimal Power Latch for Single-Slope ADCs

    Science.gov (United States)

    Hancock, Bruce R.

    2013-01-01

    Column-parallel analog-to-digital converters (ADCs) for imagers involve simultaneous operation of many ADCs. Single-slope ADCs are well adapted to this use because of their simplicity. Each ADC contains a comparator, comparing its input signal level to an increasing reference signal (ramp). When the ramp is equal to the input, the comparator triggers a latch that captures an encoded counter value (code). Knowing the captured code, the ramp value and hence the input signal are determined. In a column-parallel ADC, each column contains only the comparator and the latches; the ramp and code generation are shared. In conventional latch or flip-flop circuits, there is an input stage that tracks the input signal, and this stage consumes switching current every time the input changes. With many columns, many bits, and high code rates, this switching current can be substantial. It will also generate noise that may corrupt the analog signals. A latch was designed that does not track the input, and consumes power only at the instant of latching the data value. The circuit consists of two S-R (set-reset) latches, gated by the comparator. One is set by high data values and the other by low data values. The latches are cross-coupled so that the first one to set blocks the other. In order that the input data not need an inversion, which would consume power, the two latches are made in complementary polarity. This requires complementary gates from the comparator, instead of complementary data values, but the comparator only triggers once per conversion, and usually has complementary outputs to begin with. An efficient CMOS (complementary metal oxide semiconductor) implementation of this circuit is shown in the figure, where C is the comparator output, D is the data (code), and Q0 and Q1 are the outputs indicating the capture of a zero or one value. The latch for Q0 has a negative-true set signal and output, and is implemented using OR-AND-INVERT logic, while the latch for Q1 uses

  16. Confined gravity flow sedimentary process and its impact on the lower continental slope,Niger Delta

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    There is active gravity flow sedimentation on the lower continental slope of Niger Delta. High-resolution 3-D seismic data enable a detailed study on the gravity flow deposition process and its impact. The lower continental slope of Niger Delta is characterized by a stepped complex topography, which resulted from gravity sliding and spreading during Miocene and Pliocene. Two types of accommodations are identified on the slope: ponded accommodation as isolated sub-basins and healed slope accommodation as connected tortuous corridors, where multi-scale submarine fans and submarine channels developed. Gravity flow deposition process is affected by the characteristics of gravity flows and the receiving basin. At the early stage, gravity flow deposition process was dominated by "fill and spill" pattern in the ponded accommodation, whereas it was confined to the healed slope accommodation during the late stage. On the lower continental slope of Niger Delta, complex slope topography controlled the distribution and evolution of the gravity flow, producing complicated gravity depositional patterns.

  17. Analysis of Local Slopes at the InSight Landing Site on Mars

    Science.gov (United States)

    Fergason, R. L.; Kirk, R. L.; Cushing, G.; Galuszka, D. M.; Golombek, M. P.; Hare, T. M.; Howington-Kraus, E.; Kipp, D. M.; Redding, B. L.

    2016-10-01

    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.

  18. Observations of the evening transition processes on opposing slopes of a north-south oriented mountain

    Science.gov (United States)

    Pardyjak, E.

    2014-12-01

    The MATERHORN (Mountain Terrain Atmospheric Modeling and Observation) Program is a multiuniversity, multidisciplinary research initiative designed to improve numerical weather prediction in complex terrain and to better understand the physics of complex terrain flow phenomena across a wide range of scales. As part of MATERHORN, field campaigns were conducted at Dugway, UT, USA in Autumn 2012 and Spring 2013. A subset of the campaigns included dense observations along the East Slope of Granite Peak (40.096° N, -113.253° W), as well as additional observations on the opposing west facing slope. East Slope observations included five multi-sonic anemometer eddy covariance towers (two with full energy budget stations), eleven small energy budget stations, fifteen automated weather stations, a distributed temperature sensing (DTS) system, hot-film anemometry, infrared camera surface temperature observations and up to three Doppler lidars. West Slope operations were less intense with three main towers, two of which included sonic anemometry and one, which included full surface energy balance observations. For this presentation, our analysis will focus on characterizing and contrasting the response of mean wind circulations and thermodynamics variables, as well as turbulence quantities during the evening transitions on both the East Slope and West Slope when solar irradiation differences of the slope surfaces is extremely large.

  19. QRS slopes for assessment of myocardial damage in chronic chagasic patients

    Science.gov (United States)

    Pueyo, E.; Laciar, E.; Anzuola, E.; Laguna, P.; Jané, R.

    2007-11-01

    In this study the slopes of the QRS complex are evaluated for determination of the degree of myocardial damage in chronic chagasic patients. Previous studies have demonstrated the ability of the slope indices to reflect alterations in the conduction velocity of the cardiac impulse. Results obtained in the present study show that chronic chagasic patients have significantly flatter QRS slopes as compared to healthy subjects. Not only that but the extent of slope lessening turns out to be proportional to the degree of myocardial damage caused by the disease. Additionally, when incorporating the slope indices into a classification analysis together with other indices indicative of the presence of ventricular late potentials obtained from high resolution electrocardiography, results show that the percentages of correct classification increase up to 62.5%, which means eight points above the percentages obtained prior to incorporation of the slope indices. It can be concluded that QRS slopes have great potential for assessing the degree of severity associated with Chagas' disease.

  20. QRS slopes for assessment of myocardial damage in chronic chagasic patients

    Energy Technology Data Exchange (ETDEWEB)

    Pueyo, E [Instituto de Investigacion en Ingenieria de Aragon (13A), and CIBER-BBN, Universidad de Zaragoza (Spain); Laciar, E [Gabinete de TecnologIa Medica, Universidad Nacional de San Juan (Argentina); Anzuola, E [Instituto de Investigacion en Ingenieria de Aragon (13A), and CIBER-BBN, Universidad de Zaragoza (Spain); Laguna, P [Instituto de Investigacion en Ingenieria de Aragon (13A), and CIBER-BBN, Universidad de Zaragoza (Spain); Jane, R [Department ESAII, CREB, Universitat Politecnica de Catalunya, Barcelona (Spain)

    2007-11-15

    In this study the slopes of the QRS complex are evaluated for determination of the degree of myocardial damage in chronic chagasic patients. Previous studies have demonstrated the ability of the slope indices to reflect alterations in the conduction velocity of the cardiac impulse. Results obtained in the present study show that chronic chagasic patients have significantly flatter QRS slopes as compared to healthy subjects. Not only that but the extent of slope lessening turns out to be proportional to the degree of myocardial damage caused by the disease. Additionally, when incorporating the slope indices into a classification analysis together with other indices indicative of the presence of ventricular late potentials obtained from high resolution electrocardiography, results show that the percentages of correct classification increase up to 62.5%, which means eight points above the percentages obtained prior to incorporation of the slope indices. It can be concluded that QRS slopes have great potential for assessing the degree of severity associated with Chagas' disease.

  1. Continuum modeling and limit equilibrium analysis of slope movement due to rainfall infiltration

    Science.gov (United States)

    Borja, Ronaldo; White, Joshua; Wu, Wei

    2010-05-01

    Hydrologically-driven landslides and debris flows are highly destructive events that threaten lives and critical infrastructure worldwide. Despite decades of extensive slope stability model development, the fundamental controls connecting the hydrologic and geotechnical processes that trigger slope failure are not well quantified. We use a fully coupled, physics-based finite element model to address this shortcoming. We develop and test a 3D continuum slope-deformation model that couples solid-deformation with fluid-flow processes in variably saturated soils, and assess the capability of the coupled model to predict stresses and deformation necessary to trigger slope failure. We then compare the continuum model with traditional limit equilibrium solutions based on the modified Bishop method of slices to assess the stability of the slope as a function of rainfall infiltration using a scalar stability indicator called factor of safety. For this assessment, we use extensive measurements from a densely instrumented mountain slope (The Coos Bay Experimental Catchment) where a large, rainfall-triggered slope failure occurred. The use of sophisticated, fully coupled numerical simulations combined with comprehensive field-measurements provides an unprecedented opportunity to advance the state of understanding of landslide failure processes and effective mitigation measures.

  2. A Study on the Allowable Safety Factor of Cut-Slopes for Nuclear Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Myung Soo; Yee, Eric [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)

    2015-10-15

    In this study, the issues of allowable safety factor design criteria for cut-slopes in nuclear facilities is derived through case analysis, a proposed construction work slope design criteria that provides relatively detailed conditions can be applied in case of the dry season and some unclear parts of slope design criteria be modified in case of the rainy season. This safety factor can be further subdivided into two; normal and earthquake factors, a factor of 1.5 is applied for normal conditions and a factor of 1.2 is applied for seismic conditions. This safety factor takes into consideration the effect of ground water and rainfall conditions. However, no criteria for the case of cut-slope in nuclear facilities and its response to seismic conditions is clearly defined, this can cause uncertainty in design. Therefore, this paper investigates the allowable safety factor for cut-slopes in nuclear facilities, reviews conditions of both local and international cut-slope models and finally suggests an alternative method of analysis. It is expected that the new design criteria adequately ensures the stability of the cut-slope to reflect clear conditions for both the supervising and design engineers.

  3. Application of dynamic analysis of strength reduction in the slope engineering under earthquake

    Institute of Scientific and Technical Information of China (English)

    Ye Hailin; Zheng Yingren; Huang Runqiu; Li Anhong; Du Xiuli

    2010-01-01

    At present,the methods of analyzing the stability of slope under earthquake are not accurate and reasonable because of some limitations.Based on the real dynamic tensile-shear failure mechanism of slope,the paper proposes dynamic analysis of strength reduction FEM(finite element method)and takes the reduction of shear strength parameters and tensile strength parameters into consideration.And it comprehensively takes the transfixion of the failure surface,the non-convergence of calculation and mutation of displacement as the criterion of dynamic instability and failure of the slope.The strength reduction factor under limit state is regarded as the dynamic safety factor of the slope under earthquake effect and its advantages are introduced.Finally,the method is applied in the seismic design of anchors supporting and anti-slide pile supporting of the slope.Calculation examples show that the application of dynamic analysis of strength reduction is feasible in the seismic design of slope engineering,which can consider dynamic interaction of supporting structure and rock-soil mass.Owing to its preciseness and great advantages,it is a new method in the seismic design of slope supporting.

  4. Analysis of local slopes at the InSight landing site on Mars

    Science.gov (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.

    2016-01-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Ibnu Rusydy

    2016-04-01

    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.

  6. The effect of shearing rate and slope angle on the simple shear response of marine clays

    Science.gov (United States)

    Biscontin, G.; Rutherford, C.

    2010-12-01

    The response of submarine slopes to seismic or storm loading has become an important element in the risk assessment for offshore structures and local tsunami hazard. Evaluation of submarine slope stability requires characterization of soil behavior and relies on the selection of appropriate parameter values. Although the traditional simple shear device has been used to investigate cyclic loading effects on marine clay, it does not allow for complex loading conditions which often contribute to the failure on submarine slopes. Understanding the interaction between the initial shear stress, the slope angle, and the multi-directional shaking due to earthquakes or storm loading is an important aspect to understanding the failure mechanisms of submarine slope failures. The initial static driving force on the slope is combined with the dynamic loading by storms and earthquakes to create complex loading paths. Therefore, the ability to apply complex stress or strain paths is important to fully study the shear response of marine clays on submarine slopes. A new multi-directional simple shear device developed at Texas A&M University allows loading along three independent axes, two perpendicular horizontal directions to allow any stress or strain paths in the horizontal plane, and a third in the vertical direction. This device is used to investigate the response of Gulf of Mexico marine deposits to different loading conditions. To study the effect of slope angle on the shear response of the soil, samples are subjected to a shear stress during consolidation, Kα consolidation. One-dimensional monotonic and cyclic shearing of Ko consolidated specimens is used to simulate level ground conditions, whereas sloping surfaces were simulated using Kα consolidation for both monotonic and cyclic tests. The effects of shearing rate on the soil response are investigated using strain controlled tests at varying frequencies.

  7. Examining the influence of vegetation on slope hydrology in Hong Kong using the capacitive resistivity technique

    Science.gov (United States)

    Niu, Qifei; Zhao, Kairan; Wang, Yu-Hsing; Wu, Yuxin

    2016-06-01

    Vegetation essentially has both beneficial and detrimental hydrological effects on slope stability, and the balance between these effects changes throughout the year. For engineers considering vegetation as an ecotechnological solution to slope instability, it is therefore necessary to understand how the net hydrological effect varies with local weather conditions. In this study, year-round field monitoring was carried out to examine the influence of a native plant on slope hydrology in Hong Kong using the capacitive resistivity technique and a newly developed line-electrode resistivity array. The measured soil resistivity was used to infer the soil moisture conditions on the slopes. The results show that vegetation generally has a strong influence on soil moisture although this effect varies among seasons. During the summer time, vegetation increases the soil moisture if compared with the bare slope. This is mainly due to the high precipitation, most of which enters the vegetated slope because of the increased permeability and infiltration rate caused by the vegetation. During the autumn time, the influence of vegetation evapotranspiration on slope hydrology becomes noticeable mainly because of the low precipitation (monthly less than 100 mm) and the relatively high potential evapotranspiration (monthly around 100 mm). In dry and cold winter, resistivity measurements suggest that the vegetation helps retain the soil water. In the following spring, difference in the soil moisture in bare and vegetated slopes is gradually wiped out because of the frequent rainfall. When the monthly rainfall reaches ~ 400 mm in early summer, the influence of vegetation on slope hydrology (soil moisture) completely disappears.

  8. The effect of slope angle on splash detachment in steep forest plantation

    Science.gov (United States)

    Mizugaki, S.; Nanko, K.; Onda, Y.

    2007-12-01

    To study splash detachment rate and investigate the effects of rainfall and slope angle on splash detachment, the field observation of splash detachment was conducted for five months using 27 splash cups under natural rainfall events in Japanese cypress (Hinoki; Chamaecyparis obtusa) plantation in the Shimanto River watershed, southern Japan. In this plantation forest, the unit kinetic energy of throughfall (unit KE; J/m2/mm) was found to be constant independent of rainfall intensity. The total rainfall over six observation periods was 853 mm and the maximum rainfall intensity for 1 h ( RI1h) varied from 8.0 to 19.6 mm h-1. A significantly high coefficient of linear regression was found between RI1h and the average splash detachment of all splash cups over six periods, although the splash detachment from the individual cups had larger variations with RI1h. This variation in splash detachment may attribute to the spatial variability in soil surface condition such as slope angle. In the relationship between the splash detachment and slope angle, no correlation was found over the entire periods. However, different correlations were found among the observation periods due to the differences in rainfall intensity. The splash detachment from a lower slope angle (14°) exhibited a strong relation with the maximum rainfall intensity for a shorter period, such as 10 to 30 minutes. In contrast, the splash detachment from a slope angle of over 35° exhibited high correlation with the maximum rainfall intensity for 3 h, suggesting that longer time is required for ponding in steeper slopes than gentler slopes. In gentler slopes, prolonged rainfall may cause the higher ponding depth, resulting in reducing the raindrop impact and less splash detachment. Therefore, under the forest canopies, the effect of slope angle on the rainfall parameter should be incorporated into the future splash erosion model.

  9. Terrestrial slopes in northern high latitudes: A paradigm shift regarding sediment origin, composition, and dynamic evolution

    Science.gov (United States)

    Lønne, Ida

    2017-01-01

    High-Arctic terrestrial slopes have received limited systematic research interest, but increased vulnerability related to regional warming has driven the call for better knowledge of the dynamics of these systems. Studies of sediment transport from a plateau area in Adventdalen, Svalbard, and associated slopes extending to sea level demonstrate that glacial processes play a more prominent role than earlier anticipated, - especially the impact of glacial meltwater. Traces of drainage at the plateau and the dissection of the plateau edge and upper slope were clearly initiated during various stages of Late Glacial runoff. Further, there is a close association between the sediment distribution and composition at the plateau and the evolution of various types of slopes. The reconstructed sedimentation history shows that the landscape will undergo four stages with contrasting modes of sediment transport: 1) subglacial processes related to active ice, 2) processes related to the margin of active ice, 3) processes related to the melting of inactive ice, and 4) nonglacial processes. These stages form four successions, referred to as supply regimes A-D, which control the supply of water and sediments to a given slope segment. In this landscape, traces of glacial meltwater occur at most altitudes, in "odd" positions and in slope segments "without" catchments. The associated depocenters (isolated, composite or coalescing into aprons), are often outsized compared to the apparent slope catchment. Reworked glacial sediments form a significant part of the slope-debris but are covered partly or entirely by products of physical weathering. Colluvium, senso stricto, thus masks a distinct system shift related to the local termination of glacial meltwater. Consequently, the weathering part of the slope sediment budget in this region is considerably overestimated.

  10. E24 profile slope stability analysis in Haizhou Opencast Coal Mine of Fuxin

    Institute of Scientific and Technical Information of China (English)

    Simplice F. BOBY; Jianping CHEN

    2007-01-01

    The E24 profile slope analyzed belongs to a series of excavated slopes of the Haizhou Opencast Coal Mine. It seems to be divided into Downslope Part and Upslope Part. Its profile comprises two noticeable coal seams, called the 8# and 9# weak layers, considered as the potential failure surfaces. In consideration of the actual configuration as in the perspective of any modification, assessing the stability of this slope with various profile forms under given conditions, and assessing the risk of instability and quantifying the influence of earthworks or other modifications to the stability of this slope, have constituted the primordial objectives carried out. From assumed potential failure surfaces, any specific profiles and specified slip surfaces are defined. A factor of safety (FoS) is computed for each specified slip surface; the smallest FoS found corresponds to the least favorable slip surface. The safety factor values obtained are compared to the suggested safety factor. Limit equilibrium methods of vertical slices implemented in Slope/W, computer program for slope stability analyses, have been adopted to perform the E24 slope stability analysis. The safety factor values computed with 9# weak layer are lower than for 8#; the factors of safety obtained with Sarma's method are the smallest; more, without groundwater (long term) overall values are greater than those determined under groundwater condition (short term). The lowest safety factor value is found for a profile depending on an adopted earthwork sequence. The E24 profile slope stability analysis shows the instability risk for the deepest weak layer, and also shows the short and long term stability of this slope for the envisaged earth movements. However it demonstrates the existence of instability risk for any earthwork firstly affecting the downslope part.

  11. Hydrological heterogeneity in Mediterranean reclaimed slopes: runoff and sediment yield at the patch and slope scales along a gradient of overland flow

    Directory of Open Access Journals (Sweden)

    L. Merino-Martín

    2011-11-01

    Full Text Available Hydrological heterogeneity is recognized as a fundamental ecosystem attribute in drylands controlling the flux of water and energy through landscapes. Therefore, mosaics of runoff and sediment sinks and source patches are frequently identified in these dry environments. There is a remarkable scarcity of studies about hydrological spatial heterogeneity in restored slopes, where ecological succession and overland flow are interacting. We conducted a field research to study the hydrological role of patches and slopes along an overland flow gradient in three reclaimed slopes coming from mining reclamation in a Mediterranean-continental climate. We found that runoff generation and routing in non-rilled slopes showed a pattern of source and sink areas of runoff. Such hydrological microenvironments were associated to seven vegetation patches (characterized by plant community types and cover. Two types of sink patches were identified: shrub Genista scorpius patches could be considered as a "deep sink", while patches where the graminoids Brachypodium retusum and Lolium perenne dominate were classified as "surface sinks" or "runoff splays". A variety of source patches were also identified spanning from "extreme sources" (Medicago sativa patches; equivalent to bare soil to "poor sources" (areas scattered by dwarf-shrubs of Thymus vulgaris or herbaceous tussocks of Dactylis glomerata. Finally, we identified the volume of overland flow routing along the slope as a controlling major factor of hydrological diversity: when overland flow increases at the slope scale hydrological diversity diminishes.

  12. Modeling slope failure by the 3D discrete element method: A case study of the dip slope at the Huafan University campus in northern Taiwan

    Science.gov (United States)

    Tseng, C. H.; Chan, Y. C.; Jeng, C. J.; Hsieh, Y. C.

    2015-12-01

    Slope failure is a widely observed phenomenon in hill and mountainous areas in Taiwan, which is characterized by high erosion rates (up to 60 mm/yr) due to its climatic and geographical conditions. Slope failure events easily occur after intense rainfall, especially resulting from typhoons and accordingly cause a great loss of human lives and property. At the northern end of the Western Foothill belt in northern Taiwan, Huafan University campus (121.692448˚ E, 24.980724˚ N ) is founded on a dip slope, ~20˚ toward southwest, being composed of early Miocene alternations of sandstone and shale. Data from continuous monitoring over the years by means of inclinometers and groundwater gauges reveal that creep of 6-10 mm of the slope occurred when precipitation exceeded 300 mm during typhoons' striking. In addition, extension cracks on the ground are also found within and on the edge of the campus. Furthermore, potential slip surfaces are detected shown by rock cores to exist 10 and 30 m in depth as well. To understand the kinematic behaviors of the rock slope failure beneath the university campus, a 3D discrete element mothed is applied in this study. Results of the modeling indicate that creeping is the primary behavior pattern when the friction coefficient reduces owing to rise of groundwater during rainstorms. However, rapid slip may take place under influences of earthquake with large magnitude. Suggestions for preventing the slope creep are to construct catchpits to drainage runoff and lower the groundwater table and ground anchors through the slip surfaces to stabilize the slide blocks.

  13. Effect of slope position on physico-chemical properties of eroded soil

    Directory of Open Access Journals (Sweden)

    Farmanullah Khan, Zubair Hayat, Waqar Ahmad,

    2013-05-01

    Full Text Available The research work was conducted on eroded soil (Missa Series in Samarbagh, District Lower Dir to determine the effect of slope position on soil physico-chemical properties. Soil samples were collected from top-slope, mid-slope and bottom slope positions at horizon-A, B and C. Results showed a significant difference among the physico-chemical properties of top, mid and bottom slope soils. Bulk density of the top-slope (1.51 g cm-3 was the highest followed by mid (1.39 g cm-3 and bottom slopes (1.32 g cm-3. Conversely, electrical conductivity EC-2.47 dS m-1, phosphorus (3.40 mg kg-1, Potassium (118.8 mg kg-1, Organic matter content (1.52 %, clay content (20.39 % and silt content (49.17% were the highest at bottom slope followed by mid and top-slopes, respectively. Soil A, B and C horizons were also significantly (p<0.05 different in their physico-chemical properties. Mean values showed that horizon Ap had the highest bulk density (1.43 g cm-3 and lower electrical conductivity (1.74 dS m-1, phosphorus (2.29 mg kg-1, potassium (84.86 mg kg-1, organic matter (1.08%, clay (12.83% and silt content (40.49% than both the B and C horizons. The deterioration in physico-chemical properties of top slope as compared to mid and bottom slopes and that of Ap horizon as compared to B and C horizons were presumed to be due to past soil erosion effect that removed the finer soil particles including soil organic matter and other plant nutrients. This study concluded that increasing extent of erosion due to slope effect can further deteriorate soil properties. The control of such damaging effects would require soil conservation strategies such as proper land levelling, afforestation, terracing and inclusion of restorative crops in cropping systems on these lands.

  14. Application of the PE method to up-slope sound propagation

    DEFF Research Database (Denmark)

    Rasmussen, Karsten Bo; Arranz, Marta Galindo

    1995-01-01

    velocity at the surface. The staircase PE method approximates the normal at the slope surface with the vertical component at the stair-step surface. A numerical correction can be included. Using a scale model facility [K. B. Rasmussen, 3617–3620 (1994)], a series of measurements is carried out. The results......The wide-angle PE method is applied to the prediction of sound propagation in a range-dependent environment. The finite-difference model treats the sloping ground by a staircase approximation. The method allows impedance and slope angle variations to be taken into account. The implementation...

  15. The Effect of Rotation Period on Slope Distribution on Asteroid Itokawa

    Science.gov (United States)

    Kanamaru, Masanori; Sasaki, Sho

    2016-07-01

    The centrifugal force due to the rotation occupies a big part of the surface gravity field for small solar system bodies, for example, Asteroid 25143 Itokawa. Change of rotation period by solar radiation is known as YORP effect. This phenomenon makes a strong effect on Itokawa's history of reconfiguration and surface terrain formation in hundreds of thousand years time span. We calculated the gravity potential, acceleration and slope over the Itokawa surface by means of a calculation method for a polyhedron with a homogeneous density (Werner and Scheeres (1997)). "Slope" is defined as the separation angle of a gravity acceleration vector and a normal vector of a surface facet. In this study, we used Itokawa shape models (Gaskell et al. 2006) and the bulk density value 1.95 grams per cubic centimeters (Abe et al. 2006). We investigated slope distributions with different rotation period (4h, 6.5h, 9h, 12.1324h, 18h, 24h). In addition, we made a slope histogram only for the neck region (150 < x < 250) of Itokawa in order to investigate a difference of slope distribution between all over the body and in a specific region. We found that the number of steep slope facets decreased when we shortened the rotation period. Steep slope areas were fewest when we assumed the rotation period 6.5h. But, the surface became much steeper when we assumed the rotation period 4h. Slope distribution also depended on regions. Steep slope areas were concentrated on the neck region. The slope histogram all over the body had a peak around 10 degrees, while the histogram only for the neck region had a peak around 20 degrees and there existed more steeper areas than that. Such a steep slope seems to be unstable. If a slope angle is an indicator of mismatch between a gravity field and local topography, we can reduce that by accelerating the rotation rate. One of possible scenarios for Itokawa formation is that Itokawa rotated much faster before and surface topography was formed according to the

  16. Study on determination of the stable slope configuration for deep open pit mine

    Institute of Scientific and Technical Information of China (English)

    Nai-long ZHU; Shi-xiong ZHANG; Shu-yu YUE

    2008-01-01

    The space effects of deep pit slope are analyzed by an elastic mechanics principle.The interaction among the critical slide angle,the friction coefficient,the cohesion,and the horizontal radius of the deep pits is derived in this paper.It indicates that the deeper the pit is excavated,the greater the critical slide angle is.Both the theory for reducing stripping waste rock in deep pit and the approach to determining the configuration of the stable slope are developed from the interaction.The theory in this paper comprises the preceding principles of stability analysis of slopes and is suitable for analyzing that of deep pit.

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

    DEFF Research Database (Denmark)

    Clausen, Johan Christian; Damkilde, Lars

    2006-01-01

    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....

  18. Modeling on runoff concentration caused by rainfall on hillslopes and application in Maoping slope

    Institute of Scientific and Technical Information of China (English)

    LIU Qingquan; LI Jiachun

    2006-01-01

    Based on the fact that the concentration flowlines of overland flow depend on the surface landform of hillslope, a kinematic wave model was developed for simulating runoff generation and flow concentration caused by rainfall on hillslopes. The model-simulated results agree well with the experimental observations. Applying the model to the practical case of Maoping slope, we obtained the characteristics of runoff generation and infiltration on the slope. Especially, the simulated results adequately reflected the confluent pattern of surface runoff, which offers a scientific foundation for designing the drainage engineering on the Maoping slope.

  19. Seismic slope stability of embankments: a comparative study on EC8 provisions

    DEFF Research Database (Denmark)

    Zania, Varvara; Tsompanakis, Y.; Psarropoulos, P.N.

    2011-01-01

    According to EC8 provisions, seismic stability assessment of natural slopes is currently performed based on simplified methods i.e. the pseudostatic and the Newmark’s sliding block method. The application of these methods requires the beforehand consideration of major assumptions necessary...... for the selection of either the seismic coefficient or the acceleration time history of the rigid block. Although both ULS and SLS are defined according to acceptable level of deformations at the slope, the assigned level of displacements is not clarified. In the current study the seismic slope stability...

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

    DEFF Research Database (Denmark)

    Clausen, Johan; Damkilde, Lars

    2006-01-01

    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...