Seismic Performance Evaluation of Concrete Gravity Dams with Penetrated Cracks Considering Fluid–Structure Interaction

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A. Behshad

2018-02-01

Full Text Available In this paper, a comprehensive study on the seismic behavior of fractured concrete gravity dams during ground shakings is carried out considering dam–reservoir interaction effects. To gain the seismic behavior of the whole system, finite and boundary elements are employed to model the liquid region and the cracked structure, respectively. Formulation and different computational aspects of the suggested staggered hybrid approach are thoroughly argued. A computer code was developed in order to discuss the presented hybrid BE–DE technique and comparisons are made between the obtained results and those reported in the literature. To gain this goal, several problems of seismic excitations in frequency- and time-domains are presented employing the proposed approach, showing that the present results agree well with the results from other numerical procedures. The cracked Koyna Dam is scrutinized, considering the dynamic interaction between dam and reservoir with focus on the nonlinear behavior due to its top profile crack. The developed numerical model is rigorously validated by extensive comparisons with available results in the literature in which the dam–reservoir interaction were simplified by added masses. It can be concluded that there is significant disparity between the overturning and sliding response schemes of the nonlinear analysis and those of added mass technique.

Three-dimensional earthquake analysis of roller-compacted concrete dams

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M. E. Kartal

2012-07-01

Full Text Available Ground motion effect on a roller-compacted concrete (RCC dams in the earthquake zone should be taken into account for the most critical conditions. This study presents three-dimensional earthquake response of a RCC dam considering geometrical non-linearity. Besides, material and connection non-linearity are also taken into consideration in the time-history analyses. Bilinear and multilinear kinematic hardening material models are utilized in the materially non-linear analyses for concrete and foundation rock respectively. The contraction joints inside the dam blocks and dam–foundation–reservoir interaction are modeled by the contact elements. The hydrostatic and hydrodynamic pressures of the reservoir water are modeled with the fluid finite elements based on the Lagrangian approach. The gravity and hydrostatic pressure effects are employed as initial condition before the strong ground motion. In the earthquake analyses, viscous dampers are defined in the finite element model to represent infinite boundary conditions. According to numerical solutions, horizontal displacements increase under hydrodynamic pressure. Besides, those also increase in the materially non-linear analyses of the dam. In addition, while the principle stress components by the hydrodynamic pressure effect the reservoir water, those decrease in the materially non-linear time-history analyses.

PRINCIPAL STRESSES IN NON-LINEAR ANALYSIS OF BAKUN CONCRETE FACED ROCKFILL DAM

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Mohd Hilton Ahmad

2017-11-01

Full Text Available With rapid population growth and accelerating economic development, much of the world’s WATER which requires urgent attention to ensure sustainable use. Nowadays, Concrete Faced Rockfill Dam (CFRD is preferred among dam consultant due to its advantages. They are designed to withstand all applied loads; namely gravity load due to its massive weight and hydrostatic load due to water thrust from the reservoir. Bakun CFRD, which ranks as the second highest CFRD in the world when completed, is analyzed to its safety due to both loads mentioned earlier by using Finite Element Method. 2-D plane strain finite element analysis of non-linear Duncan-Chang hyperbolic Model which formulated by Duncan and Chang is used to study the structural response of the dam in respect to the deformation and stresses of Main dam of Bakun’s CFRD project. Dead-Birth-Ghost element technique was used to simulate sequences of construction of the dam as well as during reservoir fillings. The comparison of rigid and flexible foundation on the behaviour of the dam was discussed. The maximum and minimum principal stresses are the maximum and minimum possible values of the normal stresses. The maximum principal stress controls brittle fracture. In the finite element modeling the concrete slab on the upstream was represented through six-noded element, while the interface characteristic between dam body and concrete slab was modeled using interface element. The maximum settlement and stresses of the cross section was founded and the distribution of them were discussed and tabulated in form of contours.

Numerical modeling and experimental validation of seismic uplift pressure variations in cracked concrete dams

Energy Technology Data Exchange (ETDEWEB)

Javanmardi, F.; Leger, P. [Ecole Polytechnique, Montreal, PQ (Canada). Dept. of Civil, Mining and Geological Engineering; Tinawi, R. [Quebec Univ., Montreal, PQ (Canada)

2004-07-01

Concrete dams could sustain cracking and damage during maximum design earthquakes (MDE). Dam safety guidelines are established so that dams maintain a stable condition following MDE oscillatory motions. In this study, a theoretical model was developed to calculate the uplift pressure variations along concrete cracks with moving walls. The proposed model was verified using experimental crack test data. The model was applied in a finite element computer program for dynamic analysis of gravity dams considering hydro-mechanical water-crack coupling. An analysis of a typical 90 metre dam subjected to low and high frequency sinusoidal accelerations demonstrated that water can penetrate into part of a seismically initiated crack. Pressure tends to develop in a region close to the crack mouth, therefore detrimental effects for the global dam stability are unlikely to occur. The study showed that the seismic uplift force during the heel crack opening mode is small compared to the dam weight. This preliminary study suggests that the critical sliding safety factors (SSF) of the dam against downstream sliding could be computed by considering zero uplift pressure in the crack region subjected to tensile opening. 14 refs., 1 tab., 7 figs.

Long-term thermal two- and three-dimensional analysis of roller compacted concrete dams supported by monitoring verification

Energy Technology Data Exchange (ETDEWEB)

Kuzmanovic, V.; Savic, L. [Belgrade Univ. (Serbia). Faculty of Civil Engineering; Stefanakos, J. [National Technical Univ. of Athens (Greece). Dept. of Water Resources and Environmental Engineering

2010-04-15

This study investigated the long-term thermal-field evolution of roller compacted concrete (RCC) dams. Thermal computational analyses of the dams are needed as a result of the layer-based construction technologies used to build the dams. Two-dimensional (2-D) and 3-D unsteady phased models of the RCC dams were used to determine the time evolution of thermal field in a dam based on the Platanovryssi dam in Greece. The finite element method (FEM) was used to account for the dam geometry, different types of concrete used; actual initial and boundary conditions; the thermal and mechanical properties of the dam as a function of aging and temperature; and the RCC construction technology. The influence of all the parameters on the thermal behaviour of the RCC gravity dam was analyzed. Results of the study showed that the 2-D model accurately described the RCC dam thermal field. The thermal behaviour of the dam was influenced primarily by the thermal properties of the mixture and the boundary conditions. Variations of layer thickness did not significantly influence the temperature field. 18 refs., 3 tabs., 10 figs.

MacDonald Dam reconstruction : using roller-compacted concrete

Energy Technology Data Exchange (ETDEWEB)

O' Neil, E. [AMEC Earth and Environmental Ltd., Sydney, NS (Canada)

2007-04-01

Located in Nova Scotia, the MacDonald Dam was commissioned in 1928. The dam consists of a 122 metre-long, 16 metre-high concrete structure comprised of an intake structure, stoplog openings, and a 34 metre-long free-overflow spillway. A 488 metre-long power canal was added as an upgrade in the 1950s. This paper provided details of the roller-compact concrete (RCC) used in the dam's recent rehabilitation following a dam failure analysis in 2003 by Nova Scotia Power Inc. RCC was chosen to help keep the dam's construction project on schedule. The layout and cross-section of the spillway was selected with consideration given to the RCC placing operation. A lift thickness of 0.20 m was selected. A formed ogee crest consisting of conventional reinforced concrete was constructed on top of the RCC. The downstream steps of the spillway were also covered with cast-in-place concrete. A low level sluice was designed to resist the weight of the wet RCC. The design compressive strength of the RCC was 20 MPa. The forms used to support the cast-in-place facing concrete on the upstream face of the dam were constructed full height and were braced back to the downstream face of the existing concrete structure prior to the start of RCC placement. Formwork inserts were placed in the facing concrete as construction progressed. Crack inducers were pre-placed on the forms. Aggregates from a local source were transported to a pug mill as the RCC construction progressed. The RCC was spread into 0.20 m lifts using a small bull-dozer, and the facing concrete was vibrated into the lift below. RCC lifts were compacted using a 9 tonne vibratory drum roller. The RCC placing operation was completed over a period of 10 days. Following the completion of the RCC portion of the dam, the remainder of the cast-in-place concrete was completed. It was concluded that the RCC provided a durable, low-maintenance structure that was completed at a lower price and in a shorter time-frame than

Technical bulletin : structural considerations for dam safety

Energy Technology Data Exchange (ETDEWEB)

NONE

2007-07-01

This technical bulletin discussed issues related to the safety assessment of concrete water-retaining structures and timber dams. Structures reviewed in the paper included gravity dams; buttress dams; arch dams; spillway structures; intake structures; power plants; roller compacted concrete dams; and timber dams. A variety of issues related to the loss of cohesive bond and discontinuities in bedrock foundations were reviewed with reference to issues related to compressive strength, tensile strength, and shear strength. Static failure modes and failure mechanisms related to dam failures were also described. Visual indicators for potential failures include abutment and foundation movement, seepage, and structure movements. Loading combinations were discussed, and performance indicators for gravity dams were provided. Methods of analysis for considering load characteristics, structure types and geological conditions were also discussed. Modelling techniques for finite element analysis were also included. 16 refs., 3 tabs., 5 figs.

Estimated strength of shear keys in concrete dams

Energy Technology Data Exchange (ETDEWEB)

Curtis, D.D. [Hatch Energy, Niagara Falls, ON (Canada); Lum, K.K.Y. [BC Hydro, Burnaby, BC (Canada)

2008-07-01

BC Hydro requested that Hatch Energy review the seismic stability of Ruskin Dam which was constructed in 1930 at Hayward Lake in British Columbia. The concrete gravity dam is founded nearly entirely on rock in a narrow valley. The vertical joints between blocks are keyed and grouted. The strength of the shear keys was assessed when a non-linear finite element model found that significant forces were being transferred laterally to the abutments during an earthquake. The lateral transfer of loads to the abutment relies on the strength of the shear keys. The dynamic finite element analysis was used to determine the stability of the dam. A review of the shear strength measurements reported in literature showed that the measurements compared well to those obtained by BC Hydro from cores taken from Ruskin Dam. The cohesive strength obtained using the Griffith failure criteria was also in good agreement with both sets of measurements. A simple ultimate shear strength equation was developed using the Mohr-Coulomb failure criteria to determine combined cohesive and frictional strength of shear keys. Safety factors of 2.0 for static loads and 1.5 for seismic loads were proposed to reduce the ultimate strength to allowable values. It was concluded that given the relatively high shear strength established for the shear keys, the abutment rock or dam/abutment contact will control the amount of load which can arch to the abutments. 8 refs., 4 tabs., 5 figs.

Dam safety review using non-destructive methods for reinforced concrete structure

Energy Technology Data Exchange (ETDEWEB)

Philibert, Alain; Saint-Pierre, Francois; Turcotte, Bernard [Le Groupe S.M. International Inc., Sherbrooke, (Canada)

2010-07-01

Dams built at the beginning of the twentieth century include concrete structures that were put in under rehabilitation works. In some cases, the details of the structures are not well documented. In other cases, concrete damage can be hidden under new layers of undamaged material. This requires that the dam safety review in a real investigation gather the information necessary for carrying out the hydraulic and stability studies required by the Dam Safety Act. This paper presented the process of dam safety review using non-destructive methods for reinforced concrete structures. Two reinforced concrete dams built in the 1900's, the Eustic dam on the Coaticook River and the Frontenac dam on the Magog River near Sherbrooke, were evaluated by S.M. International using non-destructive methods such as sonic and ground penetrating radar methods. The studies allowed mapping of concrete damage and provided geometric information on some non visible structure elements that were part of previous reinforcement operations.

The Sulphate Effect on Lijiaxia Concrete Dam (China Gallery

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Xufen Zhu

2017-01-01

Full Text Available The concrete degradation is one of the most serious problems for a dam construct during the normal operation, which determines the dam service life. Hence, it is very important to reduce the extent of the dam concrete degradation for the safety of the dam normal operation. Here, Lijiaxia hydroelectric station is taken as an example, and a comprehensive method to assess the sulphate effect on dam gallery is proposed. Eleven samples in total were taken from three difference locations by the drill bore. The microstructural investigations including X-ray fluorescence spectrometry (XRF, X-ray diffraction (XRD, scanning electron microscope (SEM, and energy dispersive spectroscopy (EDS were conducted to assess the sulphate attack and the degradation degree. Meanwhile, the water chemical analysis was applied to reveal the mechanism of concrete degradation. The experimental and analysis results indicate that the concrete degradation degree varies with the location of the samples. The components of the concrete change and the content of SO3 increase dramatically during degradation. Moreover, the mineral facies of the concrete change correspondingly, with the cement paste substituted by the calcite, calcium vitriol, and gypsum. The reinforcement and precaution measures are suggested based on the results of the degradation assessment.

Nonparametric Change Point Diagnosis Method of Concrete Dam Crack Behavior Abnormality

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Zhanchao Li

2013-01-01

Full Text Available The study on diagnosis method of concrete crack behavior abnormality has always been a hot spot and difficulty in the safety monitoring field of hydraulic structure. Based on the performance of concrete dam crack behavior abnormality in parametric statistical model and nonparametric statistical model, the internal relation between concrete dam crack behavior abnormality and statistical change point theory is deeply analyzed from the model structure instability of parametric statistical model and change of sequence distribution law of nonparametric statistical model. On this basis, through the reduction of change point problem, the establishment of basic nonparametric change point model, and asymptotic analysis on test method of basic change point problem, the nonparametric change point diagnosis method of concrete dam crack behavior abnormality is created in consideration of the situation that in practice concrete dam crack behavior may have more abnormality points. And the nonparametric change point diagnosis method of concrete dam crack behavior abnormality is used in the actual project, demonstrating the effectiveness and scientific reasonableness of the method established. Meanwhile, the nonparametric change point diagnosis method of concrete dam crack behavior abnormality has a complete theoretical basis and strong practicality with a broad application prospect in actual project.

A comparative study of physical and chemical properties of different pozzolanic materials used for roller compacted concrete RCC dams

OpenAIRE

Husein Malkawi Abdallah I.; Shatnawi Ehab; Husein Malkawi Dima A.

2017-01-01

This paper addresses the feasibility and the efficiency of using Natural Pozzolan and/or Rock flour in Roller Compacted Concrete (RCC) gravity dams. For this purpose, five identical mortar trial mixes were prepared using five different supplementary materials, i.e., fly ash produced in South Africa (proven to be effective in RCC construction), fly ash produced in Turkey, Jordanian natural pozzolan, Saudi natural pozzolan, and rock flour from Mujib Dam basalt quarry. The physical and chemical ...

Cracking Behavior of a Concrete Arch Dam with Weak Upper Abutment

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Lei Xu

2017-01-01

Full Text Available The cracking behavior and failure mode of a 78 m high concrete double-curvature arch dam with weak upper abutment are investigated through performing cracking analysis. The mechanical behavior of concrete is simulated using a smeared crack model, in which a combination of the compression yield surface and the crack detection surface with a damaged elasticity concept is employed to describe the failure of concrete. The arch dam with practical mechanical properties of the upper and lower abutments is firstly studied with emphasis on its cracking behavior during overloading. Then, a comprehensive sensitivity analysis is carried out to investigate the influence of the ratio of the mechanical properties of upper abutment to those of lower abutment on dam failure with prime attention placed on the failure mode. Simulation results indicate the adopted smeared crack model is well-suited to the crack analysis of concrete arch dam. It is shown that cracking is localized around the interface between upper and lower abutments, which leads to a fast crack growth in the through-thickness direction of dam and finally causes the dam failure. Furthermore, the sensitivity analysis presents three types of failure modes corresponding to different ratio value, wherein Modes II and III should be avoided since the weak upper abutment plays a predominant role in the cracking and failure of concrete arch dam.

Dam safety investigations of the concrete structures of Hugh Keenleyside dam

International Nuclear Information System (INIS)

Hanna, A.W.; Nunn, J.O.H.; Cornish, L.; Northcott, P.

1993-01-01

The Hugh Keenleyside dam is located on the Columbia River in southeastern British Columbia, and impounds Arrow Lakes Reservoir which has a live storage of 8.8 km 3 and drains an area of 36,000 km 2 . It consists of a number of concrete structures, with a total length of 360 m and a maximum height of 58 m, and an earthfill embankment which spans across the original river channel. The 450 m long zoned earthfill dam is founded on pervious alluvium over 150 m deep. It has a sloping impervious core constructed from glacial till which extends 670 m upstream of the dam. This impervious blanket extends over the full width of the reservoir and is connected to the upstream face of the concrete structures. The results of a dam safety study, which was carried out due to the presence of high uplift pressures at some parts of the foundation, and stability concerns, are presented. The investigation concluded that the high uplift pressures were due to a localized defect in the upstream blanket and did not indicate any general deterioration of the blanket. Techniques that were found to be of particular use in the study for defining the source and nature of the foundation defects were: temperature surveys of flows from piezometers, cells and drains; air injection tests; and pressure response testing of cells, piezometers and drains to establish foundation interconnections. The concrete structures met the stability criteria for all load cases considered except for the navigation lock and the low level outlets. 3 refs., 6 figs

Performance of Damaged Soil-Concrete Wraparound Dam Sections under Dynamic Loading

Energy Technology Data Exchange (ETDEWEB)

Kanarska, Y; Lomov, I; Glascoe, L; Morris, J; Antoun, T; Hall, R; Woodson, S; Fortune, J; Hynes, M E

2009-09-28

Predicting seismic or shock loading damage of the soil-concrete interface where an embankment wraparound dam provides support to the end monoliths in a concrete gravity dam is an inherently challenging three-dimensional coupled problem. We wish to predict formation and growth of a crack between the soil and concrete with a sustained flow of water. Further, we seek to better understand all critical phenomenology of this type of problem such as the potential mitigating and stabilizing role of upstream and downstream filter zone and shell materials. This collaborative research effort will ultimately determine whether advances in computational platforms, constitutive soil models (advances in representing particulates, tension, flow, and hydraulic erosion), and physical testing (advances in centrifuge and flume testing) can be applied successfully to solve this complex problem. Our focus is (1) to develop and validate high fidelity numerical models to investigate crack formation, soil erosion, transport of materials, and stability as part of the erosion process, and deposition within interface cracks; and (2) to investigate the performance of the filter zone materials if an extreme loading event such as an earthquake or shock damages the wraparound section. Our numerical tools include both continuum and discrete approaches. The continuum approach is based on the drift-flux multiphase model where a fluid and a solid are represented as interpenetrating continua and can account for turbulent flow characteristics, particle lift forces due to shear flow, particle collisions, and gravity settling. The discrete particle approach is also applied and is useful when deriving constitutive laws and parameterizations of soil behavior. Different experimental validation studies are under consideration for model validation and calibration. Several case studies for different crack sizes and orientations, particle sizes and environmental hydraulic conditions may be required to confirm

Risk analysis of gravity dam instability using credibility theory Monte Carlo simulation model.

Science.gov (United States)

Xin, Cao; Chongshi, Gu

2016-01-01

Risk analysis of gravity dam stability involves complicated uncertainty in many design parameters and measured data. Stability failure risk ratio described jointly by probability and possibility has deficiency in characterization of influence of fuzzy factors and representation of the likelihood of risk occurrence in practical engineering. In this article, credibility theory is applied into stability failure risk analysis of gravity dam. Stability of gravity dam is viewed as a hybrid event considering both fuzziness and randomness of failure criterion, design parameters and measured data. Credibility distribution function is conducted as a novel way to represent uncertainty of influence factors of gravity dam stability. And combining with Monte Carlo simulation, corresponding calculation method and procedure are proposed. Based on a dam section, a detailed application of the modeling approach on risk calculation of both dam foundation and double sliding surfaces is provided. The results show that, the present method is feasible to be applied on analysis of stability failure risk for gravity dams. The risk assessment obtained can reflect influence of both sorts of uncertainty, and is suitable as an index value.

Nonparametric Change Point Diagnosis Method of Concrete Dam Crack Behavior Abnormality

OpenAIRE

Li, Zhanchao; Gu, Chongshi; Wu, Zhongru

2013-01-01

The study on diagnosis method of concrete crack behavior abnormality has always been a hot spot and difficulty in the safety monitoring field of hydraulic structure. Based on the performance of concrete dam crack behavior abnormality in parametric statistical model and nonparametric statistical model, the internal relation between concrete dam crack behavior abnormality and statistical change point theory is deeply analyzed from the model structure instability of parametric statistical model ...

Effects of spatial variation in cohesion over the concrete-rock interface on dam sliding stability

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Alexandra Krounis

2015-12-01

Full Text Available The limit equilibrium method (LEM is widely used for sliding stability evaluation of concrete gravity dams. Failure is then commonly assumed to occur along the entire sliding surface simultaneously. However, the brittle behaviour of bonded concrete-rock contacts, in combination with the varying stress over the interface, implies that the failure of bonded dam-foundation interfaces occurs progressively. In addition, the spatial variation in cohesion may introduce weak spots where failure can be initiated. Nonetheless, the combined effect of brittle failure and spatial variation in cohesion on the overall shear strength of the interface has not been studied previously. In this paper, numerical analyses are used to investigate the effect of brittle failure in combination with spatial variation in cohesion that is taken into account by random fields with different correlation lengths. The study concludes that a possible existence of weak spots along the interface has to be considered since it significantly reduces the overall shear strength of the interface, and implications for doing so are discussed.

The thaumasite form of sulfate attack in concrete of Yongan Dam

International Nuclear Information System (INIS)

Hu Mingyu; Long Fumei; Tang Mingshu

2006-01-01

According to microanalytical investigations, it is shown that the concrete of Yongan Dam is deteriorated due to the thaumasite form of sulfate attack (TSA). Analysis results of scanning electron microscopy (SEM), Energy Disperse X-ray (EDX) and X-ray Diffraction (XRD) are supported by the analysis of the concrete composition and the geographical conditions of the dam

Study on Semi-Parametric Statistical Model of Safety Monitoring of Cracks in Concrete Dams

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Chongshi Gu

2013-01-01

Full Text Available Cracks are one of the hidden dangers in concrete dams. The study on safety monitoring models of concrete dam cracks has always been difficult. Using the parametric statistical model of safety monitoring of cracks in concrete dams, with the help of the semi-parametric statistical theory, and considering the abnormal behaviors of these cracks, the semi-parametric statistical model of safety monitoring of concrete dam cracks is established to overcome the limitation of the parametric model in expressing the objective model. Previous projects show that the semi-parametric statistical model has a stronger fitting effect and has a better explanation for cracks in concrete dams than the parametric statistical model. However, when used for forecast, the forecast capability of the semi-parametric statistical model is equivalent to that of the parametric statistical model. The modeling of the semi-parametric statistical model is simple, has a reasonable principle, and has a strong practicality, with a good application prospect in the actual project.

Effect of water on the triaxial response under monotonic loading of asphalt concrete used in dams

Science.gov (United States)

Gaxiola Hernández, Alberto; Ossa López, Alexandra

2018-01-01

Embankment dams with asphalt concrete cores have been constructed on practically all continents with satisfactory results. Nowadays many advantages, such as the mechanical strength, are known that makes asphalt concrete a competitive alternative for the construction of the impervious elements of dams. However, the current available information does not describe the effect of prolonged contact between asphalt concrete and water on the structure of an embankment dam. In this research cylindrical asphalt concrete specimens with a void content similar to that used in impervious barriers of dams were fabricated and submerged in water for a prolonged period to simulate the conditions experienced by asphalt concrete placed inside an embankment dam as its core material. Subsequently, triaxial compression tests were conducted on the specimens. The results indicated that the asphalt concrete exhibited a reduction in strength because of the saturation process to which the material was subjected. However, no changes were observed in the mechanical response to prolonged contact with water for periods of up to 12 months.

Seismic response of concrete gravity dams with finite reservoir

International Nuclear Information System (INIS)

Baumber, T.; Ghobarah, A.

1992-01-01

In most previous analyses of dam responses to earthquake ground motion, the upstream reservoir is assumed to be infinite in length and completely straight. The meandering nature of the river system, however, results in the creation of a finite length reservoir upstream of the dam structure. A study was carried out to examine the effects of the finite length of the reservoir on the dynamic behavior of the monolith. The effect of excitation of the far end of the boundary on the monolith's response is also of interest. The dam-foundation-reservoir system is modelled using a sub-structuring approach. The analysis is conducted in the frequency domain and utilizes the finite element technique. The water in the reservoir is assumed to be compressible, inviscid, and irrotational. The upstream reservoir is assumed to have a rectangular cross-section. It was found that the finite length reservoir assumption results in supplementary response peaks in the monolith's response. The finite reservoir length allows the reservoir to resonate both in horizontal and vertical directions. The magnitude and spacing of these supplementary response peaks are dependent on the length of the reservoir. The phase of the ground motion which affects the far end boundary of the reservoir was also found to have a significant effect on the dam monolith's response. 8 refs., 5 figs

Flood and rockslide mitigative measures for the concrete sections of the Daisy Lake Dam

International Nuclear Information System (INIS)

Pataky, T.J.

1991-01-01

Studies conducted under British Columbia Hydro's dam safety program during the early 1980s indicated that dam sections of the Daisy Lake Dam would be overtopped by the probable maximum flood (PMF) and by a postulated slide generated wave (SGW). It was considered that the overtopping by either of the events could cause several sections of the concrete dam to fall, thereby resulting in uncontrolled release of the reservoir. The criteria used for determining foundation strength parameters, static and SGW induced water pressures, effective uplift and the appropriate factors of safety are discussed. The results of the analyses for the original dam sections and the design and implementation of the selected remedial measures are also described. These measures included lowering the Wing Dam and Saddle Dam by about 2 m to increase the spillway capacity and the installation of 43 post-tensioned anchors in the various sections of the main concrete and Wing dams. 9 refs., 8 figs., 3 tabs

Critical Quality Source Diagnosis for Dam Concrete Construction Based on Quality Gain-loss Function

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Bo Wang

2014-06-01

Full Text Available In dam concrete construction process, it not only has quality loss arising from quality fluctuation, but also gains quality compensation effect due to the mutual cooperation and adaptation coupling between working procedures (WPs. The calculation and transmission complexity of the quality loss and quality compensation affect the quality management of dam concrete construction. As the quality compensation effect existing in the production practice cannot be described by Taguchi quality loss function, the concept of quality gain-loss function was presented in this paper, which was based on endowing the constant term in the expansion of Taylor series with physical meaning—quality compensation. Based on quality gain-loss function theory, a new quality gain-loss transmission model of dam concrete construction based on GERT network was constructed and its effective algorithm was designed. WP quality gain-loss and its impact on the final product were reasonably measured, and the critical quality routes and critical quality WPs were detected and diagnosed in dam concrete construction network. Summer temperature-controlled concrete construction in the third phase of Three Gorges Project (TGP was taken as an example to carry out the study, and the calculation results showed the validity and practicability of the presented model and algorithm.

Reliability of Arch dams subject to concrete swelling

Energy Technology Data Exchange (ETDEWEB)

Ramos, J.M.; Silva, H.S.; Pinho, S. de [Laboratorio Nacional de Engenharia Civil (LNEC), Lisboa (Portugal)] [and others

1995-12-31

In this report, results of several studies are presented. The main aim of those studies was to assess the reliability of the three arch dams, in which swelling occurred due to alkali- aggregate reactions in various stages of development and having different effects on their reliability: the Cahora-Bassa dam, in Mozambique, where swelling accumulated up to the moment are very moderate and their development is apparently homogeneous; Santa-Luzia dam, in Portugal, where accumulated swelling have already considerable magnitude, nevertheless, important fissuration has not been observed up to the moment due to the homogeneous development of the swelling process; Alto-Ceira dam, also in Portugal, where accumulated swelling have also considerable magnitude but with a heterogeneous development, causing in conjunction with thermal variations important fissuration. Mention is made of mineralogical, chemical and petrographic analyses carried out for identification of the nature of reactions developed in each case and the back-analysis and other technics used in the assessment of the magnitude and distribution of swelling. Results are presented of measurement tests of the ultrasonic pulse velocity, used both in the assessment of alterations in the physical properties of concretes and in the determination of the depth of fissuration. Results are also presented of tests for characterisation of the rheology of integral concrete. Lastly, considerations are made about the reliability of the works on the basis of studies and the results of analyses of the state of stress, performed by means of the finite element method, by assuming for either visco-elastic or visco-elastic-plastic behaviour.

DESIGN OF OFFSHORE CONCRETE GRAVITY PLATFORMS

African Journals Online (AJOL)

gas industry. Manufacturing and construction methods are discussed. Current ... Keywords: concrete gravity platform, offshore, foundation design, manufacturing, ... forms are used to support production drilling ... Manufacture and Construction.

Study on Viscoelastic Deformation Monitoring Index of an RCC Gravity Dam in an Alpine Region Using Orthogonal Test Design

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Yaoying Huang

2018-01-01

Full Text Available The main objective of this study is to present a method of determining viscoelastic deformation monitoring index of a Roller-compacted concrete (RCC gravity dam in an alpine region. By focusing on a modified deformation monitoring model considering frost heave and back analyzed mechanical parameters of the dam, the working state of viscoelasticity for the dam is illustrated followed by an investigation and designation of adverse load cases using orthogonal test method. Water pressure component is then calculated by finite element method, while temperature, time effect, and frost heave components are obtained through deformation statistical model considering frost heave. The viscoelastic deformation monitoring index is eventually determined by small probability and maximum entropy methods. The results show that (a with the abnormal probability 1% the dam deformation monitoring index for small probability and maximum entropy methods is 23.703 mm and 22.981 mm, respectively; thus the maximum measured displacement of the dam is less than deformation monitoring index, which indicates that the dam is currently in a state of safety operation and (b the obtained deformation monitoring index using orthogonal test method is more accurate due to the full consideration of more random factors; the method gained from this study will likely be of use to diagnose the working state for those RCC dams in alpine regions.

Research on early-warning index of the spatial temperature field in concrete dams.

Science.gov (United States)

Yang, Guang; Gu, Chongshi; Bao, Tengfei; Cui, Zhenming; Kan, Kan

2016-01-01

Warning indicators of the dam body's temperature are required for the real-time monitoring of the service conditions of concrete dams to ensure safety and normal operations. Warnings theories are traditionally targeted at a single point which have limitations, and the scientific warning theories on global behavior of the temperature field are non-existent. In this paper, first, in 3D space, the behavior of temperature field has regional dissimilarity. Through the Ward spatial clustering method, the temperature field was divided into regions. Second, the degree of order and degree of disorder of the temperature monitoring points were defined by the probability method. Third, the weight values of monitoring points of each regions were explored via projection pursuit. Forth, a temperature entropy expression that can describe degree of order of the spatial temperature field in concrete dams was established. Fifth, the early-warning index of temperature entropy was set up according to the calculated sequential value of temperature entropy. Finally, project cases verified the feasibility of the proposed theories. The early-warning index of temperature entropy is conducive to the improvement of early-warning ability and safety management levels during the operation of high concrete dams.

Seismic Analysis of Concrete Dam by Using Finite Element Method

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Rozaina Ismail

2017-01-01

Full Text Available This paper reports a brief study on linear seismic analysis of Sg. Kinta Concrete Dam. The analysis was conducted in order to determine the performance and behaviour of the dam under seismic excitation. The dam was modelled as two-dimensional and developed based on the design drawing that is obtained from Angkasa Consulting Services Sdn. Bhd. The seismic analysis of the dam is conducted using finite element analysis software package LUSAS 14.3 and the dam has been analyse as a plain stress problem with a linear consideration. A set of historic data, with E1 Centro earthquake acceleration of about 0.50g is used as an earthquake excitation. The natural frequency and mode shape up to fifth mode of the dam has been obtained from the analysis to show the differences of the stress and deformation between each mode. The maximum horizontal and vertical stress of Sg. Kinta dam was found and the distribution of them was discussed in form of contours. The deformation of the dam were also been discussed by comparing the maximum displacement for each mode shaped.

Investigation on the temperature of the asphalt-concrete facing of embankment dams

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Karel Adam

2016-01-01

Full Text Available Asphalt concrete is a traditional material used for the constructions of upstream sealing of reservoir dams, particularly in upper reservoirs of pumped storage hydroelectric plants. The asphalt layer is often exposed to significant fluctuations of temperature caused, for example, by heating the facing from the sun and by its subsequent rapid cooling by water during reservoir periodical filling. To better understand the physical phenomena and behaviour of the facing in terms of vapour diffusion, the state of stress, etc., it is necessary to know temperature phenomena in the asphalt facing. This paper describes the measurement of temperature in the asphalt facing of the Dlouhe Strane pumped storage hydroelectric plant and its evaluation using 1D numerical model of heat flow in the asphalt concrete facing. Numerical simulation for selected load scenarios enabled the temperature phenomena that take place in the construction of the asphalt-concrete facing to be quantified. The analysis shows that during insolation, the asphalt facing is exposed to the significant temperature rise on its surface and also over its whole thickness. Similarly during frost weather the facing becomes frozen in its entire thickness. During the day cycle the temperature in the asphalt layers changes significantly. However, the temperature in the underlying rockfill dam body becomes steady approximately at the depth of 1.0 m. Keywords: Asphalt concrete facing, Temperature distribution analysis, Embankment dam

Cracking control in mass concrete for three gorges dam; Sankyo damu ni okeru masu konkurito no hibiware yokusei

Energy Technology Data Exchange (ETDEWEB)

Chu, CHuanying

1999-09-10

The provisional cofferdam work of the mainstream of Three Gorges Dam project was successfully finished on November 8, 1997. Now, the work enters its second stage, and the placing of large-scale concrete was started. The total quantity of concrete used in this project reaches 15.00 million m{sup 3}. Inhibition of dam concrete cracking is an important subject. In order to manufacture concrete with good crack-resistance, cements, fly ashes, aggregates and blending agents are strictly selected; and hydration-generating heat is reduced by means of strict temperature control, precooling of aggregates, reduction of placing temperature and concrete temperature in mixers, and the like. As a consequence of maintaining the highest temperature value in concrete blocks to be lower than a predetermined value, harmful cracks can be prevented from occurring when the temperature in the dam lowers. (NEDO)

Physical Model Method for Seismic Study of Concrete Dams

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Bogdan Roşca

2008-01-01

Full Text Available The study of the dynamic behaviour of concrete dams by means of the physical model method is very useful to understand the failure mechanism of these structures to action of the strong earthquakes. Physical model method consists in two main processes. Firstly, a study model must be designed by a physical modeling process using the dynamic modeling theory. The result is a equations system of dimensioning the physical model. After the construction and instrumentation of the scale physical model a structural analysis based on experimental means is performed. The experimental results are gathered and are available to be analysed. Depending on the aim of the research may be designed an elastic or a failure physical model. The requirements for the elastic model construction are easier to accomplish in contrast with those required for a failure model, but the obtained results provide narrow information. In order to study the behaviour of concrete dams to strong seismic action is required the employment of failure physical models able to simulate accurately the possible opening of joint, sliding between concrete blocks and the cracking of concrete. The design relations for both elastic and failure physical models are based on dimensional analysis and consist of similitude relations among the physical quantities involved in the phenomenon. The using of physical models of great or medium dimensions as well as its instrumentation creates great advantages, but this operation involves a large amount of financial, logistic and time resources.

Seismic Fortification Analysis of the Guoduo Gravity Dam in Tibet, China

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Peng Lin

2015-01-01

Full Text Available The primary aim of this research was to analyze the seismic performance of the Guoduo gravity dam. A nonlinear FEM method was implemented to study the deformation, stress, and overall stability of dam under both static and dynamic loading conditions, including both normal and overloading conditions. A dam seismic failure risk control method is proposed based on the cracking mechanism induced by the dynamic load to ensure dam safety and stability. Numerical simulation revealed that (1 under normal static and dynamic loading the symmetry of the displacement distributions is good, showing that the dam abutments and riverbed foundation have good overall stiffness. The stress distribution is a safe one for operation under both normal water loading and seismic loading. (2 Attention should be paid to the reinforcement design of outlets of the diversion dam monoliths, and enhance the capability of sustaining that tensile stress of dam monoliths. (3 The shape of the dam profile has a significant effect on the dynamic response of the dam. (4 By employing the “overload safety factor method,” the overall seismic fortification is as follows: K1=1.5, K2= 2~3, and K3= 3~4.

Effect of reservoir characteristics on the response of concrete gravity dams

International Nuclear Information System (INIS)

Baumber, T.; Ghobarah, A.

1992-01-01

In most previous analyses of dam responses to earthquake ground motion, the upstream reservoir is assumed to be infinite in length with horizontal bottom. This is rarely the actual geometry of a reservoir, as the upstream valley typically has complex geometry. A study was carried out to examine the effects of the geometry of the reservoir on the dynamic behavior of the monolith. The dam-foundation-reservoir system is modelled using a sub-structuring approach. The reservoir is modelled using a finite element formulation. The absorptive capacity of the reservoir's foundation is idealized as a one-dimensional boundary condition at the reservoir-foundation interface. The reservoir bottom is assumed to be sloping. It was found that the assumed shape of the upstream reservoir significantly affects the overall response of the dam-foundation-reservoir system. The frequencies and magnitudes of the response peaks are affected by the geometry of the reservoir. It was also found that the value of the wave reflection coefficient at the reservoir bottom has a significant effect on the system's response. 6 refs., 5 figs

A comparative study of physical and chemical properties of different pozzolanic materials used for roller compacted concrete RCC dams

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Husein Malkawi Abdallah I.

2017-01-01

Full Text Available This paper addresses the feasibility and the efficiency of using Natural Pozzolan and/or Rock flour in Roller Compacted Concrete (RCC gravity dams. For this purpose, five identical mortar trial mixes were prepared using five different supplementary materials, i.e., fly ash produced in South Africa (proven to be effective in RCC construction, fly ash produced in Turkey, Jordanian natural pozzolan, Saudi natural pozzolan, and rock flour from Mujib Dam basalt quarry. The physical and chemical properties of these pozzolanic materials were determined. The effectiveness of each one of these mineral admixtures used as a cement replacement material in controlling alkali silica reaction are studied and analyzed. Correlations were made between the mechanical properties for the five proposed mixes and a control mix using the Jordanian Portland Cement. The results demonstrate that the performance of Natural Pozzolana and/or rock flour as compared with that of fly ash and other pozzolanic material is very satisfactory and can be effectively used in RCC construction.

Japan`s largest composition dam, aiming for harmony with nature. Chubetsu dam; Shizen tono chowa wo mezasu, Nippon ichi no fukugo dam. Chubetsu dam

Energy Technology Data Exchange (ETDEWEB)

Mizushima, T. [Hokkaido Development Bureau, Hokkaido Development Agency, Sapporo (Japan)

1994-08-15

This paper introduces Chubetsu Dam planned with a large-scale embankment having a river bed width of 600 m. Chubetsu Dam is being constructed with such objectives as flood control of Ishikari River, river flow rate maintenance, drinking water supply, irrigation water supply and power generation. The dam site is a gravel bed having a river bed width of 600 m and a maximum foundation rock thickness of 40 m, requiring evaluations as a dam foundation and discussions of water shielding methods. As a result of discussions at the Chubetsu Dam technical discussion committee, the dam type is decided to be a composition dam consisting of a gravity type concrete dam on the left river side and a central core type fill dam using a part of the gravel bed as the foundation on the right river side. A continuous underground wall system is planned to be used for shielding water in the gravel foundation. In discussing the anti-seismic properties, analyses for bank construction and water filling to derive stress and deformation conditions prior to an earthquake and a time-history response analysis to derive conditional changes during the earthquake are performed. According to the results thereof, evaluations are given on the safety by compounding the stress and the acceleration. In plans to improve the surrounding areas, an area will be provided upstream the reservoir where the water level is kept constant to serve as a bird sanctuary. 7 figs.

The effects of rock joint geometrical parameters on safety of concrete arch dam abutments

Energy Technology Data Exchange (ETDEWEB)

Yazdani, S.; Yazdani, M.; Joorabchi, A.E. [Tarbiat Modares Univ., Tehran (Iran, Islamic Republic of)

2007-07-01

The International Commission on Large Dams (ICOLD) has stated that foundation failure is the primary cause of dam failure following overtopping. As such, concrete arch dams require strong and stiff abutments. The failure of jointed rock mass at abutments is one of the key mechanisms that may lead to uncontrolled leakage. For that reason, this study investigated the affect of the joint geometrical parameters on the stability of the concrete arch dam abutments. The study also considered the role of joints on the behaviour mechanism of rock mass because it is governed by mechanical and hydraulic properties. The orientation of joints was considered since kinematic conditions are needed for a block to move. The hydromechanical influence of joint apertures on the stability of the foundation was also investigated through nonlinear analyses of different joint orientations and apertures on a hypothetical jointed abutment. Dam abutment safety was estimated by finding the values of maximum sliding and maximum opening and determining the water flow along discontinuities. The values of these 3 indices were derived for different orientations of joints. It was concluded that abutment safety was highly dependent on the geometrical characteristics of joints. 8 refs., 1 tab., 6 figs.

Dynamic analyzing procedures adopted for concrete-faced rockfill dams in Turkey

Energy Technology Data Exchange (ETDEWEB)

Tosun, H. [Dam Safety Association, Ankara (Turkey); Tosun, K. [TVT Hydrotech Bureau, Ankara (Turkey)

2008-07-01

A concrete faced rockfill dam (CFRD) has some advantages compared to other embankment types. The advantages include minimal settlement problems through the use of compacted rockfill; increased overall stability of the dam since the water pressure acts on the upstream face; and pore water pressure does not develop in the rockfill zone if it is well designed and constructed. It is thought that well-compacted CFRD has a high resistance to earthquake loading, as based on several factors including acceptable past performance of similar dams. While numerical solutions performed for this type of dams indicate that it is as safe as other embankment dams, their behavior is still questionable when they are subjected to severe seismic loading. This paper outlined the key principals of the dynamic analyzing method adopted for CFRDs in Turkey and summarized the practice of CFRDs with heights ranging from 54 to 135 metres throughout the country. Two-dimensional finite element models were executed to estimate displacements on the crest under the different loadings of earthquake. Dams that were discussed included the Kurtun Dam, the Torul Dam, the Atasu Dam, the Dim Dam, the Gordes Dam, and the Marmaris Dam. The paper also discussed the limitation about permanent settlement provided in the national dam specification and introduced the results obtained from a case study of the Pamukluk Dam located in southern Turkey. Geology and geotechnics as well as the embankment details and materials were discussed. The case study also summarized the selection of seismic parameters and dynamic analyses. 35 refs., 1 tab., 8 figs.

Spruce Lake Dam reconstruction

Energy Technology Data Exchange (ETDEWEB)

Snyder, G. [SGE Acres Ltd., Fredericton, NB (Canada); Barnard, J. [SGE Acres Ltd., St. John' s, NF (Canada); Vriezen, C. [City of Saint John, NF (Canada); Stephenson, M. [Jacques Whitford Environment Ltd., Fredericton, NB (Canada)

2004-09-01

Spruce Lake Dam was constructed in 1898 as part of the water supply system for Saint John, New Brunswick. The original dam was a 6 meter high, 140 meter long concrete gravity dam with an intake structure at its mid point and an overflow spillway at the left abutment. A rehabilitation project was launched in 2001 to bring the deteriorated dam into conformance with the dam safety guidelines of the Canadian Dam Association. The project criteria included minimal disruption to normal operation of water supply facilities and no negative effect on water quality. The project involved installation of a new low level outlet, removal of a gate house and water intake pipes, replacement of an access road culvert in the spillway channel, and raising the earth dam section by 1.8 meters to allow for increased water storage. The new raised section has an impervious core. The project also involved site and geotechnical investigations as well as hydrotechnical and environmental studies. This presentation described the final design of the remedial work and the environmental permitting procedures. Raising the operating level of the system proved successful as demonstrated by the fewer number of pumping days required after dam rehabilitation. The dam safety assessment under the Canadian Environmental Assessment Act began in April 2001, and the rehabilitation was completed by the end of 2002. 1 tab., 8 figs.

Uncertainty Instability Risk Analysis of High Concrete Arch Dam Abutments

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Xin Cao

2017-01-01

Full Text Available The uncertainties associated with concrete arch dams rise with the increased height of dams. Given the uncertainties associated with influencing factors, the stability of high arch dam abutments as a fuzzy random event was studied. In addition, given the randomness and fuzziness of calculation parameters as well as the failure criterion, hazard point and hazard surface uncertainty instability risk ratio models were proposed for high arch dam abutments on the basis of credibility theory. The uncertainty instability failure criterion was derived through the analysis of the progressive instability failure process on the basis of Shannon’s entropy theory. The uncertainties associated with influencing factors were quantized by probability or possibility distribution assignments. Gaussian random theory was used to generate random realizations for influence factors with spatial variability. The uncertainty stability analysis method was proposed by combining the finite element analysis and the limit equilibrium method. The instability risk ratio was calculated using the Monte Carlo simulation method and fuzzy random postprocessing. Results corroborate that the modeling approach is sound and that the calculation method is feasible.

On the response of large dams to incoherent seismic excitation

International Nuclear Information System (INIS)

Ramadan, O.; Novak, M.

1993-01-01

An intensive parametric study was conducted to investigate the response of concrete gravity dams to horizontal, spatially variable seismic ground motions. Both segmented dams consisting of separate blocks, or monoliths, and continuous monolithic dams are considered. The study includes the effects of various parameters on system natural frequencies, vibration modes, modal displacement ratios, as well as dam displacements and internal stresses due to spatially variable ground motions. The dam analytical model, and dam response to incoherent ground motions are described. The results show that the dam vibrates almost as a rigid body under the fully correlated waves, but bends and twists significantly under the spatially correlated motions. Dam-foundation interaction magnifies the low frequency components of the dam response, more so for a full reservoir, but decreases the high frequency components. For long dams, the effects of spatially incoherent ground motions are qualitatively different and can be much greater than those due to surface travelling waves. 3 refs., 3 figs

Investigating Efficiency of Vector-Valued Intensity Measures in Seismic Demand Assessment of Concrete Dams

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Mohammad Alembagheri

2018-01-01

Full Text Available The efficiency of vector-valued intensity measures for predicting the seismic demand in gravity dams is investigated. The Folsom gravity dam-reservoir coupled system is selected and numerically analyzed under a set of two-hundred actual ground motions. First, the well-defined scalar IMs are separately investigated, and then they are coupled to form two-parameter vector IMs. After that, IMs consisting of spectral acceleration at the first-mode natural period of the dam-reservoir system along with a measure of the spectral shape (the ratio of spectral acceleration at a second period to the first-mode spectral acceleration value are considered. It is attempted to determine the optimal second period by categorizing the spectral acceleration at the first-mode period of vibration. The efficiency of the proposed vector IMs is compared with scalar ones considering various structural responses as EDPs. Finally, the probabilistic seismic behavior of the dam is investigated by calculating its fragility curves employing scalar and vector IMs considering the effect of zero response values.

Comparative Study on Interface Elements, Thin-Layer Elements, and Contact Analysis Methods in the Analysis of High Concrete-Faced Rockfill Dams

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Xiao-xiang Qian

2013-01-01

Full Text Available This paper presents a study on the numerical performance of three contact simulation methods, namely, the interface element, thin-layer element, and contact analysis methods, through the analysis of the contact behavior between the concrete face slab and the dam body of a high concrete-faced rockfill dam named Tianshengqiao-I in China. To investigate the accuracy and limitations of each method, the simulation results are compared in terms of the dam deformation, contact stress along the interface, stresses in the concrete face slab, and separation of the concrete face slab from the cushion layer. In particular, the predicted dam deformation and slab separation are compared with the in-situ observation data to classify these methods according to their agreement with the in-situ observations. It is revealed that the interface element and thin-layer element methods have their limitations in predicting contact stress, slab separation, and stresses in the concrete face slab if a large slip occurs. The contact analysis method seems to be the best choice whether the separation is finite or not.

THERMAL REGIME OF MASSIVE CONCRETE DAMS WITH AIR CAVITIES IN THE SEVERE CLIMATE

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Aniskin Nikolay Alekseevich

2012-12-01

The thermal regime of the concrete dam with an air cavity can be adjustable by simple structural elements, including a heat-insulating wall and artificial heating of cavities. The required intensity and duration of heating are to be identified. Final conclusions about the most favorable thermal regime pattern will be made upon completion of fundamental calculations of the thermal stress state of the dam to be performed in the next phase of the research.

Fractional order creep model for dam concrete considering degree of hydration

Science.gov (United States)

Huang, Yaoying; Xiao, Lei; Bao, Tengfei; Liu, Yu

2018-05-01

Concrete is a material that is an intermediate between an ideal solid and an ideal fluid. The creep of concrete is related not only to the loading age and duration, but also to its temperature and temperature history. Fractional order calculus is a powerful tool for solving physical mechanics modeling problems. Using a software element based on the generalized Kelvin model, a fractional order creep model of concrete considering the loading age and duration is established. Then, the hydration rate of cement is considered in terms of the degree of hydration, and the fractional order creep model of concrete considering the degree of hydration is established. Moreover, uniaxial tensile creep tests of dam concrete under different curing temperatures were conducted, and the results were combined with the creep test data and complex optimization method to optimize the parameters of a new creep model. The results show that the fractional tensile creep model based on hydration degree can better describe the tensile creep properties of concrete, and this model involves fewer parameters than the 8-parameter model.

An example of a small Design Gravity Dams | Yemanu | Zede Journal

African Journals Online (AJOL)

An example of a small Design Gravity Dams. H Yemanu. Abstract. No Abstract. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

STRESS-STRAIN STATE OF ROCKFILL DAM DOUBLE-LAYER FACE MADE OF REINFORCED CONCRETE AND SOIL-CEMENT CONCRETE

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Sainov Mikhail Petrovich

2017-05-01

Full Text Available There was studied the stress-strain state of 215 m high rockfill dam where the seepage-control element is presented by a reinforced concrete face of soil-cement concrete placed on the under-face zone. Calculations were carried out for two possible variants of deformability of rock outline taking into account the non-linearity of its deformative properties. It was obtained that the reinforced concrete face and the soil-cement concrete under-face zone work jointly as a single construction - a double-layer face. As the face assembly resting on rock is made with a sliding joint the scheme of its static operation is similar to the that of the beam operation on the elastic foundation. At that, the upstream surface of the double-layer face is in the compressed zone and lower one is in the tensile zone. This protects the face against cracking on the upstream surface but threatens with structural failure of soil-cement concrete. In order to avoid appearance of cracks in soil-cement concrete part due to tension it is necessary to achieve proper compaction of rockfill and arrange transverse joints in the double-layer face.

Application of a polycarboxylate ether admixture in RCC dam construction[ACI SP-239

Energy Technology Data Exchange (ETDEWEB)

Asmus, S.M.F.; Christensen, B.J.; Varley, N.J. [BASF Construction Chemicals Asia Pacific, Shanghai (China)

2006-07-01

Chemical admixtures are used in dam construction to improve plasticity of the dry materials mixture over time. Roller compacted concrete (RCC) has been used on many dam projects in China. However, the use of RCC has frequently resulted in water reduction problems. This paper provided details of an admixture based on polycarboxylate ether (PCE) which was developed to improve the quality of RCC constructions at the JinHong dam in China. Use of the polymer at the JinHong dam resulted in a vibration sensitive concrete that was sustained over time. Under identical mix-design and compaction conditions in the laboratory, specific gravity of the RCC was increased from 2417 kg/m{sup 3} to 2463 kg/m{sup 3}. The high specific gravity of the material resulted in satisfactory strength data from the dam project. The key-ratio of the splitting tensile strength versus compressive strength was higher than 8 per cent in all cases. A key advantage of the tailored PCE-RCC was the short Vebe times sustained over elapsed time in the RCC. Without additional compaction or vibration efforts, the specific density of RCC was better than conventional admixture technologies. The reduced viscosity provided cement paste films which formed on the surface of each layer of the RCC, which resulted in better bonding between the layers. It was concluded that the new PCE polymer is compatible with alternative retarder systems, which contributes to more extensive setting times under strict hydration regimes. 7 refs., 4 tabs., 4 figs.

Sensitivity Analysis of Temperature Control Parameters and Study of the Simultaneous Cooling Zone during Dam Construction in High-Altitude Regions

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Zhenhong Wang

2015-01-01

Full Text Available There are unprecedented difficulties in building concrete gravity dams in the high altitude province Tibet with problems induced by lack of experience and technologies and unique weather conditions, as well as the adoption of construction materials that are disadvantageous to temperature control and crack prevention. Based on the understandings of the mentioned problems and leveraging the need of building gravity dam in Tibet, 3D finite element method is used to study the temperature control and crack prevention of the dam during construction. The calculation under recommend temperature control measures and standards shows that the height and number of simultaneous cooling zone have the more obvious influencers on concrete stress; therefore, it is suggested to increase the height of simultaneous cooling zone to decrease the stress caused by temperature gradient of adjoin layers so as to raise the safety level of the whole project. The research methods and ideas used on this project have significant values and can be taken as references in similar projects in high altitude regions.

Forensic geotechniques in the re-evaluation of Ruskin Dam foundation shear strength

Energy Technology Data Exchange (ETDEWEB)

Rigbey, S.; Lawrence, M.S. [BC Hydro, Vancouver, BC (Canada); Daw, D. [Hatch Energy, Vancouver, BC (Canada)

2008-07-01

The 59 metre high Ruskin Dam was constructed in the 1930s at the south end of Hayward Lake in British Columbia. The concrete gravity dam is founded nearly entirely on rock. Although the dam has performed satisfactorily since its construction, it is categorized as a very high consequence structure based on criteria established in British Columbia Dam Safety Regulations. It was considered to have insufficient withstand for Maximum Designs earthquake (MDE). Stability analyses performed in the late 1990's relied on simplified geometry with presumed planar concrete-rock interfaces, and relatively conservative estimates of sliding resistance and no consideration for canyon geometry. The analyses suggested that the concrete base may need to be anchored to the rock foundation to achieve satisfactory seismic withstand. The sliding resistance of the dam's foundation had to be assessed in order to determine if remedial measures were needed to meet updated design criteria. A reliable 3-dimensional topographic model for the Ruskin Dam was created in 2006 following a review of construction records and drilling investigation programs. Irregularities were found in the rock concrete contact, and the canyon walls showed a positive downstream converging geometry. The potential critical failure modes were determined along the contact, along the potential subhorizontal joints within the foundation, and through a broken rock mass under the contact. Roughness for each selected case was evaluated and the Barton-Bandis basic friction angle for the rock was determined by laboratory testing. The resulting shear strengths were used in a series of dynamic stability analyses which revealed that the body of the dam would be stable in the updated design earthquake. The 3-D geotechnical model was the key to the new analyses, which showed that the abutment wedges are stable under seismic loading. As such, costly base anchoring of the dam was deemed unnecessary. 6 refs., 6 tabs., 12 figs.

OPTIMIZATION OF THE TEMPERATURE CONTROL SCHEME FOR ROLLER COMPACTED CONCRETE DAMS BASED ON FINITE ELEMENT AND SENSITIVITY ANALYSIS METHODS

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Huawei Zhou

2016-10-01

Full Text Available Achieving an effective combination of various temperature control measures is critical for temperature control and crack prevention of concrete dams. This paper presents a procedure for optimizing the temperature control scheme of roller compacted concrete (RCC dams that couples the finite element method (FEM with a sensitivity analysis method. In this study, seven temperature control schemes are defined according to variations in three temperature control measures: concrete placement temperature, water-pipe cooling time, and thermal insulation layer thickness. FEM is employed to simulate the equivalent temperature field and temperature stress field obtained under each of the seven designed temperature control schemes for a typical overflow dam monolith based on the actual characteristics of a RCC dam located in southwestern China. A sensitivity analysis is subsequently conducted to investigate the degree of influence each of the three temperature control measures has on the temperature field and temperature tensile stress field of the dam. Results show that the placement temperature has a substantial influence on the maximum temperature and tensile stress of the dam, and that the placement temperature cannot exceed 15 °C. The water-pipe cooling time and thermal insulation layer thickness have little influence on the maximum temperature, but both demonstrate a substantial influence on the maximum tensile stress of the dam. The thermal insulation thickness is significant for reducing the probability of cracking as a result of high thermal stress, and the maximum tensile stress can be controlled under the specification limit with a thermal insulation layer thickness of 10 cm. Finally, an optimized temperature control scheme for crack prevention is obtained based on the analysis results.

Dams life; La vie des barrages

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-12-31

The paper reports on the conclusions of decennial and annual inspections of French dams. Dams surveillance is performed by the operators and consists in visual examinations and measurements. Concrete dams, in particular, always have more or less developed fissures with water sweating threw the concrete mass or the foundations. Old concrete often show low swelling phenomena which are measured too. (J.S.)

An Interactive Tool for Automatic Predimensioning and Numerical Modeling of Arch Dams

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D. J. Vicente

2017-01-01

Full Text Available The construction of double-curvature arch dams is an attractive solution from an economic viewpoint due to the reduced volume of concrete necessary for their construction as compared to conventional gravity dams. Due to their complex geometry, many criteria have arisen for their design. However, the most widespread methods are based on recommendations of traditional technical documents without taking into account the possibilities of computer-aided design. In this paper, an innovative software tool to design FEM models of double-curvature arch dams is presented. Several capabilities are allowed: simplified geometry creation (interesting for academic purposes, preliminary geometrical design, high-detailed model construction, and stochastic calculation performance (introducing uncertainty associated with material properties and other parameters. This paper specially focuses on geometrical issues describing the functionalities of the tool and the fundamentals of the design procedure with regard to the following aspects: topography, reference cylinder, excavation depth, crown cantilever thickness and curvature, horizontal arch curvature, excavation and concrete mass volume, and additional elements such as joints or spillways. Examples of application on two Spanish dams are presented and the results obtained analyzed.

Patterns of gravity induced aggregate migration during casting of fluid concretes

Energy Technology Data Exchange (ETDEWEB)

Spangenberg, J. [Department of Mechanical Engineering, Technical University of Denmark (DTU) (Denmark); Roussel, N., E-mail: Nicolas.roussel@lcpc.fr [Universite Paris Est, Laboratoire Central des Ponts et Chaussees (LCPC) (France); Hattel, J.H. [Department of Mechanical Engineering, Technical University of Denmark (DTU) (Denmark); Sarmiento, E.V.; Zirgulis, G. [Department of Structural Engineering, Norwegian University of Science and Technology (NTNU) (Norway); Geiker, M.R. [Department of Structural Engineering, Norwegian University of Science and Technology (NTNU) (Norway); Department of Civil Engineering, Technical University of Denmark (DTU) (Denmark)

2012-12-15

In this paper, aggregate migration patterns during fluid concrete castings are studied through experiments, dimensionless approach and numerical modeling. The experimental results obtained on two beams show that gravity induced migration is primarily affecting the coarsest aggregates resulting in a decrease of coarse aggregates volume fraction with the horizontal distance from the pouring point and in a puzzling vertical multi-layer structure. The origin of this multi layer structure is discussed and analyzed with the help of numerical simulations of free surface flow. Our results suggest that it finds its origin in the non Newtonian nature of fresh concrete and that increasing casting rate shall decrease the magnitude of gravity induced particle migration.

Patterns of gravity induced aggregate migration during casting of fluid concretes

International Nuclear Information System (INIS)

Spangenberg, J.; Roussel, N.; Hattel, J.H.; Sarmiento, E.V.; Zirgulis, G.; Geiker, M.R.

2012-01-01

In this paper, aggregate migration patterns during fluid concrete castings are studied through experiments, dimensionless approach and numerical modeling. The experimental results obtained on two beams show that gravity induced migration is primarily affecting the coarsest aggregates resulting in a decrease of coarse aggregates volume fraction with the horizontal distance from the pouring point and in a puzzling vertical multi-layer structure. The origin of this multi layer structure is discussed and analyzed with the help of numerical simulations of free surface flow. Our results suggest that it finds its origin in the non Newtonian nature of fresh concrete and that increasing casting rate shall decrease the magnitude of gravity induced particle migration.

Cleveland Dam East Abutment : seepage control project

Energy Technology Data Exchange (ETDEWEB)

Huber, F.; Siu, D. [Greater Vancouver Regional District, Burnaby, BC (Canada); Ahlfield, S.; Singh, N. [Klohn Crippen Consultants Ltd., Vancouver, BC (Canada)

2004-09-01

North Vancouver's 91 meter high Cleveland Dam was built in the 1950s in a deep bedrock canyon to provide a reservoir for potable water to 18 municipalities. Flow in the concrete gravity dam is controlled by a gated spillway, 2 mid-level outlets and intakes and 2 low-level outlets. This paper describes the seepage control measures that were taken at the time of construction as well as the additional measures that were taken post construction to control piezometric levels, seepage and piping and slope instability in the East Abutment. At the time of construction, a till blanket was used to cover the upstream reservoir slope for 200 meters upstream of the dam. A single line grout curtain was used through the overburden from ground surface to bedrock for a distance of 166 meters from the dam to the East Abutment. Since construction, the safety of the dam has been compromised through changes in piezometric pressure, seepage and soil loss. Klohn Crippen Consultants designed a unique seepage control measure to address the instability risk. The project involved excavating 300,000 cubic meters of soil to form a stable slope and construction bench. A vertical wall was constructed to block seepage. The existing seepage control blanket was also extended by 260 meters. The social, environmental and technical issues that were encountered during the rehabilitation project are also discussed. The blanket extension construction has met design requirements and the abutment materials that are most susceptible to internal erosion have been covered by non-erodible blanket materials such as plastic and roller-compacted concrete (RCC). The project was completed on schedule and within budget and has greatly improved the long-term stability of the dam and public safety. 2 refs., 8 figs.

Remote Sensing of Deformation of a High Concrete-Faced Rockfill Dam Using InSAR: A Study of the Shuibuya Dam, China

Directory of Open Access Journals (Sweden)

Wei Zhou

2016-03-01

Full Text Available Settlement is one of the most important deformation characteristics of high concrete faced rockfill dams (CFRDs, >100 m. High CFRDs safety would pose a great threat to the security of people’s lives and property downstream if this kind of deformation were not to be measured correctly, as traditional monitoring approaches have limitations in terms of durability, coverage, and efficiency. It has become urgent to develop new monitoring techniques to complement or replace traditional monitoring approaches for monitoring the safety and operation status of high CFRDs. This study examines the Shuibuya Dam (up to 233.5 m in height in China, which is currently the highest CFRD in the world. We used space-borne Interferometric Synthetic Aperture Radar (InSAR time series to monitor the surface deformation of the Shuibuya Dam. Twenty-one ALOS PALSAR images that span the period from 28 February 2007 to 11 March 2011 were used to map the spatial and temporal deformation of the dam. A high correlation of 0.93 between the InSAR and the in-situ monitoring results confirmed the reliability of the InSAR method; the deformation history derived from InSAR is also consistent with the in-situ settlement monitoring system. In addition, the InSAR results allow continuous investigation of dam deformation over a wide area that includes the entire dam surface as well as the surrounding area, offering a clear picture continuously of the dam deformation.

Numerical Analysis on Temperature Rise of a Concrete Arch Dam after Sealing Based on Measured Data

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Qingbin Li

2014-01-01

Full Text Available The thermal boundary conditions in the construction and operation phases of a concrete arch dam are always complex. After sealing, differences between the arch dam temperature and its sealing temperature can cause compressive or tensile stresses. Based on measured temperature of an arch dam located in China, a temperature rise phenomenon (TRP is found in the after-sealed regions of the arch dam. By mining and analyzing the temperature data of various monitoring apparatus embedded in the arch dam, higher environment temperature is considered to be the main cause for the occurrence of the TRP. Mathematical methods for complex thermal boundary conditions, including external boundary conditions and internal heat source conditions, are proposed in this paper. A finite element model is implemented with the concern of the construction phase and operation phase of the arch dam. Results confirm good agreement with the measured temperature and verify the conjecture that the TRP occurs mainly because the external temperature of the arch dam is higher than its sealing temperature.

Advances on the Failure Analysis of the Dam—Foundation Interface of Concrete Dams

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Luis Altarejos-García

2015-12-01

Full Text Available Failure analysis of the dam-foundation interface in concrete dams is characterized by complexity, uncertainties on models and parameters, and a strong non-linear softening behavior. In practice, these uncertainties are dealt with a well-structured mixture of experience, best practices and prudent, conservative design approaches based on the safety factor concept. Yet, a sound, deep knowledge of some aspects of this failure mode remain unveiled, as they have been offset in practical applications by the use of this conservative approach. In this paper we show a strategy to analyse this failure mode under a reliability-based approach. The proposed methodology of analysis integrates epistemic uncertainty on spatial variability of strength parameters and data from dam monitoring. The purpose is to produce meaningful and useful information regarding the probability of occurrence of this failure mode that can be incorporated in risk-informed dam safety reviews. In addition, relationships between probability of failure and factors of safety are obtained. This research is supported by a more than a decade of intensive professional practice on real world cases and its final purpose is to bring some clarity, guidance and to contribute to the improvement of current knowledge and best practices on such an important dam safety concern.

A simplified physically-based breach model for a high concrete-faced rockfill dam: A case study

OpenAIRE

Qi-ming Zhong; Sheng-shui Chen; Zhao Deng

2018-01-01

A simplified physically-based model was developed to simulate the breaching process of the Gouhou concrete-faced rockfill dam (CFRD), which is the only breach case of a high CFRD in the world. Considering the dam height, a hydraulic method was chosen to simulate the initial scour position on the downstream slope, with the steepening of the downstream slope taken into account; a headcut erosion formula was adopted to simulate the backward erosion as well. The moment equilibrium method was util...

Dynamic tests at the Outardes 3 dam

International Nuclear Information System (INIS)

Proulx, J.; Paultre, P.; Duron, Z.; Tai Mai Phat; Im, O.

1992-01-01

At the Outardes 3 gravity dam, part of the Manicouagan-Outardes hydroelectric complex in northeastern Quebec, forced vibration tests were carried out using an eccentric mass shaker attached to the dam crest at three different locations. Accelerations were measured along the crest and in the inspection galleries, and hydrodynamic pressures were measured along the upstream dam face and at various locations in the reservoir. The tests were designed to analyze the effects of gravity dam-reservoir interactions and to generate a data base for calibrating finite element models used in studying the dynamic behavior of gravity dams. Experimental results are presented in order to demonstrate the quality of the data obtained and the effectiveness of the experimental procedures. Modes of vibration were observed which corresponded to those obtained by finite element analysis. It is shown that techniques recently developed for dynamic tests on large dams can be successfully used on gravity dams. 3 refs., 6 figs

Simulation of deformation on aged concrete dam using the date of nondestructive evaluation

International Nuclear Information System (INIS)

Kobori, O.; Yamaguchi, S.; Udagawa, Y.; Hirano, M.

2006-01-01

Stress and deformation analysis was achieved by FEM in this paper. The simulation model is concrete dam constructed more than twenty years ago and pointed out the degradation year by year such as Alkali-aggregate reaction and salt. At first to have the useful numerical data, ultrasonic traveling velocity was measured in the field. Crack length and wide are inspected by observation. And sampling cores were extracted from several spots. Elastic constants (Young's Modulus and Poisson's ratio) and density of material in dam are decided from the experimental results. Deformation and Stress distribution to horizontal and vertical cracks, crack length were calculated by FEM with some assumption, considering the boundary conditions, earth pressure, existence of additional pressure. Simulation results is shown that, distortion of the dam is now small to the only earth pressure as it is, horizontal crack will cause the more displacement than crack, and high stress occurs around the cracks.

Importance of using roller compacted concrete in techno-economic investigation and design of small dams

Science.gov (United States)

Rouissat, Bouchrit; Smail, N.; Zenagui, S.

2017-12-01

In recent years, and under constraints caused by persistent drought, Algeria has launched a new mobilization strategy for surface water resources from small and medium dams. However, by making a review of the studies and achievements of twenty small dams in the west of Algeria, some deficiencies appeared. In addition to reservoir siltation assessment, operation spillways have been the major constraint on the reliability of these types of dams. The objective of this paper is to use the roller compacted concrete (RCC) for small dams' design for the benefit it offers and its ability to incorporate spillways. The development of this reflection was applied to the Khneg Azir earth dam situated in southwest of Algeria. Its uncontrolled lateral spillway has registered significant damage following the flood of October 2005, amounted, at that time, to more than 100 million Algerian dinars (1 million US Dollars). The present research encompasses a technical and economical comparative analysis concerning multiple criteria dam design types coupled with the conjugation of the spillways. Thus, on the basis of financial estimates calculated for all design types, the variant RCC remains competitive with that of the earth dam's spillway isolated (Less than 40% of the cost). To assess the mechanical behavior of the foundations for both types of dams, (earth and RCC dams), numerical modeling has been undertaken, according to the comparative analysis of deformations in the foundations. Analysis of deformations showed that the average foundation deformations was between (0.052-0.85) m for earth dam and (0.023-0.373) m for RCC dam. These economical and technical considerations open up important prospects for the use of RCC in the design of small dams.

Patterns of gravity induced aggregate migration during casting of fluid concretes

DEFF Research Database (Denmark)

Spangenberg, Jon; Roussel, N.; Hattel, Jesper Henri

2012-01-01

In this paper, aggregate migration patterns during fluid concrete castings are studied through experiments, dimensionless approach and numerical modeling. The experimental results obtained on two beams show that gravity induced migration is primarily affecting the coarsest aggregates resulting in...

Incremental Dynamic Analysis of Koyna Dam under Repeated Ground Motions

Science.gov (United States)

Zainab Nik Azizan, Nik; Majid, Taksiah A.; Nazri, Fadzli Mohamed; Maity, Damodar; Abdullah, Junaidah

2018-03-01

This paper discovers the incremental dynamic analysis (IDA) of concrete gravity dam under single and repeated earthquake loadings to identify the limit state of the dam. Seven ground motions with horizontal and vertical direction as seismic input considered in the nonlinear dynamic analysis based on the real repeated earthquake in the worldwide. All the ground motions convert to respond spectrum and scaled according to the developed elastic respond spectrum in order to match the characteristic of the ground motion to the soil type. The scaled was depends on the fundamental period, T1 of the dam. The Koyna dam has been selected as a case study for the purpose of the analysis by assuming that no sliding and rigid foundation, has been estimated. IDA curves for Koyna dam developed for single and repeated ground motions and the performance level of the dam identifies. The IDA curve of repeated ground motion shown stiffer rather than single ground motion. The ultimate state displacement for a single event is 45.59mm and decreased to 39.33mm under repeated events which are decreased about 14%. This showed that the performance level of the dam based on seismic loadings depend on ground motion pattern.

Changes in engineering-geological conditions in the foundation of the Bratsk hydroelectric powerplant dam during 15 years of operation

Energy Technology Data Exchange (ETDEWEB)

Sukhanov, G K; Savinskaya, M K; Tizdel, R R; Sotnikova, N P

1978-04-01

Field observations of the rock foundation beneath the Bratsk Hydropower Dam have been conducted continuously and carefully, beginning during the period of construction. The dam is a concrete gravity dam with expanded seams, 125 m in height and 924 m in length. The head is 106 m. The dam was constructed in 42 column sections which were subsequently cemented together. The anchor of the dam is up to 15 m deep. Two rows of drainage wells 30 m deep and 3 m apart were drilled into the foundation beneath the dam. The observations indicate that the status of the foundation and the stability of the channel and left bank earth dam are quite satisfactory. The changes in engineering and geological conditions that are unavoidable upon construction of a large dam have apparently been completed, and the new conditions in the foundation of the dam have stabilized. The drainage devices are operating normally. However, observations should be continued at full volume.

Dynamic Response of Dam-Reservoir Systems: Review and a Semi-Analytical Proposal

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Paulo Marcelo Vieira Ribeiro

Full Text Available Abstract This paper presents a review of current techniques employed for dynamic analysis of concrete gravity dams under seismic action. Traditional procedures applied in design bureaus, such as the Pseudo-Static method, often neglect structural dynamic properties, as well as ground amplification effects. A practical alternative arises with the Pseudo-Dynamic method, which considers a simplified spectrum response in the fundamental mode. The authors propose a self-contained development and detailed examples of this latter method, including a comparison with finite element models using transient response of fluid-structure systems. It is verified that application of the traditional procedure should be done carefully and limited to extremely rigid dams. On the other hand, the proposed development is straightforward and in agreement with finite element results for general cases where dam flexibility plays an important role.

Management of dams for the next Millennium: proceedings of the 1999 Canadian Dam Association

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-07-01

The meeting featured seven sessions with 18 papers abstracted/indexed therein as follows: keynote address: tailings dams safety - implications for the dam safety community; 1 - design and performance: performance monitoring of dams: are we doing what we should be doing?; tailings dams from the perspective of conventional dam engineering; and design overview of Syncrude's Mildred Lake east toe berm; 2 - design and modelling: use of a 2D model for a dam break study on the ALCAN hydroelectric complex in Quebec; and spillway design implications resulting from changes in rainfall extremes; 3 - risk and dam safety I: closing the gaps in the dam safety guidelines; the reality of life safety consequence classification; and surveillance practices for the next millenium; 4 - risk and dam safety II: quantitative risk-assessment using the capacity-demand analysis; and new guidelines for dam safety classification; 5 - millenium issues: expectations of immortality, dam safety management into the next millenium; 6 - rehabilitation techniques: the unconventional application of conventional materials; nondestructive testing technology to characterize concrete dam/bedrock interface; method and instrument for detecting crack in concrete; and grouting of the cracks in the Arch 5-6 - Daniel Johnson Dam; and 7 - case studies: rehabilitation of an 80 year old Ambursen type dam; and debris booms for the protection of spillways.

The underwater installation of a drained geomembrane system on Lost Creek Dam

International Nuclear Information System (INIS)

Onken, S.; Harlan, R.C.; Wilkes, J.; Vaschetti, G.

1998-01-01

Lost Creek Dam was constructed in California around 1923. It is a 122 foot high concrete arch dam with a crest elevation of 3,287 feet and a crest length of 490 feet. Over the years, the dam and the condition of the concrete face have deteriorated. The concrete is porous and seeps water along the entire downstream face. In winter, the seeping water freezes, penetrates the concrete and causes expansion and spalling of the concrete surface. In some places, the concrete has very low strength to a depth of a foot or more, rendering the dam only marginally safe. Seven mitigative measures were identified as possible solutions to the problem. It was determined that the seepage of the water through the concrete dam could be stopped with the installation of a geomembrane to the upstream face. This paper describes the unique underwater installation of a drained geomembrane system on the concrete face of the dam. This was the first ever installation of a drained geomembrane system on an entire dam using divers. Monitoring will determine the success of the project, and whether the seepage of the water through the porous concrete had been reduced sufficiently to stop the deterioration of the concrete on the downstream face. 2 refs., 12 figs

An engineering geological appraisal of the Chamshir dam foundation using DMR classification and kinematic analysis, southwest of Iran

Directory of Open Access Journals (Sweden)

Torabi Kaveh Mehdi

2011-12-01

Full Text Available This paper describes the results of engineering geological  investigations and rock mechanics studies carried out at the proposed Chamshir dam site. It is proposed that a 155 m high solid concrete gravity-arc dam be built across the Zuhreh River to the southeast of the city of Gachsaran in south-western Iran. The dam and its associated structures are mainly located on the Mishan formation. Analysis consisted of rock mass classification and a kinematic
analysis of the dam foundation's rock masses. The studies were carried out in the field and the laboratory. The field studies included geological mapping, intensive discontinuity surveying, core drilling and sampling for laboratory testing. Rock mass classifications were made in line with RMR and DMR classification for the dam foundation. Dam foundation analysis regarding stability using DMR classification and kinematic analysis indicated that the left abutment's rock foundation (area 2 was unstable for planar, wedge and toppling failure modes.

The development and use of geomechanical models for use in the raising of the Thirsk arch dam, Summerland, BC

Energy Technology Data Exchange (ETDEWEB)

Schlotfeldt, P.; Palleske, C. [Golder Associates Ltd., Squamish, BC (Canada)

2009-07-01

The Thirsk Dam and spillway on the Trout River in Summerland, British Columbia were completed in 1941. The dam was recently upgraded to increase total storage capacity and to refurbish the ageing infrastructure to comply with more stringent safety requirements. The upgrades included raising the arch dam by 5.3 metres; constructing new anchored thrust blocks on each abutment; constructing a new 190 m long concrete gravity spillway dam with a maximum height of 14 m; constructing a new earth-fill saddle dam; constructing 7 anchored foundation plinths; and adding a new concrete skin to the downstream face to increase the thickness of the arch. This upgrade increased the storage capacity by 96 per cent and provided adequate support to meet current dam safety regulations. In order to complete the upgrades, it was necessary to develop an understanding of the geotechnical parameters for the site for use in the analysis and design of anchorage, reinforcement and foundations of the raised structures. This paper described how the geological model was first developed and how it was applied during the design of the arch and spillway dams. The geological model was modified for local anomalies and unforeseen rock mass conditions. The paper also described the methods used to characterize the foundation rock mass and estimate rock mass strength and deformability properties. The models provided a three-dimensional understanding of potential failure mechanisms. 9 refs., 1 tab., 6 figs.

Stability of earth dam with a vertical core

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Orekhov Vyacheslav Valentinovich

2016-01-01

Full Text Available Earth dam with impervious element in the form of asphaltic concrete core is currently the most promising type of earth dams (due to simple construction technology and universal service properties of asphaltic concrete and is widely used in the world. However, experience in the construction and operation of high dams (above 160 m is not available, and their work is scarcely explored. In this regard, the paper discusses the results of computational prediction of the stress-strain state and stability of a high earth dam (256 m high with the core. The authors considered asphaltic concrete containing 7 % of bitumen as the material of the core. Gravel was considered as the material of resistant prisms. Design characteristics of the rolled asphaltic concrete and gravel were obtained from the processing of the results of triaxial tests. The calculations were performed using finite element method in elastoplastic formulation and basing on the phased construction of the dam and reservoir filling. The research shows, that the work of embankment dam with vertical core during filling of the reservoir is characterized by horizontal displacement of the lower resistant prism in the tailrace and the formation of a hard wedge prism descending along the core in the upper resistant prism. The key issue of the safety assessment is to determine the safety factor of the overall stability of the dam, for calculation of which the destruction of the earth dam is necessary, which can be done by reducing the strength properties of the dam materials. As a results of the calculations, the destruction of the dam occurs with a decrease in the strength characteristics of the materials of the dam by 2.5 times. The dam stability depends on the stability of the lower resistant prism. The destruction of its slope occurs on the classical circular-cylindrical surface. The presence of a potential collapse surface in the upper resistant prism (on the edges of the descending wedge does

Study on MPGA-BP of Gravity Dam Deformation Prediction

Directory of Open Access Journals (Sweden)

Xiaoyu Wang

2017-01-01

Full Text Available Displacement is an important physical quantity of hydraulic structures deformation monitoring, and its prediction accuracy is the premise of ensuring the safe operation. Most existing metaheuristic methods have three problems: (1 falling into local minimum easily, (2 slowing convergence, and (3 the initial value’s sensitivity. Resolving these three problems and improving the prediction accuracy necessitate the application of genetic algorithm-based backpropagation (GA-BP neural network and multiple population genetic algorithm (MPGA. A hybrid multiple population genetic algorithm backpropagation (MPGA-BP neural network algorithm is put forward to optimize deformation prediction from periodic monitoring surveys of hydraulic structures. This hybrid model is employed for analyzing the displacement of a gravity dam in China. The results show the proposed model is superior to an ordinary BP neural network and statistical regression model in the aspect of global search, convergence speed, and prediction accuracy.

Mathematical Modeling in Systems for Operational Evaluation of the Stress-Strain State of the Arch-Gravity Dam at the Sayano-Shushenskaya Hydroelectric Power Plant

Energy Technology Data Exchange (ETDEWEB)

Bellendir, E. N.; Gordon, L. A., E-mail: lev-gordon@mail.ru; Khrapkov, A. A.; Skvortsova, A. E., E-mail: SkvortsovaAE@vniig.ru [B. E. Vedeneev All-Russia Research Institute of Hydraulic Engineering (VNIIG) (Russian Federation)

2017-01-15

Current studies of the stress-strain state of the dam at the Sayano-Shushenskaya Hydroelectric Power Plant at VNIIG based on mathematical modeling including full scale and experimental data are described. Applications and programs intended for automatic operational evaluation of the stress-strain state of the dam for optimizing control of the upper race level in the course of the annual filling-drawdown cycle and during seismic events are examined. Improvements in systems for monitoring the stress-strain state of concrete dams are proposed.

Proceedings of the Canadian Dam Association's 2006 annual conference: dams: past, present and future

International Nuclear Information System (INIS)

2006-01-01

This conference addressed particular technical challenges regarding the operation of dams with particular focus on best practices for improving dam management and safety. It featured 4 workshops and a technical program led by experts on dams and tailings facilities that addressed topics such as dam construction, design and rehabilitation; dam management in a hydrological uncertainty context; monitoring, instrumentation and maintenance; dam behaviour; dam safety, dam failure and practical approaches to emergency preparedness planning for dam owners; historical aspects and environmental issues and conflicting water use. Recent developments in dam construction were reviewed along with discharge and debris management, tailings dam issues, asset management, seismic issues, public safety, seepage monitoring, flow control, dam rehabilitation, concrete testing, hydrotechnical issues, risk assessment methodology, and dam safety guidelines for extreme flood analyses and their applications. All 80 presentations from this conference have been catalogued separately for inclusion in this database. refs., tabs., figs

Seismic performance assessment of latyan concrete buttress dam ...

African Journals Online (AJOL)

In order to design earthquake resistant dams and evaluate the safety of existing dams that will be exposed to future earthquakes, it is essential to have accurate and reliable analysis procedures to predict the stresses and deformations in dams subjected to earthquake ground motion. For a damwater- foundation system, the ...

Study of the performance of four repairing material systems for hydraulic structures of concrete dams

Directory of Open Access Journals (Sweden)

Kormann A. C. M.

2003-01-01

Full Text Available Four types of repairing materials are studied as function of either a conventional concrete or a reference-concrete (RefC, these are: polymer-modified cement mortar (PMor, steel fiber concrete (SFco, epoxy mortar (EMor and silica fume mortar (SFmo, to be applied in hydraulic structures surfaces subjected to a high velocity water flow. Besides the mechanical requests and wearing resistance of hydraulic concrete dam structures, especially the spillway surfaces, the high solar radiation, the environmental temperature and wet and dry cycles, contribute significantly to the reduction of their lifespan. RefC and the SFco were developed based on a usual concrete mixture used in slabs of spillways. The average RefC mixture used was 1: 1.61: 2.99: 0.376, with Pozzolan-modified Portland cement consumption of 425 kg/m³. EMor and PMor mixtures followed the information given by the manufacturers and lab experience. Tests on concrete samples were carried out in laboratory simulating normally found environmental situations in order to control the mechanical resistance and the aging imposed conditions, such as solar radiation and humidity. Also, physicochemical characterizing tests were made for all used materials. From the analyzed results, two of them presented a higher performance: the EMor and SFmo. SFco presented good adherence to the RefC and good mechanical performance. However, it also presented apparent metal corrosion in humidity tests, being indicated for use, with caution, as an intermediate layer in underwater repairs. In a general classification, considering all tests, including their field applications, the better performance material systems were EMor- SFmo> SFco> PMor.

Numerical Simulation on Slabs Dislocation of Zipingpu Concrete Faced Rockfill Dam during the Wenchuan Earthquake Based on a Generalized Plasticity Model

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Bin Xu

2014-01-01

Full Text Available After the Wenchuan earthquake in 2008, the Zipingpu concrete faced rockfill dam (CFRD was found slabs dislocation between different stages slabs and the maximum value reached 17 cm. This is a new damage pattern and did not occur in previous seismic damage investigation. Slabs dislocation will affect the seepage control system of the CFRD gravely and even the safety of the dam. Therefore, investigations of the slabs dislocation’s mechanism and development might be meaningful to the engineering design of the CFRD. In this study, based on the previous studies by the authors, the slabs dislocation phenomenon of the Zipingpu CFRD was investigated. The procedure and constitutive model of materials used for finite element analysis are consistent. The water elevation, the angel, and the strength of the construction joints were among major variables of investigation. The results indicated that the finite element procedure based on a modified generalized plasticity model and a perfect elastoplastic interface model can be used to evaluate the dislocation damage of face slabs of concrete faced rockfill dam during earthquake. The effects of the water elevation, the angel, and the strength of the construction joints are issues of major design concern under seismic loading.

Auscultation of concrete hydraulic dams by sonic tomography; Auscultation des structures hydrauliques en beton par tomographie sonique

Energy Technology Data Exchange (ETDEWEB)

Kharrat, Y.; Rhazi, J.; Ballivy, G. [Sherbrooke Univ., PQ (Canada). Dept. de Genie Civil; Cote, P. [Centre de Nantes, Bouguenais (France)

1995-12-31

Sonic tomography, a new nondestructive testing method, was described to document the aging and internal degradation of concrete structures. The method is based on the transmission of sonic waves through concrete structures. New tomographic methodology similar to that used in medical or geophysical imaging was applied to existing sonic auscultation techniques used in civil engineering. In the process the speed of propagation of sonic waves in structures is measured with arrays of detectors. Fissures or zones of degradation can be spatially localized and an internal image of the structure can be constructed. Case studies of two hydraulic dams, one from France, the other in Quebec were presented as illustrations. . The theory and experimental procedures involved were described. 16 refs., 1 tab., 12 figs.

Intergarted geophysical investigations by GPR and ERT on the largest rock fill dam in Europe: Monte Cotugno dam (Southern Italy)

Science.gov (United States)

Loperte, A.; Bavusi, M.; Cerverizzo, G.; Lapenna, V.; Soldovieri, F.

2012-04-01

This work is concerned with the first results of a survey based on the integration of geophysical techniques for the inspection of the Monte Cotugno dam, the largest rock fill dam in Europe. The Monte Cotugno dam, managed by National Irrigation Development and Agrarian Transformation in Puglia, Basilicata and Irpinia is located on the Sinni river (Basilicata District, South Italy) and represents the nodal point in the whole hydraulic system on the Ionic side of Italy; in fact, the dam allows harnessing of the Sinni river water for agricultural, industrial, drinking and domestic purposes. The dam is of the zoned type and consists of a central core in sandy silt and of gravelly-sandy shoulders; its water tightness is ensured by a bituminous conglomerate facing on the upstream side, welded at the bottom to the foundation sealing system. The latter is about 1,900m long and consist of a massive concrete cut-off wall based on the marly-clay formation, 300m long on the right and 600 m long on the left side. On the valley bottom it is made up of a reinforced concrete cut-off wall that is inserted in the marly-clay formation and is surmounted by an inspection and percolation water collection tunnel. The watertight face consists of a bottom levelling layer 7-8 cm thick in semi open-graded bituminous concrete, a 5 cm separation layer in dense-graded bituminous concrete, a drainage layer in very open-graded concrete varying in thickness from 10 to 16 cm from the top of the dam down, two 4-cm top layers in dense-graded bituminous concrete with stepped joints, a finishing sealing coat containing 1.5 kg/cm2 of asphalt. The shallowest part of this layering is started to show incipient small detachments due to thermal solicitations; these detachments represent a possible way for water infiltration in the dam. In this framework, it was decided to perform the identification, characterization and evaluation of the potential loss of water through small cracks in the bituminous concrete

Study on Real-Time Simulation Analysis and Inverse Analysis System for Temperature and Stress of Concrete Dam

Directory of Open Access Journals (Sweden)

Lei Zhang

2015-01-01

Full Text Available In the concrete dam construction, it is very necessary to strengthen the real-time monitoring and scientific management of concrete temperature control. This paper constructs the analysis and inverse analysis system of temperature stress simulation, which is based on various useful data collected in real time in the process of concrete construction. The system can produce automatically data file of temperature and stress calculation and then achieve the remote real-time simulation calculation of temperature stress by using high performance computing techniques, so the inverse analysis can be carried out based on a basis of monitoring data in the database; it fulfills the automatic feedback calculation according to the error requirement and generates the corresponding curve and chart after the automatic processing and analysis of corresponding results. The system realizes the automation and intellectualization of complex data analysis and preparation work in simulation process and complex data adjustment in the inverse analysis process, which can facilitate the real-time tracking simulation and feedback analysis of concrete temperature stress in construction process and enable you to discover problems timely, take measures timely, and adjust construction scheme and can well instruct you how to ensure project quality.

Coordinate reduction for the seismic analysis of dam-foundation-reservoir systems with non-proportional damping

International Nuclear Information System (INIS)

Mehai, L.; Paultre, P.; Leger, P.

1992-01-01

In the design of dams to withstand seismic events, recent studies have shown that the dam-foundation and dam-reservoir interactions have a significant influence on the dynamic response of the dam. The hypothesis of proportional damping is not realistic for such structures, in which the mechanisms of energy dissipation present notable differences between their various components. A comparative study is presented of different methods of resolution of linear systems with non-proportional damping, using recent techniques of coordinate reduction. Parametric studies were conducted on a 2-dimensional finite element model of a concrete gravity dam-foundation system. The comparison focuses essentially on the numerical efficiency and precision in the calculation of dynamic parameters (displacements, accelerations, and internal stresses) and in the distribution of damping energy among the components of the system. The evaluation of the energy dissipated in the absorbing boundaries has indicated that the algorithms retained for reducing the coordinates in real and complex space conveniently model the conditions at the limits of the structure. The high degree of numerical stability and the efficiency of the interative procedure of Ibrahimbegovic and Wilson (1989), applied to systems with a large number of degrees of freedom, has been confirmed. 10 refs., 8 figs

External sulfate attack in dam concretes with thaumasite formation

Directory of Open Access Journals (Sweden)

Chinchón-Payá, S.

2015-03-01

Full Text Available Concrete core samples extracted from different areas of the Mequinenza Dam (Spain have been studied and expansive reactions affecting the structure were not found. However, expansive reactions in the concrete of certain parts located near the abutments of two galleries have been observed as a consequence of an external sulfate attack due to the sulfur compounds contained in the lignites that are present on the surrounding terrain. Secondary gypsum, ettringite, and thaumasite, as well as several sulfate efflorescence have been detected. The thaumasite formed in the degraded concrete is related to a Thaumasite Sulfate Attack (TSA. Scanning Electron Microscopy (SEM and Rietveld analyses of the TSA samples would show that thaumasite could have been formed thanks to ettringite acting as nuclei or by a direct precipitation from solutions within the pores of the cement matrix.Se han estudiado testigos de hormigón extraídos de diferentes zonas de la presa de Mequinenza (España descartando la existencia de una reacción expansiva que pudiera afectar a la estructura. Sin embargo, se han observado reacciones expansivas en el hormigón de ciertas zonas próximas a los estribos de dos galerías, como consecuencia de un ataque sulfático externo debido a los compuestos de azufre contenidos en los lignitos que están presentes en los terrenos circundantes. Se ha identificado un conjunto de productos relacionados con el ataque sulfático: yeso secundario, ettringita y thaumasita, además de sales sulfatadas solubles. Las zonas más degradadas del hormigón coinciden con una cristalización abundante de thaumasita (Thaumasite Sulfate Attack–TSA-. El estudio de las muestras de TSA, mediante microscopía electrónica de barrido (SEM y el método de Rietveld, indicaría que la thaumasita podría haberse formado a partir de la ettringita como medio de nucleación o por precipitación directa a partir de sus componentes en disolución dentro de los poros de la

User's Guide: Arch Dam Stress Analysis System (ADSAS)

National Research Council Canada - National Science Library

1997-01-01

.... ADSAS assumes linear elastic behavior for the entire dam, i.e. the dam is assumed to support the computed tensile stresses within the concrete mass and across the monolith joints without cracking or opening the joints...

CO2 uptake potential due to concrete carbonation: A case study

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Edna Possan

2017-06-01

Full Text Available The cement manufacturing process accounts for about 5% CO2 (carbon dioxide released into the atmosphere. However, during its life cycle, concrete may capture CO2 through carbonation, in order to, partially, offset the impact of its production. Thus, this paper aims at studying the CO2 uptake potential of the Itaipu Dam due to concrete carbonation of such material. So, 155 cores were extracted from the concrete dam in different points to measure carbonation depth. In order to evaluate its influence on carbonation, the measurement of internal moisture distribution in concrete was also carried out. The results have shown that carbonation takes part of the whole dam area, indicating CO2 uptake potential. Up to the present moment, 13,384 tons of CO2 have been absorbed by concrete carbonation of the Itaipu Dam.

GIS inundation mapping and dam breach analysis of Woolwich Dam using HEC-geoRAS

Energy Technology Data Exchange (ETDEWEB)

Mocan, N. [Crozier and Associates Inc., Collingwood, ON (Canada); Joy, D.M. [Guelph Univ., ON (Canada); Rungis, G. [Grand River Conservation Authority, Cambridge, ON (Canada)

2006-07-01

A study was conducted to determine the extent of flood inundation given a hypothetical dam breach scenario of the Woolwich Dam located in the Grand River Watershed, 2.5 km north of the Town of Elmira, Ontario. The dam is operated by the Grand River Conservation Authority and was constructed to provide low-flow augmentation to Canagagigue Creek. Advances in the computational capabilities of numerical models along with the availability of fine resolution geospatial data has lead to significant advances in the evaluation of catastrophic consequences due to the ensuing flood waters when dams fail. The hydraulic models HEC-RAS and HEC-GeoRAS were used in this study along with GIS to produce high resolution spatial and temporal flood inundation mapping. Given the proximity to the Town of Elmira, the dam is classified as having a high hazard potential. The large size and high hazard potential of the dam suggests that the Inflow Design Flood (IDF) is the Probable Maximum Flood (PMF) event. The outlet structure of the spillway consists of 4 ogee-type concrete spillways equipped with radial gates. A low-level concrete pipe located within the spillway structure provides spillage for maintenance purposes. The full flow capacity of the spillway structure is 297 cubic metres per second at the full supply level of 364.8 metres. In addition to GIS flood inundation maps, this paper included the results of flood hydrographs, water surface profiles and peak flow data. It was concluded that techniques used in this analysis should be considered for use in the development of emergency management planning and dam safety assessments across Canada. 6 refs., 3 tabs., 4 figs.

Safety management of the Karapiro dam, New Zealand

International Nuclear Information System (INIS)

Everitt, S.C.

1995-01-01

The dam safety program for 36 hydraulic structures in New Zealand were presented, with special emphasis on the application of this program to the Karapiro dam. The management of the hazard presented by the dam was detailed, and the proposed solutions for its remediation were presented. Dynamic analysis was employed using an elastic 3-D finite element model, using actual earthquake time history records as an input, scaled to the required Maximum Credibility Earthquake (MCE). The results confirmed that the arch section of the Karapiro dam was satisfactory, as was the spillway block, provided that drainage was preserved, however, the left abutment and thrust block were considered unstable. Four options were proposed for strengthening the abutment: (1) lowering the groundwater, (2) installation of stresses anchors, (3) mass concrete buttressing upstream and/or downstream, and (4) installation of reinforced concrete shear keys. However, prior to undertaking any remediation work, rock mass properties and groundwater conditions should be re-investigated. 1 ref., 7 figs

Geological And Geotechnical Investigations Of Axum Dam Site Tigray Northern Ethiopia

Directory of Open Access Journals (Sweden)

Leulalem

2015-08-01

Full Text Available Geological and geotechnical study was conducted in concrete gravity dam which is planned to be constructed in the Maychew River 40 km south of Axum town for the purpose of water supply for the town. The objectives of this research were to map geology of the area to characterize geological defects within and around dam site to evaluate the water tightness of the dam site and to determine the bearing capacity of the dam foundation. The research involved review of different literatures lithological and structural mapping characterizing rock masses by using different rock mass classification methods interpretation of subsurface data geophysical core drilled data test pit data etc.. Results of the study indicate that the area is underlain by Quaternary sediments metasedimentary and metavolcanic rocks. The Quaternary sediments are characterized by low permeability low plasticity and are poorly graded nature. Metasedimentary rocks are found covering the right abutment of the dam whereas at reservoir area it is found intercalating with metavolcanic rocks. These rocks are moderately jointed and sheared with faulting and folding noticed due to these they have a relatively high permeability. Metavolcanic rocks which are found covering the left abutment are strong less permeable and fractured. Most of discontinuities such as fractures bedding and foliation in the study area are oriented E-W NNW-SSE and NNE-SSW. The VES tomography and drilled core result revealed that the potential problems seepageleakage could occur due to presence of faults joints karstified black limestone lithological variations groundwater depth and topography at right abutment. Differential settlements may also occur because empirically estimated moduli of deformation Ed of rock masses indicate that for right abutment much less than left abutment and different geological defects across the dam axis. To minimize these problems contact grouting and consolidation grouting are recommended

Dams life; La vie des barrages

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-12-31

This paper summarizes the conclusions of the annual inspections of French dams in operation (fissures, water oozing, concrete swelling etc..). Only the observations which require a special attention are reported. (J.S.)

Radiation shielding concrete

International Nuclear Information System (INIS)

Kunishima, Shigeru.

1990-01-01

The radiation shielding concretes comprise water, cement, fine aggregates consisting of serpentines and blown mist slags, coarse aggregates consisting of serpentines and kneading materials. Since serpentines containing a relatively great amount of water of crystallization in rocks as coarse aggregates and fine aggregates, the hydrogen content in the radiation shielding concretes is increased and the neutron shielding effect is improved. In addition, since serpentines are added as the fine aggregates and blown mists slags of a great specific gravity are used, the specific gravity of the shielding concretes is increased to improve the γ-ray shielding effect. Further, by the use of the kneading material having a water reducing effect and fluidizing effect, and by the bearing effect of the spherical blown mist slags used as the fine aggregates, concrete fluidity can be increased. Accordingly, workability of the radiation shielding concretes can be improved. (T.M.)

Proceedings of the Canadian Dam Association's 2005 annual conference : 100 years of dam experience : balancing tradition and innovation. CD-ROM ed.

International Nuclear Information System (INIS)

2004-09-01

This conference provided a forum to promote discussion on improving the management and safety of dams. It featured 8 technical sessions as well as workshops to discuss dam safety guidelines and guidelines for extreme flood analyses and their applications. It also featured workshops on instrumentation and performance monitoring of dams; tailing dam closures and reclamation; and, practical approaches to emergency preparedness for dam owners. The discussions provided details on large hydropower development projects, their innovations in environmental impact assessment, mitigation, and monitoring. The conference included a technical component led by experts on dams and tailings facilities. Recent developments in dam construction were reviewed along with discharge and debris management, tailings dam issues, asset management, seismic issues, public safety, seepage monitoring, flow control, dam rehabilitation, concrete testing, hydrotechnical issues, risk assessment methodology, and safety guidelines. All 24 presentations at this conference have been catalogued separately for inclusion in this database

Field evidences and theoretical analysis of the gravity-driven wetting front instability of water runoffs on concrete structures

NARCIS (Netherlands)

Kuntz, M.; Van Mier, J.G.M.

1997-01-01

A series of field observations of the evolution of water runoffs over several vertical concrete walls directly exposed to rain falls is reported in this note. In all the cases, the main water flow originated from the top horizontal surface of the walls. The observations show that the gravity-driven

History of dams at the Department of Energy's Savannah River Site, Aiken, South Carolina

International Nuclear Information System (INIS)

Jones, M.P.; Wilson, C.B.

1995-01-01

Since the production of nuclear material at SRS for weapons required large quantities of cooling water, a series of canals, dikes, and dams were constructed to provide conveyance systems and reservoirs. This paper presents a brief overview of the history of the construction of the dams and dikes. Attention is given to the use of asphaltic concrete for 30 years (and its maintenance and repair) to line the banks of dikes and the upstream slopes of dams to prevent erosion and possible failure. The ability of asphaltic concrete in preventing dam/dike failure was proven. Benefits and drawbacks to the use of this material are discussed based on the extensive experience at SRS

The Dams and Monitoring Systems and Case Study: Ataturk and Karakaya Dams

Science.gov (United States)

Kalkan, Y.; Bilgi, S.; Gülnerman, A. G.

2017-12-01

Dams are among the most important engineering structures used for flood controls, agricultural purposes as well as drinking and hydroelectric power. Especially after the Second World War, developments on the construction technology, increase the construction of larger capacity dams. There are more than 150.000 dams in the world and almost 1000 dams in Turkey, according to international criteria. Although dams provide benefits to humans, they possess structural risks too. To determine the performance of dams on structural safety, assessing the spatial data is very important. These are movement, water pressure, seepage, reservoir and tail-water elevations, local seismic activities, total pressure, stress and strain, internal concrete temperature, ambient temperature and precipitation. These physical data are measured and monitored by the instruments and equipment. Dams and their surroundings have to be monitored by using essential methods at periodic time intervals in order to determine the possible changes that may occur over the time. Monitoring programs typically consist of; surveillance or visual observation. These programs on dams provide information for evaluating the dam's performance related to the design intent and expected changes that could affect the safety performance of the dam. Additionally, these programs are used for investigating and evaluating the abnormal or degrading performance where any remedial action is necessary. Geodetic and non-geodetic methods are used for monitoring. Monitoring the performance of the dams is critical for producing and maintaining the safe dams. This study provides some general information on dams and their different monitoring systems by taking into account two different dams and their structural specifications with the required information. The case study in this paper depends on a comparison of the monitoring surveys on Atatürk Dam and Karakaya Dam, which are constructed on Firat River with two different structural

Simulation analysis of temperature control on RCC arch dam of hydropower station

Science.gov (United States)

XIA, Shi-fa

2017-12-01

The temperature analysis of roller compacted concrete (RCC) dam plays an important role in their design and construction. Based on three-dimensional finite element method, in the computation of temperature field, many cases are included, such as air temperature, elevated temperature by cement hydration heat, concrete temperature during placing, the influence of water in the reservoir, and boundary temperature. According to the corresponding parameters of RCC arch dam, the analysis of temperature field and stress field during the period of construction and operation is performed. The study demonstrates that detailed thermal stress analysis should be performed for RCC dams to provide a basis to minimize and control the occurrence of thermal cracking.

Seismic failure modes and seismic safety of Hardfill dam

Directory of Open Access Journals (Sweden)

Kun Xiong

2013-04-01

Full Text Available Based on microscopic damage theory and the finite element method, and using the Weibull distribution to characterize the random distribution of the mechanical properties of materials, the seismic response of a typical Hardfill dam was analyzed through numerical simulation during the earthquakes with intensities of 8 degrees and even greater. The seismic failure modes and failure mechanism of the dam were explored as well. Numerical results show that the Hardfill dam remains at a low stress level and undamaged or slightly damaged during an earthquake with an intensity of 8 degrees. During overload earthquakes, tensile cracks occur at the dam surfaces and extend to inside the dam body, and the upstream dam body experiences more serious damage than the downstream dam body. Therefore, under the seismic conditions, the failure pattern of the Hardfill dam is the tensile fracture of the upstream regions and the dam toe. Compared with traditional gravity dams, Hardfill dams have better seismic performance and greater seismic safety.

New Zealand's Clyde power station

Energy Technology Data Exchange (ETDEWEB)

Hatton, J W; Black, J C; Foster, P F

1987-12-01

A 100 m-high mass concrete gravity dam, for the generation of 432 MW of power, is under construction at Clyde on the Clutha River in the South Island of New Zealand. A feature of the dam is the provision of a slip joint to allow up to 2 m of movement on the plane of a fault passing through the dam foundation. Details of the dam foundations, seismic design, river channel fault and slip joint, mass concrete, spillway and sluice, powerhouse, and landslide hazard at the site are given. 3 refs.

comparative evaluation of the flexural strength of concrete and colcrete

African Journals Online (AJOL)

concrete and polymer concrete, from continuous researches being carried out on. 13 ... COMPARATIVE EVALUATION OF THE FLEXURAL STRENGTH OF CONCRETE AND COLCRETE advantage of being able to use larger sizes of ... and low permeability, colcrete has found applications in tunnel linings, dams, bridges.

Modelling approach for gravity dam break analysis

Directory of Open Access Journals (Sweden)

Boussekine Mourad

2016-09-01

Full Text Available The construction of dams in rivers can provide considerable benefits such as the supply of drinking and irrigation water; however the consequences which would result in the event of their failure could be catastrophic. They vary dramatically depending on the extent of the inundation area, the size of the population at risk.

Seepage problem in Papan dam and the treatment

Energy Technology Data Exchange (ETDEWEB)

Sharghi, A. [JTMA Co., Tehran (Iran, Islamic Republic of); Palassi, M. [Tehran Univ. (Iran, Islamic Republic of). Dept. of Civil Engineering

2003-07-01

The Papan dam in the Krygyz Republic is 97 metres high. It is located in the Osh Oblast, within a narrow and steep sided gorge on the Ak-Bura River, approximately 20 kilometres south of the City of Osh. The impoundment of the dam revealed large inflows of water to the downstream dam through the upper half of the dam and through the joints in the right abutment. A number of options were considered before a treatment method was selected. The causes of the leakage were poor grouting, and joints and fissures in the abutment. The remedial process involved the use of a plastic concrete cutoff wall extended from the crest of the dam to a depth of approximately 70 metres, in addition to the use of a grouting curtain in the right abutment. 2 figs.

Computational Aspects of Dam Risk Analysis: Findings and Challenges

Directory of Open Access Journals (Sweden)

Ignacio Escuder-Bueno

2016-09-01

Full Text Available In recent years, risk analysis techniques have proved to be a useful tool to inform dam safety management. This paper summarizes the outcomes of three themes related to dam risk analysis discussed in the Benchmark Workshops organized by the International Commission on Large Dams Technical Committee on “Computational Aspects of Analysis and Design of Dams.” In the 2011 Benchmark Workshop, estimation of the probability of failure of a gravity dam for the sliding failure mode was discussed. Next, in 2013, the discussion focused on the computational challenges of the estimation of consequences in dam risk analysis. Finally, in 2015, the probability of sliding and overtopping in an embankment was analyzed. These Benchmark Workshops have allowed a complete review of numerical aspects for dam risk analysis, showing that risk analysis methods are a very useful tool to analyze the risk of dam systems, including downstream consequence assessments and the uncertainty of structural models.

ADVANCEMENTS IN CONCRETE TECHNOLOGY

OpenAIRE

Shri Purvansh B. Shah; Shri Prakash D. Gohil; Shri Hiren J. Chavda; Shri Tejas D. Khediya

2015-01-01

Developing and maintaining world’s infrastructure to meet the future needs of industrialized and developing countries is necessary to economically grow and improve the quality of life. The quality and performance of concrete plays a key role for most of infrastructure including commercial, industrial, residential and military structures, dams, power plants. Concrete is the single largest manufactured material in the world and accounts for more than 6 billion metric tons of materials annual...

Deformation Monitoring and Bathymetry Analyses in Rock-Fill Dams, a Case Study at Ataturk Dam

Science.gov (United States)

Kalkan, Y.; Bilgi, S.

2014-12-01

Turkey has 595 dams constructed between 1936 and 2013 for the purposes of irrigation, flood control, hydroelectric energy and drinking water. A major portion of the dam basins in Turkey are deprived of vegetation and have slope topography on near surrounding area. However, landscaping covered with forest around the dam basin is desirable for erosion control. In fact; the dams, have basins deprived of vegetation, fill up quickly due to sediment transport. Erosion control and forestation are important factors, reducing the sediment, to protect the water basins of the dams and increase the functioning life of the dams. The functioning life of dams is as important as the investment and construction. Nevertheless, in order to provide safety of human life living around, well planned monitoring is essential for dams. Dams are very large and critical structures and they demand the use or application of precise measuring systems. Some basic physical data are very important for assessing the safety and performance of dams. These are movement, water pressure, seepage, reservoir and tail-water elevations, local seismic activities, total pressure, stress and strain, internal concrete temperature, ambient temperature and precipitation. Monitoring is an essential component of the dam after construction and during operation and must en­able the timely detection of any behavior that could deteriorate the dam, potentially result in its shutdown or failure. Considering the time and labor consumed by long-term measurements, processing and analysis of measured data, importance of the small structural motions at regular intervals could be comprehended. This study provides some information, safety and the techniques about the deformation monitoring of the dams, dam safety and related analysis. The case study is the deformation measurements of Atatürk Dam in Turkey which is the 6th largest dam of world considering the filling volume of embankment. Brief information is given about the

Dam geology and basic treatment(2). Adit substitution technique and measures against landslide involved in excavation

Energy Technology Data Exchange (ETDEWEB)

Shimizu, Kin' ichi [Kinki Geological Center, Co. Ltd., Kyoto, Japan (JP)

1988-12-25

This paper discusses the adit substitution technique which is a method for special treatment of dams and measures against landslide involved in excavation. The adit substitution technique consists of excavating an adit in the natural ground, excavating another adit which is in contact with the first adit and is at a level higher than the first adit, placing concrete from the upper adit to the lower adit to fill first adit completely with concrete, excavating a third adit, filling the second adit with concrete similarly, and proceeding with this process to construct a water barrier within the natural ground until the water barrier reaches the required height. The paper explains examples of this technique used on four dams. It also explains examples of measures against excavation-induced landslide adopted on three dams. 13 refs., 8 figs., 2 tabs.

Work for radiation shielding concrete in large-scaled radiation facilities

International Nuclear Information System (INIS)

Konomi, Shinzo; Sato, Shoni; Otake, Takao.

1980-01-01

This paper reports the radiation shielding concrete work in the construction of radiation laboratory facilities of Electrotechnical Laboratory, a Japanese Government agency for the research and development of electronic technology. The radiation shielding walls of the facilities are made of ordinary concrete, heavy weight concrete and raw iron ore. This paper particularly relates the use of ordinary concrete which constitutes the majority of such concretes. The concrete mix was determined so as to increase its specific gravity for better shielding effect, to improve mass concrete effect and to advance good workability. The tendency of the concrete to decrease its specific gravity and the temperature variations were also made on how to place concrete to secure good shielding effect and uniform quality. (author)

Non uniform nature of recorded ground accelerations at dam foundation interface

Energy Technology Data Exchange (ETDEWEB)

Ghaemian, Mohsen; Gilani, Morteza Sohrabi [Sharif University of Technology, Tehran, (Iran, Islamic Republic of); Noorzad, Ali [Power and Water University of Technology, Tehran, (Iran, Islamic Republic of)

2010-07-01

The Karun III is a double curved concrete arch dam located in Iran which was used to investigate earthquake motions and dam responses. This paper presented the study of the Karun III dam foundation interface. Using an array of 15 accelerometers, two major events that occurred on 2007.11.20 and 2007.11.21 were recorded during dam operation with a PGA at crest of 0.312 g and 0.109.g respectively. A finite element model of Karun III dam was performed. The response of the Karun III dam during the 2007 earthquake was investigated using the NSAD-DRI program. It was found that the motion of the dam foundation interface is non-uniform. There is a time shift and amplification at the abutment compared to those at the base of the dam. The results showed that the spatially varying earthquake assumption is in good agreement with the recorded displacement of the dam.

Physical Characteristics of Laboratory Tested Concrete as a Substituion of Gravel on Normal Concrete

Science.gov (United States)

Butar-butar, Ronald; Suhairiani; Wijaya, Kinanti; Sebayang, Nono

2018-03-01

Concrete technology is highly potential in the field of construction for structural and non-structural construction. The amount uses of this concrete material raise the problem of solid waste in the form of concrete remaining test results in the laboratory. This waste is usually just discarded and not economically valuable. In solving the problem, this experiment was made new materials by using recycle material in the form of recycled aggregate which aims to find out the strength characteristics of the used concrete as a gravel substitution material on the normal concrete and obtain the value of the substitution composition of gravel and used concrete that can achieve the strength of concrete according to the standard. Testing of concrete characteristic is one of the requirements before starting the concrete mixture. This test using SNI method (Indonesian National Standard) with variation of comparison (used concrete : gravel) were 15: 85%, 25: 75%, 35:65%, 50:50 %, 75: 25%. The results of physical tests obtained the mud content value of the mixture gravel and used concrete is 0.03 larger than the standard of SNI 03-4142-1996 that is equal to 1.03%. so the need watering or soaking before use. The water content test results show an increase in the water content value if the composition of the used concrete increases. While the specific gravity value for variation 15: 85% until 35: 65% fulfilled the requirements of SNI 03-1969-1990. the other variasion show the specifics gravity value included on the type of light materials.

Interpretation of self-potential data for dam seepage investigations

Energy Technology Data Exchange (ETDEWEB)

Corwin, R.F.; Sheffer, M.R.; Salmon, G. [BC Hydro, Burnaby, BC (Canada)

2007-04-15

This book represents one of a series on the subject of geophysical methods and their use in assessing seepage and internal erosion in embankment dams. This manual facilitates the interpretation of self-potential (SP) data generated by subsurface fluid flow, with an emphasis on dam seepage studies. It is intended for users with a background in geophysics or engineering having a general familiarity with both the SP and direct-current (DC) resistivity methods and their applications. It includes an extensive reference list covering all aspects of available SP interpretation techniques, including qualitative, analytical and numerical methods. Particular emphasis is placed on the use of geometric source analytical modeling methods to evaluate SP anomalies. These methods provide a simple yet efficient means of estimating the location and depth of current sources of observed SP data, which may be linked to fluid flow in the subsurface. The manual is primarily oriented toward embankment dams and earthen structures such as levees and dikes. SP methods have been used to investigate seepage through pervious zones and cracks in concrete and concrete-faced structures. The manual describes the nature of SP fields generated by both uniform and non-uniform dam seepage flow, as well as non-seepage sources of SP variations. These methods enable the study of more complex systems and require a more comprehensive analysis of a given field site. refs., tabs., figs.

Monitoring Strategies of Earth Dams by Ground-Based Radar Interferometry: How to Extract Useful Information for Seismic Risk Assessment.

Science.gov (United States)

Di Pasquale, Andrea; Nico, Giovanni; Pitullo, Alfredo; Prezioso, Giuseppina

2018-01-16

The aim of this paper is to describe how ground-based radar interferometry can provide displacement measurements of earth dam surfaces and of vibration frequencies of its main concrete infrastructures. In many cases, dams were built many decades ago and, at that time, were not equipped with in situ sensors embedded in the structure when they were built. Earth dams have scattering properties similar to landslides for which the Ground-Based Synthetic Aperture Radar (GBSAR) technique has been so far extensively applied to study ground displacements. In this work, SAR and Real Aperture Radar (RAR) configurations are used for the measurement of earth dam surface displacements and vibration frequencies of concrete structures, respectively. A methodology for the acquisition of SAR data and the rendering of results is described. The geometrical correction factor, needed to transform the Line-of-Sight (LoS) displacement measurements of GBSAR into an estimate of the horizontal displacement vector of the dam surface, is derived. Furthermore, a methodology for the acquisition of RAR data and the representation of displacement temporal profiles and vibration frequency spectra of dam concrete structures is presented. For this study a Ku-band ground-based radar, equipped with horn antennas having different radiation patterns, has been used. Four case studies, using different radar acquisition strategies specifically developed for the monitoring of earth dams, are examined. The results of this work show the information that a Ku-band ground-based radar can provide to structural engineers for a non-destructive seismic assessment of earth dams.

Examination of the concrete from an old Portuguese dam: Texture and composition of alkali-silica gel

International Nuclear Information System (INIS)

Fernandes, Isabel; Noronha, Fernando; Teles, Madalena

2007-01-01

Exudations and pop-outs were identified in the interior galleries of a large dam built in the 1960s. The samples collected were examined by a Scanning Electron Microscope. A dense material with a smooth surface and drying shrinkage cracks or a spongy texture were observed in the samples. The semi-quantitative composition was obtained by energy dispersive spectrometry (EDS) and it was concluded that this material corresponds to alkali-silica gel, composed of SiO 2 -Na 2 O-K 2 O-CaO. A viscous white product in contact with an aggregate particle in a cone sampled from a pop-out was observed through use of the scanning electron microscope and it has characteristics similar to the gel present in the exudations and cavities. Reference is made to the potential alkali reactivity of the aggregate present in the concrete. The texture and composition of the products probably resulting from an alkali-silica reaction are presented, set out in ternary diagrams, and discussed

76 FR 49462 - Red River Hydro LLC; Notice of Application Tendered For Filing With the Commission and...

Science.gov (United States)

2011-08-10

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 13160-002] Red River Hydro... concrete gravity structure that is 104 feet in height and 914 feet in length. The spillway consists of five... lock and dam system is navigation and not storage. The upper pool above the dam is commonly referred to...

77 FR 34371 - Red River Hydro LLC; Notice of Application Tendered for Filing With the Commission and...

Science.gov (United States)

2012-06-11

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 13160-004] Red River Hydro... the river. The existing Overton dam is a concrete gravity structure that is 104 feet in height and 914... feet wide by 685 feet long. The purpose of the lock and dam system is navigation and not storage. The...

Valorization of mud from Fergoug dam in manufacturing mortars

Directory of Open Access Journals (Sweden)

L. Laoufi

2016-12-01

Full Text Available The production of calcined mud, with pozzolanic properties, from the large quantities of sediments dredged from Algerian dams, could be a good opportunity for the formulation of high performance mortars and pozzolanic concretes, with lower costs and less greenhouse gas (CO2 emissions. The optimal temperatures selected for calcination were 750, 850 and 950 °C. The burning operation was continuous over a period of 3 h. Therefore, a series of physical, chemical, mechanical and microstructural analyses were conducted on sediment samples, collected from the waters of Fergoug dam. The results obtained from the analyses of the calcined mud, from the dam, allowed saying that mortars with different percentages of that mud represent a potential source of high reactivity pozzolanic materials.

Grouting of karstic arch dam foundation

Energy Technology Data Exchange (ETDEWEB)

Young, J.; Rigbey, S. [Acres International, Niagara Falls, ON (Canada)

2002-07-01

A 200 m high arch dam and a 2000 MW underground power house complex is under development in the Middle East. The project is located in a highly seismic area in rugged, mountainous terrain. The arch dam is constructed on good quality limestone and dolomitic limestone rock mass, but it contains several zones of disturbed or sheared rock. The basement rock is slightly karstic with hydraulic conductivities in the order of 100 Lugeons. In order to get a satisfactory foundation surface for the dam, it will be necessary to excavate extensively and backfill with concrete. Because of the presence of many clay infilled cavities and fractures, geotechnicians are considering the installation of a multiple row grout curtain to a depth of 150 m below the dam foundation to ensure adequate seepage and uplift parameters when the reservoir is impounded. Initial grouting water pressure test results suggested that the grouting and drainage curtain should be extended to the left abutment beyond the current design. However, when horizontal slide models of the dam abutment were developed using the finite element program SEEPW, it was shown that there is no benefit to extending the length of grout curtains unless they are tied to an area of much lower hydraulic conductivity much deeper in the abutment. 1 tab., 5 figs.

Walden North Dam overtopping : emergency response and rehabilitation

Energy Technology Data Exchange (ETDEWEB)

Dyer, S. [FortisBC Inc., South Slocan, BC (Canada); McCreanor, J. [Acres International Ltd., Calgary, AB (Canada); Cronin, D.L.R.; Daw, D. [Acres International Ltd., Vancouver, BC (Canada)

2004-09-01

This paper described the events that led to the overtopping of the Walden North Dam during a heavy rainfall in June 2002, resulting in a breach around an abutment wall. The dam is part of a run-of-river hydro development on Cayoosh Creek near Lillooet, British Columbia. The Walden North Dam was a low, 46 meter wide concrete dam with a single radial gate. The dam overtopping was attributed to failure of the radial gate hoist. Prior to this event, the dam had been classified by the British Columbia Dam Safety Authorities as a high and then a low consequence category of failure. As facility managers, Aquila Networks Canada Ltd. established an immediate action plan to stabilize the situation and resume normal power production by applying the following priorities: (1) ensure safety of workers and the public, (2) limit further damage to the dam and other facilities, (3) ensure environmental protection, and (4) continue to operate the generation units. Local authorities were informed to evacuate a downstream campsite and environmental agencies were contacted along with safety regulators. Repairs included demolition of the damaged portion of the structure and construction a new two-bay gate/stoplog spillway and bridge. Construction was completed by September 2003 according to the requirements of the Department of Fisheries and Oceans for minimum flow, accurate control of fish flows and environmental monitoring of the stream area. 10 figs.

Deformation behavior and load limits of asphaltic concrete under the conditions of cores in embankment dams; Deformationsverhalten und Belastungsgrenzen des Asphaltbetons unter den Bedingungen von Staudammkerndichtungen

Energy Technology Data Exchange (ETDEWEB)

Mueller, U.

1998-12-31

Based on the analysis of existing dams with asphaltic diaphragm and investigations in the three-phase-system of asphaltic concrete a recipe for the composition of asphaltic cores is recommended. For the construction, rest and operating period of an embankment dam the load and the reaction of the asphaltic concrete cores as well as the appearing stress and deformations are described. Extensive material testings have been performed and at 41 asphaltic concrete specimens triaxial stress controlled pressure and creeping tests have been carried out. The evaluation of the triaxial tests led to proportions of the main stress and deformation limits as criteria of breaking. Under application of the standard equation for nonlinear viscoelastic element-laws a rheonom element formulation was developed from the experiment data and transformed into its differential form. With this approach the stress and deformation behavior of watertight asphaltic diaphragm can be precalculated for a period up to 10 years. The applicability of this approach, which can be also used within FE-calculations as well, is illustrated in four examples. (orig.) [Deutsch] Nach der Analyse bestehender Staudaemme mit Asphaltbetonkerndichtung und Untersuchungen zum Dreiphasensystem Asphaltbeton wird eine Rezepturempfehlung fuer den Asphaltkerndichtungsbau aufgestellt. Fuer die Bau-, Ruhe- und Betriebsphase eines Staudammes werden die Beanspruchungen und Reaktionen der Asphaltbetonkerndichtung sowie die auftretenden Spannungen und Verformungen beschrieben. Nach umfangreichen Materialpruefungen sind an 41 Asphaltbetonpruefkoerpern triaxiale spannungsgesteuerte Druck-Kriechversuche durchgefuehrt worden. Die Auswertung der Triaxialversuche ergab ein Grenzhauptspannungsverhaeltnis und Deformationsgrenzen als Bruchkriterien. Unter Verwendung der Standarformulierung fuer nichtlineare viskoelastische Stoffgesetze wurde aus den Versuchsdaten ein rheonomer Stoffansatz entwickelt und in seine differentielle Form

Iterative analysis of concrete gravity dam-nonlinear foundation ...

African Journals Online (AJOL)

The solution of the coupled system is accomplished by solving the two systems separately and then considering the interaction effects at the soil–structure interface enforced by a developed iterative scheme. Emphasis has been laid on the study of material nonlinearity of the foundation material in the interaction analysis.

National Program for Inspection of Non-Federal Dams. Lower Reservoir Dam (NH 00048), NHWRB Number 108.05, Connecticut River Basin, Hanover, New Hampshire. Phase I Inspection Report.

Science.gov (United States)

1979-11-01

reservoirs, Upper Reservoir and Reservoir No. 3. The reservoir supplies to the water destribution system by gravity. h. Design and Construction History. o...continual supply to the water , destribution system as the main service area is fed by gravity. The waste pipe is usually closed. The flashboards on...however, no design calculations or b construction data were revealed.. The visual inspection revealed that the dam is in poor condition. The visual

Water Power in The Wilderness: The History of Bonneville Lock and Dam

Science.gov (United States)

1997-01-01

yards of material. Reinforced concrete cutoff walls at each abutment and reinforced concrete coun- terfort type upstream wing walls, along with...at the ends of the dam, the abutment Blasting of boulder no. 8 for navigation channel at Cascade Rapids . walls had to be built over 150 feet high...completion of the entire north section during 1936-37, the contractors placed a prefabricated struc- tural steel cofferdam over the crest section

An integral design concept for ecological self-compacting concrete

NARCIS (Netherlands)

Hunger, M.

2010-01-01

This Thesis addresses an alternative design concept for Self-Compacting Concrete (SCC). SCC is a special type of concrete with superior workability, which flows and compacts in all corners of a formwork just by the influence of gravity. Introduced to the concrete world in the late 1980s, SCC has

78 FR 28839 - ECOsponsible, Incorporated; Notice of Preliminary Permit Application Accepted for Filing and...

Science.gov (United States)

2013-05-16

...-foot-long stone and concrete gravity dam; (2) a single, proposed, low-head, horizontal bulb turbine... be paper-filed. To paper-file, mail an original and five copies to: Kimberly D. Bose, Secretary...

Dam! Dam! Dam!

International Nuclear Information System (INIS)

McCully, P.

1997-01-01

The author of ''Silenced Rivers'' a book questioning the desirability of dam building and hydroelectric power generation argues the main themes of his book in this paper. Despite being hailed by politicians as good solutions to power generation problems, and enthusiastically pursued in China, the U.S.A., the former Soviet Union, India and Japan, dams have far-reaching ecological and human consequences. The ecosystems lost to flooding, and the agricultural land use lost, the human cost in terms of homes and employment lost to reservoirs, disease from water-borne infections such as malaria, and the hazards of dams overflowing or breaking are all factors which are against the case for dam construction. The author argues the hydroelectric power may be renewable, but the social, agricultural and ecological costs are too high to justify it as a method of first choice. (UK)

Forward modeling of seepage of reservoir dam based on ground penetrating radar

Directory of Open Access Journals (Sweden)

Xueli WU

2017-08-01

Full Text Available The risk of the reservoir dam seepage will bring the waste of water resources and the loss of life and property. The ground penetrating radar (GPR is designed as a daily inspection system of dams to improve the existing technology which can't determine the actual situation of the dam seepage tunnel coordinates. The finite difference time domain (FDTD is used to solve the Yee's grids discreatization in two-dimensional space, and its electromagnetic distribution equation is obtained as well. Based on the actual structure of reservoir dam foundation, the ideal model of air layer, concrete layer, clay layer and two water seepage holes is described in detail, and the concrete layer interference model with limestone interference point is established. The system architecture is implemented by using MATLAB, and the forward modeling is performed. The results indicate that ground penetrating radar can be used for deep target detection. Through comparing the detection spectrum of three kinds of frequency electromagnetic wave by changing the center frequency of the GPR electromagnetic wave of 50 MHz, 100 MHz and 200 MHz, it is concluded that the scanning result is more accurate at 100 MHz. At the same time, the simulation results of the interference model show that this method can be used for the detection of complex terrain.

Philosopher’s Concrete: Dam Construction, Farmland Values, and Agricultural Production in the Western US, 1890–1920

Directory of Open Access Journals (Sweden)

Soudeh Mirghasemi

2017-09-01

Full Text Available Did construction of the Bureau of Reclamation dams in the early 20th century raise farm values and increase agricultural output? I construct a new county-level panel dataset from 1890 to 1920 with information on geography, climate, politics, agriculture, and major dams, and then evaluate the effect of the Bureau of Reclamation dams on the value of farms and on crop productivity. Using fixed effect panel estimation, I find that new federal dam construction increased the average value of farmland by approximately 6.4 percent. When I apply an instrument to control for potential endogeneity, the effect of Bureau dams on farmland value increases in size, although the estimate also becomes noisier and is no longer statistically significant. My results indicate that Bureau dams constructed in prior decades and the new dams constructed by other agencies did not have a statistically significant effect on the value of farms. In terms of crop output, the only crop affected by the dams was alfalfa.

WAC Bennett Dam - the characterization of a crest sinkhole

Energy Technology Data Exchange (ETDEWEB)

Stewart, R.A.; Gaffran, P.C. [British Columbia Hydro, Burnaby, BC (Canada); Watts, B.D. [Klohn-Crippen Consultants Ltd., Richmond, BC (Canada); Sobkowicz, J.C. [Thurber Engineering Ltd., Vancouver, BC (Canada); Kupper, A.G. [AGRA Earth and Environmental, Edmonton, AB (Canada)

1998-11-01

In June, 1996, a small hole was discovered in the asphaltic concrete road on the crest of the 183 m high WAC Bennett Dam on the Peace River in northeastern British Columbia. Examination of the hole resulted in a sinkhole on the dam crest. The sinkhole was 2.5 m in diameter and 7 m deep. Speculation was that the cavity was likely associated in some way with a buried survey benchmark tube. An investigation was immediately planned and executed to characterize the sinkhole, to determine the extent of damage and the safety status of this very large dam. British Columbia`s Dam Safety Regulator made the decision to lower the reservoir level. During the reservoir drawdown, various surface geophysical techniques were used to investigate the condition of the dam beyond the sinkholes. Intrusive investigations of the sinkhole were also planned. This involved trial drilling and downhole geophysical surveys in intact portions of the core at locations far from the sinkhole. The objectives and criteria developed for the investigation program are summarized. Scope of key activities at the sinkhole and important lessons learned during the investigation are also described. 9 refs., 15 figs.

Mathematical Modeling and Numerical Analysis of Thermal Distribution in Arch Dams considering Solar Radiation Effect

Science.gov (United States)

Mirzabozorg, H.; Hariri-Ardebili, M. A.; Shirkhan, M.; Seyed-Kolbadi, S. M.

2014-01-01

The effect of solar radiation on thermal distribution in thin high arch dams is investigated. The differential equation governing thermal behavior of mass concrete in three-dimensional space is solved applying appropriate boundary conditions. Solar radiation is implemented considering the dam face direction relative to the sun, the slop relative to horizon, the region cloud cover, and the surrounding topography. It has been observed that solar radiation changes the surface temperature drastically and leads to nonuniform temperature distribution. Solar radiation effects should be considered in thermal transient analysis of thin arch dams. PMID:24695817

Mathematical modeling and numerical analysis of thermal distribution in arch dams considering solar radiation effect.

Science.gov (United States)

Mirzabozorg, H; Hariri-Ardebili, M A; Shirkhan, M; Seyed-Kolbadi, S M

2014-01-01

The effect of solar radiation on thermal distribution in thin high arch dams is investigated. The differential equation governing thermal behavior of mass concrete in three-dimensional space is solved applying appropriate boundary conditions. Solar radiation is implemented considering the dam face direction relative to the sun, the slop relative to horizon, the region cloud cover, and the surrounding topography. It has been observed that solar radiation changes the surface temperature drastically and leads to nonuniform temperature distribution. Solar radiation effects should be considered in thermal transient analysis of thin arch dams.

Thermal monitoring of leakage through Karkheh embankment dam, Iran

Energy Technology Data Exchange (ETDEWEB)

Mirghasemi, A.A.; Bagheri, S.M. [Tehran Univ., Tehran (Iran, Islamic Republic of). Dept. of Civil Engineering; Heidarzadeh, M. [Tehran Univ., Tehran (Iran, Islamic Republic of). Dept. of Civil Engineering]|[Mahab Ghodss Consulting Engineers, Tehran (Iran, Islamic Republic of)

2007-07-01

A newly developed and simple method for monitoring seepage in embankment dams was presented. The method of temperature measurement is based on the fact that a change in permeability results in a change in seepage flow, thereby causing a temperature change that can be readily measured in the dam body and foundation. In this study, water leaking through the Karkheh embankment dam was thermally analyzed to determine a pattern and amount of water seepage. With nearly 33 million cubic metres of fill, the Karkheh earth and rock-fill dam is the largest dam in Iran. Construction was completed in 2000. The thermal processes in the embankment were studied due to the dam's complex thermo-hydraulic behaviour. Thermal data was collected and analyzed during construction and operation of the dam. This paper presented the temperature variations for the different dam zones, including core, upstream shell, downstream shell, upstream filter, downstream filter and the plastic concrete cut-off wall. It was determined that the clay core works very well as an impermeable curtain. It was also shown that temperature variations of the Karkheh reservoir water is seasonal, and decrease as water depth increases. The reservoir water temperature remains constant beyond depths of 60 metres. The thermal behaviour of the core is not similar to that of the reservoir, indicating a very low value of seepage through the core. The pattern of temperature variations in the upstream shell in the left abutment is harmonic, while in the right abutment it is not harmonic. A harmonic pattern of temperature variation exists in some aquifers of the dam foundation, indicating high seepage through these aquifers. The Karkheh dam cut-off wall performs satisfactorily. It was determined that one dimensional equations for estimating seepage cannot be applied for the Karkheh dam. 17 refs., 11 figs.

Biodecontamination of concrete

International Nuclear Information System (INIS)

Hamilton, M.A.; Rogers, R.D.; Benson, J.

1996-01-01

A novel technology for biologically decontaminating concrete is being jointly developed by scientists at the Idaho National Engineering Laboratory (INEL) and British Nuclear Fuels plc (BNFL). The technology exploits a naturally occurring phenomenon referred to as microbially influenced degradation (MID) in which bacteria produce acids that dissolve the cement matrix of concrete. Most radionuclide contamination of concrete is fixed in the outer few mm of the concrete surface. By capturing and controlling this natural process, a biological method of removing the surface of concrete to depths up to several mm is being developed. Three types of bacteria are known to be important in MID of concrete: nitrifying bacteria that produce nitric acid, sulfur oxidizing bacteria that produce sulfuric acid, and certain heterotrophic bacteria that produce organic acids. An investigation of natural environments demonstrated with scanning electron microscopy the presence of bacteria on concrete surfaces of a variety of structures, such as bridges and dams, where corrosion is evident. Enumeration of sulfur oxidizing and nitrifying bacteria revealed their presence and activity on structures to varying degrees in different environments. Under ideal conditions, Thiobacillus thiooxidans, a sulfur oxidizing bacteria, attached to and colonized the surface of concrete specimens. Over 1mm depth of material from a 10 cm x 10 cm square surface was removed in 68 days in the Thiobacillus treated specimen compared to a sterile control. Laboratory and field demonstrations are currently being conducted using experimental chambers designed to be mounted directly to concrete surfaces where radionuclide contamination exists. Data is being obtained in order to determine actual rates of surface removal and limitations to the system. This information will be used to develop a full scale decontamination technology

Study on real working performance and overload safety factor of high arch dam

Institute of Scientific and Technical Information of China (English)

2008-01-01

Considering the fact that high arch dams have problems such as complicated stress,high cost,and hazards after being damaged,this paper intends to study the effects of load,material strength,and safety analysis method on dam safety and working performance of arch dams.In this article,the effects of temperature,self weight exaction way and water loading on structure response are first discussed,and a more reasonable way of considering is then put forward.By taking into consideration the mechanical property of materials and comparing the effects of different yield criteria on overloading safety of high arch dams,this paper concludes that brittle characteristics of concrete should be fully considered when conducting safety assessment for high arch dams to avoid overestimating the bearing capacity of the dams.By comparing several typical projects,this paper works out a safety assessment system of multiple safety and relevant engineering analogical analysis methods,which is closer to the actual situation,and thus is able to assess the response of high arch dam structure in a more comprehensive way,elicit the safety coefficients in different situations,and provide a new way of considering the safety assessment of high arch dams.

Evaluation Standard for Safety Coefficient of Roller Compacted Concrete Dam Based on Finite Element Method

Directory of Open Access Journals (Sweden)

Bo Li

2014-01-01

Full Text Available The lack of evaluation standard for safety coefficient based on finite element method (FEM limits the wide application of FEM in roller compacted concrete dam (RCCD. In this paper, the strength reserve factor (SRF method is adopted to simulate gradual failure and possible unstable modes of RCCD system. The entropy theory and catastrophe theory are used to obtain the ultimate bearing resistance and failure criterion of the RCCD. The most dangerous sliding plane for RCCD failure is found using the Latin hypercube sampling (LHS and auxiliary analysis of partial least squares regression (PLSR. Finally a method for determining the evaluation standard of RCCD safety coefficient based on FEM is put forward using least squares support vector machines (LSSVM and particle swarm optimization (PSO. The proposed method is applied to safety coefficient analysis of the Longtan RCCD in China. The calculation shows that RCCD failure is closely related to RCCD interface strength, and the Longtan RCCD is safe in the design condition. Considering RCCD failure characteristic and combining the advantages of several excellent algorithms, the proposed method determines the evaluation standard for safety coefficient of RCCD based on FEM for the first time and can be popularized to any RCCD.

Rock Mass Behavior Under Hydropower Embankment Dams: A Two-Dimensional Numerical Study

Science.gov (United States)

Bondarchuk, A.; Ask, M. V. S.; Dahlström, L.-O.; Nordlund, E.

2012-09-01

Sweden has more than 190 large hydropower dams, of which about 50 are pure embankment dams and over 100 are concrete/embankment dams. This paper presents results from conceptual analyses of the response of typical Swedish rock mass to the construction of a hydropower embankment dam and its first stages of operation. The aim is to identify locations and magnitudes of displacements that are occurring in the rock foundation and grout curtain after construction of the dam, the first filling of its water reservoir, and after one seasonal variation of the water table. Coupled hydro-mechanical analysis was conducted using the two-dimensional distinct element program UDEC. Series of the simulations have been performed and the results show that the first filling of the reservoir and variation of water table induce largest magnitudes of displacement, with the greatest values obtained from the two models with high differential horizontal stresses and smallest spacing of sub-vertical fractures. These results may help identifying the condition of the dam foundation and contribute to the development of proper maintenance measures, which guarantee the safety and functionality of the dam. Additionally, newly developed dams may use these results for the estimation of the possible response of the rock foundation to the construction.

Sinkhole formation mechanism at Steinaker Dam : the complete story

Energy Technology Data Exchange (ETDEWEB)

Dise, K. [United States Dept. of the Interior, Washington, DC (United States). Bureau of Reclamation

2009-07-01

This case history summary described an internal erosion event that occurred at a zoned earthfill dam located within the Ashley Creek watershed area of the Uinta Mountain uplift. The incident occurred under static loading. The rocks in the region are heavily fractured with close to moderately spaced joints along the bedding planes. The joints were not grouted during the dam's construction, and the foundation was not treated with dental concrete or slush grouting. The dam's core material consisted of a mixture of clay, silt and sand. A sinkhole area appeared on the downstream face of the dam and was filled. A second sinkhole appeared in 1965. Abutment grouting was performed. A core investigation study in 1992 showed that voids were present in the core. Deep dynamic compaction was used to densify the foundation materials. Voids in the gravel envelope were filled with fine sand. The investigation showed that the sinkholes were formed by seeps travelling through abutment bedrock fractures. The voids were large enough to provide an exit for the fine-grained foundation alluvial materials. It was concluded that grouting the abutment prevented higher velocity seepages that may have eventually initiated a dam breach. 6 figs.

Precast Concrete Beam-to-Column Connection System

OpenAIRE

ECT Team, Purdue

2007-01-01

Compared to conventional concrete constructions, precast concrete is a better option which is more cost-effective for production, transport, and erection when columns and beams can be fabricated independently. The BSF connection is a hidden beam and connection for gravity loads that eliminates the need for projecting column corbels. From a steel box cast into the concrete beam end, a sliding steel “knife” plate with a safety notch is cantilevered into a steel box that has been cast into the c...

Special repairs to the eroded joints of concrete slabs of Stilling Basin-3 and strengthening of splitter pier of Tunnel No. 3, Tarbela Dam Project

Energy Technology Data Exchange (ETDEWEB)

Khan, B.A. [WAPDA Tarbela DAM Project (Pakistan)

1999-07-01

Repair alternatives to correct erosion damage to the right side of the central longitudinal joint just downstream of the chute of Stilling Basin-3 are discussed. Three alternatives were considered: (1) provide a coffer dam around the plunge pool area and dewater the stilling basin prior to undertaking any repair work; (2) use Tremie concrete , or (3) use Hydrocrete, a regular concrete with some special additives to hold the aggregate, cement and water together in under-water repairs. Because of its erosion resistance in the plastic state, and its self-compacting and leveling properties, the Hydrocrete method was chosen. While repairing the erosion damage, Hilty anchors were also installed in the damaged slab portion, and the splitter pier was also strengthened by inserting mechanical anchors. The entire operation was monitored by a CCTV camera and surface to under-water communication. By choosing this method, the repairs have been completed without dewatering the stilling basin, thus achieving substantial savings. Subsequent under-water inspection by divers and video film proved the repairs to have been fully satisfactory.

The behaviour of a large dam at severe frost

Directory of Open Access Journals (Sweden)

M. C. SPADEA

1972-06-01

Full Text Available Synthesizing the problem, the action of the thrusts in the
behaviour of t h e dam of Pieve di Cadore, makes itself conspicuous expecially
during three periods of the year:
1. - About the end of June, the air temperature, 011 t h e average, overcomes
the water one in the watershed upstream the dam: the bending of
t h e dam upstream increases from the bottom to the top.
2. - About the end of October, the thermal conditions change; the
mean air temperature grows lower than the mean water temperature; the
dam begins her bending dowstream.
3. - When the air temperature is distinctly below 0 °C, the action of
t h e t h r u s t s grows more complexe; t h e rocky waterlogged system downstream
of t h e dam, while cooling, swells and pushes t h e bottom of t h e dam upstream;
at t h e higher quote, on the contrary, the t h r u s t downstream continues.
When the strenght limit of the medium is surpassed, arises a contrast
between the rocky system and the concrete structure: this contrast can origin
a t e very small fractures, revealed from seismic station installed into the
central ashlar (XIV a t 660 metres height of t h e dam, under t h e form of microshocks
which energy is of about 10I0-10U erg.

Use of flyash in roller compacted concrete for Ghatghar pumped storage scheme in Maharashtra

Energy Technology Data Exchange (ETDEWEB)

Damani, R.L.; Kshirsagar, S.L.; Narkhede, C.L. [MERI, Nashik (India)

2003-07-01

The paper described the use of 'Roller Compacted Concrete' (RCE) in which about 60% of the cement will be replaced by fly ash for construction of two storage dams - Upper dam and Lower dam in the Thane district of India. These are part of the Ghatghar Pumped Storage Scheme to generate hydropower. Fly ash from Eklahare and Dahav thermal power plant and processed fly ash, Pozzocrete 63 and 83b grade, all proved suitable for the RCC mix. 1 tab.

Modeling and assessment of concrete and the energy infrastructure

International Nuclear Information System (INIS)

Guthrie, G.; Carey, J.

1998-01-01

This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Concrete is an essential component of the energy infrastructure. The characteristics of concrete that determine its effectiveness in any application--be it construction (e.g., roads, bridges, dams) or waste isolation--result from the chemical and structural evolution of the particular concrete structure. Geochemical and mineralogical factors are among the most important, yet most overlooked, controls of this evolutionary process. This project is geared at using a combination of advanced geochemical and mineralogical experimentation, characterization, and modeling (much of which was developed to understand geological systems such as Yucca Mountain) to understand the evolution of concrete in a mechanistic way. The goal was to develop a systematic approach to problems ranging from premature degradation of concrete to the design of next-generation concretes

A review on carbonation study in concrete

Science.gov (United States)

Venkat Rao, N.; Meena, T.

2017-11-01

In this paper the authors have reviewed the carbonation studies which are a vital durability property of concrete. One of the major causes for deterioration and destruction of concrete is carbonation. The mechanism of carbonation involves the penetration carbon dioxide (CO2) into the concrete porous system to form an environment by reducing the pH around the reinforcement and initiation of the corrosion process. The paper also endeavours to focus and elucidate the gravity of importance, the process and chemistry of carbonate and how the various parameters like water/cement ratio, curing, depth of concrete cones, admixtures, grade of concrete, strength of concrete, porosity and permeability effect carbonation in concrete. The role of Supplementary Cementitious Materials (SCMs) like Ground granulated Blast Furnace Slag (GGBS) and Silica Fume (SF) has also been reviewed along with the influence of depth of carbonation.

Detection of concrete dam leakage using an integrated geophysical technique based on flow-field fitting method

Science.gov (United States)

Dai, Qianwei; Lin, Fangpeng; Wang, Xiaoping; Feng, Deshan; Bayless, Richard C.

2017-05-01

An integrated geophysical investigation was performed at S dam located at Dadu basin in China to assess the condition of the dam curtain. The key methodology of the integrated technique used was flow-field fitting method, which allowed identification of the hydraulic connections between the dam foundation and surface water sources (upstream and downstream), and location of the anomalous leakage outlets in the dam foundation. Limitations of the flow-field fitting method were complemented with resistivity logging to identify the internal erosion which had not yet developed into seepage pathways. The results of the flow-field fitting method and resistivity logging were consistent when compared with data provided by seismic tomography, borehole television, water injection test, and rock quality designation.

Offshore concrete structures

International Nuclear Information System (INIS)

Lamas Pardo, M.; Carral Couce, L. M.

2011-01-01

proof that in certain cases the benefits to the steel tip the lance toward the concrete. concrete Gravity Baseplaforms type Con deep have been building since the first unit became operational in 1976, together with a few floating platforms, that in its geometry are similar to those made of steel (barges, semi-submersibles and TLP type platforms). Some of the concepts in concrete that are being emerging last years are floating and gravity base platforms for use as offshore LNG terminals and as offshore industrial plants. The life of these barges can be designed up to 200 years, as the floating Nkossabarge, so they con be a good alternative to the construction of these facilities an land, thus avoiding landfills on the coast that degrade the already punished coast in industrialized countries. the challenge is precisely to optimize their capital costs to complete for an offshore installation against a shore facility. The environment will undoubtedly benefit from this great challenge that lies ahead in the XXI century. (Author) 29 refs.

High flow concrete 2; Koryudo konkurito 2

Energy Technology Data Exchange (ETDEWEB)

Naruse, Hiroyasu [Mitsubishi Materials Corp., Tokyo (Japan)

1998-09-10

Hashimoto et al. compared U-type repletion test that evaluation method of the consistency in design of mix of high workable concrete was proposed as a repletion test with the box test, and it was examined, and it had clarified the difference between the behavior in the test by the analysis of the shearing strain speed by the visualization as the technique, and the important proposal was done, when the evaluation method would be divided in future. Anchors showed that it analyzed it in order to quantitatively evaluate separating resistance-ness of the coarse aggregate, with model and proposes the analysis method on separating resistance-ness of high workable concrete according to the original model, and that the correlation is high. In the future, further examination was carried out on aggregate shapes and lees aggregate amount, etc. and intended to propose the technique which could be analyzed more high-precise. Branch pines examined the effect of the fineness modulus in addition to factors such as real width rate and particle size of a fine aggregate in the technique in which researchers have proposed the setting of class aggregate amount in the top in search of the optimum value. It can be expected that it is future effectively utilized, because it is a proposed equation which sufficiently added characteristics of the Tsumugi aggregate. Temple areas found and proposed that viscosity and of the optimum mortar minute in design of mix in high workable concrete for the dam for the downward flow hour differed from the case in which the 20 mm aggregate was used on the design of mix technique in using the 40 mm aggregate. It is the research which considered the application of high workable concrete to the concrete for the dam, and it seems to be very much useful to future popularization. (translated by NEDO)

Special design issues related to the G. Ross Lord Dam constructed in Metropolitan Toronto

Energy Technology Data Exchange (ETDEWEB)

Sowa, V.A. [Jacques Whitford and Associates Ltd., Vancouver, BC (Canada); Tawil, A.H. [Acres International Ltd., Niagara Falls, ON (Canada); Haley, D.R. [Toronto Region and Conservation Authority, Downsview, ON (Canada)

2002-07-01

This paper describes the special considerations required to build a flood control dam in a metropolitan area that holds major city infrastructures such as power transmission towers, pipelines, sanitary sewers and graveyards. The paper refers to the G. Ross Lord Dam, a 20 m high earth fill flood control dam which was constructed in 1973 on the West Branch of the Don River in Toronto. It was built following recommendations after Hurricane Hazel caused widespread flooding and the death of 81 people in 1954. The dam includes a concrete chute spillway and stilling basin. The geotechnical design of the dam was described along with the dam structures and the methods used to flood proof the infrastructure. The dam has a sloping impervious core and an upstream blanket to reduce seepage. Seepage control is provided by a drainage blanket and a chimney drain. A main overflow spillway was constructed on the south abutment, and a low level outlet was constructed at the base of the dam to accommodate normal river flows through the dam. Most of the water level control during a flood event is provided by the main overflow spillway. Spillway slab anchor keys prevent down slope creep of the slabs. The dam, the spillway and the reservoir structure have performed well since construction. 6 refs., 10 figs.

Aylmer Dam : past, present and future; Barrage Aylmer : passe, present et futur

Energy Technology Data Exchange (ETDEWEB)

Giguere, H; Lehoux, B; Toma, G [Quebec Ministere du Developpement durable, de l' Environnement et des Parcs, Quebec, PQ (Canada). Centre d' Expertise Hydrique

2006-07-01

The Aylmer gravity dam was built in 1953 in Weedon in Quebec's Eastern Townships. The water reservoir retained by the Aylmer Dam has a capacity of 201,928,700 cubic metres and many houses and cottages now line its shores. As such, the water level must be kept high during the summer holiday season. The initial purpose of the dam was for log transportation, the regulation of the Saint-Francois River and the production of electricity. The retention structure belongs to the Quebec government and is managed by the Centre d'Expertise Hydrique du Quebec (CEHQ). Underwater inspection of the dam in 1998 showed signs of erosion damage that required repair. Five of the dam's seven sluices were equipped with stop logs while the others had metallic floodgates. The damage was caused by the preferential use of the 2 floodgates over the years. This paper described the 3 phases for modernizing the evacuation devices of this dam. The first phase began in 2003 with the repair of the dam. The second phase involved the construction of a more modern building in 2004, and the third phase involved the replacement of wooden girders with heated metallic sluices in 2005. The modernization of this dam has reduced the time for required for water evacuation operations during all seasons and has eliminated the danger linked to de-icing techniques. 1 ref., 8 figs.

Evolution of an interfacial crack on the concrete-embankment boundary

Energy Technology Data Exchange (ETDEWEB)

Glascoe, Lee [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Antoun, Tarabay [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kanarska, Yuliya [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lomove, Ilya [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hall, Robert [US Army Corps of Engineers, Washington, DC (United States); Woodson, Stan [US Army Corps of Engineers, Washington, DC (United States); Smith, Jerrell [US Army Corps of Engineers, Washington, DC (United States); Ezzedine, Souheil [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2013-07-10

Failure of a dam can have subtle beginnings. A small crack or dislocation at the interface of the concrete dam and the surrounding embankment soil initiated by, for example, a seismic or an explosive event can lead to a catastrophic failure of the dam. The dam may ‘self-rehabilitate’ if a properly designed granular filter is engineered around the embankment. Currently, the design criteria for such filters have only been based on experimental studies. We demonstrate the numerical prediction of filter effectiveness at the soil grain scale. This joint LLNL-ERDC basic research project, funded by the Department of Homeland Security’s Science and Technology Directorate (DHS S&T), consists of validating advanced high performance computer simulations of soil erosion and transport of grain- and dam-scale models to detailed centrifuge and soil erosion tests. Validated computer predictions highlight that a resilient filter is consistent with the current design specifications for dam filters. These predictive simulations, unlike the design specifications, can be used to assess filter success or failure under different soil or loading conditions and can lead to meaningful estimates of the timing and nature of full-scale dam failure.

Integrated modelling of corrosion-induced deterioration in rein-forced concrete structures

DEFF Research Database (Denmark)

Michel, Alexander; Geiker, M.R.; Stang, Henrik

2013-01-01

at the reinforcement surface, a FEM based me-chanical model was used to simulate corrosion-induced concrete damage. Both FEM models were fully coupled, i.e. information, such as corrosion current density, dam-age state of concrete cover, etc., were constantly exchanged between the models. To demonstrate the potential......An integrated finite element based modelling approach is presented, which allows for fully coupled simulation of reinforcement corrosion and corrosion-induced concrete damage. While a finite element method (FEM) based corrosion model was used to describe electrochemical processes...... use of the modelling approach, a numerical example is presented which illustrates full coupling of formation of corrosion cells, propagation of corrosion, and subsequent development of corrosion-induced concrete damage....

Sorption of Cs, I, and actinides in concrete systems

International Nuclear Information System (INIS)

Allard, B.; Eliasson, L.; Andersson, K.

1984-09-01

Samples of seven different concretes were prepared (Standard Portland cement of two kinds; sulphate resistant, blast furnace slag, high alumina, fly ash, and silica cements) and the corresponding pore waters were analyzed. Batch-wise distribution studies were performed in the various concrete/pore water systems, as well as for three old concrete samples from a hydro power station dam (more than 60 years old), for the elements Cs, I, Th, U, Np, Pu, and Am at trace concentration levels. Generally the sorption of Cs was low, and somewhat higher for I. All the actinides, including U and Np in their hexa- and pentavalent states, respectively, were strongly sorbed on the cement phase. (Author)

Tailings dams from the perspective of conventional dam engineering

International Nuclear Information System (INIS)

Szymanski, M.B.

1999-01-01

A guideline intended for conventional dams such as hydroelectric, water supply, flood control, or irrigation is used sometimes for evaluating the safety of a tailings dam. Differences between tailings dams and conventional dams are often substantial and, as such, should not be overlooked when applying the techniques or safety requirements of conventional dam engineering to tailings dams. Having a dam safety evaluation program developed specifically for tailings dams is essential, if only to reduce the chance of potential errors or omissions that might occur when relying on conventional dam engineering practice. This is not to deny the merits of using the Canadian Dam Safety Association Guidelines (CDSA) and similar conventional dam guidelines for evaluating the safety of tailings dams. Rather it is intended as a warning, and as a rationale underlying basic requirement of tailings dam emgineering: specific experience in tailings dams is essential when applying conventional dam engineering practice. A discussion is included that focuses on the more remarkable tailings dam safety practics. It is not addressed to a technical publications intended for such dams, or significantly different so that the use of conventional dam engineering practice would not be appropriate. The CDSA Guidelines were recently revised to include tailings dams. But incorporating tailings dams into the 1999 revision of the CDSA Guidelines is a first step only - further revision is necessary with respect to tailings dams. 11 refs., 2 tabs

Validation study by finite element method: the case of the Daniel Johnson Dam

International Nuclear Information System (INIS)

Lariviere, R.; Phat, T. M.; Poirier, C.; Thibeault, N.

1997-01-01

A structural study of the Daniel-Johnson multi-arch dam undertaken by Hydro-Quebec to determine the safest way of grouting the cracks at the base of some arches was described. A numerical model in the linear elastic domain was constructed. The model will be modified to incorporate other features such as the cracks at the base of arches, the cracks at the concrete-rock foundation contact area, and the restraining effect of downstream rock foundation. This paper highlights the quality assurance procedure related to model validation as recommended by the International Committee on Large Dams. 2 refs., 11 figs

Study of discharge coefficients of the flapper gates in the Tiete River movable dam; Estudo dos coeficientes de vazao das comportas tipo basculante (CLAPET) da barragem movel do Rio Tiete

Energy Technology Data Exchange (ETDEWEB)

Lucca, Yvone de Faria Lemos de [Universidade de Sao Paulo (CTH/DAEE/USP), SP (Brazil). Departamento de Aguas e Energia Eletrica. Centro Tecnologico de Hidraulica e Recursos Hidricos; Souza, Podalyro Amaral de [Universidade de Sao Paulo (EP/USP), SP (Brazil). Escola Politecnica. Dept. de Aguas e Energia Eletrica], E-mail: podalyro@usp.br

2011-04-15

This article refers to the study of discharge coefficients of the flapper gates in the Tiete River Movable Dam. This dam is made of a reinforced concrete structure with nine flapper gates, which can be operated independently from each other, opening angle from zero to 70 degree. This type of dam structure produces complex flow conditions due to the several opening combinations which make this study very challenging. This paper presents the development of a mathematical model that can estimate the coefficient flow taking into account all major variables present in this dam structure, like the angle of operation of each gate, the approaching flow velocity, the concrete column between gates, the downed outflow effects and the presence of a completely closed gate between two in operation. (author)

A class of minimally modified gravity theories

Energy Technology Data Exchange (ETDEWEB)

Lin, Chunshan; Mukohyama, Shinji, E-mail: chunshan.lin@yukawa.kyoto-u.ac.jp, E-mail: shinji.mukohyama@yukawa.kyoto-u.ac.jp [Center for Gravitational Physics, Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan)

2017-10-01

We investigate the Hamiltonian structure of a class of gravitational theories whose actions are linear in the lapse function. We derive the necessary and sufficient condition for a theory in this class to have two or less local physical degrees of freedom. As an application we then find several concrete examples of modified gravity theories in which the total number of local physical degrees of freedom in the gravity sector is two.

Monitoring the Startup of a Sacrificial Concrete Sewer for Odor Control

DEFF Research Database (Denmark)

Nielsen, Asbjørn Haaning; Vollertsen, Jes

2014-01-01

with extended retention time. For the purpose of the study, a 50-m long sacrificial concrete gravity sewer was constructed using a high alkalinity concrete pipe. The monitoring campaign reported in this paper covers the first 9 months of operation. The results clearly demonstrate the ability of the system...

A numerical analysis method on thermal and shrinkage stress of concrete

International Nuclear Information System (INIS)

Takiguchi, Katsuki; Hotta, Hisato

1991-01-01

Thermal stress often causes cracks in large scale concrete such as that for dam construction. The drying shrinkage of concrete causes cracks in concrete structures. These thermal stress and drying shrinkage stress may be the main reasons cracks occur in concrete, however there is few research which dealt with both stresses together. The problems on the thermal stress and the drying shrinkage are not independent, and should be dealt with together, because both temperature and water content of concrete affect hydration reaction, and the degree of hydration determines all the characteristics of concrete at early age. In this study, the degree of hydration is formulated experimentally, and a numerical stress analysis method taking the hydration reaction in consideration is presented. The formulation of the rate of hydration reaction, the method of analyzing thermal and drying shrinkage stresses, the analytical results for a concrete column and the influence that continuous load exerted to the tensile strength of concrete are reported. The relatively high stress nearly equal to the tensile strength of concrete arises near the surface. (K.I.)

Predicting temperature drop rate of mass concrete during an initial cooling period using genetic programming

Science.gov (United States)

Bhattarai, Santosh; Zhou, Yihong; Zhao, Chunju; Zhou, Huawei

2018-02-01

Thermal cracking on concrete dams depends upon the rate at which the concrete is cooled (temperature drop rate per day) within an initial cooling period during the construction phase. Thus, in order to control the thermal cracking of such structure, temperature development due to heat of hydration of cement should be dropped at suitable rate. In this study, an attempt have been made to formulate the relation between cooling rate of mass concrete with passage of time (age of concrete) and water cooling parameters: flow rate and inlet temperature of cooling water. Data measured at summer season (April-August from 2009 to 2012) from recently constructed high concrete dam were used to derive a prediction model with the help of Genetic Programming (GP) software “Eureqa”. Coefficient of Determination (R) and Mean Square Error (MSE) were used to evaluate the performance of the model. The value of R and MSE is 0.8855 and 0.002961 respectively. Sensitivity analysis was performed to evaluate the relative impact on the target parameter due to input parameters. Further, testing the proposed model with an independent dataset those not included during analysis, results obtained from the proposed GP model are close enough to the real field data.

An integrated approach to dam safety evaluation. A case study: Upper Lake Falls Dam, Nova Scotia, Canada

International Nuclear Information System (INIS)

Pelletier, P.M.; Rattue, D.A.; Brown, E.R.

1990-01-01

Upper Lake Falls Dam is located in southwestern Nova Scotia. It is the uppermost hydroelectric development in a series of six developments on the Mersey River. The total capacity of the Mersey River system is 42 MW. The reservoir of Upper Lake Falls, Lake Rossignol, is the largest in Nova Scotia with a total area of 66 square miles and a gross storage of 800,000 acre-feet. An overview is presented of the hydrologic and hydraulic investigations carried out for the dam, which is classified as having high hazard potential because of permanent village and urban developments located downstream. The general methodology adopted in the study consisted of the following: gathering and verifying all meteorologic and hydrologic data; evaluating the Probable Maximum Precipitation (PMP) assumed to occur over the basin, and of the antecedent conditions prior to the PMP; calibrating a watershed model on flood events generated by rainfall, and by a combination of snowmelt and rainfall, and verifying the model using additional hydrologic events; deriving the Probable Maximum Flood (PMF) using the PMP results simulated on the calibrated watershed model; hydrodynamic routing of the flood hydrograph through all the developments; dambreak analysis, following sequential or independent failures; and flood inundation mapping. Details are given of safety analysis of the earthfill and concrete dam structures, reservoir management and cost-benefit analyses. 7 refs., 8 figs., 1 tab

Behind an ambitious megaproject in Asia: The history and implications of the Bakun hydroelectric dam in Borneo

International Nuclear Information System (INIS)

Sovacool, Benjamin K.; Bulan, L.C.

2011-01-01

Using a case-study, inductive, narrative approach, this article explores the history, drivers, benefits, and barriers to the Bakun Hydroelectric Project in East Malaysia. Situated on the island of Borneo, Bakun Dam is a 204 m high concrete face, rock filled dam on the Balui River in the Upper Rajang Basin in the rainforests of Sarawak. Bakun Dam and its affiliated infrastructure could be the single largest and most expensive energy project ever undertaken in Southeast Asia. Based on data collected through site visits, original field research in Sarawak, and more than 80 research interviews, the article begins by teasing out the complex history and drivers behind the Bakun project before identifying a set of potential social, political, and economic benefits the project could deliver. It then delves into six sets of barriers in the technical, economic, political, legal and regulatory, social, and environmental realms. We find that Bakun illustrates how centralized energy megaprojects, while ostensibly championed for reasons of economies of scale and the ability to bring about transformational change in the shortest period of time, often fail to address broader development goals such as fighting energy poverty and improving the livelihoods of the local communities they are supposed to serve. - Highlights: → Bakun Dam is concrete face, rock filled dam on the Balui River in the Upper Rajang Basin in the rainforests of Sarawak. → The project faces technical, economic, political, legal and regulatory, social, and environmental barriers. → We conclude the project will fail to fight energy poverty or improve the livelihoods of local populations.

Behind an ambitious megaproject in Asia: The history and implications of the Bakun hydroelectric dam in Borneo

Energy Technology Data Exchange (ETDEWEB)

Sovacool, Benjamin K., E-mail: bsovacool@nus.edu.sg [Lee Kuan Yew School of Public Policy, National University of Singapore, Oei Tiong Ham Building, 469C Bukit Timah Road, Singapore 259772 (Singapore); Bulan, L.C. [Lee Kuan Yew School of Public Policy, National University of Singapore, Oei Tiong Ham Building, 469C Bukit Timah Road, Singapore 259772 (Singapore)

2011-09-15

Using a case-study, inductive, narrative approach, this article explores the history, drivers, benefits, and barriers to the Bakun Hydroelectric Project in East Malaysia. Situated on the island of Borneo, Bakun Dam is a 204 m high concrete face, rock filled dam on the Balui River in the Upper Rajang Basin in the rainforests of Sarawak. Bakun Dam and its affiliated infrastructure could be the single largest and most expensive energy project ever undertaken in Southeast Asia. Based on data collected through site visits, original field research in Sarawak, and more than 80 research interviews, the article begins by teasing out the complex history and drivers behind the Bakun project before identifying a set of potential social, political, and economic benefits the project could deliver. It then delves into six sets of barriers in the technical, economic, political, legal and regulatory, social, and environmental realms. We find that Bakun illustrates how centralized energy megaprojects, while ostensibly championed for reasons of economies of scale and the ability to bring about transformational change in the shortest period of time, often fail to address broader development goals such as fighting energy poverty and improving the livelihoods of the local communities they are supposed to serve. - Highlights: > Bakun Dam is concrete face, rock filled dam on the Balui River in the Upper Rajang Basin in the rainforests of Sarawak. > The project faces technical, economic, political, legal and regulatory, social, and environmental barriers. > We conclude the project will fail to fight energy poverty or improve the livelihoods of local populations.

High volume fly ash RCC for dams - I : mixture optimization and mechanical properties

Energy Technology Data Exchange (ETDEWEB)

Jacobsen, S. [PEAB Construction Co., Oslo (Norway); Lahus, O. [Norwegian Building Research Inst., Oslo (Norway)

2001-07-01

Roller compacted concretes (RCC) were developed for the Norwegian Skjerka hydropower project. RCCs were developed to have a high-volume fly ash content to address environmental issues, including the reduction of carbon dioxide emissions associated with dam construction. They also makes good use of waste product and conserve natural resources. This study examined a series of mixtures to determine the appropriateness of using RCC as a competing alternative to the traditional rock fill dam proposed for the Skjerka hydropower project. The main advantage of RCC is speed, allowing a relatively large dam to be constructed in just one summer season, saving financial costs and providing early return on the investment. In addition, fly ash can be used in the structure, using clean and renewable energy. Several procedures to proportion RCC mixtures were proposed, including the optimal paste volume method which is based on the assumption that an optimal RCC should have just enough paste to fill the space between particles when the granular skeleton has reached its maximum density under compaction. With this assumption, RCC tests began in 1998 in the laboratories of the Norwegian Building Research Institute. An ordinary portland cement was used and combined with ordinary low lime fly ash. Both coarse and fine aggregate were used. The tests determined the optimum paste-mortar ratio, the content of coarse aggregates and the production of specimens for test on hardened and fresh concrete. The study showed that the compressive strength of RCC increased with increasing cement/(cement + fly ash) ratio. The permeability coefficient decreased with increasing cement-content and increasing cement/(cement + fly ash) ratio due to the slow pozzolanic reaction of fly ash making a more open pore structure. It was concluded that an optimized mixture can result in a high performance RCC in terms of fresh and hardened concrete properties. 15 refs., 5 tabs., 11 figs.

77 FR 30523 - Albany Engineering Corporation; Notice of Preliminary Permit Application Accepted for Filing and...

Science.gov (United States)

2012-05-23

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 14387-000] Albany...-long and 15-foot-high ogee-shaped concrete gravity dam with a 356-foot-long tainter-gated structure... a storage capacity of 5,000 acre-feet at the spillway crest elevation of 28.3 feet National Geodetic...

78 FR 22873 - Hamilton Street Hydro, LLC; Notice of Preliminary Permit Application Accepted for Filing and...

Science.gov (United States)

2013-04-17

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 14500-000] Hamilton Street... Hydroelectric Project would consist of the following: (1) An existing 14-foot-high concrete gravity dam with a 480-foot-long spillway; (2) an existing impoundment having a surface area of 50 acres and a storage...

Hypergravity disruption of homeorhetic adaptations to lactation in rat dams include changes in circadian clocks

Directory of Open Access Journals (Sweden)

Theresa Casey

2012-04-01

Altered gravity load induced by spaceflight (microgravity and centrifugation (hypergravity is associated with changes in circadian, metabolic, and reproductive systems. Exposure to 2-g hypergravity (HG during pregnancy and lactation decreased rate of mammary metabolic activity and increased pup mortality. We hypothesize HG disrupted maternal homeorhetic responses to pregnancy and lactation are due to changes in maternal metabolism, hormone concentrations, and maternal behavior related to gravity induced alterations in circadian clocks. Effect of HG exposure on mammary, liver and adipose tissue metabolism, plasma hormones and maternal behavior were analyzed in rat dams from mid-pregnancy (Gestational day [G]11 through early lactation (Postnatal day [P]3; comparisons were made across five time-points: G20, G21, P0 (labor and delivery, P1 and P3. Blood, mammary, liver, and adipose tissue were collected for analyzing plasma hormones, glucose oxidation to CO2 and incorporation into lipids, or gene expression. Maternal behavioral phenotyping was conducted using time-lapse videographic analyses. Dam and fetal-pup body mass were significantly reduced in HG in all age groups. HG did not affect labor and delivery; however, HG pups experienced a greater rate of mortality. PRL, corticosterone, and insulin levels and receptor genes were altered by HG. Mammary, liver and adipose tissue metabolism and expression of genes that regulate lipid metabolism were altered by HG exposure. Exposure to HG significantly changed expression of core clock genes in mammary and liver and circadian rhythms of maternal behavior. Gravity load alterations in dam's circadian system may have impacted homeorhetic adaptations needed for a successful lactation.

Internal erosion under spillway rested on an embankment dam

Directory of Open Access Journals (Sweden)

Mohammad Sedghi-Asl

2015-12-01

Full Text Available In this paper we investigate the mechanism of internal erosion caused in the right abutment of the Shahghasem dam’s spillway. Shahghasem dam is an earthen dam located in Yasouj, in southwest of Iran. A significant hole and pipe have been observed in the corner of the right abutment from upstream view. The foundation is Marlstone, which has low cohesion and susceptible for internal erosion and piping in some conditions. Going through details of the design maps has shown that Lane’s criteria for selecting safe dimensions of the seepage control measures have not been considered properly. A series of the supportive walls are designed to attach to the right part of the spillway in order to increase the length of seepage. The pipe route of the erosion should also be grouted with high quality concrete.

Estimated sedimentation rate by radionuclide techniques at Lam Phra Phloeng dam, Northeastern of Thailand

International Nuclear Information System (INIS)

Sasimonton Moungsrijun; Kanitha Srisuksawad; Kosit Lorsirirat; Tuangrak Nantawisarakul

2009-01-01

The Lam Phra Phloeng dam is located in Nakhon Ratchasima province, northeastern of Thailand. Since it was constructed in 1963, the dam is under severe reduction of its water storage capacity caused by deforestation to agricultural land at the upper catchment. Sediment cores were collected using a gravity corer. Sedimentation rates were estimated from the vertical distribution of unsupported Pb-210 in sediment cores. Total Pb-210 was determined by measuring Po-210 activities. The Po-210 and Ra-226 activities were used to determine the rate of sediment by using alpha and gamma spectrometry. The sedimentation rate was estimated using the Constant Initial Concentration model (CIC), the sedimentation rate crest dam 0.265 gcm -2 y -1 and the upstream 0.213 gcm -2 y -1 (Author)

Salt-saturated concrete strength and permeability

International Nuclear Information System (INIS)

Pfeifle, T.W.; Hansen, F.D.; Knowles, M.K.

1996-01-01

Laboratory-scale experiments applicable to the use of salt-saturated concrete as a seal material for a transuranic waste repository have been completed. Nitrogen gas permeability measurements were made using a flexible-wall permeameter, a confining pressure of 1 MPa, and gas pressure gradients ranging from 0.3 MPa to 0.75 MPa. Results show that salt-saturated concrete has very low intrinsic permeability with values ranging from 9.4 x 10 -22 m 2 to 9.7 x 10 -17 m 2 . Strength and deformation characteristics were investigated under conditions of triaxial compression with confining pressures ranging from 0 to 15 MPa using either axial strain-rate or axial stress-rate control and show that the failure strength of concrete increases with confining pressure which can be adequately described through pressure-sensitive failure criteria. Axial, radial, and volumetric strains were also measured during each test and these data were used to determine elastic properties. Experimental results are applicable in the design and analysis of scale-related functions and apply to other concrete structures subjected to compressive loadings such as dams and prestressed structural members

77 FR 50490 - Notice of Application Tendered for Filing with the Commission and Establishing Procedural...

Science.gov (United States)

2012-08-21

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 6597-013] Notice of...-long, 18.6- foot-high dam consisting of a gated 228-foot-long concrete gravity spillway with a crest... spillway; (4) a 435-acre impoundment with a storage capacity of 1,940 acre-feet and a normal maximum...

75 FR 65311 - Renew Hydro, LLC; Notice of Preliminary Permit Application Accepted for Filing and Soliciting...

Science.gov (United States)

2010-10-22

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 13815-000] Renew Hydro, LLC... Municipal Utilities Authority's existing 115-foot-high, 2,150-foot-long concrete gravity dam, with 500-foot...; (3) the existing Boonton reservoir with an 825-acre surface area and a 28,200 acre-foot storage area...

78 FR 22872 - Hamilton Street Hydro, LLC; Notice of Preliminary Permit Application Accepted for Filing and...

Science.gov (United States)

2013-04-17

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 14499-000] Hamilton Street... Project would consist of the following: (1) An existing 20-foot-high concrete gravity dam with a 690-foot-long spillway; (2) an existing impoundment having a surface area of 300 acres and a storage capacity of...

Constrained dynamics of universally coupled massive spin 2-spin 0 gravities

International Nuclear Information System (INIS)

Pitts, J Brian

2006-01-01

The 2-parameter family of massive variants of Einsteins gravity (on a Minkowski background) found by Ogievetsky and Polubarinov by excluding lower spins can also be derived using universal coupling. A Dirac-Bergmann constrained dynamics analysis seems not to have been presented for these theories, the Freund-Maheshwari-Schonberg special case, or any other massive gravity beyond the linear level treated by Marzban, Whiting and van Dam. Here the Dirac-Bergmann apparatus is applied to these theories. A few remarks are made on the question of positive energy. Being bimetric, massive gravities have a causality puzzle, but it appears soluble by the introduction and judicious use of gauge freedom

Geomorphic and Ecological Issues in Removal of Sediment-Filled Dams in the California Coast Ranges (Invited)

Science.gov (United States)

Kondolf, G. M.; Oreilly, C.

2010-12-01

Water-supply reservoirs in the actively eroding California Coast Ranges are vulnerable to sediment filling, thus creating obsolete impounding dams (Minear & Kondolf 2009). Once full of sediment, there is more impetus to remove dams for public safety and fish passage, but managing accumulated sediments becomes a dominant issue in dam removal planning. We analyzed the planning process and sediment management analyses for five dams, all of which have important ecological resources but whose dam removal options are constrained by potential impacts to downstream urban populations. Ringe Dam on Malibu Ck, Matilija Dam on the Ventura River, Searsville Dam on San Francisquito Ck, and Upper York Creek Dam on York Ck cut off important habitat for anadromous steelhead trout (Oncorhynchus mykiss). San Clemente Dam on the Carmel River has a working fish ladder, but only some of the migratory steelhead use it. By virtue of having filled with sediment, all five dams are at greater risk of seismic failure. San Clemente Dam is at greater risk because its foundation is on alluvium (not bedrock), and the poor-quality concrete in Matilija Dam is deteriorating from an akali-aggregate reaction. Simply removing the dams and allowing accumulated sediments to be transported downstream is not an option because all these rivers have extremely expensive houses along downstream banks and floodplains, so that allowing the downstream channel to aggrade with dam-dervied sediments could expose agencies to liability for future flood losses. Analyses of potential sediment transport have been based mostly on application of tractive force models, and have supported management responses ranging from in-situ stabilization (San Clemente and Matilija) to removal of stored sediment (York) to annual dredging to maintain capacity and prevent sediment passing over the dam (proposed for Searsville).

Repair Works for Uplift and Seepage Control in Existing Concrete Dams

Science.gov (United States)

1989-08-01

weathered and therefore where the presence of soil mterials is likely to occur in joints and fractures. Fig.5 - Varosa dam. Main results of mechanical...situations are associated with: emptying of reservoir by hot summer; water effects due to hydrostatic pressure and uplift; winter, spring and autumn...design stage were supported by tests of three-dimensional plaster- diatomite models, carried out at LNEC (1971c). The models were built in a scale of 1

Simplicial quantum gravity

International Nuclear Information System (INIS)

Hartle, J.B.

1985-01-01

Simplicial approximation and the ideas associated with the Regge calculus provide a concrete way of implementing a sum over histories formulation of quantum gravity. A simplicial geometry is made up of flat simplices joined together in a prescribed way together with an assignment of lengths to their edges. A sum over simplicial geometries is a sum over the different ways the simplices can be joined together with an integral over their edge lengths. The construction of the simplicial Euclidean action for this approach to quantum general relativity is illustrated. The recovery of the diffeomorphism group in the continuum limit is discussed. Some possible classes of simplicial complexes with which to define a sum over topologies are described. In two dimensional quantum gravity it is argued that a reasonable class is the class of pseudomanifolds

78 FR 62348 - Erie Boulevard Hydropower L.P.; Notice of Application Tendered for Filing With the Commission and...

Science.gov (United States)

2013-10-18

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 7518-015] Erie Boulevard... and a maximum storage capacity of approximately 112 acre-feet; (2) a 247- foot-long, 11.5-foot-high concrete gravity dam with a spillway crest elevation of 165.2 feet above mean sea level; (3) a 34-foot-long...

Alkali aggregate reactivity in concrete structures in western Canada

International Nuclear Information System (INIS)

Morgan, D.R.; Empey, D.

1989-01-01

In several regions of Canada, particularly parts of Ontario, Quebec and the Maritime Provinces, research, testing and evaluation of aged concrete structures in the field has shown that alkali aggregate reactivity can give rise to pronounced concrete deterioration, particularly in hydraulic structures subjected to saturation or alternate wetting and drying such as locks, dams, canals, etc. Concrete deterioration is mainly caused by alkali-silica reactions and alkali-carbonate reactions, but a third type of deterioration involves slow/late expanding alkali-silicate/silica reactivity. The alkalies NaOH and KOH in the concrete pore solutions are mainly responsible for attack on expansive rocks and minerals in concrete. Methods for evaluating alkali-aggregate reaction potential in aggregates, and field and laboratory methods for detecting deterioration are discussed. Examples of alkali-aggregate reactions in structures is western Canada are detailed, including a water reservoir at Canadian Forces Base Chilliwack in British Columbia, the Oldman River diversion and flume, the Lundbreck Falls Bridge, and the St Mary's Reservoir spillway, all in southern Alberta. Mitigative measures include avoidance of use of suspect aggregates, but if this cannot be avoided it is recommended to keep the total alkalies in the concrete as low as possible and minimize opportunities for saturation of concrete by moisture. 16 refs., 19 figs., 1 tab

Measuring autogenous strain of concrete with corrugated moulds

DEFF Research Database (Denmark)

Tian, Qian; Jensen, Ole Mejlhede

2008-01-01

A reliable technique to quantify autogenous strain is a prerequisite to numerical modeling in stress calculations for high performance concrete. The introducing of a special kind of corrugated tube mould helps to transforming volume strain measurement into liner strain measurement in horizontal...... direction for fluid concrete, which not only realizes the continuous monitoring of the autogenous shrinkage since casting, but also effectively eliminates the disturbance resulting from gravity, temperature variation and mould restraint on measuring results. Based on this measuring technique, this paper...

National Program for Inspection of Non-Federal Dams. Babson Reservoir Dam (MA 00187), Massachusetts-Rhode Island Coastal Basin, Gloucester, Massachusetts. Phase I Inspection Report.

Science.gov (United States)

1978-11-01

DIVISION, CORPS OF ENGINEERSWALTHAM, MASS 02154 NTIS GRA&n F NOVEMBER 1978 DTIC TAB Ŕ Justiftcati n r r D stributijon/ Availabilit -" os Dist jSpecial...flashboards removed and can pass the PMF outflow of 1530 cfs (750 csm) with the water level 0.6 ft.Ui below the top of the concrete core wall. Within... water treatment plant and responsible for the day-to-day operation of the dam. He represented the owner during this investigation. His address and

Grouting of the cracks in the Arch 5-6 Daniel Johnson dam

International Nuclear Information System (INIS)

Lariviere, R.; Routhier, L.; Roy, V.; Saleh, K.; Tremblay, S.

1999-01-01

The Daniel-Johnson dam is located 800 km northeast of Montreal, PQ, and is 1314 m in length and 214 m high. Just after completion of dam construction different types of cracks started to appear on the upstream and downstream faces. During and after the construction of the dam, numerous cracks and joints were grouted in order to reduce water infiltration. In some cases, as a result of high injection pressures and inaccurate methods, the injections provoked the propagation of the existing cracks or the initiation of new ones. Because of this situation and to determine the contribution of injection to dam safety, in 1985, Hydro-Quebec applied a moratorium on all future injection work on the dam. Research work was initiated in 1986 in the areas of grouting materials, methods, equipment and behavioral analysis to establish a safe method for the injection of the cracks. A committee was formed in 1993 with members from various groups, in order to: carry out extensive behavioral analysis of the Arch 5-6 dam, carry out an investigation program in order to determine the cause of the increase of the water infiltration, undertake a structural analysis program in order to evaluate the impact of an injection on the safety of the dam, and identify the proper method and injection products to use. In 1997, as a result of the progress of the structural analysis studies and the injection research project, a decision was made to proceed with the injection of the dam. A description is included of the results of the investigation, recommendations and results of the injection research project, as well as some details of the grouting campaign carried out in January 1999. On the whole, a better knowledge was acquired of the structure, of the plunging cracks and the behaviour of the dam during the injection. In the field of injection methods, materials and equipment, research work was invaluable when it came to the injection of micro-fine cracks in concrete dams. 5 refs., 8 figs

Semiclassical analysis of loop quantum gravity

International Nuclear Information System (INIS)

Conrady, F.

2005-01-01

In this Ph.D. thesis, we explore and develop new methods that should help in determining an effective semiclassical description of canonical loop quantum gravity and spin foam gravity. A brief introduction to loop quantum gravity is followed by three research papers that present the results of the Ph.D. project. In the first article, we deal with the problem of time and a new proposal for implementing proper time as boundary conditions in a sum over histories: we investigate a concrete realization of this formalism for free scalar field theory. In the second article, we translate semiclassical states of linearized gravity into states of loop quantum gravity. The properties of the latter indicate how semiclassicality manifests itself in the loop framework, and how this may be exploited for doing semiclassical expansions. In the third part, we propose a new formulation of spin foam models that is fully triangulation- and background-independent: by means of a symmetry condition, we identify spin foam models whose triangulation-dependence can be naturally removed. (orig.)

Semiclassical analysis of loop quantum gravity

Energy Technology Data Exchange (ETDEWEB)

Conrady, F.

2005-10-17

In this Ph.D. thesis, we explore and develop new methods that should help in determining an effective semiclassical description of canonical loop quantum gravity and spin foam gravity. A brief introduction to loop quantum gravity is followed by three research papers that present the results of the Ph.D. project. In the first article, we deal with the problem of time and a new proposal for implementing proper time as boundary conditions in a sum over histories: we investigate a concrete realization of this formalism for free scalar field theory. In the second article, we translate semiclassical states of linearized gravity into states of loop quantum gravity. The properties of the latter indicate how semiclassicality manifests itself in the loop framework, and how this may be exploited for doing semiclassical expansions. In the third part, we propose a new formulation of spin foam models that is fully triangulation- and background-independent: by means of a symmetry condition, we identify spin foam models whose triangulation-dependence can be naturally removed. (orig.)

Contrastive Numerical Investigations on Thermo-Structural Behaviors in Mass Concrete with Various Cements

Science.gov (United States)

Zhou, Wei; Feng, Chuqiao; Liu, Xinghong; Liu, Shuhua; Zhang, Chao; Yuan, Wei

2016-01-01

This work is a contrastive investigation of numerical simulations to improve the comprehension of thermo-structural coupled phenomena of mass concrete structures during construction. The finite element (FE) analysis of thermo-structural behaviors is used to investigate the applicability of supersulfated cement (SSC) in mass concrete structures. A multi-scale framework based on a homogenization scheme is adopted in the parameter studies to describe the nonlinear concrete behaviors. Based on the experimental data of hydration heat evolution rate and quantity of SSC and fly ash Portland cement, the hydration properties of various cements are studied. Simulations are run on a concrete dam section with a conventional method and a chemo-thermo-mechanical coupled method. The results show that SSC is more suitable for mass concrete structures from the standpoint of temperature control and crack prevention. PMID:28773517

Dam Safety Concepts

NARCIS (Netherlands)

Duricic, J.

2014-01-01

The majority of dams constructed in the world are dams that can be categorized as embankment dams. Throughout history we can point to many failures of dams, and embankment dams in particular. Nowadays it is clear that the goal to construct stable dams has not been achieved, even with advanced

76 FR 4097 - Erie Boulevard Hydropower, L.P.; Notice of Application Tendered for Filing With the Commission...

Science.gov (United States)

2011-01-24

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 2713-082] Erie Boulevard... Oswegatchie River and consists of: (1) A 941-foot-long dam with a 192-foot-long, 69-foot-high concrete gravity... seasonal flash boards; (2) a 168-acre reservoir with a gross storage capacity of 3,234 acre-feet and a...

77 FR 50682 - KC Scoby Hydro, LLC; Notice of Preliminary Permit Application Accepted for Filing and Soliciting...

Science.gov (United States)

2012-08-22

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 14423-000] KC Scoby Hydro... concrete gravity dam with a 183-foot-long spillway; (2) an existing impoundment having a surface area of 22 acres and a storage capacity of 52 acre-feet at an elevation of 1,080 feet mean sea level (msl); (3) a...

Circular symmetry in topologically massive gravity

International Nuclear Information System (INIS)

Deser, S; Franklin, J

2010-01-01

We re-derive, compactly, a topologically massive gravity (TMG) decoupling theorem: source-free TMG separates into its Einstein and Cotton sectors for spaces with a hypersurface-orthogonal Killing vector, here concretely for circular symmetry. We then generalize the theorem to include matter; surprisingly, the single Killing symmetry also forces conformal invariance, requiring the sources to be null. (note)

Circular symmetry in topologically massive gravity

Energy Technology Data Exchange (ETDEWEB)

Deser, S [Physics Department, Brandeis University, Waltham, MA 02454 (United States); Franklin, J, E-mail: deser@brandeis.ed, E-mail: jfrankli@reed.ed [Reed College, Portland, OR 97202 (United States)

2010-05-21

We re-derive, compactly, a topologically massive gravity (TMG) decoupling theorem: source-free TMG separates into its Einstein and Cotton sectors for spaces with a hypersurface-orthogonal Killing vector, here concretely for circular symmetry. We then generalize the theorem to include matter; surprisingly, the single Killing symmetry also forces conformal invariance, requiring the sources to be null. (note)

Emergent gravity from vanishing energy-momentum tensor

Energy Technology Data Exchange (ETDEWEB)

Carone, Christopher D.; Erlich, Joshua [High Energy Theory Group, Department of Physics, College of William and Mary,Williamsburg, VA 23187-8795 (United States); Vaman, Diana [Department of Physics, University of Virginia,Box 400714, Charlottesville, VA 22904 (United States)

2017-03-27

A constraint of vanishing energy-momentum tensor is motivated by a variety of perspectives on quantum gravity. We demonstrate in a concrete example how this constraint leads to a metric-independent theory in which quantum gravity emerges as a nonperturbative artifact of regularization-scale physics. We analyze a scalar theory similar to the Dirac-Born-Infeld (DBI) theory with vanishing gauge fields, with the DBI Lagrangian modulated by a scalar potential. In the limit of a large number of scalars, we explicitly demonstrate the existence of a composite massless spin-2 graviton in the spectrum that couples to matter as in Einstein gravity. We comment on the cosmological constant problem and the generalization to theories with fermions and gauge fields.

Emergent gravity from vanishing energy-momentum tensor

International Nuclear Information System (INIS)

Carone, Christopher D.; Erlich, Joshua; Vaman, Diana

2017-01-01

A constraint of vanishing energy-momentum tensor is motivated by a variety of perspectives on quantum gravity. We demonstrate in a concrete example how this constraint leads to a metric-independent theory in which quantum gravity emerges as a nonperturbative artifact of regularization-scale physics. We analyze a scalar theory similar to the Dirac-Born-Infeld (DBI) theory with vanishing gauge fields, with the DBI Lagrangian modulated by a scalar potential. In the limit of a large number of scalars, we explicitly demonstrate the existence of a composite massless spin-2 graviton in the spectrum that couples to matter as in Einstein gravity. We comment on the cosmological constant problem and the generalization to theories with fermions and gauge fields.

Dam Break Analysis of Embankment Dams Considering Breach Characteristics

Directory of Open Access Journals (Sweden)

Abolfazl Shamsaei

2004-05-01

Full Text Available The study of dam's break, needs the definition of various parameters such as the break cause, its type, its dimension and the duration of breach development. The precise forecast for different aspects of the breach is one of the most important factors for analyzing it in embankment dam. The characteristics of the breach and determination of their vulnerability has the most effect on the waves resulting from dam break. Investigating, about the parameters of the breach in "Silveh" earth dam have been determined using the suitable model. In Silve dam a trapezoid breach with side slope z=0.01m and the average base line b=80m was computed. The duration of the breaches development is 1.9 hour. Regarding the above results and the application of DAM Break software the consequences of the probable break of the dam was determined. The analysis of the results of water covering of the city of Piranshahr located 12km from silve dam confirms that in 3 hours the water will reach the height (level of 1425 meters.

National Dam Safety Program. Waterloo Dam (I.D. Number NY 709), Oswego River Basin, Seneca County, New York. Phase I Inspection Report,

Science.gov (United States)

1980-09-30

0.6. The two gravity sections were analyzed as sharp - crested weirs with a C of 3.2. For water surface elevations rising above the top-of-dam...elevation, a broad - crested weir C of 2.63 was used. Although there exists a small water-control structure at a bridge 200 feet left of the spiliway’s left...operating service I/ M/A Chute Length __ _ _ 7t± Height Between Spillway Crest IA & Approach Channel Invert ( Weir Flow) :5 50I1A. GqA1ES @ AJ I - CO

Application of parallel computing to seismic damage process simulation of an arch dam

International Nuclear Information System (INIS)

Zhong Hong; Lin Gao; Li Jianbo

2010-01-01

The simulation of damage process of high arch dam subjected to strong earthquake shocks is significant to the evaluation of its performance and seismic safety, considering the catastrophic effect of dam failure. However, such numerical simulation requires rigorous computational capacity. Conventional serial computing falls short of that and parallel computing is a fairly promising solution to this problem. The parallel finite element code PDPAD was developed for the damage prediction of arch dams utilizing the damage model with inheterogeneity of concrete considered. Developed with programming language Fortran, the code uses a master/slave mode for programming, domain decomposition method for allocation of tasks, MPI (Message Passing Interface) for communication and solvers from AZTEC library for solution of large-scale equations. Speedup test showed that the performance of PDPAD was quite satisfactory. The code was employed to study the damage process of a being-built arch dam on a 4-node PC Cluster, with more than one million degrees of freedom considered. The obtained damage mode was quite similar to that of shaking table test, indicating that the proposed procedure and parallel code PDPAD has a good potential in simulating seismic damage mode of arch dams. With the rapidly growing need for massive computation emerged from engineering problems, parallel computing will find more and more applications in pertinent areas.

77 FR 47618 - Algonquin Power Company; Notice of Application Accepted for Amendment of License and Soliciting...

Science.gov (United States)

2012-08-09

... more information on how to submit these types of filings, please go to the Commission's Web site.... The project Lower Beaver Falls project works consist of: (1) A 4-acre reservoir formed by a 400-foot long concrete gravity dam with a maximum height of 14 feet, and a head pond elevation of 769.3 feet...

NRC inventory of dams

International Nuclear Information System (INIS)

Lear, G.E.; Thompson, O.O.

1983-01-01

The NRC Inventory of Dams has been prepared as required by the charter of the NRC Dam Safety Officer. The inventory lists 51 dams associated with nuclear power plant sites and 14 uranium mill tailings dams (licensed by NRC) in the US as of February 1, 1982. Of the 85 listed nuclear power plants (148 units), 26 plants obtain cooling water from impoundments formed by dams. The 51 dams associated with the plants are: located on a plant site (29 dams at 15 plant sites); located off site but provide plant cooling water (18 dams at 11 additional plant sites); and located upstream from a plant (4 dams) - they have been identified as dams whose failure, and ensuing plant flooding, could result in a radiological risk to the public health and safety. The dams that might be considered NRC's responsibility in terms of the federal dam safety program are identified. This group of dams (20 on nuclear power plant sites and 14 uranium mill tailings dams) was obtained by eliminating dams that do not pose a flooding hazard (e.g., submerged dams) and dams that are regulated by another federal agency. The report includes the principal design features of all dams and related useful information

Anticipated sediment delivery to the lower Elwha River during and following dam removal: Chapter 2 in Coastal habitats of the Elwha River, Washington--biological and physical patterns and processes prior to dam removal

Science.gov (United States)

Czuba, Christiana R.; Randle, Timothy J.; Bountry, Jennifer A.; Magirl, Christopher S.; Czuba, Jonathan A.; Curran, Christopher A.; Konrad, Christopher P.; Duda, Jeffrey J.; Warrick, Jonathan A.; Magirl, Christopher S.

2011-01-01

During and after the planned incremental removal of two large, century-old concrete dams between 2011 and 2014, the sediment-transport regime in the lower Elwha River of western Washington will initially spike above background levels and then return to pre-dam conditions some years after complete dam removal. Measurements indicate the upper reaches of the steep-gradient Elwha River, draining the northeast section of the Olympic Mountains, carries between an estimated 120,000 and 290,000 cubic meters of sediment annually. This large load has deposited an estimated 19 million cubic meters of sediment within the two reservoirs formed by the Elwha and Glines Canyon Dams. It is anticipated that from 7 to 8 million cubic meters of this trapped sediment will mobilize and transport downstream during and after dam decommissioning, restoring the downstream sections of the sediment-starved river and nearshore marine environments. Downstream transport of sediment from the dam sites will have significant effects on channel morphology, water quality, and aquatic habitat during and after dam removal. Sediment concentrations are expected to be between 200 and 1,000 milligrams per liter during and just after dam removal and could rise to as much as 50,000 milligrams per liter during high flows. Downstream sedimentation in the river channel and flood plain will be potentially large, particularly in the lower Elwha River, an alluvial reach with a wide flood plain. Overall aggradation could be as much as one to several meters. Not all reservoir sediment, however, will be released to the river. Some material will remain on hill slopes and flood plains within the drained reservoirs in quantities that will depend on the hydrology, precipitation, and mechanics of the incising channel. Eventually, vegetation will stabilize this remaining reservoir sediment, and the overall sediment load in the restored river will return to pre-dam levels.

An Experimental Study of High Strength-High Volume Fly Ash Concrete for Sustainable Construction Industry

Science.gov (United States)

Kate, Gunavant K.; Thakare, Sunil B., Dr.

2017-08-01

Concrete is the most widely used building material in the construction of infrastructures such as buildings, bridges, highways, dams, and many other facilities. This paper reports the development, the basic idea, the main properties of high strength-high volume fly ash with application in concrete associated with the development and implementation of Sustainable Properties of High Volume Fly Ash Concrete (HVFAC) Mixtures and Early Age Shrinkage and mechanical properties of concrete for 7,28,56 and 90days. Another alternative to make environment-friendly concrete is the development of high strength-high-volume fly ash concrete which is an synthesized from materials of geological origin or by-product materials such as fly ash which is rich in silicon and aluminum. In this paper 6 concrete mixtures were produced to evaluate the effect of key parameters on the mechanical properties of concrete and its behavior. The study key parameters are; binder material content, cement replacement ratios, and the steel fibers used to High Volume Fly Ash mixtures for increasing performance of concrete.

Evaluation of microbially-influenced degradation of massive concrete structures

International Nuclear Information System (INIS)

Hamilton, M.A.; Rogers, R.D.; Zolynski, M.; Veeh, R.

1996-01-01

Many low level waste disposal vaults, both above and below ground, are constructed of concrete. One potential contributing agent to the destruction of concrete structures is microbially-influenced degradation (MID). Three groups of bacteria are known to create conditions that are conducive to destroying concrete integrity. They are sulfur oxidizing bacteria, nitrifying bacteria, and heterotrophic bacteria. Research is being conducted at the Idaho National Engineering Laboratory to assess the extent of naturally occurring microbially influenced degradation (MID) and its contribution to the deterioration of massive concrete structures. The preliminary steps to understanding the extent of MID, require assessing the microbial communities present on degrading concrete surfaces. Ultimately such information can be used to develop guidelines for preventive or corrective treatments for MID and aid in formulation of new materials to resist corrosion. An environmental study was conducted to determine the presence and activity of potential MID bacteria on degrading concrete surfaces of massive concrete structures. Scanning electron microscopy detected bacteria on the surfaces of concrete structures such as bridges and dams, where corrosion was evident. Enumeration of sulfur oxidizing thiobacilli and nitrogen oxidizing Nitrosomonas sp. and Nitrobacter sp. from surface samples was conducted. Bacterial community composition varied between sampling locations, and generally the presence of either sulfur oxidizers or nitrifiers dominated, although instances of both types of bacteria occurring together were encountered. No clear correlation between bacterial numbers and degree of degradation was exhibited

Effect of fast freeze-thaw cycles on mechanical properties of ordinary-air-entrained concrete.

Science.gov (United States)

Shang, Huai-shuai; Cao, Wei-qun; Wang, Bin

2014-01-01

Freezing-thawing resistance is a very significant characteristic for concrete in severe environment (such as cold region with the lowest temperature below 0°C). In this study, ordinary-air-entrained (O-A-E) concrete was produced in a laboratory environment; the compressive strength, cubic compressive strength of C50, C40, C30, C25, and C20 ordinary-air-entrained concrete, tensile strength, and cleavage strength of C30 ordinary-air-entrained concrete were measured after fast freeze-thaw cycles. The effects of fast freeze-thaw cycles on the mechanical properties (compressive strength and cleavage strength) of ordinary-air-entrained concrete materials are investigated on the basis of the experimental results. And the concise mathematical formula between mechanical behavior and number of fast freeze-thaw cycles was established. The experiment results can be used as a reference in design, maintenance, and life prediction of ordinary-air-entrained concrete structure (such as dam, offshore platform, etc.) in cold regions.

Deformation mechanism of the dam heel of Dagangshan high arch dam based on microseismic monitoring during initial impoundment%基于微震监测的大岗山高拱坝坝踵蓄水初期变形机制研究

Institute of Scientific and Technical Information of China (English)

马克; 金峰; 唐春安; 吕鹏飞; 庄端阳

2017-01-01

混凝土高拱坝坝踵是蓄水初期阶段拱坝安全的重点关注部位.通过构建国内首套高拱坝坝踵微震监测系统,实现对蓄水初期阶段大岗山拱坝坝踵区微破裂的实时监测,探究坝踵蓄水初期变形机制及其与微震活动性的关系.采用人工敲击试验确定坝踵等效P波波速为4 300 rn/s,系统定位误差小于8m.对系统获取的事件波形进行噪声滤除,并在自动定位基础上进行人工二次校核,提高定位精度,验证了微震监测技术应用于大体积混凝土工程的可行性.分析认为:蓄水初期阶段,大岗山高拱坝坝踵区微震活动性与库水位密切相关,微震事件聚集区实现从坝踵向坝趾的转移,坝踵压缩变形减小,而坝趾区变形量增加.此外,通过拱坝坝踵区微震变形演化过程,揭示了导流洞下闸蓄水前940 m高程基础廊道拱顶裂缝产生的根本诱因.研究成果可为混凝土高拱坝微震监测和真实工作性态研究提供参考.%The safety of the heel of the concrete high arch dam is highly concemed during the initial impoundment.The microseismic monitoring system was installed for the first time in China at the high arch dam heel.The real-time monitoring of the micro-cracks was achieved in the heel zone of the Dagangshan arch dam during the initial impoundment.The deformation mechanism of the arch dam heel and its relationship with the microseismic activities were investigated.The P wave velocity was determined using the manual tapping test and was 4 300 m/s with the error of system positioning less than 8 m.The event waveforms were denoised.The automatic positioning results were manually verified for better accuracy.The results proved the feasibility of applying the microseismic monitoring technology in the large-scale concrete structures.During the initial impoundment period,the microseismic activities of the high arch dam heel were closely related to the water level of reservoir.The accumulation

Approach, passage, and survival of juvenile salmonids at Little Goose Dam, Washington: Post-construction evaluation of a temporary spillway weir, 2009

Science.gov (United States)

Beeman, J.W.; Braatz, A.C.; Hansel, H.C.; Fielding, S.D.; Haner, P.V.; Hansen, G.S.; Shurtleff, D.J.; Sprando, J.M.; Rondorf, D.W.

2010-01-01

-type' fish that cease to migrate around July. Detection sites were installed in the forebay 2 kilometers upstream of the dam, on the dam, and at several sites downstream. Detection equipment was operated from April 18 to June 5, 2009, and from June 6 to July 6, 2009, hereinafter referred to as the study periods. We describe passage behaviors through the forebay, main passage routes, and tailrace, survival probabilities through the pool (release to the forebay) and forebay and passage and survival probabilities through the main passage routes (TSW, conventional spill bays, turbines, juvenile bypass), and survival passing the concrete (the dam itself) and the dam (concrete plus the forebay).

The hydraulic turbines of the Three Gorges dam; Les turbines hydrauliques du barrage des trois gorges

Energy Technology Data Exchange (ETDEWEB)

Bremond, J. [Societe GEC-Alsthom Neyrpic (France); Vuillerod, G. [Alsthom Hydro (France)

1999-10-01

As part of the hydroelectric installation of the Three Gorges on the Yangtze river in China, the Alsthom group recorded a major order for the supply of 8 Francis turbines out of the 14 to be installed in the left bank power station. This colossal project will include 26 Francis turbines of 710 MW, a spillway designed for a maximum flow of 116 000 m{sup 3}/s, a ship-lock of 5 steps with a capacity of 10 000 tons and a ship-lift of 3000 tons. The concrete gravity dam will be 2.3 km long. As oriented by the Specifications, and due to their exceptional size (runner diameter: 9800 mm), the design of these units relies upon well-proofed solutions such as those already experienced on the Itaipu south American large scale hydro project, in which Alsthom already contributed 20 years ago. The runners (450 tons each, external diameter 10 600 mm) will be fabricated by welding of separate elements made of martensitic stainless steel. Most of the components have to be delivered in several parts and reassembled at site by welding or bolting. The left bank power station is scheduled to be operational in 2006. (authors) 2 refs.

Dams

Data.gov (United States)

Vermont Center for Geographic Information — This dataset �is generated from from the Vermont Dam Inventory (VDI). The VDI is managed by the VT DEC's Dam Safety and Hydrology Section and contains information...

Monitoring evaluation of a spillway pilaster for Premiere Chute Dam

Energy Technology Data Exchange (ETDEWEB)

Crepeau, Louis; Kassem, Chakib [OSMOS Canada Inc., Montreal, (Canada)

2010-07-01

The Premiere-Chute hydroelectric power station, commissioned in 1968, has four hydraulic turbines for a total of 130 MW. One of the pilasters of the dam weir, built with pre-stressed concrete, showed a crack at the level of the post-tension cable. This paper presented an evaluation of the behaviour of the pilaster in question, No. 9. The main goal was to prevent any disruption to the gate opening through adequate monitoring for a long term data follow-up. Six long-base OSMOS type optical sensors were installed on each face of the spillway pilaster. The behaviour of the No. 9 pilaster was then compared with that of other pilasters with respect to the effects of temperature and water level fluctuation in the dam. After the pilasters had been monitored for six months, it was found that No. 9 pilaster showed the least deformation of all. It was therefore concluded that the behaviour of this pilaster was normal.

NOTE: Circular symmetry in topologically massive gravity

Science.gov (United States)

Deser, S.; Franklin, J.

2010-05-01

We re-derive, compactly, a topologically massive gravity (TMG) decoupling theorem: source-free TMG separates into its Einstein and Cotton sectors for spaces with a hypersurface-orthogonal Killing vector, here concretely for circular symmetry. We then generalize the theorem to include matter; surprisingly, the single Killing symmetry also forces conformal invariance, requiring the sources to be null.

Flow induced particle migration in fresh concrete: Theoretical frame, numerical simulations and experimental results on model fluids

DEFF Research Database (Denmark)

Spangenberg, J.; Roussel, N.; Hattel, J.H.

2012-01-01

In this paper, we describe and compare the various physical phenomena which potentially lead to flow induced particle migration in concrete. We show that, in the case of industrial casting of concrete, gravity induced particle migration dominates all other potential sources of heterogeneities ind...

Results of Laboratory Tests of the Filtration Characteristics of Clay-Cement Concrete

Energy Technology Data Exchange (ETDEWEB)

Sol’skii, S. V., E-mail: solskiysv@vniig.ru; Lopatina, M. G., E-mail: LoptainaMG@vniig.ru; Legina, E. E.; Orishchuk, R. N.; Orlova, N. L. [B. E. Vedeneev All-Russia Research Institute of Hydraulic Engineering (VNIIG) (Russian Federation)

2017-01-15

Laboratory studies of the filtration characteristics of clay-cement concrete materials for constructing filtering diaphragms of earth dams by the method of secant piles are reported. Areas for further study aimed at improving the quality of construction, increasing operational safety, and developing a standards base for the design, construction, and operation of these systems are discussed.

Optimizing the use of natural gravel Brantas river as normal concrete mixed with quality fc = 19.3 Mpa

Science.gov (United States)

Limantara, A. D.; Widodo, A.; Winarto, S.; Krisnawati, L. D.; Mudjanarko, S. W.

2018-04-01

The use of natural gravel (rivers) as concrete mixtures is rarely encountered after days of demands for a higher strength of concrete. Moreover, today people have found High-Performance Concrete which, when viewed from the rough aggregate consisted mostly of broken stone, although the fine grain material still used natural sand. Is it possible that a mixture of concrete using natural gravel as a coarse aggregate is capable of producing concrete with compressive strength equivalent to a concrete mixture using crushed stone? To obtain information on this, a series of tests on concrete mixes with crude aggregates of Kalitelu Crusher, Gondang, Tulungagung and natural stone (river gravel) from the Brantas River, Ngujang, Tulungagung in the Materials Testing Laboratory Tugu Dam Construction Project, Kab. Trenggalek. From concrete strength test results using coarse material obtained value 19.47 Mpa, while the compressive strength of concrete with a mixture of crushed stone obtained the value of 21.12 Mpa.

Effect of imperfect knowledge of hazards on the reliability of concrete face rockfill dam and breakwater

Directory of Open Access Journals (Sweden)

D. De León–Escobedo

2008-07-01

Full Text Available A formulation to treat aleatory and epistemic uncertainties, in a separate way, on infrastructures is proposed and applied to a dam and a breakwater in Mexico. The purpose of that is to de termine 2nd order bounds on the reliability estimation due to the in complete knowledge of some design parameters. These bounds provide a quantitative basis for risk management according to the risk–aversion of owners and operators of the infrastructure. Also, acceptable values of reliability, are assessed in terms of consequences costs, and an initial cost curve for a breakwater is presented, as they may contribute to enhance the decision making process.The in corporation of epistemic uncertainty makes the reliability index to become a random variable and its his to gram is obtained to estimate percentiles as a means to measure a new additional room for decisions as compared to the traditionally used mean value of the reliability. Conservative decisions are illustrated for design and assessment of structures like a dam and a breakwater.The procedure involves a double loop of Monte Carlo simulation and represents a basis for the optimal design and risk management of dams and breakwaters.

Preparation and Mechanical Properties of Pressed Straw Concrete Brick

Science.gov (United States)

Sumarni, S.; Wijanarko, W.

2018-03-01

Rice straws have been widely used as wall filler material in China, Australia, and United States, by spinning them into hays with an approximate dimension of 40 cm of height, 40cm of thickness and 60 cm of width, using a machine. Then, the hays are placed into a wall frame until they fill it completely. After that, the wall frame is covered with wire mesh and plastered. In this research, rice straws are to be used as concrete brick fillers, by pressing the straws into hays and then putting them into the concrete brick mold along with mortar. The objective of this research is to investigate the mechanical properties of concrete brick, namely: compressive strength, specific gravity, and water absorption power. This research used experimental research method. It was conducted by using concrete bricks which had 400 cm of width, 200 cm of height, and 100 cm of thickness, made from rice straws, cement, sand, and water as the test sample. The straws were each made different by their volume. The mortars used in this research were made from cement, sand, and water, with the ratio of 1:7:0.5. The concrete bricks were made by pressing straws mixed with glue into hays, and then cut by determined variations of volume. The variations of hays volume were 0 m3, 0.000625 m3, 0.00075 m3, 0.000875 m3, 0.00125 m3, 0.0015 m3, 0.00175 m3, 0.001875 m3, 0.00225 m3, and 0.002625 m3. There were 3 samples for each volumes of hays. The result shows that the straw concrete bricks reached the maximum compressive strength of 1.92 MPa, specific gravity of 1,702 kg/m3, and water absorption level of 3.9 %. Based on the provided measurements of products in the Standar Nasional Indonesia (Indonesian product standardization), the concrete bricks produced attained the prescribed standard quality.

Influence of calcined mud on the mechanical properties and shrinkage of self-compacting concrete

Directory of Open Access Journals (Sweden)

Fatima Taieb

2018-01-01

Full Text Available The use of SCC has a particular interest in terms of sustainable development. Indeed, their specific formulation leads to a greater volume of dough than for common concretes, thus, a larger quantity of cement. However, for economical, ecological and technical reasons, it is sought to limit their cement content [1]. It is therefore necessary to almost always use mineral additions as a partial replacement for cement because the technology of self-compacting concretes can consume large quantities of fines, in this case calcinated mud issued from dams dredging sediments that can give and/or ameliorate characteristics and performances of this type of concretes. Four SCCs had been formulated from the same composition where the only percentage of calcinated mud of Chorfa (west of Algeria dam changed (0%, 10%, 20% and 30%. The effect of calcinated mud on characteristics at fresh state of SCC according to AFGC was quantified. Mechanical strengths and shrinkage deformation (total, autogenous, drying were evaluated. The results show the possibility to make SCCs with different dosages of calcinated mud having strengths that can defy those of the control SCC. The analysis of free deformations indicates the beneficial impact of the mud by contributing to decrease the amplitudes of the shrinkage compared to those of the control SCC.

Compressive Strength of Concrete made from Natural Fine Aggregate Sources in Minna, Nigeria

Directory of Open Access Journals (Sweden)

M. Abdullahi

2017-12-01

Full Text Available This work presented an investigation of concrete developed from five fine aggregate sources in Minna, Niger state, Nigeria. Tests conducted on the fine aggregate samples included specific gravity, sieve analysis, bulk density and moisture content. The concrete mix design was done using absolute volume method at various mix proportion of 1:2:4, 1:2:3 and 1:1:2 and water-cement ratios of 0.4, 0.45, 0.5, 0.55 and 0.6. The compressive strengths of concrete were determined at 28-day curing age. Test results revealed that the specific gravities of the aggregate were between 2.60 to 2.70, compacted bulk densities also ranged from 1505.18 to 1701.15kg/m3, loose bulk densities ranged from 1379.32 to 1478.17kg/m3, and moisture content ranged from 0.93 to 2.47%. All the fine aggregate samples satisfied the overall and medium grading limits for natural fine aggregates. The coarse aggregate used fairly followed the grading limit for aggregate size of 20 to 5 mm. The compressive strength of the concrete obtained using the aggregate samples A, B, C, D, and Eall within the ranges of 18.97 to 34.98 N/mm2. Statistical models were developed for the compressive strength of concrete as a function of water-cement ratio for various fine aggregate sources and mix proportions. The models were found to have good predictive the capabilities of the compressive strength of concrete for given water-cement ratio. The properties of fine aggregates and the resulting concrete characteristics showed that all the fine aggregate samples are suitable to be used for concrete production.

Entropy bound and causality violation in higher curvature gravity

International Nuclear Information System (INIS)

Neupane, Ishwaree P; Dadhich, Naresh

2009-01-01

In any quantum theory of gravity we do expect corrections to Einstein gravity to occur. Yet, at a fundamental level, it is not apparent what the most relevant corrections are. We argue that the generic curvature square corrections present in the lower dimensional actions of various compactified string theories provide a natural passage between the classical and quantum realms of gravity. The Gauss-Bonnet and (Riemann) 2 gravities, in particular, provide concrete examples in which inconsistency of a theory, such as a violation of microcausality, and a classical limit on black hole entropy are correlated. In such theories the ratio of the shear viscosity to the entropy density, η/s, can be smaller than for a boundary conformal field theory with Einstein gravity dual. This result is interesting from the viewpoint that nuclear matter or quark-gluon plasma produced (such as at RHIC) under extreme densities and temperatures may violate the conjectured KSS bound η/s ≥ 1/4π, albeit marginally so.

Safety Aspects of Sustainable Storage Dams and Earthquake Safety of Existing Dams

Directory of Open Access Journals (Sweden)

Martin Wieland

2016-09-01

Full Text Available The basic element in any sustainable dam project is safety, which includes the following safety elements: ① structural safety, ② dam safety monitoring, ③ operational safety and maintenance, and ④ emergency planning. Long-term safety primarily includes the analysis of all hazards affecting the project; that is, hazards from the natural environment, hazards from the man-made environment, and project-specific and site-specific hazards. The special features of the seismic safety of dams are discussed. Large dams were the first structures to be systematically designed against earthquakes, starting in the 1930s. However, the seismic safety of older dams is unknown, as most were designed using seismic design criteria and methods of dynamic analysis that are considered obsolete today. Therefore, we need to reevaluate the seismic safety of existing dams based on current state-of-the-art practices and rehabilitate deficient dams. For large dams, a site-specific seismic hazard analysis is usually recommended. Today, large dams and the safety-relevant elements used for controlling the reservoir after a strong earthquake must be able to withstand the ground motions of a safety evaluation earthquake. The ground motion parameters can be determined either by a probabilistic or a deterministic seismic hazard analysis. During strong earthquakes, inelastic deformations may occur in a dam; therefore, the seismic analysis has to be carried out in the time domain. Furthermore, earthquakes create multiple seismic hazards for dams such as ground shaking, fault movements, mass movements, and others. The ground motions needed by the dam engineer are not real earthquake ground motions but models of the ground motion, which allow the safe design of dams. It must also be kept in mind that dam safety evaluations must be carried out several times during the long life of large storage dams. These features are discussed in this paper.

Damming evidence : Canada and the World Commission on Dams

Energy Technology Data Exchange (ETDEWEB)

Vert, P.; Parkinson, B.

2003-06-01

Large hydroelectric projects have been met with strong resistance from affected communities, particularly indigenous groups who have been displaced from their flooded communities following the damming of a river. The World Commission on Dams (WCD) was formed in 1998 to review the effectiveness of large dams and develop internationally acceptable guidelines and standards for large dams or hydro energy projects. The Canadian government, through the Canadian International Development Agency, was one of many governments to fund the WCD. However, the authors argue that despite the financial support, the Canadian government was absent from any effort to follow-up on the recommendations of the WCD. The seven strategic priorities in the decision making process include: (1) gaining public acceptance, (2) comprehensive option assessment of water, energy, food and development needs, (3) addressing existing dams to improve the benefits that can be derived from them, (4) sustaining livelihoods, (5) recognizing the entitlements and sharing benefits, (6) ensuring compliance, and (7) sharing rivers for peace, development and security. This report offers a means to assess planned or existing dams and presents a set of guidelines for good practices linked to the seven strategic priorities. Ten case studies from around the world were presented, including the Three Gorges Dam in China. 154 refs., 3 figs., 3 appendices.

Proceedings of the 2010 Canadian Dam Association's public safety around dams workshop

Energy Technology Data Exchange (ETDEWEB)

NONE

2010-07-01

Nearly 30 people have drowned in dam-related incidents over the last 10 years in Canada. The Canadian public is now calling for improved safety guidelines. Public interaction with dams is increasing as a result of interest in extreme sports and perceived rights of access. However, many members of the public are not aware of the dangers posed by dams. This workshop provided a forum to discuss proposals for a draft publication of the Canadian Dam Association (CDA) guidelines for public safety and security around dams. Issues related to current legislation and liability were discussed. Methods of increasing public awareness of the hazards posed by dams included increased signage in dam locations, the use of audible and visual alert systems, and the use of booms and buoys. The responsibilities of dam owners in ensuring the safety of dams were also discussed. The conference featured 5 presentations, of which 2 have been catalogued separately for inclusion in this database. tabs., figs.

Research on Safety Factor of Dam Slope of High Embankment Dam under Seismic Condition

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Li Bin

2015-01-01

Full Text Available With the constant development of construction technology of embankment dam, the constructed embankment dam becomes higher and higher, and the embankment dam with its height over 200m will always adopt the current design criteria of embankment dam only suitable for the construction of embankment dam lower than 200m in height. So the design criteria of high embankment dam shall be improved. We shall calculate the stability and safety factors of dam slope of high embankment dam under different dam height, slope ratio and different seismic intensity based on ratio of safety margin, and clarify the change rules of stability and safety factors of dam slope of high embankment dam with its height over 200m. We calculate the ratio of safety margin of traditional and reliable method by taking the stable, allowable and reliability index 4.2 of dam slope of high embankment dam with its height over 200m as the standard value, and conduct linear regression for both. As a result, the conditions, where 1.3 is considered as the stability and safety factors of dam slope of high embankment dam with its height over 200m under seismic condition and 4.2 as the allowable and reliability index, are under the same risk control level.

Concrete for the construction of No. 1 nuclear power generator of Tokyo Denryoku Co.'s Kashiwazaki, Kariha nuclear power station

International Nuclear Information System (INIS)

Suzuki, Yasuyoshi; Eguchi, Kiyoshi; Nakakomi, Akira.

1985-01-01

The construction of the No.1 power generator of Kariha nuclear power generator was completed on March 1985, and the installations of equipments are on their way aiming the start in October 1960. About 900,000 m 3 of concrete was produced and used for whole work and about 500,000 m 3 out of total was used for the construction of plant building. For constructing reactor building and turbin building, the concrete must have shielding property against radiation. The specific gravity no less than 2.5 was required for dry state of laid concrete. In order to supply very large amount of concrete with stable quality, preliminary investigation on raw materials including aggregates, fly-ash and surface active agents, were made. Aggregates were stored in underground bins to keep the temperature constant for the purpose of obtaining mixed concrete with constant temperature. For determining the mixing rate of concrete, physical test such as slump test, determination of air content, determinations of strengths and specific gravities of solidified concrete. Quality control committee was established to observe the optimum condition, which were confirmed by preliminary tests, of concrete preparation. As the results of detailed preliminary investigation on respective raw material and strict quality control from the source of raw material to mixed concrete, the supply of concrete with stable quality which conforms every requirement of standard, was possible. (Ishimitsu, A.)

Repair in Mourao power plant spillway: application of recycled material concrete admixtures - stage one; Reparos no vertedouro da UHE Mourao: aplicacao de concretos com adicao de material reciclado - 1a. parte

Energy Technology Data Exchange (ETDEWEB)

Galvao, Jose Carlos Alves; Portella, Kleber Franke; Joukoski, Alex; Mendes, Roberto [Instituto de Tecnologia para o Desenvolvimento (LACTEC), Curitiba, PR (Brazil)], Emails: jose.galvao@lactec.org.br, portella@lactec.org.br, alex@lactec.org.br; roberto.mendes@lactec.org.br; Ferreira, Elizeu Santos [Companhia Paranaense de Energia (COPEL), Curitiba, PR (Brazil)], Email: elizeu.sf@copel.com

2009-10-15

The Mourao hydroelectric power plant located in the city of Campo Mourao, in the state of Parana, southern region of Brazil, was inaugurated in 1964, with 7500 kW of installed power. Defects in the spillway surface of the dam had been identified throughout the time. With the purpose of recovering the concrete hydraulic surface, repair materials were proposed in this paper, considering technology development and environment conservation. Concrete mixtures containing recycled materials - low-density polyethylene (LDPE), polyethylene terephthalate (PET) and waste tires - had its performance tested in laboratory. Mechanical properties, such as compressive strength, tensile strength and adherence were evaluated using cylindrical concrete specimens. Results were appraised and the best compositions were selected to be tested on spillway surface of Mourao dam. (author)

Development of Large Concrete Object Geometrical Model Based on Terrestrial Laser Scanning

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Zaczek-Peplinska Janina

2015-02-01

Full Text Available The paper presents control periodic measurements of movements and survey of concrete dam on Dunajec River in Rożnów, Poland. Topographical survey was conducted using laser scanning technique. The goal of survey was data collection and creation of a geometrical model. Acquired cross- and horizontal sections were utilised to create a numerical model of object behaviour at various load depending of changing level of water in reservoir. Modelling was accomplished using finite elements technique. During the project an assessment was conducted to terrestrial laser scanning techniques for such type of research of large hydrotechnical objects such as gravitational water dams. Developed model can be used to define deformations and displacement prognosis.

Long-term behaviour of concrete under saline conditions for long-term stable sealing structures; Langzeitverhalten von Beton unter salinaren Bedingungen fuer langzeitstabile Verschlussbauwerke

Energy Technology Data Exchange (ETDEWEB)

Dahlhaus, Frank; Haucke, Joerg [Technische Univ. Bergakademie Freiberg (Germany). Inst. fuer Bergbau und Spezialtiefbau

2012-03-15

The authors of the contribution under consideration examine the long-term behaviour of concrete under saline conditions and in particular the suitability of the dam construction materials salt concrete and brine concrete for the use as a part of a sealing system of long-term stable geotechnical sealing structures. The long-term stability of the building material mainly is determined by the corrosion of the cement paste phases. The specific shrinkage behaviour of the construction material is analyzed experimentally in order to verify the expected cracks. The mechanisms of cracking in the salt concrete and brine concrete are analyzed by means of a mesomechanical approach in numerical finite-element calculations.

Dams designed to fail

Energy Technology Data Exchange (ETDEWEB)

Penman, A. [Geotechnical Engineering Consultants, Harpenden (United Kingdom)

2004-09-01

New developments in geotechnical engineering have led to methods for designing and constructing safe embankment dams. Failed dams can be categorized as those designed to fail, and those that have failed unexpectedly. This presentation outlined 3 dam failures: the 61 m high Malpasset Dam in France in 1959 which killed 421; the 71 m high Baldwin Hills Dam in the United States in 1963 which killed 5; and, the Vajont Dam in Italy in 1963 which killed 2,600 people. Following these incidents, the International Commission for Large Dams (ICOLD) reviewed regulations on reservoir safety. The 3 dams were found to have inadequate spillways and their failures were due to faults in their design. Fuse plug spillways, which address this problem, are designed to fail if an existing spillway proves inadequate. They allow additional discharge to prevent overtopping of the embankment dam. This solution can only be used if there is an adjacent valley to take the additional discharge. Examples of fuse gates were presented along with their effect on dam safety. A research program is currently underway in Norway in which high embankment dams are being studied for overtopping failure and failure due to internal erosion. Internal erosion has been the main reason why dams have failed unexpectedly. To prevent failures, designers suggested the use of a clay blanket placed under the upstream shoulder. However, for dams with soft clay cores, these underblankets could provide a route for a slip surface and that could lead to failure of the upstream shoulder. It was concluded that a safe arrangement for embankment dams includes the use of tipping gates or overturning gates which always fail at a required flood water level. Many have been installed in old and new dams around the world. 14 refs., 19 figs.

Hydro in China: Sino-Canadian cooperation

International Nuclear Information System (INIS)

Wiebe, P.A.; Webb, N.K.

1988-01-01

Despite a population of over 1 billion, China's installed electric generating capacity is similar to Canada's. To help alleviate the energy shortfalls, the government's seventh 5 year plan (1985-1990) calls for annual installation of new capacity of ca 7,000 MW, the equivalent of a James Bay and Churchill Falls complex every two years. In the short term, 2/3 of new capacity will be filled by thermal stations, but in the longer term, China will turn to its huge undeveloped hydroelectric generating capacity. Information is presented on China's hydroelectric resources, and four hydro projects currently under development in conjunction with Canadian International Project Managers (CIPM), a company whose members are Acres International Inc. of Toronto, Lavalin International Inc. of Montreal and S.N.C. Inc. of Montreal. The Zhao Ping project is a conventional 200 MW project on the Gui River in Guangxi Province in south China, comprising a 73 m high concrete gravity dam and spillway. The Gehe Yan comprises a 151 m high concrete gravity arch dam and spillway and a 1,200 MW powerhouse. The Longtan project would be a 215 m high concrete rockfaced dam with ten 500 MW units and an inclined shiplift with a 500 tonne vessel capacity. The Three Gorges is a multi-purpose water control project that will provide flood control to the regions on the middle reaches of the Yangtze, generate over 8,300 MW of power, and improve navigation on the Yangtze River as far as Chongqing. Up to 750,000 people will have to be resettled to higher land within the river valley. 4 figs., 2 tabs

Dam removal: Listening in

Science.gov (United States)

Foley, M. M.; Bellmore, J. R.; O'Connor, J. E.; Duda, J. J.; East, A. E.; Grant, G. E.; Anderson, C. W.; Bountry, J. A.; Collins, M. J.; Connolly, P. J.; Craig, L. S.; Evans, J. E.; Greene, S. L.; Magilligan, F. J.; Magirl, C. S.; Major, J. J.; Pess, G. R.; Randle, T. J.; Shafroth, P. B.; Torgersen, C. E.; Tullos, D.; Wilcox, A. C.

2017-07-01

Dam removal is widely used as an approach for river restoration in the United States. The increase in dam removals—particularly large dams—and associated dam-removal studies over the last few decades motivated a working group at the USGS John Wesley Powell Center for Analysis and Synthesis to review and synthesize available studies of dam removals and their findings. Based on dam removals thus far, some general conclusions have emerged: (1) physical responses are typically fast, with the rate of sediment erosion largely dependent on sediment characteristics and dam-removal strategy; (2) ecological responses to dam removal differ among the affected upstream, downstream, and reservoir reaches; (3) dam removal tends to quickly reestablish connectivity, restoring the movement of material and organisms between upstream and downstream river reaches; (4) geographic context, river history, and land use significantly influence river restoration trajectories and recovery potential because they control broader physical and ecological processes and conditions; and (5) quantitative modeling capability is improving, particularly for physical and broad-scale ecological effects, and gives managers information needed to understand and predict long-term effects of dam removal on riverine ecosystems. Although these studies collectively enhance our understanding of how riverine ecosystems respond to dam removal, knowledge gaps remain because most studies have been short (< 5 years) and do not adequately represent the diversity of dam types, watershed conditions, and dam-removal methods in the U.S.

Public safety around dams

Energy Technology Data Exchange (ETDEWEB)

Bourassa, H. [Centre d' expertise hydrique du Quebec, Quebec, PQ (Canada)

2009-07-01

Fourty public dams are managed on a real-time basis by the Centre d'expertise hydrique du Quebec (CEHQ). This presentation described the public dams owned by the CEHQ and discussed the public safety measures at the dams. The dams serve various purposes, including protection against floods; industrial or drinking water supply; resort or recreational activities; hydroelectric development; and wildlife conservation. Trigger events were also discussed, such as the complaint at Rapides-des-Cedres dam and deaths that occurred in 2004 when water from a dam was released without warning. Several photographs were presented to illustrate that people were unaware of the danger. Initiatives aimed at raising awareness and studying public safety issues were discussed. A pilot project was launched and a permanent committee was created to evaluate all aspects of public safety at the dams owned by CEHQ. The first tasks of the committee were to establish requirements for waterway safety barriers, both upstream and downstream, for all public dams; to establish requirements for safety signage for all public dams; and to develop criteria to decide on safety signage at each dam. figs.

Public safety around dams

Energy Technology Data Exchange (ETDEWEB)

Bourassa, H [Centre d' expertise hydrique du Quebec, Quebec, PQ (Canada)

2009-07-01

Fourty public dams are managed on a real-time basis by the Centre d'expertise hydrique du Quebec (CEHQ). This presentation described the public dams owned by the CEHQ and discussed the public safety measures at the dams. The dams serve various purposes, including protection against floods; industrial or drinking water supply; resort or recreational activities; hydroelectric development; and wildlife conservation. Trigger events were also discussed, such as the complaint at Rapides-des-Cedres dam and deaths that occurred in 2004 when water from a dam was released without warning. Several photographs were presented to illustrate that people were unaware of the danger. Initiatives aimed at raising awareness and studying public safety issues were discussed. A pilot project was launched and a permanent committee was created to evaluate all aspects of public safety at the dams owned by CEHQ. The first tasks of the committee were to establish requirements for waterway safety barriers, both upstream and downstream, for all public dams; to establish requirements for safety signage for all public dams; and to develop criteria to decide on safety signage at each dam. figs.

Physical Hydraulic Model of Side-Channel Spillway of Lambuk DAM, Bali

Science.gov (United States)

Harifa, A. C.; Sholichin, M.; Othman, F. B.

2013-12-01

The spillway is among the most important structures of a dam project. A spillway is designed to prevent overtopping of a dam at a place that is not designed for overtopping. Side-channel spillways are commonly used to release water flow from a reservoir in places where the sides are steep and have a considerable height above the dam. Experimental results were collected with a hydraulic model of the side-channel spillway for releasing the peak overflow of Lambuk Dam. This dam is, located on the Lambuk River, which is a tributary of the Yeh Hoo River ~ 34.6 km north of Denpasar on the island of Bali. The bituminous geomembrane faced dam is 24 m in height, with a 35-m wide spillway. The length of the side channel is 35 m long, with 58 m of transition channel, 67.37 m of chuteway channel and 22.71 m of stilling basin. The capacity of the spillway is 231.91 m3/s and the outlet works capacity is 165.28 m3/s. The reservoir is designed for irrigation and water supply. The purpose of this study was to optimize the designed of the structure and to ensure its safe operation. In hydraulic model may help the decision-makers to visualize the flow field before selecting a ';suitable' design. The hydraulic model study was performed to ensure passage of the maximum discharge at maximum reservoir capacity; to study the spillway approach conditions, water surface profiles, and flow patterns in the chuteway; and to reveal potential demerits of the proposed hydraulic design of various structures and explore solutions. The model was constructed at 1 : 40 scale, Reservoir topography was modeled using concrete, the river bed using sand and some gravel, the river berm using concrete, and the spillway and channel using Plexiglas. Water was measured using Rectangular contracted weir. Design floods (with return period in year) were Q2 = 111.40 m3/s, Q5 = 136.84 m3/s, Q10 = 159.32 m3/s, Q25 = 174.61 m3/s, Q50 = 185.13 m3/s, Q100 = 198.08 m3/s, Q200 = 210.55 m3/s, Q1000 = 231.91 m3/s and the

Causes of Early Age Cracking on Concrete Bridge Deck Expansion Joint Repair Sections

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Jared R. Wright

2014-01-01

Full Text Available Cracking of newly placed binary Portland cement-slag concrete adjacent to bridge deck expansion dam replacements has been observed on several newly rehabilitated sections of bridge decks. This paper investigates the causes of cracking by assessing the concrete mixtures specified for bridge deck rehabilitation projects, as well as reviewing the structural design of decks and the construction and curing methods implemented by the contractors. The work consists of (1 a comprehensive literature review of the causes of cracking on bridge decks, (2 a review of previous bridge deck rehabilitation projects that experienced early-age cracking along with construction observations of active deck rehabilitation projects, and (3 an experimental evaluation of the two most commonly used bridge deck concrete mixtures. Based on the literature review, the causes of concrete bridge deck cracking can be classified into three categories: concrete material properties, construction practices, and structural design factors. The most likely causes of the observed early-age cracking were found to be inadequate curing and failure to properly eliminate the risk of plastic shrinkage cracking. These results underscore the significance of proper moist curing methods for concrete bridge decks, including repair sections. This document also provides a blueprint for future researchers to investigate early-age cracking of concrete structures.

Dam failure analysis for the Lago El Guineo Dam, Orocovis, Puerto Rico

Science.gov (United States)

Gómez-Fragoso, Julieta; Heriberto Torres-Sierra,

2016-08-09

The U.S. Geological Survey, in cooperation with the Puerto Rico Electric Power Authority, completed hydrologic and hydraulic analyses to assess the potential hazard to human life and property associated with the hypothetical failure of the Lago El Guineo Dam. The Lago El Guineo Dam is within the headwaters of the Río Grande de Manatí and impounds a drainage area of about 4.25 square kilometers.The hydrologic assessment was designed to determine the outflow hydrographs and peak discharges for Lago El Guineo and other subbasins in the Río Grande de Manatí hydrographic basin for three extreme rainfall events: (1) a 6-hour probable maximum precipitation event, (2) a 24-hour probable maximum precipitation event, and (3) a 24-hour, 100-year recurrence rainfall event. The hydraulic study simulated a dam failure of Lago El Guineo Dam using flood hydrographs generated from the hydrologic study. The simulated dam failure generated a hydrograph that was routed downstream from Lago El Guineo Dam through the lower reaches of the Río Toro Negro and the Río Grande de Manatí to determine water-surface profiles developed from the event-based hydrologic scenarios and “sunny day” conditions. The Hydrologic Engineering Center’s Hydrologic Modeling System (HEC–HMS) and Hydrologic Engineering Center’s River Analysis System (HEC–RAS) computer programs, developed by the U.S. Army Corps of Engineers, were used for the hydrologic and hydraulic modeling, respectively. The flow routing in the hydraulic analyses was completed using the unsteady flow module available in the HEC–RAS model.Above the Lago El Guineo Dam, the simulated inflow peak discharges from HEC–HMS resulted in about 550 and 414 cubic meters per second for the 6- and 24-hour probable maximum precipitation events, respectively. The 24-hour, 100-year recurrence storm simulation resulted in a peak discharge of about 216 cubic meters per second. For the hydrologic analysis, no dam failure conditions are

Study on abrasion resisting material for apron of dam; Dam apron bu no taimamo sozai ni kansuru kenkyu

Energy Technology Data Exchange (ETDEWEB)

Inaba, H.; Hiraki, M.; Miyamoto, T. [Hokuriku Electric Power Co. Inc., Toyama (Japan)

1995-01-25

A `laminated rubber tile` and a `shock absorbing holed-in anchor` were devised in connection with the apron of a dam for a hydroelectric power plant. As the result of a survey on the hydroelectric power plants, ten plus places were observed where a general kind of concrete was severely worn in the company territory; but, there were substantial number of rubber materials that had still been sound for over ten years after the installation. In spite of the soundness of the rubber tiles, however, it was observed that their anchor supports had been cut and separated. An abrasion comparison test of concrete and rubber materials revealed that the rubber materials were considerably superior in abrasion resistance. Various rubber tiles were tested for abrasion resistance, tear strength, tensile strength, impact strength, etc.; and methods for fixing rubber tiles were also tested such as a holed-in anchor, chemical anchor and adhesives. As a result, a laminated rubber tile was designed with its upper layer constituted of a rubber sold on the market and its lower layer of a fiber reinforced rubber also on the market, and so was a shock absorbing type holed-in anchor. 1 ref., 11 figs., 4 tabs.

New Findings in Hydrogen Sulfide Related Corrosion of Concrete Sewers

DEFF Research Database (Denmark)

Nielsen, Asbjørn Haaning; Jensen, Henriette Stokbro; Hvitved-Jacobsen, Thorkild

2009-01-01

This paper summarizes major findings of a long-term study of hydrogen sulfide gas (H2S) adsorption and oxidation on concrete and plastic sewer pipe surfaces. The processes have been studied using a pilot-scale setup designed to replicate conditions in a gravity sewer located downstream of a force...... main. H2S related concrete corrosion and odor is often observed at such locations. The experiments showed that the rate of H2S oxidation was significantly faster on concrete pipe surfaces than on plastic pipe surfaces. Steady state calculations based on the kinetic data demonstrated that the gas phase...... H2S concentration in concrete sewers would typically amount to a few percent of the equilibrium concentration calculated from Henrys law. In plastic pipe sewers, significantly higher concentrations were predicted because of the slower adsorption and oxidation kinetics on these surfaces. Finally...

influence of severe conditions on the concrete employed in nuclear technology

International Nuclear Information System (INIS)

Khalil, W.M.K.S.

2006-01-01

this thesis is mainly concentrating on honing the efficiency of heavy-weight high -performance (HWHP) concrete, developed from local aggregates together with additives that are waste products of other manufacturing processes, for the purpose of producing radiation shields, to attenuate gamma-rays in peaceful active-service facilitations . in other words, the thesis is in attempt to develop a special type of heavy concrete of various advantages that would enhance its performance in severe environment. such advantages may embrace concurrent improvements; such as high specific gravity, workability, high compressive strength, efficient attenuator for gamma radiation, and resistant to elevated temperature along with chemical attack.the named HWHP concrete was mainly prepared using two types of heavy aggregates, ilmenite (iron ore) and barite . in addition usual concrete (dolomite/sand) was also employed in this thesis to compare the obtained HWHP concrete. the practical facet of this thesis accounts for evaluating the influence of severe conditions, concomitantly and consecutively, on mechanical , morphological and attenuation characteristics for the three types of concrete

Nonlinear analysis and evaluation of a reinforced concrete spent fuel storage pool for accidental thermal loads

International Nuclear Information System (INIS)

Kabir, A.F.; Bolourchi, S.

1991-01-01

A feasibility study was conducted for addition of consolidated fuel racks to an existing reinforced concrete spent fuel storage pool of a Mark I BWR plant. Nonlinear analysis of a detailed three-dimensional model of the fuel pool, considering cracking in concrete under gravity and thermal load conditions, showed that the pool has reserve capacities to carry the additional loads. (author)

Analysis of the behaviour of embankment dams during and after impoundment; Analyse du comportement de barrages en remblai pendant et apres leur mise en eau

Energy Technology Data Exchange (ETDEWEB)

Massiera, M. [Moncton Univ., Moncton, NB (Canada). Dept. of Civil Engineering; Szostak-Chrzanowski, A; Bazanowski, M. [New Brunswick Univ., Fredericton, NB (Canada). Canadian Centre for Geodetic Engineering; Withaker, C. [Metropolitan Water District of Southern California MWD, Glendora, CA (United States)

2009-07-01

This paper analyzed the behaviour of 2 embankment dams during impoundment. The study compared the values of the observed and calculated displacements of the crest during the initial filling of the reservoirs at the zoned earth West Dam in California and the Tounustouc concrete face rockfill dam (CFRD) in Quebec. The calculations were performed using finite element analysis. Rock and earthfill dams constructed on moraine deposits are known to deform under the influence of water load as the reservoir is filled. Therefore, this study also analyzed the long term deformations of the West Dam during 4 subsequent years of operation of the reservoir. Modelling rock and earthfill dams takes into account the nonlinear behaviour of the construction materials; interaction between the structure and the underlying soil and rock strata; influence of water load on the structure and on the foundation bedrock; and the effects of water saturation. This paper showed that geotechnical and geodetic monitoring may provide a warning system in case of abnormal behaviour of the embankment dam. In tectonically active zones, monitoring surveys may also provide information on the effects of seismic disturbances. 18 refs., 11 figs.

A Real-Time Temperature Data Transmission Approach for Intelligent Cooling Control of Mass Concrete

Directory of Open Access Journals (Sweden)

Peng Lin

2014-01-01

Full Text Available The primary aim of the study presented in this paper is to propose a real-time temperature data transmission approach for intelligent cooling control of mass concrete. A mathematical description of a digital temperature control model is introduced in detail. Based on pipe mounted and electrically linked temperature sensors, together with postdata handling hardware and software, a stable, real-time, highly effective temperature data transmission solution technique is developed and utilized within the intelligent mass concrete cooling control system. Once the user has issued the relevant command, the proposed programmable logic controllers (PLC code performs all necessary steps without further interaction. The code can control the hardware, obtain, read, and perform calculations, and display the data accurately. Hardening concrete is an aggregate of complex physicochemical processes including the liberation of heat. The proposed control system prevented unwanted structural change within the massive concrete blocks caused by these exothermic processes based on an application case study analysis. In conclusion, the proposed temperature data transmission approach has proved very useful for the temperature monitoring of a high arch dam and is able to control thermal stresses in mass concrete for similar projects involving mass concrete.

Displacement response of a concrete arch dam to seasonal temperature fluctuations and reservoir level rise during the first filling period: evidence from geodetic data

Directory of Open Access Journals (Sweden)

Cemal Ozer Yigit

2016-07-01

Full Text Available The present study evaluates the dynamic behaviour of the Ermenek Dam, the second highest dam in Turkey, based on conventional geodetic measurements and Finite Element Model (FEM analyses during its first filling period. In total, eight periods of measured deformation are considered from the end of construction until the reservoir reached its full capacity. The displacement response of the dam to the reservoir level and to seasonal temperature variations is examined in detail. Time series of apparent total displacements at the middle of the crest of the dam exhibits periodicity and linear trends. Correlation analysis revealed that periodic and linear displacement responses of the dam are related to variations of seasonal temperature and linearly increased reservoir level, respectively, indicating a relation between temperature, water load and dam deformation. It is also concluded that measured deformations based on geodetic data show good agreement with the predicted deformation obtained by the FEM analysis.

Lightweight self-compacting concrete with light expanded clay aggregate (LECA

Directory of Open Access Journals (Sweden)

Heiza Khaled

2018-01-01

Full Text Available Lightweight concretes have been successfully applied in building constructions for many years due to their favorable material properties, particularly their low specific weight in connection with a high strength, a high capability of thermal insulation and a high durability. The development leading to lightweight self-compacting concrete (LWSCC represents an important advanced step within the recent years. This concrete combines the favorable properties of a lightweight concrete with those of a self-compacting concrete. Research work is aimed on development of (LWSCC with the use of light aggregates “Light expanded clay aggregate (LECA”. In this research, first by specific gravity factor method, twenty different mix designs of (LWSCC were cast and tested to find out the values of slump flow, J-ring , V-funnel and 28 day compressive strength. Based on the results obtained, the best mix design was selected for further investigation. This paper also focuses on studying the effect of changing the reinforcement ratio on reinforced two way slabs when the dimensions were kept constant.

A study of concrete properties using phyllite as coarse aggregates

International Nuclear Information System (INIS)

Adom-Asamoah, Mark; Afrifa, Russell Owusu

2010-01-01

Nowadays, industrial activities generate a huge amount of waste. One such activity is underground mining which generates phyllite wastes that are recycled as coarse aggregates for use in concrete production. Aggregate use in concrete is dependent on availability. This paper reports of an experimental study on some of the physical and mechanical properties of phyllite aggregate concrete as compared to granite (conventional) aggregate concrete. The obtained physical and mechanical properties of both aggregates for specific gravity, water absorption (%), dry density, aggregate impact value (%), aggregate crushing value (%), 10% fines, elongation index (%), flakiness index (%) and Los Angeles abrasion values satisfied minimum requirements for aggregates suitable for concrete production. Five mixes of concrete mix proportions designated M1, M2, M3, M4 and M5 were cast using phyllite and granite aggregates. A total of 400 concrete cubes and 210 modulus of rupture beams were cast and cured by total submerging in water for ages 3, 7, 14, 28, 56, 90, 180 and 360 days before compression and bending tests were performed. The results show that the trends in the development of compressive and bending strengths of plain phyllite concrete were similar to those in granite (conventional) aggregate concrete. However the compressive and bending strengths of phyllite concrete mixes were on the average 15-20% lower than those of the corresponding granite concrete mixes at all ages. The same concrete mix proportions gave lower concrete classes for phyllite compared to granite with the exception of the lowest grade. This was probably because the flakiness and elongation properties coupled with reactive materials in phyllite aggregates affect the absorption and bond characteristics of its concrete.

A GIS based approach for the prediction of the dam break flood hazard – A case study of Zardezas reservoir “Skikda, Algeria”

Directory of Open Access Journals (Sweden)

Derdous Oussama

2015-12-01

Full Text Available The construction of dams in rivers can offer many advantages, however the consequences resulting from their failure could result in major damage, including loss of life and property destruction. To mitigate the threats of dam break it is essential to appreciate the characteristics of the potential flood in realistic manner. In this study an approach based on the integration of hydraulic modelling and GIS has been used to assess the risks resulting from a potential failure of Zardezas dam, a concrete dam located in Skikda, in the North East of Algeria. HEC-GeoRAS within GIS was used to extract geometric information from a digital elevation model and then imported into HEC-RAS. Flow simulation of the dam break was performed using HEC-RAS and results were mapped using the GIS. Finally, a flood hazard map based on water depth and flow velocity maps was created in GIS environment. According to this map the potential failure of Zardezas dam will place a large number in people in danger. The present study has shown that Application of Geographical Information System (GIS techniques in integration with hydraulic modelling can significantly reduce the time and the resources required to forecast potential dam break flood hazard which can play a crucial role in improving both flood disaster management and land use planning downstream of dams.

Offshore concrete structures; Estructuras Offshore (mar adentro) de Hormigon

Energy Technology Data Exchange (ETDEWEB)

Lamas Pardo, M.; Carral Couce, L. M.

2011-07-01

proof that in certain cases the benefits to the steel tip the lance toward the concrete. concrete Gravity Baseplaforms type Con deep have been building since the first unit became operational in 1976, together with a few floating platforms, that in its geometry are similar to those made of steel (barges, semi-submersibles and TLP type platforms). Some of the concepts in concrete that are being emerging last years are floating and gravity base platforms for use as offshore LNG terminals and as offshore industrial plants. The life of these barges can be designed up to 200 years, as the floating Nkossabarge, so they con be a good alternative to the construction of these facilities an land, thus avoiding landfills on the coast that degrade the already punished coast in industrialized countries. the challenge is precisely to optimize their capital costs to complete for an offshore installation against a shore facility. The environment will undoubtedly benefit from this great challenge that lies ahead in the XXI century. (Author) 29 refs.

Properties, sustainability and elevated temperature behavior of concrete containing Portland limestone cement

Science.gov (United States)

El-Hawary, Moetaz; Ahmed, Mahmoud

2017-09-01

The utilization of some type of cheap filler as partial cement replacement is an effective way of improving concrete sustainability. With the recent trends to reduce water to cement ratio and improve compaction, there is no enough space or water for complete hydration of cement. This means that actually, a portion of mixed cement acts as expensive filler. Replacing this portion with cheaper filler that requires less energy to produce is, therefore, beneficial. Crushed limestone is the most promising filler. This work is to investigate the effect of the amount of limestone fillers on the sustainability and the fresh and mechanical properties of the resulting concrete. A rich mix is designed with a low water/cement ratio of 0.4. Lime is introduced as a replacement percentage of cement. Ratios of 0, 10, 20 and 30% were used. Slump, compressive strength, specific gravity and water absorption are evaluated for every mix. In addition, the effect of the amount of lime on the residual strength of concrete subjected to elevated temperatures is also investigated. Samples are subjected to six different temperature stations of 20, 100, 200, 300, 500 and 700°C for six hours before being cooled and subsequently tested for compressive strength and specific gravity. Sustainability of the tested mixes is evaluated through reductions in the emitted carbon dioxide, energy and reduction in cost. Based on the annual use of concrete in Kuwait, the sustainability benefits resulting from the use of limestone filler in Kuwait are evaluated and assessed. The paper is concluded with the recommendation of the use of 15% limestone filler as partial cement replacement where the properties and the behavior under high temperature of the resulting concrete are almost the same as those of conventional concrete with considerable cost and sustainability benefits.

Teton Dam failure

Energy Technology Data Exchange (ETDEWEB)

Snorteland, N. [United States Dept. of the Interior, Washington, DC (United States). Bureau of Reclamation

2009-07-01

This case summary discussed an internal erosion failure that occurred at the embankment foundation of Teton Dam. The project was designed as a run-of-the-river power generation facility and to provide irrigation, flood protection, and power generation to the lower Teton region of southern Idaho. The dam site was located next to the eastern Snake River plain, a volcanic filled depression. The foundation's cutoff trench was excavated into the bedrock along the length of the dam. The dam was designed as a zoned earthfill with a height of 305 feet. A trench made of low plasticity windblown silt was designed to connect the embankment core to the rock foundation. Seeps were noted in 1976, and a leak was observed near the toe of the dam. A wet spot appeared on the downstream face of the dam at elevation 5200. A sinkhole then developed. The embankment crest collapsed, and the dam breached. Peak outflow was estimated at 1,000,000 cfs. The failure was attributed to a lack of communication between designers, a failure to understand geologic information about the region, and an insufficient review of designs and specifications by designers and field personnel. No monitoring instrumentation was installed in the embankment. Approximately 300 square miles were inundated, and 25,000 people were displaced. Eleven people were killed. A review group noted that the rock surface was not adequately sealed, and that the dam failed as a result of inadequate protection of the impervious core material from internal erosion. 42 figs.

How big of an effect do small dams have? Using geomorphological footprints to quantify spatial impact of low-head dams and identify patterns of across-dam variation

Science.gov (United States)

Fencl, Jane S.; Mather, Martha E.; Costigan, Katie H.; Daniels, Melinda D.

2015-01-01

Longitudinal connectivity is a fundamental characteristic of rivers that can be disrupted by natural and anthropogenic processes. Dams are significant disruptions to streams. Over 2,000,000 low-head dams (research and conservation is impaired by not knowing the magnitude of low-head dam impacts. Based on the geomorphic literature, we refined a methodology that allowed us to quantify the spatial extent of low-head dam impacts (herein dam footprint), assessed variation in dam footprints across low-head dams within a river network, and identified select aspects of the context of this variation. Wetted width, depth, and substrate size distributions upstream and downstream of six low-head dams within the Upper Neosho River, Kansas, United States of America were measured. Total dam footprints averaged 7.9 km (3.0–15.3 km) or 287 wetted widths (136–437 wetted widths). Estimates included both upstream (mean: 6.7 km or 243 wetted widths) and downstream footprints (mean: 1.2 km or 44 wetted widths). Altogether the six low-head dams impacted 47.3 km (about 17%) of the mainstem in the river network. Despite differences in age, size, location, and primary function, the sizes of geomorphic footprints of individual low-head dams in the Upper Neosho river network were relatively similar. The number of upstream dams and distance to upstream dams, but not dam height, affected the spatial extent of dam footprints. In summary, ubiquitous low-head dams individually and cumulatively altered lotic ecosystems. Both characteristics of individual dams and the context of neighboring dams affected low-head dam impacts within the river network. For these reasons, low-head dams require a different, more integrative, approach for research and management than the individualistic approach that has been applied to larger dams.

Mechanics of slide dams

International Nuclear Information System (INIS)

Young, G.A.

1970-01-01

Studies which promote the use of nuclear energy for peaceful projects in engineering are sponsored by the Atomic Energy Commission under the Plowshare program. Specific projects being considered include the construction of harbors, canals, and dams. Of these projects, perhaps the most difficult to accomplish will be the latter. This paper which is in two parts considers the problems which are associated with the construction of slide dams with nuclear explosives. It examines first the characteristics of conventional earth and rock-fill dams which are based upon proven techniques developed after many years of experience. The characteristics of natural landslide dams are also briefly considered to identify potential problems that must be overcome by slide dam construction techniques. Second, the mechanics of slide dams as determined from small-scale laboratory studies are presented. It is concluded that slide dams can be constructed and that small-scale field tests and additional laboratory studies are justified. (author)

Mechanics of slide dams

Energy Technology Data Exchange (ETDEWEB)

Young, G A [Engineering, Agbabian-Jacobsen Associates, Los Angeles (United States)

1970-05-15

Studies which promote the use of nuclear energy for peaceful projects in engineering are sponsored by the Atomic Energy Commission under the Plowshare program. Specific projects being considered include the construction of harbors, canals, and dams. Of these projects, perhaps the most difficult to accomplish will be the latter. This paper which is in two parts considers the problems which are associated with the construction of slide dams with nuclear explosives. It examines first the characteristics of conventional earth and rock-fill dams which are based upon proven techniques developed after many years of experience. The characteristics of natural landslide dams are also briefly considered to identify potential problems that must be overcome by slide dam construction techniques. Second, the mechanics of slide dams as determined from small-scale laboratory studies are presented. It is concluded that slide dams can be constructed and that small-scale field tests and additional laboratory studies are justified. (author)

Dam break analysis and flood inundation map of Krisak dam for emergency action plan

Science.gov (United States)

Juliastuti, Setyandito, Oki

2017-11-01

The Indonesian Regulation which refers to the ICOLD Regulation (International Committee on Large Dam required have the Emergency Action Plan (EAP) guidelines because of the dams have potential failure. In EAP guidelines there is a management of evacuation where the determination of the inundation map based on flood modeling. The purpose of the EAP is to minimize the risk of loss of life and property in downstream which caused by dam failure. This paper will describe about develop flood modeling and inundation map in Krisak dam using numerical methods through dam break analysis (DBA) using hydraulic model Zhong Xing HY-21. The approaches of dam failure simulation are overtopping and piping. Overtopping simulation based on quadrangular, triangular and trapezium fracture. Piping simulation based on cracks of orifice. Using results of DBA, hazard classification of Krisak dam is very high. The nearest village affected dam failure is Singodutan village (distance is 1.45 kilometer from dam) with inundation depth is 1.85 meter. This result can be used by stakeholders such as emergency responders and the community at risk in formulating evacuation procedure.

Heavy density concrete for nuclear radiation shielding and power stations: [Part]3

International Nuclear Information System (INIS)

Singha Roy, P.K.

1987-01-01

This article is the third part of the paper entitled 'Heavy density concrete for nuclear radiation shielding and power stations'. Specific considerations relevant to natural but manufactured heavy aggregates like haematite used in India are briefly discussed. They include water-cement ratio, strength versus water-cement ratio, mix design strength and aggregate grading. Some typical mix proportions in haematite concretes used in India are given. Equipment for heavy density concrete is mentioned. Quality control methods and tests for heavy density concrete are described under the heading: type and chemical composition of the rock, specific gravity and surface absorption of the aggregates, grading of aggregates, cement, batching, mixing, compressive strength, and density. Construction aspects such as form work, placement, vibration, finishing, and temperature control are discussed. Finally it is pointed out that for optimising the design and economy of heavy density concrete, it is necessary to carry out country-wide survey of suitable materials, to study their properties, suitability and effectiveness in shielding radiation. (M.G.B.)

DETERMINATION OF ADHESIVE STRENGTH LAYER’S ROLLER COMPACTED CONCRETE THE METHOD AXIAL EXTENSION

Directory of Open Access Journals (Sweden)

Tang Van Lam

2017-07-01

Full Text Available Roller compacted concrete for the construction of hydraulic and hydroelectric buildings is a composite material, which consists of a binder, fine aggregate (sand, coarse aggregate (gravel or crushed stone, water and special additives that provide the desired concrete workability and impart the required concrete performance properties. Concrete mixture is prepared at from concrete mixing plants strictly metered quantities of cement, water, additives and graded aggregates, whereupon they are delivered to the site laying Mixer Truck and sealing layers with each stack layer. The advantages of roller compaction technology should include the reduction of construction time, which allows fast commissioning construction projects, as well as reduce the amount of investment required. One of the main problems encountered in the process of roller compaction of the concrete mix is the need to provide the required adhesion strength between layers of concrete. This paper presents a method for determining the strength of adhesion between the concrete layers of different ages roller compacted concrete using axial tension. This method makes it possible to obtain objective and accurate results with a total thickness of layers of compacted concrete of up to 300…400 mm. Results from this method, studies have shown that the value of strength between the concrete layers in addition to the composition of the concrete and adhesion depends on the quality and the parallel end surfaces of the cylinder-models, which are mounted steel plates for axial tension, as well as the state of the contact surfaces of the concrete layer. The method can be used to determine the strength of interlayer adhesion in roller compacted concrete, which are used in the construction of dams and other hydraulic structures.

Small dams need better management

Science.gov (United States)

Balcerak, Ernie

2012-03-01

Many small dams around the world are poorly maintained and represent a safety hazard, according to Pisaniello et al. Better oversight of small dams is needed, the authors argue. The researchers reviewed literature, conducted case studies in four states in Australia, and developed policy benchmarks and best practices for small-dam management. Small dams, often just several meters high and typically privately owned by individual farmers, have historically caused major damage when they fail. For instance, in China in 1975, 230,000 people died when two large dams failed because of the cumulative failure of 60 smaller upstream dams. In the United States, in 1977 the 8-meter-high Kelly Barnes Lake dam failed, killing 39 people. Many other small-dam failures around the world have resulted in casualties and severe ecological and economic damage.

Flexural Performance of Transparent Plastic Bar Reinforced Concrete

Directory of Open Access Journals (Sweden)

Byoungil Kim

2018-02-01

Full Text Available In this study, experiments were conducted to derive a mix design for improving the flexural performance of light transparent concrete, which is attracting much attention and interest as an interior and exterior material for buildings, so that it could be easily applied in the field as a non-structural element by securing a lightweight, workability, and economic efficiency through the improvement of the concrete mix design and the use of economical materials for promoting its practical use. It was found that the mixing of polyvinyl alcohol (PVA fiber was effective in improving the consistency by preventing the aggregate from floating due to the mixing of lightweight aggregate with a low specific gravity. The flexural performance test results showed that the load transfer factor (LTF from the concrete matrix to the fiber was highest in the test specimens without plastic bars, followed by those with 5 and 10 mm plastic bars, respectively.

Study of Dam-break Due to Overtopping of Four Small Dams in the Czech Republic

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Zakaraya Alhasan

2015-01-01

Full Text Available Dam-break due to overtopping is one of the most common types of embankment dam failures. During the floods in August 2002 in the Czech Republic, several small dams collapsed due to overtopping. In this paper, an analysis of the dam break process at the Luh, Velký Bělčický, Melín, and Metelský dams breached during the 2002 flood is presented. Comprehensive identification and analysis of the dam shape, properties of dam material and failure scenarios were carried out after the flood event to assemble data for the calibration of a numerical dam break model. A simple one-dimensional mathematical model was proposed for use in dam breach simulation, and a computer code was compiled. The model was calibrated using the field data mentioned above. Comparison of the erodibility parameters gained from the model showed reasonable agreement with the results of other authors.

The use of Impact-Echo and Spectral-Analysis-of-Surface-Waves methods for the concrete investigation of Rogers Dam spillway structure

International Nuclear Information System (INIS)

Olson, L.D.; Sack, D.A.; Chan, Y.F.; Gilmore, R.T.; Christy, J.T.; Dumont, M.F.

1994-01-01

IE and SASW NDT methods were employed to investigate the concrete conditions of the Rogers Hydro Station's concrete spillway. The results showed that the surface gunite/shotcrete on the majority of the piers and walls was delaminated from the interior sound concrete and that there was a significant amount of sound concrete in the interior cores of the piers and walls. The NDT results correspond well in general trend with those of the concrete coring performed in 1988 and 1991; however, because of the greatly varying concrete conditions and additional concrete deterioration since 1988 when the majority of the horizontal cores were taken, a direct point-per-point comparison cannot be made. The NDT results correspond well with the as-found conditions on Pier 1 and on the east abutment wall except that the deep degradation (SASW results) conditions on the west face of Pier 1 did not exist. The highly deteriorated nature of the concrete could have contributed to the lower wave velocities. The cracking conditions below the demolition line were not verified. Some of the IE echoes could have been caused by the boundary conditions, in view of the highly fractured nature of the surface concrete/shotcrete and the very low strength and deteriorated concrete at the construction joints

Surface water leakage, sedimentation and evaporation in arid regions: A case study of the Gargar dam, Algeria

Directory of Open Access Journals (Sweden)

Hassen Benfetta

2017-12-01

Full Text Available This study was carried out in order to assess the total capacity loss in Gargar dam, third-largest in Algeria, due to the mudding of the reservoir, intense evaporation and water leaks. We analysed the variation in leakage as a function of the reservoir level, and quantify losses due to leaks, sedimentation and evaporation. We relied on site visits and data obtained from the Algerian Agency for Dams and Transfers to assess the leakage volume; reservoir level; sedimentation and evaporation levels for the period 1988–2015. We present an updated report of this problem through the dam. We estimated total average losses of 23 million m3·year−1 for the period 1988–2015, made up of leakage (0.3 million m3·year−1, evaporation (18 million m3·year−1 and dead storage for 4.6 million m3·year−1. However, total losses for 2004 were estimated at 113.9 million m3, which increased to the alarming value of 166.8 million m3 in 2015. We suggest improving the waterproofness by a concrete screen, and reducing mudding and evaporation by reforestation, to increase the storage capacity of the dam.

Investigation of geophysical methods for assessing seepage and internal erosion in embankment dams : a study of through-dam seismic testing at WAC Bennett Dam

Energy Technology Data Exchange (ETDEWEB)

Gaffran, P.; Jeffries, M. [BC Hydro, Burnaby, BC (Canada)

2005-07-15

Crosshole tomography is used to establish the distribution of seismic velocity between drill holes. The through-dam mode takes advantage of the triangular cross-section of earth embankments, obviating the need for drill holes. Seismic energy, generated on one face of the dam, passes underneath the crest and is detected by sensors arrayed on the opposite face. The sinkholes discovered at WAC Bennett Dam in 1996 provided an opportunity to test the procedure. Using p-wave energy, two series of measurements were conducted, notably one immediately before remediation of one sinkhole, and a second one shortly after the sinkhole was repaired. The known defect was successfully imaged by the first round of measurements. This report presented the results of an investigation of the through-dam seismic method using propagation of seismic waves through a dam from upstream to downstream, or vice-versa. The purpose of the study was to determine if this procedure could characterize the distribution of seismic velocity within a dam in an accurate and cost effective manner. The report presented the methods of velocity testing such as crosshole and downhole, and tomography; and through-dam measurements. Background to the Bennett Dam studies was also provided, with particular reference to the Bennett Dam sinkholes; sinkhole investigations; working hypothesis for sinkhole development; sinkhole number one characterization; and sinkhole remediation. An analysis of compression wave testing at Bennett Dam and shear wave testing was then offered. Other topics that were discussed included field test procedures; methodologies for data processing; p-waves versus s-waves; applicability of the research; and costs of through-dam surveys. It was concluded that under the right circumstances, through-dam seismic testing was capable of detecting changed conditions in an embankment dam. 15 refs., 2 tabs., 41 figs., 1 appendix.

Enhancement of wadi recharge using dams coupled with aquifer storage and recovery wells

KAUST Repository

Missimer, Thomas M. M.

2014-06-25

Wadi channel recharge to the underlying alluvial aquifer is naturally limited by the flashy nature of flood events, evapotranspiration losses of water from the vadose zone, and aquifer heterogeneity, particularly low vertical hydraulic conductivity. Anthropogenic lowering of the water table in many wadi aquifers has also reduced the potential recharge by increasing the thickness of the vadose zone, causing interflow water loss from surface emergence and evaporation. A method to enhance recharge is to slow the flow within wadi channels by placement of dam structures, thereby ponding water and increasing the vertical head gradient to create a more rapid rate of infiltration and percolation. Effectiveness of wadi dams to enhance aquifer recharge reduces over time due to mud deposition within the reservoir caused by storm events. Up to 80 % of the water in old wadi reservoirs is lost to free-surface evaporation before infiltration and recharge can occur. One method to maintain or increase the rate of recharge is to convey clean water by gravity flow from the reservoir down-gradient to artificially recharge the aquifer using existing wells. This type of system is a low-cost and low-energy recharge method which could greatly enhance groundwater storage in wadi aquifers. Modeling results show that existing wells could store up to 1,000 m3/day under gravity-feed conditions and up to 3,900 m3/day with the shut-in of the well to produce a pressurized system. © 2014 Springer-Verlag Berlin Heidelberg.

Economic viability in concrete dams by multivariable regression tool for implantation of small hydroelectric plants

International Nuclear Information System (INIS)

Lima, Reginaldo Agapito de; Ribeiro Junior, Leopoldo Uberto

2010-01-01

For implantation of a SHP, the barrage is the main structure where its sizing represents from 30% - 50% of general cost of civil works. Considering this it is very important to have a fast, didactic and accurate tool for elaborating a budget, also allowing a quantitative analysis of inherent cost for civil building of barrages concrete made for small hydropower plants. In face of this, the multi changing regression tool is very important as it allows a fast and correct establishing of preliminary costs, even approximate, for estimates of barrages in concrete cost, enabling to ease the budget, guiding feasibility decisions for selecting or neglecting new alternatives of fall. (author)

Perspectives on dam safety in Canada

International Nuclear Information System (INIS)

Halliday, R.

2004-01-01

Canadian dam safety issues were reviewed from the perspective of a water resources engineer who is not a dam safety practitioner. Several external factors affecting dam safety were identified along with perceived problems in dam safety administration. The author claims that the main weakness in safety practices can be attributed to provincial oversights and lack of federal engagement. Some additions to the Canadian Dam Safety Guidelines were proposed to address these weaknesses. Canada has hundreds of large dams and high hazard dams whose failure would result in severe downstream consequences. The safety of dams built on boundary waters shared with the United States have gained particular attention from the International Joint Commission. This paper also examined safety criteria for concerns such as aging dams, sabotage and global climate change that may compromise the safety of a dam. 26 refs

78 FR 53494 - Dam Safety Modifications at Cherokee, Fort Loudoun, Tellico, and Watts Bar Dams

Science.gov (United States)

2013-08-29

... Bar Dams AGENCY: Tennessee Valley Authority. ACTION: Issuance of Record of Decision. SUMMARY: This... the dam safety modifications at Cherokee, Fort Loudoun, Tellico, and Watts Bar Dams. The notice of... Loudoun, Tellico, and Watts Bar Dams was published in the Federal Register on May 31, 2013. This...

MOBILE MORTAR CONCRETE PLANTS FOR BUILDING COMPLEX OF BELARUS: ADVANTAGES AND DISADVANTAGES

Directory of Open Access Journals (Sweden)

S. N. Leonovich

2015-01-01

infrastructure and transportation networks: bridges, dams, highways, transport junctions. While ensuring the same production output of concrete these plants are located in close proximity to the construction site and the required mortars can be supplied directly to the site with the help of special concrete pumps.

Thermal analysis of mass concrete embedded with double-layer staggered heterogeneous cooling water pipes

International Nuclear Information System (INIS)

Yang Jian; Hu Yu; Zuo Zheng; Jin Feng; Li Qingbin

2012-01-01

Removal of hydration heat from mass concrete during construction is important for the quality and safety of concrete structures. In this study, a three-dimensional finite element program for thermal analysis of mass concrete embedded with double-layer staggered heterogeneous cooling water pipes was developed based on the equivalent equation of heat conduction including the effect of cooling water pipes and hydration heat of concrete. The cooling function of the double-layer staggered heterogeneous cooling pipes in a concrete slab was derived from the principle of equivalent cooling. To improve the applicability and precision of the equivalent heat conduction equation under small flow, the cooling function was revised according to its monotonicity and empirical formulas of single-phase forced-convection heat transfer in tube flow. Considering heat hydration of concrete at later age, a double exponential function was proposed to fit the adiabatic temperature rise curve of concrete. Subsequently, the temperature variation of concrete was obtained, and the outlet temperature of cooling water was estimated through the energy conservation principle. Comparing calculated results with actual measured data from a monolith of an arch dam in China, the numerical model was proven to be effective in sufficiently simulating accurate temperature variations of mass concrete. - Highlights: ► Three-dimensional program is developed to model temperature history of mass concrete. ► Massive concrete is embedded with double-layer heterogeneous cooling pipes. ► Double exponential function is proposed to fit the adiabatic temperature rise curve. ► Outlet temperature of cooling water is estimated. ► A comparison is made between the calculated and measured data.

Experimental and Numerical Evaluation of Direct Tension Test for Cylindrical Concrete Specimens

Directory of Open Access Journals (Sweden)

Jung J. Kim

2014-01-01

Full Text Available Concrete cracking strength can be defined as the tensile strength of concrete subjected to pure tension stress. However, as it is difficult to apply direct tension load to concrete specimens, concrete cracking is usually quantified by the modulus of rupture for flexural members. In this study, a new direct tension test setup for cylindrical specimens (101.6 mm in diameter and 203.2 mm in height similar to those used in compression test is developed. Double steel plates are used to obtain uniform stress distributions. Finite element analysis for the proposed test setup is conducted. The uniformity of the stress distribution along the cylindrical specimen is examined and compared with rectangular cross section. Fuzzy image pattern recognition method is used to assess stress uniformity along the specimen. Moreover, the probability of cracking at different locations along the specimen is evaluated using probabilistic finite element analysis. The experimental and numerical results of the cracking location showed that gravity effect on fresh concrete during setting time might affect the distribution of concrete cracking strength along the height of the structural elements.

Soil-fluid-structure interaction applied to the Oued Taht dam (taking into account the membrane effect.

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Nasreddine Krenich

2018-01-01

Full Text Available The objective of this work is to analyze the dynamic behavior (modal behavior of the "Oued Taht" arch dam located at MASCARA, taking into consideration the effect of soil-fluid-structure interaction. The finite element code "Ansys" was chosen for the dynamic modeling of the dam that is the subject of this study. Three hypotheses were used for soil-structure interaction modeling; model with embedded base which corresponds to the case where the phenomenon of interactions soil-structure is neglected, model with ground of foundation without mass which consists in taking into account the kinematic component of interaction soil structure and neglecting the inertial component and the model with foundation soil with mass where the two components of soil-structure interaction are taken into account. For the fluid, the model of added masses (equivalent to the westergaard approach using the SURF element available in the Ansys code library was used. A comparison between the different models of the "Oued Taht" dam was made; it has been found that the taking into account of the soil-fluid-structure interaction phenomenon modifies the period of the system and that the modeling of the dam with and without fluid gives a very important difference of the periods. The results obtained were compared with those of the "Brezina" dam, which is a gravity dam located in BAYADH. The work has shown that the periods of the "Oued Taht" dam with soil-fluid-structure interaction modeling are very out of phase with the periods without fluid modeling (taking into account only the soilstructure interaction phenomenon. which is not the case for the Brezina dam where the periods for the two models are getting closer. The periods between the two models mentioned before are close to the dam of Brézina because the latter is a dam which participates much more by its own weight than by its vault (thickness of the vault varies between 36.3 m at the base and 5m in crest which is the

Post-Newtonian parameter γ in generalized non-local gravity

Science.gov (United States)

Zhang, Xue; Wu, YaBo; Yang, WeiQiang; Zhang, ChengYuan; Chen, BoHai; Zhang, Nan

2017-10-01

We investigate the post-Newtonian parameter γ and derive its formalism in generalized non-local (GNL) gravity, which is the modified theory of general relativity (GR) obtained by adding a term m 2 n-2 R☐-n R to the Einstein-Hilbert action. Concretely, based on parametrizing the generalized non-local action in which gravity is described by a series of dynamical scalar fields ϕ i in addition to the metric tensor g μν, the post-Newtonian limit is computed, and the effective gravitational constant as well as the post-Newtonian parameters are directly obtained from the generalized non-local gravity. Moreover, by discussing the values of the parametrized post-Newtonian parameters γ, we can compare our expressions and results with those in Hohmann and Järv et al. (2016), as well as current observational constraints on the values of γ in Will (2006). Hence, we draw restrictions on the nonminimal coupling terms F̅ around their background values.

Investigation on the Causes of Cracking in Earth Dams (Case study: Mahmood-Abad Earth Dam

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H. Rahimi

2016-09-01

Full Text Available Introduction: Cracking of earth dams is a one of the main threat causes of stability of embankment dams. In this research by modeling of the behavior of an embankment dam and employing conditions of the earthquake, the reasons of cracking were inspected using by modeling of earth dam behavior. Based on the literature, one of the main causes of dam failures is sliding and cracking of the dam structure during earthquake. Localized liquefaction of foundation soils was one of the causes of the observed post-earthquake distress within these dams. Material and Methods: In order to study the causes and the results of crack on earth dams, Mahmoodabad earthen dam with a height of 19 m, is located in Zanjan province, northwest of Iran, which suffered a longitudinal crack on the crest and slight sliding of the upstream slope due to 2001 Avaj earthquake was studied. This dam has faced earthquake two times with an interval of two years. During the first earthquake with the magnitude about 6.6 in Richter scale small longitudinal cracks had created on the crest. The developed cracks had been repaired by injecting the cement and then has been hidden by passing the time. After the second earthquake with the magnitude about 6.5 in Richter scale the hidden cracks had been appeared again and the slight movement of the upper slopes of dam reported. Based on the site investigation and documented information about dam, including maps and parameter data, the behavior of the dam has modeled by using Plaxis as a finite element model. In order to check the accuracy of the design of dam, the stability analysis has been conducted using by Xslope as a limit equilibrium model. The foundation conditions and the Geotechnical properties of the layer beneath the dam has been inspected by open excavation. Results and Discussion: Underground investigation about Geotechnical properties of dam foundation has showed that there is a thin sandy layer confined in alluvium material of the

Gravity inversion of deep-crust and mantle interfaces in the Three Gorges area

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Wang Jian

2012-11-01

Full Text Available To better understand the heterogeneity of deep-crust and mantle interfaces in the region of the Three Gorges, China, we used the Parker-Oldenburg iterative inversion method to invert existing Bouguer gravity data from the Three Gorges area (1 : 500000, a new gravity map of the Three Gorges Dam (1 : 200000, and the results of deep seismic soundings. The inversion results show a Moho depth of 42 km between Badong and Zigui and the depth of the B2 lower-crustal interface beneath the Jianghan Plain and surrounding areas at 21–25 km. The morphology of crustal interfaces and the surface geology present an overpass structure. The mid-crust beneath the Three Gorges Dam is approximately 9 km thick, which is the thinnest in the Three Gorges area and may be related to the shallow low-density body near the Huangling anticline. The upper crust is seismogenic, and there is a close relationship between seismicity and the deep-crust and mantle interfaces. For example, the M5. 1 Zigui earthquake occurred where the gradients of the Moho and the B2 interface are the steepest, showing that deep structure has a very important effect on regional seismicity.

Ragged Chute rehabilitation project

Energy Technology Data Exchange (ETDEWEB)

Kemp, Paul; Slopek, Richard [Canadian Projects Ltd., Calgary, (Canada); Guzwell, Robert [TransAlta, Calgary, (Canada)

2010-07-01

The Ragged Chute development, located in northern Ontario, was originally constructed to provide compressed air to a local silver mining company. It was composed of a free overflow spillway, the air plant intake, a concrete gravity retaining wall and an earthfill dyke abutment. The advantage of the river flow and the head developed by the dam for the air plant was recently put to use by the addition of a hydro plant. This paper provided an overview of the use of the river flow over the years and described the recent rehabilitation work being done to upgrade the installations to current dam safety standards. Site inspections were carried out in 2006 as part of the dam safety review to assess the overall condition of the structures. The major operation of the rehabilitation work involved the upgrading of the original fixed crest spillway with a new labyrinth spillway structure. Canadian Hydro completed the dam safety safety rehabilitation work by October 2009.

Dynamic decision making for dam-break emergency management - Part 2: Application to Tangjiashan landslide dam failure

Science.gov (United States)

Peng, M.; Zhang, L. M.

2013-02-01

Tangjiashan landslide dam, which was triggered by the Ms = 8.0 Wenchuan earthquake in 2008 in China, threatened 1.2 million people downstream of the dam. All people in Beichuan Town 3.5 km downstream of the dam and 197 thousand people in Mianyang City 85 km downstream of the dam were evacuated 10 days before the breaching of the dam. Making such an important decision under uncertainty was difficult. This paper applied a dynamic decision-making framework for dam-break emergency management (DYDEM) to help rational decision in the emergency management of the Tangjiashan landslide dam. Three stages are identified with different levels of hydrological, geological and social-economic information along the timeline of the landslide dam failure event. The probability of dam failure is taken as a time series. The dam breaching parameters are predicted with a set of empirical models in stage 1 when no soil property information is known, and a physical model in stages 2 and 3 when knowledge of soil properties has been obtained. The flood routing downstream of the dam in these three stages is analyzed to evaluate the population at risk (PAR). The flood consequences, including evacuation costs, flood damage and monetized loss of life, are evaluated as functions of warning time using a human risk analysis model based on Bayesian networks. Finally, dynamic decision analysis is conducted to find the optimal time to evacuate the population at risk with minimum total loss in each of these three stages.

Fundamental and assessment of concrete structure monitoring by using acoustic emission technique testing: A review

Science.gov (United States)

Desa, M. S. M.; Ibrahim, M. H. W.; Shahidan, S.; Ghadzali, N. S.; Misri, Z.

2018-04-01

Acoustic emission (AE) technique is one of the non-destructive (NDT) testing, where it can be used to determine the damage of concrete structures such as crack, corrosion, stability, sensitivity, as structure monitoring and energy formed within cracking opening growth in the concrete structure. This article gives a comprehensive review of the acoustic emission (AE) technique testing due to its application in concrete structure for structural health monitoring (SHM). Assessment of AE technique used for structural are reviewed to give the perception of its structural engineering such as dam, bridge and building, where the previous research has been reviewed based on AE application. The assessment of AE technique focusing on basic fundamental of parametric and signal waveform analysis during analysis process and its capability in structural monitoring. Moreover, the assessment and application of AE due to its function have been summarized and highlighted for future references

Splitting strength and abrasion resistance of concrete paving blocks as a function of dry bulk specific gravity and ultrasonic pulse velocity

Directory of Open Access Journals (Sweden)

Haktanir, T.

2005-06-01

Full Text Available Artificial Portland cement concrete paving blocks are widely used in many countries. These paving blocks come in a variety of designs with names such as "Interlocking" and "Italian Flower", and are manufactured with special machinery using rather high quality concrete having a compressive strength of about 50 MPa. Concrete blocks are employed instead of natural cobble stones for essentially economic reasons. The laboratoiy equipment required to measure paving block splitting strength and abrasion resistance, two of the chief properties to be tested in quality checks, is costly and the tests are time-consuming and labour-intensive. The present paper reports on a detailed experimental study performed to relate the splitting strength and abrasion resistance of concrete paving blocks to "dry bulk specific gravity" (DBSG and "ultrasonic pulse velocity" (UPV, respectively. Statistically significant regression equations describing the dependence of splitting strength on DBSG and abrasion resistance on UPV were obtained with data from random samples of material provided by seven different manufacturers.

RESUMEN Los bloques para pavimentos (adoquines elaborados con hormigón se utilizan habitualmente en numerosos países. Estos bloques de pavimentación se diseñan de diversas formas, como por ejemplo "Entrelazado " ("Interlocking " o "Flor Italiana " ("Italian Flower"; se fabrican con maquinaria especial y con frecuencia se utiliza hormigón de la más alta calidad, con resistencia a la compresión de alrededor de 50 MPa. La razón de utilizar bloques de hormigón en lugar de bloques de piedra natural es básicamente económica. Los equipos de laboratorio necesarios para medir la resistencia a la compresión y a la abrasión -dos de las propiedades más importantes para determinar la calidad de los bloques en estudio- son costosos y los ensayos requieren tiempo y mano de obra considerables. En el presente trabajo se exponen ensayos experimentales

Sub-critical cohesive crack propagation with hydro-mechanical coupling and friction

Directory of Open Access Journals (Sweden)

S. Valente

2016-01-01

Full Text Available Looking at the long-time behaviour of a dam, it is necessary to assume that the water can penetrate a possible crack washing away some components of the concrete. This type of corrosion reduces the tensile strength and fracture energy of the concrete compared to the same parameters measured during a short-time laboratory test. This phenomenon causes the so called sub-critical crack propagation. That is the reason why the International Commission of Large Dams recommends to neglect the tensile strength of the joint between the dam and the foundation, which is the weakest point of a gravity dam. In these conditions a shear displacement discontinuity starts growing in a point, called Fictitious Crack Tip (shortened FCT, which is still subjected to a compression stress. In order to manage this problem, in this paper the cohesive crack model is re-formulated with the focus on the shear stress component. In this context, the classical Newton-Raphson method fails to converge to an equilibrium state. Therefore the approach used is based on two stages: (a a global one in which the FCT is moved ahead of one increment; (b a local one in which the non-linear conditions occurring in the Fracture Process Zone are taken into account. This two-stage approach, which is known in the literature as a Large Time Increment method, is able to model three different mechanical regimes occurring during the crack propagation between a dam and the foundation rock.

Historic Concrete : From Concrete Repair to Concrete Conservation

NARCIS (Netherlands)

Heinemann, H.A.

2013-01-01

Concrete like materials were already applied during the Roman Empire. After the decline of the Roman Empire, a wide scale application of concrete only reappeared in the 19th century. Here lies also the origin of modern (reinforced) concrete. Since then, both concrete application and composition have

EVALUASI KEAMANAN DAM JATILUHUR BERBASIS INDEKS RESIKO

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Avazbek Ishbaev

2014-12-01

Full Text Available The dams have very important roles to agricultural activities. Especially, West Java with 240,000 hectares of agricultural land, needs a good dam structure that can be used sustainably. Jatiluhur dam in Purwakarta, West Java is one of big dams in Indonesia which has important rules not only for Purwakarta but also for Jakarta, Karawang and Bekasi residents. A study and observation about safety and dam stability is needed to prevent any damage. The purpose of this research were to identify parameters that influenced dam safety and to evaluate dam reliability based on index tools. Analysis was done using risk index tools. The result showed that the condition of the dam of Jatiluhur is still satisfied with indicators, "Idam"-750. The total index risk was 127.22 and the safety factor was 83.04 out of 100. Therefore, Jatiluhur dam could be classified as safe and no need for particular treatments. Jatiluhur dam can be operated in normal condition or abnormal condition with periodic monitoring. Keywords: dam safety, evaluation, Jatiluhur Dam, risk index tools

Dam safety operating guidelines

International Nuclear Information System (INIS)

Elsayed, E.; Leung, T.; Kirkham, A.; Lum, D.

1990-01-01

As part of Ontario Hydro's dam structure assessment program, the hydraulic design review of several river systems has revealed that many existing dam sites, under current operating procedures, would not have sufficient discharge capacity to pass the Inflow Design Flood (IDF) without compromising the integrity of the associated structures. Typical mitigative measures usually considered in dealing with these dam sites include structural alterations, emergency action plans and/or special operating procedures designed for extreme floods. A pilot study was carried out for the Madawaska River system in eastern Ontario, which has seven Ontario Hydro dam sites in series, to develop and evaluate the effectiveness of the Dam Safety Operating Guidelines (DSOG). The DSOG consist of two components: the flood routing schedules and the minimum discharge schedules, the former of which would apply in the case of severe spring flood conditions when the maximum observed snowpack water content and the forecast rainfall depth exceed threshold values. The flood routing schedules would identify to the operator the optimal timing and/or extent of utilizing the discharge facilities at each dam site to minimize the potential for dam failures cased by overtopping anywhere in the system. It was found that the DSOG reduced the number of structures overtopped during probable maximum flood from thirteen to four, while the number of structures that could fail would be reduced from seven to two. 8 refs., 4 figs., 3 tabs

Dam risk reduction study for a number of large tailings dams in Ontario

Energy Technology Data Exchange (ETDEWEB)

Verma, N. [AMEC Earth and Environmental Ltd., Mississauga, ON (Canada); Small, A. [AMEC Earth and Environmental Ltd., Fredericton, NB (Canada); Martin, T. [AMEC Earth and Environmental, Burnaby, BC (Canada); Cacciotti, D. [AMEC Earth and Environmental Ltd., Sudbury, ON (Canada); Ross, T. [Vale Inco Ltd., Sudbury, ON (Canada)

2009-07-01

This paper discussed a risk reduction study conducted for 10 large tailings dams located at a central tailings facility in Ontario. Located near large industrial and urban developments, the tailings dams were built using an upstream method of construction that did not involve beach compaction or the provision of under-drainage. The study provided a historical background for the dam and presented results from investigations and instrumentation data. The methods used to develop the dam configurations were discussed, and remedial measures and risk assessment measures used on the dams were reviewed. The aim of the study was to address key sources of risk, which include the presence of high pore pressures and hydraulic gradients; the potential for liquefaction; slope instability; and the potential for overtopping. A borehole investigation was conducted and piezocone probes were used to obtain continuous data and determine soil and groundwater conditions. The study identified that the lower portion of the dam slopes were of concern. Erosion gullies could lead to larger scale failures, and elevated pore pressures could lead to the risk of seepage breakouts. It was concluded that remedial measures are now being conducted to ensure slope stability. 6 refs., 1 tab., 6 figs.

The Effects of Dams on Downstream Channel Characteristics in Pennsylvania and Maryland: Assessing the Potential Consequences of Dam Removal

Science.gov (United States)

Skalak, K. J.; Pizzuto, J. E.; Jenkins, P.

2003-12-01

The potential downstream effects of dam removal were assessed on fifteen sites of varying dam size and characteristics in Pennsylvania and Maryland. The dams ranged in size from a 30 cm high fish weir to a water supply dam 57 m high. Stream order ranged from 1 to 4. The dams are located in watersheds with varying degrees of human disturbance and urbanization. The dams are also operated differently, with significant consequences for hydraulic residence time and downstream flow variability. Most streams were alluvial, but 6 of the reaches were clearly bedrock channels. We hypothesize that the channel upstream, which is unaffected by the dam, will provide an accurate model for the channel downstream of the dam long after dam removal. Therefore, reaches upstream and downstream of the dam were compared to determine the effects of the dam as well as the condition of the stream that will ultimately develop decades after dam removal. Surprisingly, the dams had no consistent influence on channel morphology. However, the percentage of sand is significantly lower downstream than upstream: the mean % sand downstream is 11.47%, while the mean % sand upstream is 21.39%. The coarser fractions of the bed, as represented by the 84th percentile grain diameter, are unaffected by the presence of the dam. These results imply that decades after dam removal, the percentage of sand on the bed will increase, but the coarse fraction of the bed will remain relatively unchanged.

Physico-mechanical properties of high performance concrete using different aggregates in presence of silica fume

Directory of Open Access Journals (Sweden)

Salah A. Abo-El-Enein

2014-04-01

Full Text Available Heavy weight high performance concrete (HPC can be used when particular properties, such as high strength and good radiation shielding are required. Such concrete, using ilmenite and hematite coarse aggregates can significantly have higher specific gravities than those of concrete made with dolomite and air-cooled slag aggregates. Four different concrete mixes with the same cement content and different w/c ratios were designed using normal dolomite aggregate, air-cooled slag by-product and two different types of iron ore aggregates. High performance concrete (grade-M60 can be achieved using superplasticizer to reduce the water/cement ratio; the effect of SF on the performance of concrete was studied by addition of 10% silica fume to the total cement content. The physico-mechanical properties of coarse aggregates and hardened concrete were studied. The results show that, Ilmenite coarse aggregate gives higher physical and mechanical properties than the other aggregates. Also, addition of 10% silica fume developed a stronger and a denser interfacial transition zone (ITZ between concrete particles and the cement matrix. Crushed air-cooled slag can be used to produce a high-strength concrete with better mechanical properties than corresponding concrete made with crushed hematite and ilmenite. Heavy density concrete made with fine aggregates of ilmenite and air-cooled slag are expected to be suitable as shielding materials to attenuate gamma rays.

Public safety around dams guidelines

Energy Technology Data Exchange (ETDEWEB)

Bennett, T [Canadian Dam Association, Edmonton, AB (Canada)

2010-07-01

This presentation discussed Canadian and international initiatives for improving dam safety and described some of the drivers for the development of new Canadian Dam Association (CDA) public safety guidelines for dams. The CDA guidelines were divided into the following 3 principal sections: (1) managed system elements, (2) risk assessment and management, and (3) technical bulletins. Public and media responses to the drownings have called for improved safety guidelines. While the public remains unaware of the hazards of dams, public interaction with dams is increasing as a result of interest in extreme sports and perceived rights of access. Guidelines are needed for dam owners in order to provide due diligence. Various organizations in Canada are preparing technical and public safety dam guidelines. CDA guidelines have also been prepared for signage, booms and buoys, and audible and visual alerts bulletins. Working groups are also discussing recommended practices for spill procedures, spillways and the role of professional engineers in ensuring public safety. Methods of assessing risk were also reviewed. Managed system elements for risk assessment and public interactions were also discussed, and stepped control measures were presented. tabs., figs.

Odelouca Dam Construction: Numerical Analysis

OpenAIRE

Brito, A.; Maranha, J. R.; Caldeira, L.

2012-01-01

Odelouca dam is an embankment dam, with 76 m height, recently constructed in the south of Portugal. It is zoned with a core consisting of colluvial and residual schist soil and with soil-rockfill mixtures making up the shells (weathered schist with a significant fraction of coarse sized particles). This paper presents a numerical analysis of Odelouca Dam`s construction. The material con-stants of the soil model used are determined from a comprehensive testing programme carried out in the C...

Effect of a dam on epilithic algal communities of a mountain stream: before-after dam construction comparison

Directory of Open Access Journals (Sweden)

Luciana Cibils Martina

2013-02-01

Full Text Available In this study we evaluated the effect of a dam on epilithic algal communities by analyzing community response after dam construction and by comparing community composition, structure and biomass upstream and downstream of the dam. Samples of epilithic algae and environmental data were collected at each site during high and low water periods before and after dam construction in Achiras Stream (Córdoba, Argentina. Ordinations showed modifications in algal assemblages after dam construction and downstream of the dam. Ordinations also suggested a loss of seasonality at the downstream site since the assemblages were similar between hydrological periods after dam construction. Indicator species, obtained by the Indicator Value method, showed that, after dam construction, there could have been an increase in nutrient concentration and a release of plankton from the impoundment. Abundance, richness and diversity were altered after dam construction as assessed by ANOVAs derived from a modified BACI Design. Proportion of early-successional species was higher at the upstream site while late-successional species were dominant at the downstream site, as predicted. Lower fluctuations in discharge downstream of the dam may have helped succession advance, whereas at the upstream site, mainly during the high water period, floods could have caused sloughing of life forms from the outer layers of the biofilm, resetting the algal community to early successional stages. It may be concluded that the dam affected algal community and favored succession advance mainly by reducing current velocity and flow fluctuations.

Effect of gravity loading on inelastic seismic response of reinforced concrete structures

International Nuclear Information System (INIS)

Chowdhury, Rajib; Reddy, G. Rami; Roy, Raghupati; Dutta, Sekhar Chandra

2003-01-01

The effect of gravity loading is not considered in inelastic seismic response to avoid complexity and to reduce the number of influencing parameters. However, the possibility of considerable effect of this factor is indicated in many studies on inelastic seismic behaviour of structures. Hence, it is necessary to study the nature and extent of this effect on inelastic seismic behaviour of structures. The present paper attempts to fulfill this objective by studying the variation of energy dissipation due to presence of various level of axial load. The study is further extended to see the effect of axial force due to gravity loading on the ductility demand of hysteretic energy demand arising in structural elements of a simple one storey structures. The study shows that the presence of axial force may increase the energy dissipation capacity of structure leading to a reduction in ductility demand. (author)

Evaluation of pyrite and pyrrhotite in concretes

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A. P. Marcelino

Full Text Available ABSTRACT It is well known that aggregate characteristics can intensively interfere in concrete behavior especially when sulfides are presented in the aggregates. The lack of consensus to content limit value of these deleterious sulfur compounds in concrete structures for dams has motivated several investigations worldwide. Within this scenario, this work presents a methodology to evaluate the presence of pyrite and pyrrhotite in concretes produced with aggregates containing sulfides. For the study, rock samples from the Irapé hydroelectric power plant area in Minas Gerais (Brazil were used. This plant was built in a geological site where the rock presented sulfide levels of at least 3%. These rock samples were first ground and then used as aggregates in mortars, which were, during almost one year, subjected to three different exposed conditions: temperature of 23° ± 2°C and relative humidity of 95 to 100%; calcium hydroxide solution diluted in water kept at two different temperatures: room temperature and 50° C. The presence and amount of pyrrhotite were obtained from a leaching process of the material (aggregate or mortar in a solution of hydrochloric acid. This procedure allowed also the evaluation of the pyrite content. The results showed that the amount of pyrite has remained virtually constant over time in the three exposure situations. This finding indicates that sulfur limits in aggregates should be set according to the type of iron sulfide presented and not solely by the total amount of sulfur.

78 FR 77397 - Flood Control Regulations, Marshall Ford Dam (Mansfield Dam and Lake Travis), Colorado River, Texas

Science.gov (United States)

2013-12-23

... Regulations, Marshall Ford Dam (Mansfield Dam and Lake Travis), Colorado River, Texas AGENCY: U.S. Army Corps... Marshall Ford Dam (Mansfield Dam and Lake Travis), Colorado River, Texas. In 1997, the Lower Colorado River... regulations to reflect changes in ownership and responsibilities of flood control management of Marshall Ford...

7 CFR 1724.55 - Dam safety.

Science.gov (United States)

2010-01-01

... 7 Agriculture 11 2010-01-01 2010-01-01 false Dam safety. 1724.55 Section 1724.55 Agriculture... § 1724.55 Dam safety. (a) The provisions of this section apply only to RUS financed electric system... for Dam Safety,”(Guidelines), as applicable. A dam, as more fully defined in the Guidelines, is...

The Olympic Dam copper-uranium-gold deposit, Roxby Downs, South Australia

International Nuclear Information System (INIS)

Roberts, D.E.; Hudson, G.R.T.

1983-01-01

The Olympic Dam copper-uranium-gold deposit appears to be a new type of strata-bound sediment-hosted ore deposit. It is located 650 km north-northwest of Adelaide in South Australia and was discovered in 1975. It has an areal extent exceeding 20 km 2 with vertical thicknesses of mineralization up to 350 m. The deposit is estimated to contain in excess of 2,000 million metric tons of mineralized material with an average grade of 1.6 percent copper, 0.06 percent uranium oxide, and 0.6 g/metric ton gold. The deposit occurs in the basement beneath 350 m of unmineralized, flat-lying Adelaidean (late Proterozoic) to Cambrian sediments in the Stuart shelf region of South Australia. The host rocks of the deposit are unmetamorphosed and are probably younger than 1,580 m.y. The deposit is spatially related to coincident gravity and magnetic anomalies and the intersection of west-northwest- and north-northwest-trending lineaments. The Proterozoic sediments comprising the local basement sequence are predominantly sedimentary breccias ranging from matrix-poor granite breccias to matrix-rich polymict breccias containing clasts of a variety of rock types. This sequence is over 1 km thick and has been divided into two main units--the Olympic Dam Formation and the Greenfield Formation. The Olympic Dam Formation has five members, three of which are matrix rich. The Greenfield Formation has three members, the lower two being very hematite rich while the upper has a significant volcanic component. Pervasive hematite, chlorite, and sericite alteration of varying intensity affects all the basement sequence

Information theory, spectral geometry, and quantum gravity.

Science.gov (United States)

Kempf, Achim; Martin, Robert

2008-01-18

We show that there exists a deep link between the two disciplines of information theory and spectral geometry. This allows us to obtain new results on a well-known quantum gravity motivated natural ultraviolet cutoff which describes an upper bound on the spatial density of information. Concretely, we show that, together with an infrared cutoff, this natural ultraviolet cutoff beautifully reduces the path integral of quantum field theory on curved space to a finite number of ordinary integrations. We then show, in particular, that the subsequent removal of the infrared cutoff is safe.

New guidelines for dam safety classification

International Nuclear Information System (INIS)

Dascal, O.

1999-01-01

Elements are outlined of recommended new guidelines for safety classification of dams. Arguments are provided for the view that dam classification systems should require more than one system as follows: (a) classification for selection of design criteria, operation procedures and emergency measures plans, based on potential consequences of a dam failure - the hazard classification of water retaining structures; (b) classification for establishment of surveillance activities and for safety evaluation of dams, based on the probability and consequences of failure - the risk classification of water retaining structures; and (c) classification for establishment of water management plans, for safety evaluation of the entire project, for preparation of emergency measures plans, for definition of the frequency and extent of maintenance operations, and for evaluation of changes and modifications required - the hazard classification of the project. The hazard classification of the dam considers, as consequence, mainly the loss of lives or persons in jeopardy and the property damages to third parties. Difficulties in determining the risk classification of the dam lie in the fact that no tool exists to evaluate the probability of the dam's failure. To overcome this, the probability of failure can be substituted for by a set of dam characteristics that express the failure potential of the dam and its foundation. The hazard classification of the entire project is based on the probable consequences of dam failure influencing: loss of life, persons in jeopardy, property and environmental damage. The classification scheme is illustrated for dam threatening events such as earthquakes and floods. 17 refs., 5 tabs

War damages and reconstruction of Peruca dam

International Nuclear Information System (INIS)

Nonveiller, E.; Sever, Z.

1999-01-01

The paper describes the heavy damages caused by blasting in the Peruca rockfill dam in Croatia in January 1993. Complete collapse of the dam by overtopping was prevented through quick action of the dam owner by dumping clayey gravel on the lowest sections of the dam crest and opening the bottom outlet of the reservoir, thus efficiently lowering the water level. After the damages were sufficiently established and alternatives for restoration of the dam were evaluated, it was decided to construct a diaphragm wall through the damaged core in the central dam part as the impermeable dam element and to rebuild the central clay core at the dam abutments. Reconstruction works are described

RILEM recommendations for the prevention of damage by alkali-aggregate reactions in new concrete structures state-of-the-art report of the RILEM technical committee 219-ACS

CERN Document Server

Sims, Ian

2016-01-01

This book contains the full set of RILEM Recommendations which have been produced to enable engineers, specifiers and testing houses to design and produce concrete which will not suffer damage arising from alkali reactions in the concrete. There are five recommended test methods for aggregates (designated AAR-1 to AAR-5), and an overall recommendation which describes how these should be used to enable a comprehensive aggregate assessment (AAR-0). Additionally, there are two Recommended International Specifications for concrete (AAR-7.1 & 7.2) and a Preliminary International Specification for dams and other hydro structures (AAR-7.3), which describe how the aggregate assessment can be combined with other measures in the design of the concrete to produce a concrete with a minimised risk of developing damage from alkali-aggregate reactions.

33 CFR 208.19 - Marshall Ford Dam and Reservoir (Mansfield Dam and Lake Travis), Colorado River, Tex.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Marshall Ford Dam and Reservoir... Marshall Ford Dam and Reservoir (Mansfield Dam and Lake Travis), Colorado River, Tex. The Secretary of the Interior, through his agent, the Lower Colorado River Authority (LCRA) shall operate the Marshall Ford Dam...

Excavation of the Surikamigawa dam diversion tunnel. Surikamigawa dam karihaisui tunnel kantsu

Energy Technology Data Exchange (ETDEWEB)

Ikeda, T.; Konno, T. (Ministry of Construction, Tokyo (Japan))

1994-04-01

A bypass tunnel construction has been completed at the Surikamigawa dam (Japan). This paper describes the summary of the construction. The full-swing dam construction work is scheduled to begin in 1995. The soils distributed near the dam site consist of lapillus tuff containing andesite-based light stones and tuff-based conglomerates containing large gravels. Excavation of the dam diversion tunnel has used a blasting method, and the tunnel construction has adopted an automatic tunnel cross section marking system and a non-electric explosion method. This marking system is a system to irradiate a laser beam onto the facing to depict excavation lines that realizes labor saving and high-accuracy excavation. The error at the tunnel completion was found 20 mm. The non-electric explosion method ignites a coated explosive layer with an impact wave, which is electrostatically safe, and reduces blasting vibration. Electric detonators have also been used because of using ANFO explosives. The result obtained from measurements of inner space displacement necessary for the blasting process has indicated that the area near the dam site consists of stable mountains. 6 figs., 4 tabs.

Three Sisters Dam modifications and performance

Energy Technology Data Exchange (ETDEWEB)

Courage, L.J.R. [Monenco AGRA Inc., Calgary, AB (Canada)

1995-12-31

Recent modifications and maintenance carried out at the Three Sisters Dam, in the Alberta Rockies south of the town of Canmore, were described. A detailed account was given of the dam`s geological setting, its abnormally high leakage through the foundation and its sinkhole activity. Results of studies aimed at finding the cause of leakage and sinkhole occurrences were reviewed. Modifications made to the dam since 1951 were detailed, as were modifications to handle probable maximum flood levels. Three approaches for estimating failure probabilities after identification of failure modes were described. The overall conclusion was that based on constant leakage, no settlement in the dam, penstocks, or the powerhouse since construction, the Three Sisters Dam was stable. 1 ref.

Effect of Hand Mixing on the Compressive Strength of Concrete

Directory of Open Access Journals (Sweden)

James Isiwu AGUWA

2010-12-01

Full Text Available This paper presents the effect of hand mixing on the compressive strength of concrete. Before designing the concrete mix, sieve analysis of sharp sand and chippings was carried out and their fineness moduli were determined. Also the dry weight of chippings and the specific gravities of both sand and chippings were determined. A designed concrete mix of 1:2:4 was used and the number of turnings of the mixture over from one end to another by hand mixing was varying from one time up to and including seven times. The strengths were measured at the curing ages of 7, 14, 21 and 28 days respectively using 150mm concrete cubes cast, cured and crushed. The results revealed that the compressive strengths of concrete cubes appreciably increased with increase in number of turnings from one to four times but remained almost constant beyond four times of turning for all the ages tested. For example, at 1, 2, and 3 times turning; the compressive strengths at 28 days were 4.67, 13.37 and 20.28N/mm2 respectively while at 4, 5 and 6 times turning; the compressive strengths at 28 days were 21.15, 21.34 and 21.69N/mm2. From the data, adequate strengths were not developed at turnings below three times of hand mixing, concluding that a minimum of three times turning is required to produce concrete with satisfactory strength.

Dams and Levees: Safety Risks

Science.gov (United States)

Carter, N. T.

2017-12-01

The nation's flood risk is increasing. The condition of U.S. dams and levees contributes to that risk. Dams and levee owners are responsible for the safety, maintenance, and rehabilitation of their facilities. Dams-Of the more than 90,000 dams in the United States, about 4% are federally owned and operated; 96% are owned by state and local governments, public utilities, or private companies. States regulate dams that are not federally owned. The number of high-hazard dams (i.e., dams whose failure would likely result in the loss of human life) has increased in the past decade. Roughly 1,780 state-regulated, high-hazard facilities with structural ratings of poor or unsatisfactory need rehabilitation. Levees-There are approximately 100,000 miles of levees in the nation; most levees are owned and maintained by municipalities and agricultural districts. Few states have levee safety programs. The U.S. Army Corps of Engineers (Corps) inspects 15,000 miles of levees, including levees that it owns and local levees participating in a federal program to assist with certain post-flood repairs. Information is limited on how regularly other levees are inspected. The consequence of a breach or failure is another aspect of risk. State and local governments have significant authority over land use and development, which can shape the social and economic impacts of a breach or failure; they also lead on emergency planning and related outreach. To date, federal dam and levee safety efforts have consisted primarily of (1) support for state dam safety standards and programs, (2) investments at federally owned dams and levees, and (3) since 2007, creation of a national levee database and enhanced efforts and procedures for Corps levee inspections and assessments. In Public Law 113-121, enacted in 2014, Congress (1) directed the Corps to develop voluntary guidelines for levee safety and an associated hazard potential classification system for levees, and (2) authorized support for the

Health impacts of large dams

International Nuclear Information System (INIS)

Lerer, L.B.

1999-01-01

Large dams have been criticized because of their negative environmental and social impacts. Public health interest largely has focused on vector-borne diseases, such as schistosomiasis, associated with reservoirs and irrigation projects. Large dams also influence health through changes in water and food security, increases in communicable diseases, and the social disruption caused by construction and involuntary resettlement. Communities living in close proximity to large dams often do not benefit from water transfer and electricity generation revenues. A comprehensive health component is required in environmental and social impact assessments for large dam projects

Autogenous Crack Control during Construction Phases of MOSE Venice Dams

Science.gov (United States)

Bertagnoli, Gabriele; Anerdi, Constanza; Malavisi, Marzia; Zoratto, Nadia

2017-10-01

The design of concrete structures exposed to severe environmental attack, like in marine environment, requires serious attention for concrete durability. Early age cracking due to autogenous deformations can be detrimental to the performance of tidal structures. The study of the structural effects of hydration heat and rheological behaviour of a set of huge concrete structures of the Mobile Venice Dams known with the MOSE acronym (Experimental Electromechanical Module) is presented in this paper. Together with other measures such as coastal reinforcement, the raising of quaysides, and the paving and improvement of the lagoon, MOSE is designed to protect Venice and the lagoon from tides of up to 3 meters. Construction began simultaneously in 2003 at all three lagoon inlets, and the project has been completed in 2014. Floods have caused damage since ancient times and have become more frequent and intense as a result of the combined effect of eustatism (a rise in sea level) and subsidence (a drop in land level) caused by natural and man-induced phenomena. Nowadays, towns and villages in the lagoon are about 23 cm lower with respect to the water level than at the beginning of the 1900s. Each year, floods can cause serious problems for the inhabitants as well as deterioration of architecture, urban structures and the ecosystem. Over the entire lagoon area, there is also a constant risk of a catastrophic event such as that of 4 November 1966, when a tide of 194 cm submerged Venice, Chioggia and the other built-up areas.

Deformation performance of Waba Dam

Energy Technology Data Exchange (ETDEWEB)

Salloum, T.; Bhardwaj, V.; Hassan, P. [Ontario Power Generation, Niagara-on-the-Lake, ON (Canada); Cragg, C. [Cragg Consulting Services, Toronto, ON (Canada)

2009-07-01

This paper described the performance of the Waba Dam which is being monitored as part of Ontario Power Generation's Dam Safety Program. It described the deformations that have been observed in this 3600 ft long earthfill dam which lies on marine clay in eastern Ontario. An extensive instrumentation program, including foundation settlement gauges, surface monuments, slope inclinometers, load cells and piezometers has been in effect since the construction of the dam in 1975. Significant settlement has occurred at Waba Dam since its construction. Wide berms were provided upstream and downstream beyond the slopes of the main fill to ensure stability of the dyke on the soft clay foundation and the crest elevations were designed to allow for the expected settlement in the foundation which would be overstressed by the dam loading. Based on current settlements, future settlements are predicted based on Asaoka's method. Inclinometer measurements have shown a foundation lateral spreading of 12 in. The lateral versus vertical deformations were found to be comparable to well behaving embankments reported in the literature. These analyses indicate that Waba Dam is performing well and should continue to perform well into the future. 8 refs., 1 tab., 14 figs.

Mineral processing and characterization of coal waste to be used as fine aggregates for concrete paving blocks

Directory of Open Access Journals (Sweden)

C. R. Santos

Full Text Available Commercial coal production in the southern region of Brazil has been occurring since the beginning of the twentieth century. Due to the geological characteristics of the region, large amounts of solid wastes are generated. The aim of this work was to evaluate the use of coal waste to produce concrete paving blocks. A procedure to process the coal waste with the purpose of reducing the sulfur content and changing the particle size distribution of the material to meet the specification of fine aggregates was developed. The methodology considered the following steps: (a sampling of a coal mining waste; (b gravity separation of the fraction with specific gravity between 2.4 and 2.8; (c comminution of the material and particle size analysis; (d technological characterization of the material and production of concrete paving blocks; and (e acidity generation prediction (environmental feasibility. The results showed that the coal waste considered in this work can be used to replace conventional sand as a fine aggregate for concrete paving blocks in a proportion of up to 50%. This practice can result in cleaner coal production and reduce the demand for exploitation of sand deposits.

DAM-LAKEFRONT PLAZA: Revitalization of an Agriculture Reservoir Dam in Kashar-Tirana/Albania

Directory of Open Access Journals (Sweden)

Valbona Koçi

2014-12-01

Full Text Available The Dam-Lakefront Plaza in Kashar-Tirana/Albania is a research project that proposes not only the re-consideration and reinforcement of the artificial Reservoirs Dams built during Socialism in Albania, but envisions the maintenance of dams and revitalization of the lakeside area promoting the public-private collaboration. In addition, it envisions the generation of qualitative and lively public spaces in sub-urban areas as well. Admitting the artificial lakes as specific nodes of man-made infrastructure in the landscape, and consequently the dams (together with the drainage channels as important hydrotechnic elements of the flood protection infrastructure, this research intends to elaborate on one type of landscape infrastructure - the vertical screens, offering a mediation between the natural and built landscape.

Availability of special local rock materials for using in radiation shielding concrete

International Nuclear Information System (INIS)

Rammah, S.; Al-Hent, R.; Aissa, M.; Yousef, S.

2003-11-01

Concrete is an excellent and versatile material for using in radiation shielding of nuclear power plants, hot cells and medical facilities that deal with ionizing radiations, Because it is easy controlled with composition and density by using aggregates with high specific gravity such as Barite, Hematite, Magnetite, or minerals with high hydrogen content such as Serpentine. This research offered the essential information about local resources rocks and minerals can be used in this inclination, as aggregates for heavy/high hydrion concrete. The present work indicates that iron ores, which located in RAJO-EFREEN is better than other locations like ANTI-LEBANON or AL-KADMOUS. While the heavy beach sands in AL-BASSIT are the best compared with other locations on the Syrian seaside, because it has acceptable percentage of heavy mineral. Barite concretions were found in KALAMON, HOMS and other sites, which its percentages approach 50%, but however in small quantities. Finally, high hydrion concrete can be used by Serpentinite were found with high Serpentine percentage in BAYER and BASSIT blocks. (author)

The constructive backlash dissipate effect model for concrete blocks

International Nuclear Information System (INIS)

Tepes-Onea Florin

2004-01-01

From physical point of view, the dumping represents the soil seismic excitation energy taken over process through internal absorption, rubbed between existent layers, as and cracks on rocky foundations. Generally, on heavy dams dynamic analysis it is considered a viscous dump, proportional with deformation speed. The dumping can be evaluated on experimental bases or on environmental conditions measurements. The latest determine higher values of dumping elements. This it could be explained with the local factors influence which is not possible to modeled as backlash treatment, foundation ground characteristics, the concrete technology. This represents atypical dissipate phenomenon. A major influence is done by the excitation level as real seism or experimental excitation. The present work is about to establish the influence of the dissipate effect of the backlash on concrete blocks. The backlash finite elements modeling make this possible, studying different situations as rub effect, cohesion effect, seismic action on varying directions with the same accelerogram of 0.4 g. The studied blocks have the same dimensions, the relative displacement being obtained by foundation stiffness modified under two block parts. (author)

The role of dams in development

International Nuclear Information System (INIS)

Cakmak, C.

2001-01-01

Although the amounts of water resources are enough for the entire world, the distribution of them in time and space shows uneven pattern. The water need is increasing with heavy industrial and agricultural requirements, while available water in the world remains as a fixed source. Economic growth, socio-cultural, and environmental developments are being realized following these changes. In order to achieve sustainable management of water resources, these changes have to be taken into consideration in water-related development projects. Demand for water is steadily increasing through out the world, even though the fresh water resources are limited and unevenly distributed, during the past three centuries, the amount of water withdrawn from fresh water resources has increased by a factor of 35, whereas world population by a factor 8. The engineering of dams, which provides regular water from reservoirs of dams to be used in case of demand pattern, is a vital part of the civilization. Dams have played a key rote in the development since the third millennium B C when the first great civilizations evolved on major rivers, such as Tigris-Euphrates, the Nile and the Indus. From these early times dams were built for flood control, water supply, irrigation and navigation. Dams also had been built to produce motive power and electricity since the industrial revolution. Development priorities changed, experience accumulated with the construction and operation of dams. Although the importance of water is well known in the human life and civilization around the world, still various groups argue that expected economic benefits are not being produced and that major environmental, economic and social costs are not being taken into account. By the end of 20th century, there were 45000 large dams in over 150 countries. According to the same classification there are 625 large dams in Turkey. All over the world, 50 % of the large dams were built mainly for irrigation. It is estimated

Matahina Dam : lessons learned from an earthquake-related internal erosion incident at the Matahina Dam, New Zealand

Energy Technology Data Exchange (ETDEWEB)

Gillon, M. [Damwatch Services Ltd., Wellington (New Zealand)

2009-07-01

This case history discussed internal erosion damage and crest subsidence caused by an earthquake at the Matahina Dam in New Zealand. The study showed that cracking and internal erosion was initiated during the 1967 reservoir filling operation. Located in an area of active volcanism and faulting, the dam is located on a river with extensive erosion through an ignimbrite flow. The dam's core is founded on compact Tertiary age sediments overlain by sand and gravel deposits beneath the shoulders of the dam. The earthquake caused a rupture along an unidentified fault trace 12 km from the dam. The horizontal base acceleration recorded at the dam was 3.25 m/s. Transverse cracking was observed at each abutment, and deformations were observed in the rockfill. An investigation program was conducted to determine the dam's integrity. Piezometer measurements showed widespread fluctuations. It was concluded that the lack of an effective filter was a significant design omission. 12 refs., 12 figs.

Dam-breach analysis and flood-inundation mapping for selected dams in Oklahoma City, Oklahoma, and near Atoka, Oklahoma

Science.gov (United States)

Shivers, Molly J.; Smith, S. Jerrod; Grout, Trevor S.; Lewis, Jason M.

2015-01-01

Dams provide beneficial functions such as flood control, recreation, and storage of water supplies, but they also entail risk; dam breaches and resultant floods can cause substantial property damage and loss of life. The State of Oklahoma requires each owner of a high-hazard dam, which the Federal Emergency Management Agency defines as dams for which failure or improper operation probably will cause loss of human life, to develop an emergency action plan specific to that dam. Components of an emergency action plan are to simulate a flood resulting from a possible dam breach and map the resulting downstream flood-inundation areas. The resulting flood-inundation maps can provide valuable information to city officials, emergency managers, and local residents for planning an emergency response if a dam breach occurs.

Assessing Risks of Mine Tailing Dam Failures

Science.gov (United States)

Concha Larrauri, P.; Lall, U.

2017-12-01

The consequences of tailings dam failures can be catastrophic for communities and ecosystems in the vicinity of the dams. The failure of the Fundão tailings dam at the Samarco mine in 2015 killed 19 people with severe consequences for the environment. The financial and legal consequences of a tailings dam failure can also be significant for the mining companies. For the Fundão tailings dam, the company had to pay 6 billion dollars in fines and twenty-one executives were charged with qualified murder. There are tenths of thousands of active, inactive, and abandoned tailings dams in the world and there is a need to better understand the hazards posed by these structures to downstream populations and ecosystems. A challenge to assess the risks of tailings dams in a large scale is that many of them are not registered in publicly available databases and there is little information about their current physical state. Additionally, hazard classifications of tailings dams - common in many countries- tend to be subjective, include vague parameter definitions, and are not always updated over time. Here we present a simple methodology to assess and rank the exposure to tailings dams using ArcGIS that removes subjective interpretations. The method uses basic information such as current dam height, storage volume, topography, population, land use, and hydrological data. A hazard rating risk was developed to compare the potential extent of the damage across dams. This assessment provides a general overview of what in the vicinity of the tailings dams could be affected in case of a failure and a way to rank tailings dams that is directly linked to the exposure at any given time. One hundred tailings dams in Minas Gerais, Brazil were used for the test case. This ranking approach could inform the risk management strategy of the tailings dams within a company, and when disclosed, it could enable shareholders and the communities to make decisions on the risks they are taking.

The socio-economics dynamics of Dam on Rural Communities: A case study of Oyan Dam, Nigeria

Science.gov (United States)

Ayeni, Amidu; Ojifo, Lawrence

2018-06-01

Dams construction and operations have many benefits, nevertheless, they have also led to lots of negative social, health and human impacts. It is based on this that this study assesses the potential and socio-economics dynamics of Oyan dam between 1980 and 2016. The data used for this study include water level and discharge records of the dam between 2007 and 2016, Landsat imageries of 1984 and 2016 and socio-economic datasets for the period. Analysis of the dam potentials (water supply, agriculture and hydropower) and socio-economic impacts of the dam were carried out using basic statistical tools, land use change anaysis and field survey using questionnaire, structured interview with major stakeholders and personal observation. The results revealed that the water level and storage of the Oyan dam had a relative reduction of about 2 % as well as non-stationarity pattern of water abstraction and production for the period. The landuse classes show all classes decreased in extent except the cultivated landuse that acrued an increased of 19.9 % between 1984 and 2016. Furthermore, commercial water supply varied significantly between 2010 and 2016 while irrigation scheme is grossly under-utilized from the inception in 1983 to 2016. Finally, the result of socio-economic impacts revealed that majority of the selected communities' members are actually not benefiting from the dam and their livelihoods are not from the dam.

Sediment Transport Over Run-of-River Dams

Science.gov (United States)

O'Brien, M.; Magilligan, F. J.; Renshaw, C. E.

2016-12-01

Dams have numerous documented effects that can degrade river habitat downstream. One significant effect of large dams is their ability to trap sediment delivered from upstream. This trapping can alter sediment transport and grain size downstream - effects that often motivate dam removal decisions. However, recent indirect observations and modeling studies indicate that small, run-of-river (ROR) dams, which do not impede discharge, may actually leak sediment downstream. However, there are no direct measurements of sediment flux over ROR dams. This study investigates flow and sediment transport over four to six different New England ROR dams over a summer-fall field season. Sediment flux was measured using turbidity meters and tracer (RFID) cobbles. Sediment transport was also monitored through an undammed control site and through a river where two ROR dams were recently removed. These data were used to predict the conditions that contribute to sediment transport and trapping. Year 1 data show that tracer rocks of up to 61 mm were transported over a 3 m ROR dam in peak flows of 84% of bankfull stage. These tracer rocks were transported over and 10 m beyond the dam and continue to move downstream. During the same event, comparable suspended sediment fluxes of up to 81 g/s were recorded both upstream and downstream of the dam at near-synchronous timestamps. These results demonstrate the potential for sediment transport through dammed rivers, even in discharge events that do not exceed bankfull. This research elucidates the effects of ROR dams and the controls on sediment transport and trapping, contributions that may aid in dam management decisions.

Effects of a thin liquefiable foundation layer on deformations of a rockfill dam subjected to earthquake shaking

Energy Technology Data Exchange (ETDEWEB)

Seid-Karbasi, M.; Atukorala, U. [Golder Associates Ltd., Burnaby, BC (Canada); Gowan, M.; Barrett, A. [Golder Associates Pty, Toowong, Queensland (Australia)

2008-07-01

This paper discussed a coupled stress-flow dynamic analysis procedure designed to predict the stability and seismic deformations of an 85 meter high earth dam located near a polymetallic mine in Vietnam. The procedure was developed to capture sand element behaviours observed in previous laboratory tests. The analysis was conducted using a UBCSAND model to capture the liquefiable soil response. Nonlinear behaviour of the non-liquefiable materials was modelled using the UBCHYST simulation tool. Both models were incorporated within the FLAC model. Dam specifications, foundation characteristics, and predicted behaviours were discussed. The dam body and its foundation were analyzed under gravity loads with drained conditions in order to establish the pre-earthquake stress state. A dynamic analysis was then conducted using undrained properties for fine-grained soils. The FLAC model finite difference analysis was used to examine stress-flow under static and dynamic loading conditions. Earthquake motions were applied as a time history of excitation at the model's boundaries. Volumetric strains were controlled by the compressibility of the pore fluid and the flow of water through the soil elements. The model was calibrated using laboratory and centrifuge data. Results of the study showed that the tailings and downstream free-field alluvial soils developed high excess pore water pressures and liquefied during strong shaking motions. Results suggested that the seismic performance of the Oxide dam were satisfactory. 41 refs., 1 tab., 7 figs.

Hydraulics of embankment-dam breaching

Science.gov (United States)

Walder, J. S.; Iverson, R. M.; Logan, M.; Godt, J. W.; Solovitz, S.

2012-12-01

Constructed or natural earthen dams can pose hazards to downstream communities. Experiments to date on earthen-dam breaching have focused on dam geometries relevant to engineering practice. We have begun experiments with dam geometries more like those of natural dams. Water was impounded behind dams constructed at the downstream end of the USGS debris-flow flume. Dams were made of compacted, well-sorted, moist beach sand (D50=0.21 mm), 3.5 m from toe to toe, but varying in height from 0.5 to 1 m; the lower the dam, the smaller the reservoir volume and the broader the initially flat crest. Breaching was started by cutting a slot 30-40 mm wide and deep in the dam crest after filling the reservoir. Water level and pore pressure within the dam were monitored. Experiments were also recorded by an array of still- and video cameras above the flume and a submerged video camera pointed at the upstream dam face. Photogrammetric software was used to create DEMs from stereo pairs, and particle-image velocimetry was used to compute the surface-velocity field from the motion of tracers scattered on the water surface. As noted by others, breaching involves formation and migration of a knickpoint (or several). Once the knickpoint reaches the upstream dam face, it takes on an arcuate form whose continued migration we determined by measuring the onset of motion of colored markers on the dam face. The arcuate feature, which can be considered the head of the "breach channel", is nearly coincident with the transition from subcritical to supercritical flow; that is, it acts as a weir that hydraulically controls reservoir emptying. Photogenic slope failures farther downstream, although the morphologically dominant process at work, play no role at all in hydraulic control aside from rare instances in which they extend upstream so far as to perturb the weir, where the flow cross section is nearly self-similar through time. The domain downstream of the critical-flow section does influence

Dam that social networking: connecting South Africa's major dams to social media

CSIR Research Space (South Africa)

Butgereit, L

2011-10-01

Full Text Available where four major South African dams are connected to Twitter and Facebook (and other social media such as MXit and Google Chat) in a mechanism which would be easy to replicate for additional dams or rivers. Data is supplied by the South African...

TYPOLOGY OF LARGE DAMS. A REVIEW

Directory of Open Access Journals (Sweden)

Gheorghe ROMANESCU

2015-06-01

Full Text Available The dams represent hydrotechnical constructions meant to ensure a judicious use of water resources. The international literature is extremely rich in data regarding the large dams on Earth. In this context, a hierarchy of the main dams is attempted and the role they play in the economic development of the regions they were built in is underlined. The largest dams are built on the big rivers in Asia, North America, South America and Africa. The reservoirs have multiple roles: electricity production, drinking or industrial water supply, irrigations, recreation, etc. High costs and land fragility do not allow the construction of dams in the places most affected by drought or flood. This is why they are usually built in mountainous areas, at great distance from the populated centres. On the Romanian territory, there are 246 large dams, built in the hydrographical basins of Siret, Olt, Arges, Somes, etc. The largest rivers on Earth, by discharge, (Amazon and Zair do not also include the largest dams because the landform and the type of flow have not allowed such constructions.

Construction of anhydrite dams

Energy Technology Data Exchange (ETDEWEB)

Bortoluzzi, L; Francois, G

1977-05-01

To construct a ventilation dam, the road is closed with a fibreglass sheet onto which 3 or 4 cm of anhydrite paste is sprayed. The equipment necessary is described, and the cost is compared with that of an aggregate dam.

Study on Characteristics of Lightweight Aggregate Concrete Made From Foam and Ordinary Portland Cement

Directory of Open Access Journals (Sweden)

Ibrahim N.M.

2016-01-01

Full Text Available The production and characteristic of lightweight bubble aggregates (LBA are presented in this paper. The LBA are produced by mixing between the foam and ordinary Portland cement according to the composition which has been set. Then, the characteristics of LBA such as density, water absorption, specific gravity, compressive strength, aggregate impact value and microscopic analysis of the LBA are analyzed. Those characteristics are identified in order to ensure that the LBA are successfully categorized into lightweight aggregate. The loose bulk density is obtained at 812.5 kg/m3 which can be categorized under lightweight aggregate group. For water absorption the value obtained is 9.7 % which is slightly higher compared to normal aggregate. Meanwhile the average specific gravity obtained for the samples of LBAis 1.75. Compressive strength for the aggregates was 17.76 MPa. The highest compressive strength for LBA foamed concrete was obtained at 25% replacement with 7.83MPa. Thus, the LBA have a significant features and characteristics that can be used as coarse aggregates in concrete.

Dams, Hydrology and Risk in Future River Management

Science.gov (United States)

Wegner, D. L.

2017-12-01

Across America there are over 80,000 large to medium dams and globally the number is in excess of 800,000. Currently there are over 1,400 dams and diversion structures being planned or under construction globally. In addition to these documented dams there are thousands of small dams populating watersheds. Governments, agencies, native tribes, private owners and regulators all have a common interest in safe dams. Often dam safety is characterized as reducing structural risk while providing for maximum operational flexibility. In the 1970's there were a number of large and small dam failures in the United States. These failures prompted the federal government to issue voluntary dam safety guidelines. These guidelines were based on historic information incorporated into a risk assessment process to analyze, evaluate and manage risk with the goal to improve the quality of and support of dam management and safety decisions. We conclude that historic and new risks need to be integrated into dam management to insure adequate safety and operational flexibility. A recent assessment of the future role of dams in the United States premises that future costs such as maintenance or removal beyond the economic design life have not been factored into the long-term operations or relicensing of dams. The converging risks associated with aging water storage infrastructure, multiple dams within watersheds and uncertainty in demands policy revisions and an updated strategic approach to dam safety. Decisions regarding the future of dams in the United States may, in turn, influence regional water planning and management. Leaders in Congress and in the states need to implement a comprehensive national water assessment and a formal analysis of the role dams play in our water future. A research and national policy agenda is proposed to assess future impacts and the design, operation, and management of watersheds and dams.

Mitigating Dam Impacts Using Environmental Flow Releases

Science.gov (United States)

Richter, B. D.

2017-12-01

One of the most ecologically disruptive impacts of dams is their alteration of natural river flow variability. Opportunities exist for modifying the operations of existing dams to recover many of the environmental and social benefits of healthy ecosystems that have been compromised by present modes of dam operation. The potential benefits of dam "re-operation" include recovery of fish, shellfish, and other wildlife populations valued both commercially and recreationally, including estuarine species; reactivation of the flood storage and water purification benefits that occur when floods are allowed to flow into floodplain forests and wetlands; regaining some semblance of the naturally dynamic balance between river erosion and sedimentation that shapes physical habitat complexity, and arresting problems associated with geomorphic imbalances; cultural and spiritual uses of rivers; and many other socially valued products and services. Assessing the potential benefits of dam re-operation begins by characterizing the dam's effects on the river flow regime, and formulating hypotheses about the ecological and social benefits that might be restored by releasing water from the dam in a manner that more closely resembles natural flow patterns. These hypotheses can be tested by implementing a re-operation plan, tracking the response of the ecosystem, and continually refining dam operations through adaptive management. This presentation will highlight a number of land and water management strategies useful in implementing a dam re-operation plan, with reference to a variety of management contexts ranging from individual dams to cascades of dams along a river to regional energy grids. Because many of the suggested strategies for dam re-operation are predicated on changes in the end-use of the water, such as reductions in urban or agricultural water use during droughts, a systemic perspective of entire water management systems will be required to attain the fullest possible

Simulation of Breach Outflow for Earthfill Dam

International Nuclear Information System (INIS)

Razad, Azwin Zailti Abdul; Muda, Rahsidi Sabri; Sidek, Lariyah Mohd; Azia, Intan Shafilah Abdul; Mansor, Faezah Hanum; Yalit, Ruzaimei

2013-01-01

Dams have been built for many reasons such as irrigation, hydropower, flood mitigation, and water supply to support development for the benefit of human. However, the huge amount of water stored behind the dam can seriously pose adverse impacts to the downstream community should it be released due to unwanted dam break event. To minimise the potential loss of lives and property damages, a workable Emergency Response Plan is required to be developed. As part of a responsible dam owner and operator, TNB initiated a study on dam breach modelling for Cameron Highlands Hydroelectric Scheme to simulate the potential dam breach for Jor Dam. Prediction of dam breach parameters using the empirical equations of Froehlich and Macdonal-Langridge-Monopolis formed the basis of the modelling, coupled with MIKE 11 software to obtain the breach outflow due to Probable Maximum Flood (PMF). This paper will therefore discuss the model setup, simulation procedure and comparison of the prediction with existing equations.

Restoring Environmental Flows by Modifying Dam Operations

Directory of Open Access Journals (Sweden)

Brian D. Richter

2007-06-01

Full Text Available The construction of new dams has become one of the most controversial issues in global efforts to alleviate poverty, improve human health, and strengthen regional economies. Unfortunately, this controversy has overshadowed the tremendous opportunity that exists for modifying the operations of existing dams to recover many of the environmental and social benefits of healthy ecosystems that have been compromised by present modes of dam operation. The potential benefits of dam "re-operation" include recovery of fish, shellfish, and other wildlife populations valued both commercially and recreationally, including estuarine species; reactivation of the flood storage and water purification benefits that occur when floods are allowed to flow into floodplain forests and wetlands; regaining some semblance of the naturally dynamic balance between river erosion and sedimentation that shapes physical habitat complexity, and arresting problems associated with geomorphic imbalances; cultural and spiritual uses of rivers; and many other socially valued products and services. This paper describes an assessment framework that can be used to evaluate the benefits that might be restored through dam re-operation. Assessing the potential benefits of dam re-operation begins by characterizing the dam's effects on the river flow regime, and formulating hypotheses about the ecological and social benefits that might be restored by releasing water from the dam in a manner that more closely resembles natural flow patterns. These hypotheses can be tested by implementing a re-operation plan, tracking the response of the ecosystem, and continually refining dam operations through adaptive management. The paper highlights a number of land and water management strategies useful in implementing a dam re-operation plan, with reference to a variety of management contexts ranging from individual dams to cascades of dams along a river to regional energy grids. Because many of the

Sustainability of dams-an evaluation approach

Science.gov (United States)

Petersson, E.

2003-04-01

Situated in the stream bed of a river, dams and reservoirs interrupt the natural hydrological cycle. They are very sensitive to all kinds of changes in the catchment, among others global impacts on land use, climate, settlement structures or living standards. Vice versa dams strongly affect the spatially distributed, complex system of ecology, economy and society in the catchment both up- and downstream of the reservoir. The occurrence of negative impacts due to large dams led to serious conflicts about future dams. Nevertheless, water shortages due to climatic conditions and their changes, that are faced by enormous water and energy demands due to rising living standards of a growing world population, seem to require further dam construction, even if both supply and demand management are optimised. Although environmental impact assessments are compulsory for dams financed by any of the international funding agencies, it has to be assumed that the projects lack sustainability. Starting from an inventory of today's environmental impact assessments as an integral part of a feasibility study the presentation will identify their inadequacies with regard to the sustainability of dams. To improve the sustainability of future dams and avoid the mistakes of the past, the planning procedures for dams have to be adapted. The highly complex and dynamical system of interrelated physical and non-physical processes, that involves many different groups of stakeholders, constitutes the need for a model-oriented decision support system. In line with the report of the World Commission of Dams an integrated analysis and structure of the complex interrelations between dams, ecology, economy and society will be presented. Thus the system, that a respective tool will be based on, is analysed. Furthermore an outlook will be given on the needs of the potential users of a DSS and how it has to be embedded in the overall planning process. The limits of computer-based decision-support in the

The investigation of gamma and neutron shielding properties of concrete including basalt fibre for nuclear energy applications

International Nuclear Information System (INIS)

Nulk, H.; Ipbuker, C.; Gulik, V.; Tkaczyk, A.; Biland, A.

2015-01-01

In this study, we would like to draw attention to the prospect of basalt fibre as the main component for concrete reinforcement of NPP. This work describes the computational study of gamma attenuation parameters, the effective atomic number Z(eff) and the effective electron density N e (eff), of relatively light-weight concrete with chopped basalt fibre used as reinforcement in different mixture rates. We can draw the following conclusions. Basalt fibre is a relatively cheap material that can be used as reinforcement instead of metallic fibers. Basalt fibre has a similar specific gravity to that of concrete elements. Basalt fibre has high chemical and abrasion resistance. Basalt fibre has almost 10 times the tensile strength of steel re-bars. Gamma-ray attenuation coefficients increase with addition of basalt fibre into concrete in every case. The effective atomic number of the concrete increases with the addition of basalt fibre. The results show that basalt fibre reinforced concrete have improved shielding properties against gamma rays in comparison with regular concrete. This result is based on a regular concrete with only basalt fiber reinforcement. We estimate that with addition of standard aggregates for radiation shielding concrete, such as barite, magnetite or hematite, the shielding properties will increase exponentially

Gravitational field of static p -branes in linearized ghost-free gravity

Science.gov (United States)

Boos, Jens; Frolov, Valeri P.; Zelnikov, Andrei

2018-04-01

We study the gravitational field of static p -branes in D -dimensional Minkowski space in the framework of linearized ghost-free (GF) gravity. The concrete models of GF gravity we consider are parametrized by the nonlocal form factors exp (-□/μ2) and exp (□2/μ4) , where μ-1 is the scale of nonlocality. We show that the singular behavior of the gravitational field of p -branes in general relativity is cured by short-range modifications introduced by the nonlocalities, and we derive exact expressions of the regularized gravitational fields, whose geometry can be written as a warped metric. For large distances compared to the scale of nonlocality, μ r →∞ , our solutions approach those found in linearized general relativity.

Phase transition and thermodynamic stability of topological black holes in Hořava-Lifshitz gravity

Science.gov (United States)

Ma, Meng-Sen; Zhao, Ren; Liu, Yan-Song

2017-08-01

On the basis of horizon thermodynamics, we study the thermodynamic stability and P-V criticality of topological black holes constructed in Hořava-Lifshitz (HL) gravity without the detailed-balance condition (with general ɛ). In the framework of horizon thermodynamics, we do not need the concrete black hole solution (the metric function) and the concrete matter fields. It is shown that the HL black hole for k=0 is always thermodynamically stable. For k=1 , the thermodynamic behaviors and P-V criticality of the HL black hole are similar to those of RN-AdS black hole for some \

Comparison of performance of partial prestressed beam-column subassemblages made of reactive powder concrete and normal concrete materials using finite element models

Science.gov (United States)

Nurjannah, S. A.; Budiono, B.; Imran, I.; Sugiri, S.

2016-04-01

Research on concrete material continues in several countries and had produced a concrete type of Ultra High Performance Concrete (UHPC) which has a better compressive strength, tensile strength, flexural strength, modulus of elasticity, and durability than normal concrete (NC) namely Reactive Powder Concrete (RPC). Researches on structures using RPC material showed that the RPC structures had a better performance than the NC structures in resisting gravity and lateral cyclic loads. In this study, an experiment was conducted to apply combination of constant axial and lateral cyclic loads to a prototype of RPC interior partial prestressed beam-column subassemblage (prototype of BCS-RPC) with a value of Partial Prestressed Ratio (PPR) of 31.72% on the beam. The test results were compared with finite element model of beam-column subassemblage made of RPC by PPR of 31.72% (BCS-RPC-31.72). Furthermore, there was BCS-RPC modeling with PPR of 21.39% (BCS-RPC-21.39) and beam-column subassemblages made of NC materials modeling with a value of PPR at 21.09% (BCS-NC-21.09) and 32.02% (BCS-NC-32.02). The purpose of this study was to determine the performance of the BCS-RPC models compared to the performance of the BCS-NC models with PPR values below and above 25%, which is the maximum limit of permitted PPR. The results showed that all models of BCS-RPC had a better performance than all models of BCS-NC and the BCS-RPC model with PPR above 25% still behaved ductile and was able to dissipate energy well.

33 CFR 100.1102 - Marine Events on the Colorado River, between Davis Dam (Bullhead City, Arizona) and Headgate Dam...

Science.gov (United States)

2010-07-01

... River, between Davis Dam (Bullhead City, Arizona) and Headgate Dam (Parker, Arizona). 100.1102 Section... MARINE PARADES SAFETY OF LIFE ON NAVIGABLE WATERS § 100.1102 Marine Events on the Colorado River, between Davis Dam (Bullhead City, Arizona) and Headgate Dam (Parker, Arizona). (a) General. Sponsors are...

Brazil's Amazonian dams: Ecological and socioeconomic impacts

Science.gov (United States)

Fearnside, P. M.

2016-12-01

Brazil's 2015-2024 Energy Expansion Plan calls for 11 hydroelectric dams with installed capacity ≥ 30 MW in the country's Amazon region. Dozens of other large dams are planned beyond this time horizon, and dams with environmental and socioeconomic impacts. Loss of forest to flooding is one, the Balbina and Tucuruí Dams being examples (each 3000 km2). If the Babaquara/Altamira Dam is built it will flood as much forest as both of these combined. Some planned dams imply loss of forest in protected areas, for example on the Tapajós River. Aquatic and riparian ecosystems are lost, including unique biodiversity. Endemic fish species in rapids on the Xingu and Tapajós Rivers are examples. Fish migrations are blocked, such as the commercially important "giant catfish" of the Madeira River. Dams emit greenhouse gases, including CO2 from the trees killed and CH4 from decay under anoxic conditions at the bottom of reservoirs. Emissions can exceed those from fossil-fuel generation, particularly over the 20-year period during which global emissions must be greatly reduced to meet 1.5-2°C limit agreed in Paris. Carbon credit for dams under the Climate Convention causes further net emission because the dams are not truly "additional." Anoxic environments in stratified reservoirs cause methylation of mercury present in Amazonian soils, which concentrates in fish, posing a health risk to human consumers. Population displacement is a major impact; for example, the Marabá Dam would displace 40,000 people, mostly traditional riverside dwellers (ribeirinhos). Various dams impact indigenous peoples, such as the Xingu River dams (beginning with Belo Monte) and the São Luiz do Tapajós and Chacorão Dams on the Tapajós River. Brazil has many energy options other than dams. Much energy use has little benefit for the country, such as exporting aluminum. Electric showerheads use 5% of the country's power. Losses in transmission lines (20%) are far above global averages and can be

Behavior and dam passage of juvenile Chinook salmon at Cougar Reservoir and Dam, Oregon, March 2011 - February 2012

Science.gov (United States)

Beeman, John W.; Hansel, Hal C.; Hansen, Amy C.; Haner, Philip V.; Sprando, Jamie M.; Smith, Collin D.; Evans, Scott D.; Hatton, Tyson W.

2013-01-01

The movements and dam passage of juvenile Chinook salmon implanted with acoustic transmitters and passive integrated transponder tags were studied at Cougar Reservoir and Dam, near Springfield, Oregon. The purpose of the study was to provide information to aid with decisions about potential alternatives for improving downstream passage conditions for juvenile salmonids in this flood-control reservoir. In 2011, a total of 411 hatchery fish and 26 wild fish were tagged and released during a 3-month period in the spring, and another 356 hatchery fish and 117 wild fish were released during a 3-month period in the fall. A series of 16 autonomous hydrophones throughout the reservoir and 12 hydrophones in a collective system near the dam outlet were used to determine general movements and dam passage of the fish over the life of the acoustic transmitter, which was expected to be about 3 months. Movements within the reservoir were directional, and it was common for fish to migrate repeatedly from the head of the reservoir downstream to the dam outlet and back to the head of the reservoir. Most fish were detected near the temperature control tower at least once. The median time from release near the head of the reservoir to detection within about 100 meters of the dam outlet at the temperature control tower was between 5.7 and 10.8 days, depending on season and fish origin. Dam passage events occurred over a wider range of dates in the spring and summer than in the fall and winter, but dam passage numbers were greatest during the fall and winter. A total of 10.5 percent (43 of 411) of the hatchery fish and 15.4 percent (4 of 26) of the wild fish released in the spring are assumed to have passed the dam, whereas a total of 25.3 percent (90 of 356) of the hatchery fish and 16.9 percent (30 of 117) of the wild fish released in the fall are assumed to have passed the dam. A small number of fish passed the dam after their transmitters had stopped working and were detected at

Dams and Intergovernmental Transfers

Science.gov (United States)

Bao, X.

2012-12-01

Gainers and Losers are always associated with large scale hydrological infrastructure construction, such as dams, canals and water treatment facilities. Since most of these projects are public services and public goods, Some of these uneven impacts cannot fully be solved by markets. This paper tried to explore whether the governments are paying any effort to balance the uneven distributional impacts caused by dam construction or not. It showed that dam construction brought an average 2% decrease in per capita tax revenue in the upstream counties, a 30% increase in the dam-location counties and an insignificant increase in downstream counties. Similar distributional impacts were observed for other outcome variables. like rural income and agricultural crop yields, though the impacts differ across different crops. The paper also found some balancing efforts from inter-governmental transfers to reduce the unevenly distributed impacts caused by dam construction. However, overall the inter-governmental fiscal transfer efforts were not large enough to fully correct those uneven distributions, reflected from a 2% decrease of per capita GDP in upstream counties and increase of per capita GDP in local and downstream counties. This paper may shed some lights on the governmental considerations in the decision making process for large hydrological infrastructures.

Research on shape optimization of CSG dams

Directory of Open Access Journals (Sweden)

Xin Cai

2011-12-01

Full Text Available The multi-objective optimization method was used for shape optimization of cement sand and gravel (CSG dams in this study. The economic efficiency, the sensitivities of maximum horizontal displacement and maximum settlement of the dam to water level changes, the overall stability, and the overall strength security were taken into account during the optimization process. Three weight coefficient selection schemes were adopted to conduct shape optimization of a dam, and the case studies lead to the conclusion that both the upstream and downstream dam slope ratios for the optimal cross-section equal 1:0.7, which is consistent with the empirically observed range of 1:0.6 to 1:0.8 for the upstream and downstream dam slope ratios of CSG dams. Therefore, the present study is of certain reference value for designing CSG dams.

Nonlinear fracture mechanics investigation on the ductility of reinforced concrete beams

Directory of Open Access Journals (Sweden)

A. Carpinteri

Full Text Available In the present paper, a numerical algorithm based on the finite element method is proposed for the prediction of the mechanical response of reinforced concrete (RC beams under bending loading. The main novelty of such an approach is the introduction of the Overlapping Crack Model, based on nonlinear fracture mechanics concepts, to describe concrete crushing. According to this model, the concrete dam- age in compression is represented by means of a fictitious interpenetration. The larger is the interpenetration, the lower are the transferred forces across the damaged zone. The well-known Cohesive Crack Model in tension and an elastic-perfectly plastic stress versus crack opening displacement relationship describing the steel reinforcement behavior are also integrated into the numerical algorithm. The application of the proposed Cohesive-Overlapping Crack Model to the assessment of the minimum reinforcement amount neces- sary to prevent unstable tensile crack propagation and to the evaluation of the rotational capacity of plastic hinges, permits to predict the size-scale effects evidenced by several experimental programs available in the literature. According to the obtained numerical results, new practical design formulae and diagrams are proposed for the improvement of the current code provisions which usually disregard the size effects.

The World Commission on Dams + 10: Revisiting the Large Dam Controversy

Directory of Open Access Journals (Sweden)

Deborah Moore

2010-06-01

Full Text Available The World Commission on Dams (WCD was an experiment in multi-stakeholder dialogue and global governance concerned with a subject area – large dams – that was fraught with conflict and controversy. The WCD Report, Dams and Development: A New Framework for Decision-Making, was published in 2000 and accompanied by hopes that broad-based agreements would be forged on how to better manage water and energy development. Ten years later, this special issue of Water Alternatives revisits the WCD and its impacts, exploring the question: Is the WCD still relevant? The editorial team and the Guest Editors of this special issue of Water Alternatives have selected a range of 20 papers, 6 viewpoints, and 4 book reviews that help to illustrate the evolution in the dams debate. The goal of this special issue is to examine the influence and the impacts of the WCD on the dam enterprise, in general, and on the policies and practices of key stakeholders and institutions, and on the development outcomes for affected communities and environments, in particular. In this introduction, the Guest Editors provide an overview of the special issue, exploring the new drivers of dam development that have emerged during the last decade, including climate change and new financiers of dams, and describing the themes emerging from this diverse set of papers and viewpoints. This special issue demonstrates the need for a renewed multi-stakeholder dialogue at multiple levels. This would not be a redo of the WCD, but rather a rekindling and redesigning of processes and forums where mutual understanding, information-sharing, and norm-setting can occur. One of the most promising developments of the last decade is the further demonstration, in case studies described here, that true partnership amongst key stakeholders can produce transformative resource-sharing agreements, showing that many of the WCD recommendations around negotiated decision making are working in practice. We hope

Research progress on dam-break floods

KAUST Repository

Wu, Jiansong; Bao, Kai; Zhang, Hui

2011-01-01

Because of the catastrophic effects downstream of dam-break failure, more and more researchers around the world have been working on the study of dam-break flows to accurately forecast the downstream inundation mapping. With the rapid development of computer hardware and computing techniques, numerical study on dam-break flows has been a popular research subject. In the paper, the numerical methodologies used to solve the governing partial differential equations of dam-break flows are classified and summarized, and their characteristics and applications are discussed respectively. Furthermore, the fully-developed mathematical models developed in recent decades are reviewed, and also introduced the authors' on-going work. Finally, some possible future developments on modeling the dam-break flows and some solutions are presented and discussed. © 2011 IEEE.

Research progress on dam-break floods

KAUST Repository

Wu, Jiansong

2011-08-01

Because of the catastrophic effects downstream of dam-break failure, more and more researchers around the world have been working on the study of dam-break flows to accurately forecast the downstream inundation mapping. With the rapid development of computer hardware and computing techniques, numerical study on dam-break flows has been a popular research subject. In the paper, the numerical methodologies used to solve the governing partial differential equations of dam-break flows are classified and summarized, and their characteristics and applications are discussed respectively. Furthermore, the fully-developed mathematical models developed in recent decades are reviewed, and also introduced the authors\\' on-going work. Finally, some possible future developments on modeling the dam-break flows and some solutions are presented and discussed. © 2011 IEEE.

Tenaga Nasional Berhad dam safety and surveillance program

International Nuclear Information System (INIS)

Jansen Luis; Zulkhairi Abd Talib

2006-01-01

This paper discusses the current practice of dam surveillance, which includes dam monitoring which is a process of visual inspections, measuring, processing, compiling and analyzing dam instrumentation data to determine the performance of a dam. The prime objective of the dam surveillance system is to ensure that any occurrence and development of safety deficiencies and problems are quickly detected, identified, analyzed and the required remedial actions are determined and consequently carried out in due time. In brief, the section is responsible to ensure that the dam monitoring and surveillance works are implemented as per scheduled and in accordance with the requirement and guidelines prepared by the dam designers and in accordance with international commission on large dams, ICOLD. The paper also illustrates and recommends an alternative approach for dam surveillance program using risk management approach, which is currently being actively adopted by some countries like USA, Canada, Australia and etc, towards improving the dam safety management and the decision making process. The approach provides a wider area of opportunity, improvements and benefits particular in the evaluation and modifications to the dam performance and safety. The process provides an effective and efficient tool for the decision makers and engineers through a comprehensive evaluation and a good understanding of the hazards, risks and consequences in relation to dam safety investigations. (Author)

Massive gravity from bimetric gravity

International Nuclear Information System (INIS)

Baccetti, Valentina; Martín-Moruno, Prado; Visser, Matt

2013-01-01

We discuss the subtle relationship between massive gravity and bimetric gravity, focusing particularly on the manner in which massive gravity may be viewed as a suitable limit of bimetric gravity. The limiting procedure is more delicate than currently appreciated. Specifically, this limiting procedure should not unnecessarily constrain the background metric, which must be externally specified by the theory of massive gravity itself. The fact that in bimetric theories one always has two sets of metric equations of motion continues to have an effect even in the massive gravity limit, leading to additional constraints besides the one set of equations of motion naively expected. Thus, since solutions of bimetric gravity in the limit of vanishing kinetic term are also solutions of massive gravity, but the contrary statement is not necessarily true, there is no complete continuity in the parameter space of the theory. In particular, we study the massive cosmological solutions which are continuous in the parameter space, showing that many interesting cosmologies belong to this class. (paper)

WinDAM C earthen embankment internal erosion analysis software

Science.gov (United States)

Two primary causes of dam failure are overtopping and internal erosion. For the purpose of evaluating dam safety for existing earthen embankment dams and proposed earthen embankment dams, Windows Dam Analysis Modules C (WinDAM C) software will simulate either internal erosion or erosion resulting f...

Recycled Concrete as Aggregate for Structural Concrete Production

Directory of Open Access Journals (Sweden)

Mirjana Malešev

2010-04-01

Full Text Available A comparative analysis of the experimental results of the properties of fresh and hardened concrete with different replacement ratios of natural with recycled coarse aggregate is presented in the paper. Recycled aggregate was made by crushing the waste concrete of laboratory test cubes and precast concrete columns. Three types of concrete mixtures were tested: concrete made entirely with natural aggregate (NAC as a control concrete and two types of concrete made with natural fine and recycled coarse aggregate (50% and 100% replacement of coarse recycled aggregate. Ninety-nine specimens were made for the testing of the basic properties of hardened concrete. Load testing of reinforced concrete beams made of the investigated concrete types is also presented in the paper. Regardless of the replacement ratio, recycled aggregate concrete (RAC had a satisfactory performance, which did not differ significantly from the performance of control concrete in this experimental research. However, for this to be fulfilled, it is necessary to use quality recycled concrete coarse aggregate and to follow the specific rules for design and production of this new concrete type.

How Concrete Is Concrete?

Science.gov (United States)

Gravemeijer, Koeno

2011-01-01

If we want to make something concrete in mathematics education, we are inclined introduce, what we call, "manipulatives", in the form of tactile objects or visual representations. If we want to make something concrete in a everyday-life conversation, we look for an example. In the former, we try to make a concrete model of our own,…

Usage of Crushed Concrete Fines in Decorative Concrete

Science.gov (United States)

Pilipenko, Anton; Bazhenova, Sofia

2017-10-01

The article is devoted to the questions of usage of crushed concrete fines from concrete scrap for the production of high-quality decorative composite materials based on mixed binder. The main problem in the application of crushed concrete in the manufacture of decorative concrete products is extremely low decorative properties of crushed concrete fines itself, as well as concrete products based on them. However, crushed concrete fines could have a positive impact on the structure of the concrete matrix and could improve the environmental and economic characteristics of the concrete products. Dust fraction of crushed concrete fines contains non-hydrated cement grains, which can be opened in screening process due to the low strength of the contact zone between the hydrated and non-hydrated cement. In addition, the screening process could increase activity of the crushed concrete fines, so it can be used as a fine aggregate and filler for concrete mixes. Previous studies have shown that the effect of the usage of the crushed concrete fines is small and does not allow to obtain concrete products with high strength. However, it is possible to improve the efficiency of the crushed concrete fines as a filler due to the complex of measures prior to mixing. Such measures may include a preliminary mechanochemical activation of the binder (cement binder, iron oxide pigment, silica fume and crushed concrete fines), as well as the usage of polycarboxylate superplasticizers. The development of specific surface area of activated crushed concrete fines ensures strong adhesion between grains of binder and filler during the formation of cement stone matrix. The particle size distribution of the crushed concrete fines could achieve the densest structure of cement stone matrix and improve its resistance to environmental effects. The authors examined the mechanisms of structure of concrete products with crushed concrete fines as a filler. The results of studies of the properties of

Sinkhole remediation at Swinging Bridge Dam

Energy Technology Data Exchange (ETDEWEB)

Jones, A. [Devine Tarbell and Associates, Portland, ME (United States)

2009-07-01

This case history summary described a piping-related sinkhole that occurred after a flood at the Swinging Bridge Dam. The earth-filled embankment dam was constructed using a hydraulic fill technique. A foundation drilling and grouting program was constructed in areas of the dam founded on jointed sandstone and shale. The storage volumes of the reservoir is 32,000 acre-feet. A sinkhole 25 to 300 feet in diameter was observed on May 5, 2005 along the edge of the dam crest. The sinkhole extended to within 10 feet of the reservoir and was separated by a shallow berm of soil and driftwood. Cracking of the crest extended across an area of 180 feet. Operations staff notified the appropriate agencies, implemented a monitoring program, and mobilized construction equipment and sands for use as emergency sinkhole filler. An increase in tailrace turbidity was observed. Historical records for the dam showed significant cracking during the initial filling of the reservoir. Failure modes included increased pore pressures and seepages resulting in the piping of soil along the outside of the dam conduit. Emergency repairs included chemical grouting and weld repairs in the penstocks. A Federal Emergency Management Agency (FEMA) is currently addressing safety issues associated with conduits through dams. 4 refs., 11 figs.

Modeling the capacity of riverscapes to support beaver dams

Science.gov (United States)

Macfarlane, William W.; Wheaton, Joseph M.; Bouwes, Nicolaas; Jensen, Martha L.; Gilbert, Jordan T.; Hough-Snee, Nate; Shivik, John A.

2017-01-01

The construction of beaver dams facilitates a suite of hydrologic, hydraulic, geomorphic, and ecological feedbacks that increase stream complexity and channel-floodplain connectivity that benefit aquatic and terrestrial biota. Depending on where beaver build dams within a drainage network, they impact lateral and longitudinal connectivity by introducing roughness elements that fundamentally change the timing, delivery, and storage of water, sediment, nutrients, and organic matter. While the local effects of beaver dams on streams are well understood, broader coverage network models that predict where beaver dams can be built and highlight their impacts on connectivity across diverse drainage networks are lacking. Here we present a capacity model to assess the limits of riverscapes to support dam-building activities by beaver across physiographically diverse landscapes. We estimated dam capacity with freely and nationally-available inputs to evaluate seven lines of evidence: (1) reliable water source, (2) riparian vegetation conducive to foraging and dam building, (3) vegetation within 100 m of edge of stream to support expansion of dam complexes and maintain large colonies, (4) likelihood that channel-spanning dams could be built during low flows, (5) the likelihood that a beaver dam is likely to withstand typical floods, (6) a suitable stream gradient that is neither too low to limit dam density nor too high to preclude the building or persistence of dams, and (7) a suitable river that is not too large to restrict dam building or persistence. Fuzzy inference systems were used to combine these controlling factors in a framework that explicitly also accounts for model uncertainty. The model was run for 40,561 km of streams in Utah, USA, and portions of surrounding states, predicting an overall network capacity of 356,294 dams at an average capacity of 8.8 dams/km. We validated model performance using 2852 observed dams across 1947 km of streams. The model showed

National dam inventory provides data for analysis

International Nuclear Information System (INIS)

Spragens, L.

1992-01-01

The Association of State Dam Safety Officials completed a dam inventory this fall. Information on approximately 90,000 state-regulated dams in the US collected during the four-year inventory is being used to build a database managed by the Federal Emergency Management Agency. In addition to ASDSO's work, the federal government conducted an inventory of federal dams. This data will be added to the state information to form one national database. The database will feature 35 data fields for each entry, including the name of the dam, its size, the name of the nearest downstream community, maximum discharge and storage volume, the date of the last inspection, and details about the emergency action plan. The program is an update of the nation's first dam inventory, required by the Dam Safety Act of 1972. The US Army Corps of Engineers completed the original inventory in 1981. The Water Resources Development Act of 1986 authorized appropriations of $2.5 million for the Corps to update the inventory. FEMA and the Corps entered into an agreement for FEMA to undertake the task for the Corps and to coordinate work on both the federal and state inventories. ASDSO compiles existing information on state-regulated dams into a common format for the database, added missing information, and established a process for continually updating data. ASDSO plans to analyze the information collected for the database. It will look at statistics for the number of dams regulated, communities that could be affected, and the number of high-hazard dams. FEMA is preparing reports for Congress on the project. The reports, which are expected to be ready by May 1993, will include information on the methodology used and facts about regulated dams under state jurisdiction

Qu'Appelle River Dam, dam break analysis using advanced GIS tools for rapid modelling and inundation mapping

Energy Technology Data Exchange (ETDEWEB)

Bonin, D. [Hatch Energy, Winnipeg, MB (Canada); Campbell, C. [Saskatchewan Watershed Authority, Moose Jaw, SK (Canada); Groeneveld, J. [Hatch Energy, Calgary, AB (Canada)

2008-07-01

The South Saskatchewan River Project (SSRP) comprises a multi-purpose reservoir that provides water for conservation and irrigation, flood control, power generation, recreation, and municipal and industrial water supply. In addition to the 64 m high Gardiner Dam, the 27 m high Qu'Appelle River Dam and the 22 km long Lake Diefenbaker Reservoir, the SSRP also includes ancillary works. The Qu'Appelle River valley extends for 458 km before connecting to the Assiniboine River. The valley is incised up to 90 m in depth and is a popular cottaging and recreational area with several major communities located in the flood plain. In the event of a breach of the Qu'Appelle Dam, the discharge will increase from a normal maximum discharge of under 60 m{sup 3} per second to over 50,000 m{sup 3} per second. The Saskatchewan Watershed Authority (SWA) is responsible for ensuring safe development of the Province's water resources, without affecting reservoir or lake operations, and preventing damage from flooding, erosion or land slides. It is in the process of developing Hazard Assessments and emergency preparedness plans for each of their dams in accordance with the Canadian Dam Safety Guidelines. Studies using GIS technology and the hydrodynamic routing model HEC-RAS have been completed to evaluate the potential inundation that may result in the event of failure of the Qu'Appelle River Dam. These studies involved the development of a breach parameter model using a breach data set revised to better reflect the Qu'Appelle River Dam; the development of a dam break model for the Qu'Appelle River Dam and downstream river and flood plain; and, the use of this model to simulate two potential dam failure scenarios for the Qu'Appelle River Dam, notably failure during passage of the PMF and failure during fair weather conditions. Inundation maps have been prepared for the downstream Qu'Appelle River valley for each of the above events. 3 refs., 4

Geodynamical behavior of some active area in Egypt, as deduced from geodetic and gravity data

Science.gov (United States)

Issawy, E.; Mrlina, J.; Radwan, A.; Mahmoud, S.; Rayan, A.

2009-04-01

Temporal gravity variation in parallel with the space geodetic technique (GPS) had been started in Egypt for real campaigns in 1997. The geodetic networks around the High Dam, Aswan area was the first net to be measured. More than five measurement epochs were performed. The results had a considerable limit of coincidence between gravity and GPS observations. The trend of gravity changes indicated a positive stress and had the vertical displacement observed for leveling points. The lowest gravity changes along Kalabsha fault reflect extensional and/or strike component of the stress field. Also, the areas around Cairo (Greater Cairo) and due to the occurrence of an earthquake of 1992, such type of measurements were useful for monitoring the recent activity. The data of the geodetic network around Cairo after 5 campaigns showed that, the estimated horizontal velocities for almost all points are 5.5± mm/year in approximately NW-SE direction. The non-tidal changes can explain the dynamic process within the upper crust related to the development of local stress conditions. The trends of gravity changes are more or less coincident with that deduced from GPS deformation analysis and the occurrence of the main shocks in the area. In additions, in 2005 the geodetic network around the southern part of Sinai and the Gulf of Suez were established. One campaign of measurements had been performed and the gravity values were obtained.

Dam Design can Impede Adaptive Management of Environmental Flows: A Case Study from the Opuha Dam, New Zealand

Science.gov (United States)

Lessard, JoAnna; Murray Hicks, D.; Snelder, Ton H.; Arscott, David B.; Larned, Scott T.; Booker, Doug; Suren, Alastair M.

2013-02-01

The Opuha Dam was designed for water storage, hydropower, and to augment summer low flows. Following its commissioning in 1999, algal blooms (dominated first by Phormidium and later Didymosphenia geminata) downstream of the dam were attributed to the reduced frequency and magnitude of high-flow events. In this study, we used a 20-year monitoring dataset to quantify changes associated with the dam. We also studied the effectiveness of flushing flows to remove periphyton from the river bed. Following the completion of the dam, daily maximum flows downstream have exceeded 100 m3 s-1 only three times; two of these floods exceeded the pre-dam mean annual flood of 203 m3 s-1 (compared to 19 times >100 m3 s-1 and 6 times >203 m3 s-1 in the 8 years of record before the dam). Other changes downstream included increases in water temperature, bed armoring, frequency of algal blooms, and changes to the aquatic invertebrate community. Seven experimental flushing flows resulted in limited periphyton reductions. Flood wave attenuation, bed armoring, and a shortage of surface sand and gravel, likely limited the effectiveness of these moderate floods. Floods similar to pre-dam levels may be effective for control of periphyton downstream; however, flushing flows of that magnitude are not possible with the existing dam infrastructure. These results highlight the need for dams to be planned and built with the capacity to provide the natural range of flows for adaptive management, particularly high flows.

The interplay of activists and dam developers : the case of Myanmar’s mega-dams

NARCIS (Netherlands)

Kirchherr, Julian|info:eu-repo/dai/nl/411261487; J. Charles, Katrina; Walton, Matthew J.

2017-01-01

Scholars investigating activism against large dam developments in Asia usually focus on those campaigning, but not on those the campaigns are aimed at–the dam developers. Yet the developers’ perspective is crucial to comprehensively understand the dynamics of social and environmental activism in

A technique for the determination of center of gravity and rolling resistance for tilt-seat wheelchairs.

Science.gov (United States)

Lemaire, E D; Lamontagne, M; Barclay, H W; John, T; Martel, G

1991-01-01

A balance platform setup was defined for use in the determination of the center of gravity in the sagittal plane for a wheelchair and patient. Using the center of gravity information, measurements from the wheelchair and patient (weight, tire coefficients of friction), and various assumptions (constant speed, level-concrete surface, patient-wheelchair system is a rigid body), a method for estimating the rolling resistance for a wheelchair was outlined. The center of gravity and rolling resistance techniques were validated against criterion values (center of gravity error = 1 percent, rolling resistance root mean square error = 0.33 N, rolling resistance Pearson correlation coefficient = 0.995). Consistent results were also obtained from a test dummy and five subjects. Once the center of gravity is known, it is possible to evaluate the stability of a wheelchair (in terms of tipping over) and the interaction between the level of stability and rolling resistance. These quantitative measures are expected to be of use in the setup of wheelchairs with a variable seat angle and variable wheelbase length or when making comparisons between different wheelchairs.

Data Mining of the Thermal Performance of Cool-Pipes in Massive Concrete via In Situ Monitoring

OpenAIRE

Zuo, Zheng; Hu, Yu; Li, Qingbin; Zhang, Liyuan

2014-01-01

Embedded cool-pipes are very important for massive concrete because their cooling effect can effectively avoid thermal cracks. In this study, a data mining approach to analyzing the thermal performance of cool-pipes via in situ monitoring is proposed. Delicate monitoring program is applied in a high arch dam project that provides a good and mass data source. The factors and relations related to the thermal performance of cool-pipes are obtained in a built theory thermal model. The supporting ...

Computer aided seismic and fire retrofitting analysis of existing high rise reinforced concrete buildings

CERN Document Server

Hussain, Raja Rizwan; Hasan, Saeed

2016-01-01

This book details the analysis and design of high rise buildings for gravity and seismic analysis. It provides the knowledge structural engineers need to retrofit existing structures in order to meet safety requirements and better prevent potential damage from such disasters as earthquakes and fires. Coverage includes actual case studies of existing buildings, reviews of current knowledge for damages and their mitigation, protective design technologies, and analytical and computational techniques. This monograph also provides an experimental investigation on the properties of fiber reinforced concrete that consists of natural fibres like coconut coir and also steel fibres that are used for comparison in both Normal Strength Concrete (NSC) and High Strength Concrete (HSC). In addition, the authors examine the use of various repair techniques for damaged high rise buildings. The book will help upcoming structural design engineers learn the computer aided analysis and design of real existing high rise buildings ...

Recycled Concrete as Aggregate for Structural Concrete Production

OpenAIRE

Mirjana Malešev; Vlastimir Radonjanin; Snežana Marinković

2010-01-01

A comparative analysis of the experimental results of the properties of fresh and hardened concrete with different replacement ratios of natural with recycled coarse aggregate is presented in the paper. Recycled aggregate was made by crushing the waste concrete of laboratory test cubes and precast concrete columns. Three types of concrete mixtures were tested: concrete made entirely with natural aggregate (NAC) as a control concrete and two types of concrete made with natural fine and recycle...

The Future Concrete: Self-Compacting Concrete

OpenAIRE

Iureş, Liana; Bob, Corneliu

2010-01-01

The paper presents the characteristics of the self-compacting concretes, their advantages and disadvantages when they are used in buildings. Due to its properties and composition, the self-compacting concrete is described here as being one of the future friendly enviromental material for buildings. Tests concerning to obtaining a self-compacting concrete, together with the specific fresh concrete properties tests, are described.

Effect of Silica Fume on two-stage Concrete Strength

Science.gov (United States)

Abdelgader, H. S.; El-Baden, A. S.

2015-11-01

Two-stage concrete (TSC) is an innovative concrete that does not require vibration for placing and compaction. TSC is a simple concept; it is made using the same basic constituents as traditional concrete: cement, coarse aggregate, sand and water as well as mineral and chemical admixtures. As its name suggests, it is produced through a two-stage process. Firstly washed coarse aggregate is placed into the formwork in-situ. Later a specifically designed self compacting grout is introduced into the form from the lowest point under gravity pressure to fill the voids, cementing the aggregate into a monolith. The hardened concrete is dense, homogeneous and has in general improved engineering properties and durability. This paper presents the results from a research work attempt to study the effect of silica fume (SF) and superplasticizers admixtures (SP) on compressive and tensile strength of TSC using various combinations of water to cement ratio (w/c) and cement to sand ratio (c/s). Thirty six concrete mixes with different grout constituents were tested. From each mix twenty four standard cylinder samples of size (150mm×300mm) of concrete containing crushed aggregate were produced. The tested samples were made from combinations of w/c equal to: 0.45, 0.55 and 0.85, and three c/s of values: 0.5, 1 and 1.5. Silica fume was added at a dosage of 6% of weight of cement, while superplasticizer was added at a dosage of 2% of cement weight. Results indicated that both tensile and compressive strength of TSC can be statistically derived as a function of w/c and c/s with good correlation coefficients. The basic principle of traditional concrete, which says that an increase in water/cement ratio will lead to a reduction in compressive strength, was shown to hold true for TSC specimens tested. Using a combination of both silica fume and superplasticisers caused a significant increase in strength relative to control mixes.

The Future Concrete: Self-Compacting Concrete

Directory of Open Access Journals (Sweden)

Liana Iureş

2010-01-01

Full Text Available The paper presents the characteristics of the self-compacting concretes, their advantages and disadvantages when they are used in buildings. Due to its properties and composition, the self-compacting concrete is described here as being one of the future friendly enviromental material for buildings. Tests concerning to obtaining a self-compacting concrete, together with the specific fresh concrete properties tests, are described.

Potential Mixture of POFA and SCBA as Cement Replacement in Concrete – A Review

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Ali Noorwirdawati

2017-01-01

Full Text Available Concrete is an important material used in all kind of building construction and ordinary Portland cement (OPC is one of an important element in the production of concrete. However, the production of cement causes a problem because of high CO2 emission to atmosphere. The manufacture of 1 tonnes of cement would produce approximately released 1 tonnes of CO2. So, the need to search another material that can replace a cement with same properties and environmental friendly are crucial. The suitable material to replace cement has to be a pozzolanic materials. This is because pozzolanic materials has cementitious properties and high silica content. Palm oil fuel ash (POFA and sugarcane bagasse ash (SCBA are the material that suitable to replace cement because of high silica content. The use of POFA and SCBA in concrete has been studied by many researcher and it has been proved to improve the mechanical strength of the concrete either in normal concrete, high strength concrete or lightweight concrete. This paper would discuss the overview of the previous study on the cement replacement by POFA and SCBA and the potential of the both materials to be mix together to improve its properties. The chemical element which will be the focus point is SiO4, MgO, CaO and SO3, while the physical and mechanical properties such as workability, specific gravity, compressive strength and tensile strength will also be reviewed.

Dam safety management in Victoria (Australia)

International Nuclear Information System (INIS)

Adem, J.

1996-01-01

The Victoria state government's decision to make dam owners accountable for safety and upkeep of their dams was reported. To give effect to this decision a series of guidelines have been developed which outline the required activities and skills to ensure that dams are properly managed within a framework of 'light-handed' regulation. The guidelines are also intended to ensure that dam management becomes an integral part of the business decision making process, not just a set of prescribed technical procedures. Details of the direction being taken and the proposed controls to ensure compliance with national and international standards were described. 4 refs., 2 figs

Large Dam Effects on Flow Regime and Hydraulic Parameters of river (Case study: Karkheh River, Downstream of Reservoir Dam

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Farhang Azarang

2017-06-01

Full Text Available Introduction: The critical role of the rivers in supplying water for various needs of life has led to engineering identification of the hydraulic regime and flow condition of the rivers. Hydraulic structures such dams have inevitable effects on their downstream that should be well investigated. The reservoir dams are the most important hydraulic structures which are the cause of great changes in river flow conditions. Materials and Methods: In this research, an accurate assessment was performed to study the flow regime of Karkheh river at downstream of Karkheh Reservoir Dam as the largest dam in Middle East. Karkheh River is the third waterful river of Iran after Karun and Dez and the third longest river after the Karun and Sefidrud. The Karkheh Dam is a large reservoir dam built in Iran on the Karkheh River in 2000. The Karkheh Reservoir Dam is on the Karkheh River in the Northwestern Khouzestan Province, the closest city being Andimeshk to the east. The part of Karkheh River, which was studied in this research is located at downstream of Karkheh Reservoir Dam. This interval is approximately 94 km, which is located between PayePol and Abdolkhan hydrometric stations. In this research, 138 cross sections were used along Karkheh River. Distance of cross sections from each other was 680m in average. The efficient model of HEC-RAS has been utilized to simulate the Karkheh flow conditions before and after the reservoir dam construction using of hydrometric stations data included annually and monthly mean discharges, instantaneous maximum discharges, water surface profiles and etc. Three defined discharges had been chosen to simulate the Karkheh River flow; maximum defined discharge, mean defined discharge and minimum defined discharge. For each of these discharges values, HEC-RAS model was implemented as a steady flow of the Karkheh River at river reach of study. Water surface profiles of flow, hydraulic parameters and other results of flow regime in

Stability of cosmic structures in scalar-tensor theories of gravity

Energy Technology Data Exchange (ETDEWEB)

Panotopoulos, Grigoris [Universidade de Lisboa, Centro Multidisciplinar de Astrofisica, Instituto Superior Tecnico, Lisbon (Portugal); Rincon, Angel [Pontificia Universidad Catolica de Chile, Instituto de Fisica, Santiago (Chile)

2018-01-15

In the present work we study a concrete model of scalar-tensor theory of gravity characterized by two free parameters, and we compare its predictions to observational data and constraints coming from supernovae, solar system tests and the stability of cosmic structures. First an exact analytical solution at the background level is obtained. Using that solution the expression for the turnaround radius is computed. Finally we show graphically how current data and limits put bounds on the parameters of the model at hand. (orig.)

Exporting dams: China's hydropower industry goes global.

Science.gov (United States)

McDonald, Kristen; Bosshard, Peter; Brewer, Nicole

2009-07-01

In line with China's "going out" strategy, China's dam industry has in recent years significantly expanded its involvement in overseas markets. The Chinese Export-Import Bank and other Chinese financial institutions, state-owned enterprises, and private firms are now involved in at least 93 major dam projects overseas. The Chinese government sees the new global role played by China's dam industry as a "win-win" situation for China and host countries involved. But evidence from project sites such as the Merowe Dam in Sudan demonstrates that these dams have unrecognized social and environmental costs for host communities. Chinese dam builders have yet to adopt internationally accepted social and environmental standards for large infrastructure development that can assure these costs are adequately taken into account. But the Chinese government is becoming increasingly aware of the challenge and the necessity of promoting environmentally and socially sound investments overseas.

Measuring and managing safety at Wahleach Dam

International Nuclear Information System (INIS)

Salmon, G. M.; Cattanach, J. D.; Hartford, D. N. D.

1996-01-01

Safety improvements recently implemented at the Wahleach Dam were described as one of the first instances in international dam safety practice where risk concepts have been used in conjunction with acceptable risk criteria to evaluate safety of a dam relative to required level of safety. Erosion was identified as the greatest threat to the safety of the dam. In addressing the deficiencies B.C. Hydro formulated a process which advocates a balanced level of safety,i.e. the probability of failure multiplied by the consequences of failure, integrated over a range of initiators. If the risk posed by the dam is lower than a 'tolerable' risk, the dam is considered to be safe enough. In the case of the Wahleach Dam, the inflow design flood (IDF) was selected to be about one half of the probable maximum flow (PMF), hence it was more likely than not that the spillway could pass floods up to and including the PMF. By accepting the determined level of risk, expenditures of several million dollars for design and construction of dam safety improvements were made redundant. Another byproduct of this new concept of risk assessment was the establishment of improved life safety protection by means of an early warning system for severe floods through the downstream community and emergency authorities. 3 refs., 5 tabs

Large dams and alluvial rivers in the Anthropocene: The impacts of the Garrison and Oahe Dams on the Upper Missouri River

Science.gov (United States)

Skalak, Katherine; Benthem, Adam J.; Schenk, Edward R.; Hupp, Cliff R.; Galloway, Joel M.; Nustad, Rochelle A.; Wiche, Gregg J.

2013-01-01

The Missouri River has had a long history of anthropogenic modification with considerable impacts on river and riparian ecology, form, and function. During the 20th century, several large dam-building efforts in the basin served the needs for irrigation, flood control, navigation, and the generation of hydroelectric power. The managed flow provided a range of uses, including recreation, fisheries, and habitat. Fifteen dams impound the main stem of the river, with hundreds more on tributaries. Though the effects of dams and reservoirs are well-documented, their impacts have been studied individually, with relatively little attention paid to their interaction along a river corridor. We examine the morphological and sedimentological changes in the Upper Missouri River between the Garrison Dam in ND (operational in 1953) and Oahe Dam in SD (operational in 1959). Through historical aerial photography, stream gage data, and cross sectional surveys, we demonstrate that the influence of the upstream dam is still a major control of river dynamics when the backwater effects of the downstream reservoir begin. In the “Anthropocene”, dams are ubiquitous on large rivers and often occur in series, similar to the Garrison Dam Segment. We propose a conceptual model of how interacting dams might affect river geomorphology, resulting in distinct and recognizable morphologic sequences that we term “Inter-Dam sequence” characteristic of major rivers in the US.

Assessing the Influence of the Three Gorges Dam on Hydrological Drought Using GRACE Data

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Fupeng Li

2018-05-01

Full Text Available With worldwide economic and social development, more dams are being constructed to meet the increasing demand for hydropower, which may considerably influence hydrological drought. Here, an index named the “Dam Influence Index” (DII is proposed to assess the influence of the Three Gorges Dam (TGD on hydrological drought in the Yangtze River Basin (YRB in China. First, the total terrestrial water storage (TTWS is derived from Gravity Recovery and Climate Experiment data. Then, the natural-driven terrestrial water storage (NTWS is predicted from the soil moisture, precipitation, and temperature data based on an artificial neural network model. Finally, the DII is derived using the empirical (Kaplan-Meier cumulative distribution function of the differences between the TTWS and the NTWS. The DIIs of the three sub-basins in the YRB were 1.38, −4.66, and −7.32 between 2003 and 2008, which indicated an increase in TTWS in the upper sub-basin and a reduction in the middle and lower sub-basins. According to the results, we concluded that impoundments of the TGD between 2003 and 2008 slightly alleviated the hydrological drought in the upper sub-basin and significantly aggravated the hydrological drought in the middle and lower sub-basins, which is consistent with the Palmer Drought Severity Index. This study provides a new perspective for estimating the effects of large-scale human activities on hydrological drought and a scientific decision-making basis for the managing water resources over the operation of the TGD.

The utilization of stone ash on cellular lightweight concrete

Science.gov (United States)

Karolina, R.; Sianipar, Y. G. C.

2018-02-01

Lightweight concrete brick is a brick which made of cement, sand, water, and foam as the basic composition. This brick are divided into 2, based on the foam used such as AAC (Autoclave Aerated Concrete) that use aluminium paste and CLC(Cellular Lightweight Concrete) that use foaming agent from BASF as its foaming material. In this trial, the lightweight brick that are ging to be use are the CLC with foaming agent as its foaming material with the mixture of stone ash that are produced by the Stone Crusher with spesific gravity 2666 kg/m3 as their partly sand substitution . In this research, the stone ash variant that are used are 10%, 15%, and 20% from the amount of sand that planned before. After casting, the result of the 10% will receive a reduction of compressive strength while an increasing in absorption as 25.07% and 39.005% and the 15% variant will recieve a reduction of compressive strength as much as 65.8% and a reduction of absorption as much as 17.441% and the 20% variant will recieve a reduction of compressive strength as much as 67.4% while an increasing of absorption as much as 17.956%.

The changing hydrology of a dammed Amazon

Science.gov (United States)

Timpe, Kelsie; Kaplan, David

2017-01-01

Developing countries around the world are expanding hydropower to meet growing energy demand. In the Brazilian Amazon, >200 dams are planned over the next 30 years, and questions about the impacts of current and future hydropower in this globally important watershed remain unanswered. In this context, we applied a hydrologic indicator method to quantify how existing Amazon dams have altered the natural flow regime and to identify predictors of alteration. The type and magnitude of hydrologic alteration varied widely by dam, but the largest changes were to critical characteristics of the flood pulse. Impacts were largest for low-elevation, large-reservoir dams; however, small dams had enormous impacts relative to electricity production. Finally, the “cumulative” effect of multiple dams was significant but only for some aspects of the flow regime. This analysis is a first step toward the development of environmental flows plans and policies relevant to the Amazon and other megadiverse river basins. PMID:29109972

Isotope technique in JPS dam surveillance: its potential

International Nuclear Information System (INIS)

Sabri Hassan

2006-01-01

Controlling seepage is one of the most important requirements for safe dams. Any leakage at an earth embankment may be potentially dangerous since rapid internal erosion may quickly enlarge an initially minor defect. Thus dam owners need to have thorough surveillance programs that can forewarn of impending problems from seepage or other factors influencing the safety of dams. In carrying out dam surveillance works, all possible efforts should be considered and foreseeing the potential of isotope technique, JPS (Department of Irrigation and Drainage, Malaysia) and MINT (Malaysian Institute for Nuclear Technology Research) participated actively in the UNDP/RCA/IAEA program under RAS/8/093 project sponsored by the International Atomic Energy Agency (IAEA). Through these activities, it was noted that the technique demonstrated very promising potentials such as in assisting dam site selections, site investigations, watershed studies, dam and reservoir design, leakage investigations and sediments related issues, the two latter ones being relatively critical during the operational life of the dam. Establishment of baseline isotopic characteristics (or fingerprint), hydrochemistry, electrical conductivity and temperature profiles is underway for all JPS dams to be later utilized in diagnosing seepage related issues it is suggested that application of this technique be extended to other dam owners nationwide. (Author)

Boundary element analysis of earthquake induced hydrodynamic pressures in a water reservoir

International Nuclear Information System (INIS)

Jablonski, A.M.

1988-11-01

The seismic analysis of concrete gravity and arch dams is affected by the hydrodynamic pressures in the water reservoir. Boundary element method (BEM) formulations are derived for the hydrodynamic pressures arising in a gravity dam-reservoir-foundation system, treating both 2- and 3-dimensional cases. The formulations are based on the respective mathematical models which are governed by two- and three-dimensional Helmholtz equations with appropriate boundary conditions. For infinite reservoirs, loss of energy due to pressure waves moving away toward infinity strongly influence response. Since it is not possible to discretize an infinite extent, the radiation damping due to outgoing waves is accounted for by incorporating special boundary conditions at the far end, and in a similar manner the loss of energy due to absorption of waves by a flexible bottom of reservoir and banks can be accounted for by a special condition along the boundaries. Numerical results are obtained and compared with available classical solutions and convergence of numerical results with the size and number of boundary elements is studied. It is concluded that the direct boundary element method is an effective tool for the evaluation of the hydrodynamic pressures in finite and infinite dam-reservoir-foundation systems subjected to harmonic-type motion, and can easily be extended to any type of random motion with fast Fourier transform techniques. 82 refs., 65 figs., 25 tabs

TRANSPARENT CONCRETE

OpenAIRE

Sandeep Sharma*, Dr. O.P. Reddy

2017-01-01

Transparent concrete is the new type of concrete introduced in todays world which carries special property of light transmitting due to presence of light Optical fibres. Which is also known as translucent concrete or light transmitting concrete, it is achieved by replacing coarse aggregates with transparent alternate materials (Optical fibres). The binding material in transparent concrete may be able to transmit light by using clear resins the concrete mix. The concrete used in industry in pr...

Numerical modelling for stability of tailings dams

OpenAIRE

Auchar, Muhammad; Mattsson, Hans; Knutsson, Sven

2013-01-01

A tailings dam is a large embankment structure that is constructed to store the waste from the mining industry. Stability problems may occur in a tailings dam due to factors such as quick rate of raising, internal erosion and liquefaction. The failure of a tailings dam may cause loss of human life and environmental degradation. Tailings Dams must not only be stable during the time the tailings storage facility is in operation, but also long time after the mine is closed. In Sweden, the licens...

Dams and transnational advocacy: Political opportunities in transnational collective action

Science.gov (United States)

Fu, Teng

Possible arguments to explain the gradual decline in big dam development and its site transferring from developed to developing countries include technical, economic, and political factors. This study focuses on the political argument---the rise of transnational anti-dam advocacy and its impact on state policy-making. Under what conditions does transnational anti-dam advocacy matter? Under what conditions does transnational advocacy change state dam policies (delay, scale down, or cancel)? It examines the role of transnational anti-dam actors in big dam building in a comparative context in Asia. Applying the social movement theory of political opportunity structure (POS) and using the qualitative case-study method, the study provides both within-case and cross-case analyses. Within-case analysis is utilized to explain the changing dynamics of big dam building in China (Three Gorges Dam and proposed Nu/Salween River dam projects), and to a lesser extent, Sardar Sarovar Project in India and Nam Theun 2 Dam in Laos. Different domestic and international POS (DPOS and IPOS) impact the strategies and outcomes of anti-dam advocacies in these countries. The degree of openness of the POS directly affects the capacity of transnational efforts in influencing state dam policies. The degree of openness or closure is measured by specific laws, institutions, discourse, or elite allies (or the absence of these) for the participation of non-state actors on big dam issues at a particular moment. This degree of openness is relative, varying over time, across countries and regions. This study finds that the impact of transnational anti-dam activism is most effective when both DPOS and IPOS are relatively open. Transnational anti-dam advocacy is least effective in influencing state dam policies when both DPOS and IPOS are relatively closed. Under a relatively open DPOS and closed IPOS, transnational anti-dam advocacy is more likely to successfully change state dam policies and even

Monitoring Vertical Crustal Deformation and Gravity Variations during Water Level Changes at the Three Gorges Reservoir

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WANG Wei

2017-06-01

Full Text Available Monitoring vertical crustal deformation and gravity changes during water level changes at the Three Gorges reservoir is important for the safe operation of the Three Gorges Dam and for the monitoring and prevention of a regional geological disaster. In this study, we determined vertical crustal deformation and gravity changes during water level variations of the Three Gorges reservoir from direct calculations and actual measurements and a comprehensive solution. We used water areas extracted image data from the ZY-3 satellite and water level data to calculate gravity changes and vertical crustal deformation caused by every 5 m change in the water level due to storage and drainage of the Three Gorges reservoir from 145 m to 175 m. The vertical crustal deformation was up to 30 mm. The location of gravity change above 20 μ Gal(1 Gal=10-2 m/s2 was less than 2 km from the centerline of the Yangtze River. The CORS ES13 in Badong, near the reservoir, measured the vertical crustal deformation during water level changes. Because of the small number of CORS and gravity stations in the Three Gorges reservoir area, monitoring deformation and gravity related to changes in the Three Gorges reservoir water level cannot be closely followed. Using 26 CORS and some of the gravity stations in the Three Gorges area and based on loading deformation and the spherical harmonic analysis method, an integrated solution of vertical deformation and gravity variations during water level changes of the reservoir was determined, which is consistent with the actual CORS monitoring results. By comparison, we found that an integrated solution based on a CORS network can effectively enhance the capability of monitoring vertical crustal deformation and gravity changes during water level variations of the reservoir.

Environmental impacts of small dams on agriculture and ground water development: a case study of Khan pur Dam, Pakistan

International Nuclear Information System (INIS)

Ejaz, N.; Shahmim, M.A.; Elahi, A.; Khan, N.M.

2012-01-01

The water scarcity issues are increasing through out the world. Pakistan is also facing water crises and its water demands are increasing every day. During this research it is investigated that small dams are playing an important role for the sustainability of groundwater and agriculture. The main objective of this study was to assess the environmental impacts of small dam on agricultural and ground water. Proper planning and management of small dams may improve the sustainable agriculture in Pakistan. It is also concluded that small dams are significantly contributing towards economy, environment, local climate, recreational activities and crop production. Small dams can also be utilized for the production of electricity at local level. On the other hand, water management issues can be resolved by the involvement of local farmer's associations. Water losses through seepage, unlined channels and old irrigation methods are most critical in developing world. Considering the overall positive environmental impacts, construction of small dams must be promoted. (author)

Large dams and risk management

International Nuclear Information System (INIS)

Cazelais, N.

2003-01-01

In July 1996, Quebec's Saguenay region was subjected to intensive rainfall which caused severe floods and uncontrolled release of several reservoirs, resulting in extensive damage to dam structures and reservoirs. The probability of occurrence for that disaster was 1:10,000. Following the disaster, the Quebec government established a dam management body entitled the Commission scientifique et technique sur la gestion des barrages, which pointed out several safety shortcomings of existing dams. Many were either very old or had undergone significant function change without being subsequently re-evaluated. A report by the Commission stated that damage following the floods could have been limited if the design and operating standards of the dams had been more stringent. A Dam Safety Act was adopted by the Quebec National Assembly on May 30, 2000 following recommendations to retain safer structures. The Act demands regular reporting of operating procedures. Seismic activity was noted as being a topic that requires in-depth examination since Quebec's St. Lawrence Valley, particularly the Charlevoix region, is one of Canada's largest seismic zones. The other is on the west coast in British Columbia. Earthquakes in Quebec are less intense than the ones in British Columbia, but they have higher frequency content which exerts a quasi-resonance wave effect which impacts roads, bridges, buildings and hydroelectric generating facilities. Hydro-Quebec is a public utility which owns 563 retaining structures, of which 228 are ranked as large dams that measure more than 15 metres high, 400 metres long and with a reservoir capacity of more than 1 million cubic metres of water. Hydro-Quebec addresses hydrological, seismic, technological and human risks through a dam safety procedure that includes structured plans for choosing best alternatives through staged exercises. Hazard levels are minimized through the adoption of emergency, prevention and alleviation measures. The utility

78 FR 62627 - Sam Rayburn Dam Rate

Science.gov (United States)

2013-10-22

..., Wholesale Rates for Hydro Power and Energy Sold to Sam Rayburn Dam Electric Cooperative, Inc. (Contract No... Schedule SRD-08, Wholesale Rates for Hydro Power and Energy Sold to Sam Rayburn Dam Electric Cooperative... ADMINISTRATION RATE SCHEDULE SRD-13 \\1\\ WHOLESALE RATES FOR HYDRO POWER AND ENERGY SOLD TO SAM RAYBURN DAM...

Evaluatie Dam tot Damloop 2014

NARCIS (Netherlands)

Deutekom-Baart de la Faille, Marije

In het weekend van 20 en 21 september 2014 vond de 30ste editie van de Dam tot Damloop plaats. Onderzoekers van de Hogeschool van Amsterdam en Hogeschool Inholland hebben bij de Dam tot Damloop een evaluatieonderzoek uitgevoerd met als doel het vinden van aanknopingspunten voor het structureel

Investigation of the existence of self compacting properties in high performance concrete through experimental tests

Directory of Open Access Journals (Sweden)

Heitor H. Yoshida

2007-03-01

Full Text Available The self compacting concrete is characterized by its capacity to flow inside the formwork filling it exclusively by the force of the gravity with adequate cohesion and viscosity in such a way that segregation does not occur. One of its characteristic is the presence of fines which provide the necessary cohesion,and grains with maximum diameter of 20 mm. This work presents some procedures and experimental methods that make it possible to evaluate self compacting properties of high performance concrete. First, a bibliographical review on the subject was carried out, and later, the equipment used for the accomplishment of the assays were manufactured, in order to verify the properties related to the self compacting concrete: cohesion, viscosity and segregation. As for the work, two concretes were produced with Portland ARI Cement, thick sand, stone powder, sand 0, superplasticizer made of ether-carboxilate chains that differentiate from each other for the presence of active silica in one of them and fly ash in the other. Based on the results, it was verified whether the high performance concrete had self compacting characteristics. In this case, both were considered positive. It was also analyzed the behavior of these concretes in their hardened state by means of the compressive strength test. The Self Compacting Concrete has many advantages such as: reduction in the number of employees, shorter construction period, the non-use of the vibrator and the filling of formworks with high density of… or of complex geometry.

The Total Risk Analysis of Large Dams under Flood Hazards

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Yu Chen

2018-02-01

Full Text Available Dams and reservoirs are useful systems in water conservancy projects; however, they also pose a high-risk potential for large downstream areas. Flood, as the driving force of dam overtopping, is the main cause of dam failure. Dam floods and their risks are of interest to researchers and managers. In hydraulic engineering, there is a growing tendency to evaluate dam flood risk based on statistical and probabilistic methods that are unsuitable for the situations with rare historical data or low flood probability, so a more reasonable dam flood risk analysis method with fewer application restrictions is needed. Therefore, different from previous studies, this study develops a flood risk analysis method for large dams based on the concept of total risk factor (TRF used initially in dam seismic risk analysis. The proposed method is not affected by the adequacy of historical data or the low probability of flood and is capable of analyzing the dam structure influence, the flood vulnerability of the dam site, and downstream risk as well as estimating the TRF of each dam and assigning corresponding risk classes to each dam. Application to large dams in the Dadu River Basin, Southwestern China, demonstrates that the proposed method provides quick risk estimation and comparison, which can help local management officials perform more detailed dam safety evaluations for useful risk management information.

How Concrete is Concrete

Directory of Open Access Journals (Sweden)

Koeno Gravemeijer

2010-07-01

Full Text Available If we want to make something concrete in mathematics education, we are inclined introduce, what we call, ‘manipulatives’, in the form of tactile objects or visual representations. If we want to make something concrete in a everyday-life conversation, we look for an example. In the former, we try to make a concrete model of our own, abstract, knowledge; in the latter, we try to find an example that the others will be familiar with. This article first looks at the tension between these two different ways of making things concrete. Next another role of manipulatives, will be discussed, namely that of means for scaffolding and communication. In this role, manipulatives may function as means of support in a process that aims at helping students to build on their own thinking while constructing more sophisticated mathematics

Analysis the dynamic response of earth dam in free vibration and forced by introducing the effect of the interaction dam foundation

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Malika Boumaiza

2018-01-01

Full Text Available The present study concerns the analysis of the dynamic response of earth dam, in free and forced vibration (under the effect of earthquake using the finite element method. The analysis is carried out at the end of dam construction without filling. The behavior of the dam materials and the foundation is linear elastic. In free vibration, to better understand the effect of the dam foundation interaction, we will take into account different site conditions and see their influence on the free vibration characteristics of the dam. In forced vibration, to study the seismic response of the dam, the system is subjected to the acceleration of the Boumerdes earthquake of May 21, 2003 recorded at the station n ° 2 of the dam of Kaddara in the base, with a parametric study taking into account the influence of the main parameters such as the mechanical properties of the soil: rigidity, density.

Ice interactions at a dam face

Energy Technology Data Exchange (ETDEWEB)

Morse, B.; Morse, J.; Beaulieu, P.; Pratt, Y. [Laval Univ., Quebec City, PQ (Canada). Dept. of Civil Engineering; Stander, E. [State Univ. of New York, Cobleskill College, Cobleskill, NY (United States). Dept. of Natural Sciences; Cote, A.; Tarras, A.; Noel, P. [Hydro-Quebec, Varennes, PQ (Canada). IREQ

2009-07-01

This paper reported on a joint research project between Laval University and Hydro-Quebec to study ice forces on dams in an effort to harmonize design criteria and develop mitigation strategies. This paper introduced the project and explored some of the preliminary results of the 2007-2008 field season. Ice displacement, ice stresses and ice forces on the LaGabelle dam were measured at several locations. The paper identified and discussed the complex relationships between data sets and discussed the spatial-temporal variability of the ice forces and its impact on design criteria. The project objective was to develop design criteria for ice forces on dams and to provide a scientific basis for interpreting and harmonizing existing recommended criteria. The methodology and site description were presented. It was concluded that the ice processes in a reservoir near a dam face subject to water fluctuations are quite complex. Therefore, in order to know the real average pressure on the dam, a significant amount of panels are required, having important implications for determining safe design values. 9 refs., 10 figs.

How Concrete is Concrete

OpenAIRE

Koeno Gravemeijer

2010-01-01

If we want to make something concrete in mathematics education, we are inclined introduce, what we call, ‘manipulatives’, in the form of tactile objects or visual representations. If we want to make something concrete in a everyday-life conversation, we look for an example. In the former, we try to make a concrete model of our own, abstract, knowledge; in the latter, we try to find an example that the others will be familiar with. This article first looks at the tension between these two diff...

Thermal effects of dams in the Willamette River basin, Oregon

Science.gov (United States)

Rounds, Stewart A.

2010-01-01

Methods were developed to assess the effects of dams on streamflow and water temperature in the Willamette River and its major tributaries. These methods were used to estimate the flows and temperatures that would occur at 14 dam sites in the absence of upstream dams, and river models were applied to simulate downstream flows and temperatures under a no-dams scenario. The dams selected for this study include 13 dams built and operated by the U.S. Army Corps of Engineers (USACE) as part of the Willamette Project, and 1 dam on the Clackamas River owned and operated by Portland General Electric (PGE). Streamflows in the absence of upstream dams for 2001-02 were estimated for USACE sites on the basis of measured releases, changes in reservoir storage, a correction for evaporative losses, and an accounting of flow effects from upstream dams. For the PGE dam, no-project streamflows were derived from a previous modeling effort that was part of a dam-relicensing process. Without-dam streamflows were characterized by higher peak flows in winter and spring and much lower flows in late summer, as compared to with-dam measured flows. Without-dam water temperatures were estimated from measured temperatures upstream of the reservoirs (the USACE sites) or derived from no-project model results (the PGE site). When using upstream data to estimate without-dam temperatures at dam sites, a typical downstream warming rate based on historical data and downstream river models was applied over the distance from the measurement point to the dam site, but only for conditions when the temperature data indicated that warming might be expected. Regressions with measured temperatures from nearby or similar sites were used to extend the without-dam temperature estimates to the entire 2001-02 time period. Without-dam temperature estimates were characterized by a more natural seasonal pattern, with a maximum in July or August, in contrast to the measured patterns at many of the tall dam sites

The Political Ecology of Chinese Large Dams in Cambodia: Implications, Challenges and Lessons Learnt from the Kamchay Dam

Directory of Open Access Journals (Sweden)

Giuseppina Siciliano

2016-09-01

Full Text Available Given the opportunities offered by foreign investment in energy infrastructure mostly by Chinese firms, the Government of Cambodia is giving high priority to developing hydropower resources for reducing energy poverty and powering economic growth. Using a “Political ecology of the Asian drivers” framework, this paper assesses China’s involvement in the development of large dams’ in Cambodia and its impacts on the access of natural resources such as water and energy by dam builders, local communities and the government. This analysis is based on 61 interviews and 10 focus group discussions with affected communities, institutional actors, Chinese dam builders and financiers in relation to the first large Chinese dam built in Cambodia: the Kamchay dam. Based on the results of the analysis this paper makes recommendations on how to improve the planning, implementation and governance of future large dams in Cambodia.

Effect of insulating concrete forms in concrete compresive strength

Science.gov (United States)

Martinez Jerez, Silvio R.

The subject presented in this thesis is the effect of Insulating Concrete Forms (ICF's) on concrete compressive strength. This work seeks to identify if concrete cured in ICF's has an effect in compressive strength due to the thermal insulation provided by the forms. Modern construction is moving to energy efficient buildings and ICF's is becoming more popular in new developments. The thesis used a concrete mixture and a mortar mixture to investigate the effects of ICF's on concrete compressive strength. After the experimentations were performed, it was concluded that the ICF's do affect concrete strength. It was found that the forms increase concrete strength without the need for additional curing water. An increase of 50% in strength at 56 days was obtained. It was concluded that the longer concrete cures inside ICF's, the higher strength it reaches, and that ICF's effect on concrete strength is proportional to volume of concrete.

Douglas County Dam Breach Inundation Areas

Data.gov (United States)

Kansas Data Access and Support Center — Dam breach analysis provides a prediction of the extent and timing of flooding from a catastrophic breach of the dams. These results are sufficient for developing...

Expectations of immortality: dam safety management into the next millennium

Energy Technology Data Exchange (ETDEWEB)

Palmer, M.D. [Tonkin and Taylor International Ltd., Auckland, (New Zealand)

1999-07-01

Topics concerning the problems associated with older and aging dams are considered including: what can be done to extent the lifetime of an old dam, the decision to decommission a dam based on a value judgment that the risk of maintaining the dam is too great for society's acceptance, the possibility of change in the level of risk tolerance with time in a technological environment, traditional surveillance methods used by dam owners in the Y2K situation, and the unreality of dam immortality. Trends and means for preserving older dams for their owner's purposes are outlined, as well as their lifetime compared to that of the downstream systems they serve. Despite the fact that we live in a throwaway society, dam owners cannot just leave their dam asset when they are through with using it. Someone has to maintain the dam, or ensure that it is safely decommissioned when the owner is finished with it. On a worldwide scale the available pool of experienced dam engineers is shrinking. This problem needs to be addressed by a shift towards operating and dam safety management skills based on a firm awareness of dam design principles. A shift in society's expectations has occurred such that dam designers and owners must now recognize the impact a dam can have both on its natural and social environments. Because of the increasing emphasis on paying attention to the impacts of people's activities on the planet, engineers more than anyone else must have a significant influence in that direction. 9 refs.

Expectations of immortality: dam safety management into the next millennium

International Nuclear Information System (INIS)

Palmer, M.D.

1999-01-01

Topics concerning the problems associated with older and aging dams are considered including: what can be done to extent the lifetime of an old dam, the decision to decommission a dam based on a value judgment that the risk of maintaining the dam is too great for society's acceptance, the possibility of change in the level of risk tolerance with time in a technological environment, traditional surveillance methods used by dam owners in the Y2K situation, and the unreality of dam immortality. Trends and means for preserving older dams for their owner's purposes are outlined, as well as their lifetime compared to that of the downstream systems they serve. Despite the fact that we live in a throwaway society, dam owners cannot just leave their dam asset when they are through with using it. Someone has to maintain the dam, or ensure that it is safely decommissioned when the owner is finished with it. On a worldwide scale the available pool of experienced dam engineers is shrinking. This problem needs to be addressed by a shift towards operating and dam safety management skills based on a firm awareness of dam design principles. A shift in society's expectations has occurred such that dam designers and owners must now recognize the impact a dam can have both on its natural and social environments. Because of the increasing emphasis on paying attention to the impacts of people's activities on the planet, engineers more than anyone else must have a significant influence in that direction. 9 refs

Langbjorn dam : adaptation for safe discharge of extreme floods

Energy Technology Data Exchange (ETDEWEB)

Yang, J. [Vattenfall Research and Development, Alvkarleby (Sweden); Ericsson, H.; Gustafsson, A. [SWECO, Stockholm (Sweden); Stenmark, M. [Vattenfall Power Consultant, Ludvika (Sweden); Mikaelsson, J. [Vattenfall Nordic Generation, Bispgarden (Sweden)

2007-07-01

The Langbjorn hydropower scheme, composed of an embankment dam with an impervious core of compacted moraine, a spillway section and a powerhouse, is located on the Angermanalven River in north Sweden. The scheme was commissioned in 1959 and is owned by Vattenfall. As part of its dam safety program, Vattenfall plans to adapt and refurbish many of its dams to the updated design-flood and dam-safety guidelines. Langbjorn is classified as a high hazard dam, as its updated design flood is 30 per cent higher than the existing spillway capacity. Safety evaluations were conducted for the Langbjorn dam, and, as required by the higher safety standard, there was a need to rebuild the dam, so that the design flood could be safely released without causing failure of the dam. This paper provided information on the Langbjorn hydropower scheme and discussed the planned rebuilding measures. For example, the design flood was accommodated by allowing a temporary raise of the water level by 1.3 metres above the legal retention reservoir level, which required heightening and reinforcement of the dam. Specifically, the paper discussed measures to increase the discharge capacity; handling and control of floating debris; improvement and heightening of impervious core in left and right connecting dam and abutment; measures to increase the stability of the left steep riverbank; and measures to increase stability of the spillway monoliths and the left guide wall. In addition, the paper discussed measures to ensure stability of the downstream stretch of the river bank and increase instrumentation. The paper also presented the results of hydraulic investigations to investigate the risk of erosion downstream of the dam. It was concluded that the dam could discharge the design flood and that the stability of the dam was improved and judged to be satisfactory during all foreseeable conditions. 2 refs., 8 figs.

Red Indian Lake fishway, an innovative design for difficult conditions

International Nuclear Information System (INIS)

Helwig, P.C.; Goosney, R.; Smith, W.L.

1993-01-01

Red Indian Lake Dam is a large concrete gravity structure, 10-12 m high and 245 m long, in the Exploits River watershed in Newfoundland. The watershed is an ideal habitat for production of Atlantic salmon. Since 1985, the watershed above the dam has undergone an extensive stocking program to optimize the salmon production capacity of the upper reaches of the system. To sustain this development, a fishway was needed to permit returning salmon to bypass Red Indian Lake Dam, the last remaining migrational barrier. The difficulties with installing a fishway at the dam site included extreme variation in upstream water levels, the need to retrofit a fishway into an existing structure, and the necessity to attract fish into the fishway in competition with other flows from power plant, spillway, or waterfall. After examining several design approaches, an innovative design was developed incorporating two separate but interrelated flow ways: one to handle attraction water and the other for transportation water. The latter passage leads to a trap at the upper end of the fishway from which salmon are hoisted via a hopper/monorail system across the dam and into the lake. Construction of the fishway was staged over four phases between December 1985 and December 1988. 3 refs., 1 fig

The mathematics of dam safety

Energy Technology Data Exchange (ETDEWEB)

Widmann, R. [Osterreichische Gesellschaft fuer Geomechanik, Salzburg (Austria)

1997-05-01

The safety of a dam is determined by its design, construction and supervision during operation. High arch dam failures have dropped dramatically since the early part of this century. An essential part of the success story relates to improved measurement techniques that can detect earlier unexpected behaviour that may lead to failure. (UK)

Massive Niagara Falls power generation project uses unique concrete locking system

Energy Technology Data Exchange (ETDEWEB)

Polski, A. [Con Cast Pipe, Niagara Falls, ON (Canada)

2006-09-15

A 512 metre long accelerating wall and a 360 metre-long approach wall in the Niagara River are being built using a novel locking system to withstand the forces of nature. The walls have been designed to direct continuous flow to a new diversion tunnel below the City of Niagara Falls, Ontario. The walls are made of a single row of pre-cast concrete boxes that lock together in a special configuration to prevent movement from extreme load combinations in the Niagara River. The system was designed as part of a larger project to increase the power generating capabilities of the Sir Adam Beck 2 power generation station. Water channelled into the new tunnel will provide an estimated additional 1.6 terawatt-hours of renewable electricity annually and expand capacity at the station by about 15 per cent. The pre-cast reinforced concrete box design was chosen for the walls as it allowed fast and simple assembly of the structures. The basic structural system for each box is 4 vertical panels that form an open rectangular wall. The boxes are filled with clean rock fragments that are uniformly graded. Once the boxes are installed, cast-in-place concrete slabs will be poured to a depth of approximately 600 mm on top of the wall to cap the entire structure. The value of the design-build contract for the Niagara project is nearly $600 million out of an estimated $985 million budget. Commonly used for the design of culverts, the concrete box technology holds promise for applications including the stabilization of shorelines and the construction of small dams. 3 figs.

the effect of age of dam on weaning mass for ftve dam breed types

African Journals Online (AJOL)

SUMMARY: The effect of age of dam on adjusted 210 day calf weaning mass was estimated by the Least Squares method for 5 dam types on 2 farms. ... the later maturing breeds would have a low level of productivity because these cows would be eliminated in their potentially prime .... time at 28 (2A) or 3l (28) months old.

Self-Placing Concrete

OpenAIRE

ECT Team, Purdue

2007-01-01

Certain concrete pours have areas where the congestion of reinforcing bars make placement of concrete almost impossible. Using conventional placing and vibration techniques, the resulting concrete can have considerable honeycombing due to the development of voids. Self-placing concrete is a possible solution to the problem. Also known as self-compactable concrete, self-consolidating concrete, flowable concrete, and non-vibration concrete. These concretes eliminate the need for vibration in a ...

Proceeding of the public safety around dams conference

Energy Technology Data Exchange (ETDEWEB)

NONE

2011-07-01

The Canadian Dam Association hosted the Public Safety Around Dams workshop in which presentations were given in the morning to describe the different measures and methods implemented by the Ontario Ministry of Natural Resources, Ontario Power Generation and others to improve safety around dams. In the afternoon, the participants toured the Auburn and Lakefield dams and facilities to view the infrastructures and equipment. A roundtable discussion concluded the day. Following this workshop, a Public Safety Around Dams group was created on the social network site, LinkedIn. This conference featured 6 presentations, 3 of which have been catalogued separately for inclusion in this database.

Thermodynamic laws for generalized f(R) gravity with curvature-matter coupling

International Nuclear Information System (INIS)

Wu Yabo; Zhao Yueyue; Cai Ronggen; Lu Jianbo; Lu Junwang; Gao Xiaojing

2012-01-01

The first law and the generalized second law (GSL) of thermodynamics for the generalized f(R) gravity with curvature-matter coupling are studied in the spatially homogeneous, isotropic FRW universe. The research results show that the field equations of the generalized f(R) gravity with curvature-matter coupling can be cast to the form of the first law of thermodynamics with the so-called the entropy production terms dS ¯ and the GSL can be given by considering the FRW universe filled only with ordinary matter enclosed by the dynamical apparent horizon with the Hawking temperature. Furthermore, as a concrete example, by utilizing the GSL the constraints on the gravitational model with f 1 (R)=R+αR l and f 2 (R)=R m are also discussed. It is worth noting these results given by us are quite general and can degenerate to the ones in Einstein's general relativity and pure f(R) gravity with non-coupling and non-minimal coupling as special cases. Comparing with the case of Einstein's general relativity, the appearance of the entropy production term dS ¯ in the first law of thermodynamics demonstrates that the horizon thermodynamics is non-equilibrium one for generalized f(R) gravity with curvature-matter coupling, which is consistent with the arguments given in Akbar and Cai (2007) [13] and Eling et al. (2006) [18].

Quality control of concrete in construction of No.2 and No.5 plants in Kashiwazaki Kariwa Nuclear Power Station, Tokyo Electric Power Co., Inc