• Title/Summary/Keyword: concrete dams

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Thermo-structural monitoring of RCC dam in India through instrumentation

  • Ashtankar, V.B.;Chore, H.S.
    • Structural Monitoring and Maintenance
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    • v.2 no.2
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    • pp.95-113
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    • 2015
  • The knowledge of the behavior of any roller compacted concrete (RCC) dam and its foundation is gained by studying the service action of the dam and its foundation using measurements of an external and internal nature. The information by which a continuing assurance of structural safety of the RCC dam can be gauged is of primary importance. Similarly, the fact that the information on structural and thermal behavior and the properties of concrete that may be used to give added criteria for use in the design of future RCC dams is of secondary importance. Wide spread attention is now being given to the installation of more expensive instrumentation for studying the behavior of concrete dams and reservoirs and forecasting of any adverse trends. In view of this, the paper traces installation and need of the comprehensive instrumentation scheme implemented to monitor the structural and thermal behavior of 102.4 m high RCC dam constructed near Mumbai in India. An attempt is made in the present paper to emphasize the need to undertake an instrumentation program and evaluate their performance during construction and post construction stage of RCC structures. Few typical results, regarding the thermal and structural behavior of the dam, obtained through instrumentation installed at the dam site are presented and compared with the design considerations. The fair agreement is seen in the response observed through instrumentation with that governing the design criteria.

Crack Analysis of Concrete Gravity Dam subjected to Uplift Pressure using Surface Integral Method (표면적분법을 이용한 양압력이 작용하는 중력식 콘코리트 댐의 균열해석)

  • 진치섭;이영호;엄장섭;김태완
    • Proceedings of the Korea Concrete Institute Conference
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    • 2000.10a
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    • pp.267-272
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    • 2000
  • The modeling on uplift pressure on the foundation of a dam on which it was constructed, and on the interface between the dam and foundation is a critical aspect in the analysis of concrete gravity dams. The evaluation of stress intensity factor at the crack tip of concrete gravity dam due to uplift pressure effect by surface integral method is performed in this study. The effects of body force, overtopping pressure and water pressure on the crack-face are also considered in this study.

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An Effect of Uplift Pressure Applied to Concrete Gravity Dam on the Stress Intensity Factor (중력식 콘크리트 댐에 작용하는 양압력이 응력확대계수에 미치는 영향)

  • Lee Young-Ho;Jang Hee-Suk;Kim Tae-Wan;Jin Chi-Sub
    • Journal of the Korea Concrete Institute
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    • v.16 no.6 s.84
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    • pp.841-850
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    • 2004
  • The modeling of uplift pressure within dam, on the foundation on which it was constructed, and on the interface between the dam and foundation is a critical aspect in the analysis of concrete gravity dams, i.e. crack stability in concrete dam can correctly be predicted when uplift pressures are accurately modelled. Current models consider a uniform uplift distribution, but recent experimental results show that it varies along the crack faces and the procedures for modeling uplift pressures are well established for the traditional hand-calculation methods, but this is not the case for finite element (FE) analysis. In large structures, such as dams, because of smaller size of the fracture process zone with respect to the structure size, limited errors should occur under the assumptions of linear elastic fracture mechanics (LEFM). In this paper, the fracture behaviour of concrete gravity dams mainly subjected to uplift Pressure at the crack face was studied. Triangular type, trapezoidal type and parabolic type distribution of the uplift pressure including uniform type were considered in case of evaluating stress intensity factor by surface integral method. The effects of body forces, overtopping pressures are also considered and a parametric study of gravity dams under the assumption of LEFM is performed.

Modeling the Effect of Geology on Uplift in Concrete Gravity Dam Foundations with the Discontinuous Deformation Analysis (불연속 변형 해석을 통한 콘크리트 중력댐 기초에 작용하는 부양력에 대한 지질구조의 영향 모델링)

  • Kim, Yong-Il
    • Tunnel and Underground Space
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    • v.13 no.4
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    • pp.304-315
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    • 2003
  • In this paper, the DDA method with a new hydro-mechanical algorithm is used to study the effect of rock discontinuities on uplift and seepage in concrete gravity dam foundations. This paper presents an alternative method of predicting uplift and seepage at the base of concrete gravity dams. A sensitivity analysis was carried out to study the importance of several parameters on dam stability such as the orientation, spacing, and location of discontinuities. The study shows that joint water flow and adverse geological conditions could result in unusual uplift at the base of concrete gravity dams, well in excess of what is predicted with the classical linear or hi-linear pressure assumption. It is shown that, in general, the DDA program with the hydro-mechanical algorithm can be used as a practical tool in the design of gravity dams built on fractured rock masses.

Pseudo seismic and static stability analysis of the Torul Dam

  • Karabulut, Muhammet;Genis, Melih
    • Geomechanics and Engineering
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    • v.17 no.2
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    • pp.207-214
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    • 2019
  • Dams have a great importance on energy and irrigation. Dams must be evaluated statically and dynamically even after construction. For this purpose, Torul dam built between years 2000 and 2007 Harsit River in Gümüşhane province, Turkey, is selected as an application. The Torul dam has 137 m height and 322 GWh annual energy production capacity. Torul dam is a kind of concrete face rock fill dam (CFRD). In this study, static and pseudo seismic stability of Torul dam was investigated using finite element method. Torul dam model is constituted by numerical stress analysis named Phase2 which is based on finite element method. The dam was examined under 11 different water filling levels. Thirteenth stage of the numerical model is corresponding full reservoir condition which water filled up under crest line. Besides, pseudo static coefficients for dynamic condition applied to the dam in fourteenth stage of the model. Stability assessment of the Torul dam has been discussed according to the displacement throughout the dam body. For static and pseudo seismic cases, the displacements in the dam body have been compared. The total displacements of the dam according to its the empty state increase dramatically at the height of the water level of about 70 m and above. Compared to the pseudo-seismic analysis, the displacement of dam at the full reservoir condition is approximately two times as high as static analysis.

Review on the Seismic Design Standards of Fill Dam (필댐의 내진설계기준의 비교검토)

  • 신동훈
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 1999.10a
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    • pp.129-136
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    • 1999
  • Several seismic design standards for fill dams adopted in Japan USA and Korea are reviewed in this study. The review on those standards is tried to provide a thinking way for a new seismic design standard which is urgently requested by the government I. e. the Ministry of Construction & Transportation and the Ministry of Science & Techniology. This study suggest that as a new seismic design standard of fill dam including concrete face rockfill dam(CFRD) the modified earthquake intensity method based on dynamic analysis be adopted in Korea while the dynamic analysis method should be used in evaluatiing the performance of fill dams precisely.

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Failure Probability Assessment for Risk Analysis of Concrete Gravity Dam under Flood (홍수 시 콘크리트 중력식댐의 위험도 분석을 위한 파괴확률 산정)

  • Cho, Soojin;Shin, Sung Woo;Sim, Sung-Han;Lim, Jeong-Yeul
    • Journal of the Korean Society of Safety
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    • v.31 no.6
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    • pp.58-66
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    • 2016
  • This study aims to estimate the failure probability of concrete gravity dams for their risk analysis under flood situation. To the end, failure modes of concrete gravity dams and their limit state functions are proposed based on numerous review of domestic and international literatures on the dam failure cases and design standards. Three failure modes are proposed: overturning, sliding, and overstress. Based on the failure modes the limit state functions, the failure probability is assessed for a weir section and a non-weir section of a dam in Korea. As water level is rising from operational condition to extreme flood condition, the failure probability is found to be raised up to the warning condition, especially for overturning mode at the non-weir section. The result can be used to reduce the risk of the dam by random environmental variables under possible flood situation.

Construction stages analyses using time dependent material properties of concrete arch dams

  • Sevim, Baris;Altunisik, Ahmet C.;Bayraktar, Alemdar
    • Computers and Concrete
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    • v.14 no.5
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    • pp.599-612
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    • 2014
  • This paper presents the effects of the construction stages using time dependent material properties on the structural behaviour of concrete arch dams. For this purpose, a double curvature Type-5 arch dam suggested in "Arch Dams" symposium in England in 1968 is selected as a numerical example. Finite element models of Type-5 arch dam are modelled using SAP2000 program. Geometric nonlinearity is taken into consideration in the construction stage analysis using P-Delta plus large displacement criterion. In addition, the time dependent material strength variations and geometric variations are included in the analysis. Elasticity modulus, creep and shrinkage are computed for different stages of the construction process. In the construction stage analyses, a total of 64 construction stages are included. Each stage has generally $6000m^3$ concrete volume. Total duration is taken into account as 1280 days. Maximum total step and maximum iteration for each step are selected as 200 and 50, respectively. The structural behaviour of the arch dam at different construction stages has been examined. Two different finite element analyses cases are performed. In the first case, construction stages using time dependent material properties are considered. In the second case, only linear static analysis (not considered construction stages) is taken into account. Variation of the displacements and stresses are obtained from the both analyses. It is highlighted that construction stage analysis using time dependent material strength variations and geometric variations has an important effect on the structural behaviour of arch dams. The maximum longitudinal, transverse and vertical displacements obtained from construction stages and static analyses are 1.35 mm and 0 mm; -8.44 and 6.68 mm; -4.00 and -9.90 mm, respectively. In addition, vertical displacements increase from the base to crest of the dam for both analyses. The maximum S11, S22 and S33 stresses are obtained as 1.60MPa and 2.84MPa; 1.39MPa and 2.43MPa; 0.60MPa and 0.50MPa, respectively. The differences between maximum longitudinal, transverse, and vertical stresses obtained from construction stage and static analyses are 78%, 75%, and %17, respectively. On the other hand, there is averagely 12% difference between minimum stresses for all three directions.