• Title/Summary/Keyword: 콘크리트 표면차수벽형 석괴댐

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Evaluation of the Compaction Characteristics of CFRD Construction Materials (CFRD 시공시 축조재료의 다짐특성 평가)

  • Han, Sang-Hyun;Yea, Geu-Guwen;Park, Jong-Hwa
    • The Journal of Engineering Geology
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    • v.20 no.4
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    • pp.415-424
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    • 2010
  • A prototype of a Concrete-Faced Rock-fill Dam (CFRD) was constructed to evaluate the behavior of the materials in each zone within the dam. The tested materials, selected based on their grain size distribution, were used in constructing the prototype dam with layers of variable thickness, settlement ratio, and water content. We investigated the suitability of various values of hydraulic conductivity, water content, dry unit weight, and settlement ratio for zones within the dam. The test results revealed the relationships between the number of passes and the dry unit weight, between the dry unit weight and the settlement ratio, and between the settlement ratio and the number of passes. This paper focuses on the relationship between hydraulic conductivity and the number of passes. The results of the present analysis could be used to establish reasonable compaction standards for materials used in dam construction.

A Case Study on Deformation Characteristics of Concrete Face Rockfill Dam (콘크리트 표면차수벽형 석괴댐(CFRD)의 거동해석)

  • Kim, Hun;Chung, Kyu-Jung;Lee, Wang-Gon;Jang, Jung-Ryeol
    • Proceedings of the Korean Geotechical Society Conference
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    • 2003.03a
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    • pp.111-116
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    • 2003
  • Instrumentation system in Concrete Face Rockfill Dam(CFRD) can give special attention to the deformation characteristics of the rockfill and behavior of the concrete membrane during construction, reservoir filling and subsequent phase of operation. It also contains data about vertical and transversal compressibility moduli of the rockfill, deflections in the concrete slab, and draws comparisons with other concrete face rockfill dams of recent construction. In this paper, the internal deformation data from D dam monitored by means of hydrostatic settlements cells are analyzed. Observations cover the construction stage, reservoir filling and up to March 1991. The above method can be concluded D dam was well constructed and maintained.

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A Case Study on the Leakage in Concrete Face Rockfill Dam (콘크리트 표면차수벽형 석괴댐(CFRD)의 누수특성에 관한 사례연구)

  • 방돈석;신창건;이강용;안상로
    • Proceedings of the Korean Geotechical Society Conference
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    • 2003.03a
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    • pp.197-202
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    • 2003
  • The leakage quantity through concrete facing of Concrete Face Rockfill Dam(CFRD) is very small due to its low permeability of intact concrete. Even though the concrete facing is well designed and constructed, fine cracks can be generated due to effects of thermal and drying shrinkage. Therefore, it can be said that the leakage from the CFRD is subjected to not permeability of intact concrete but poor joints, cracks and foundation rocks. The Safety of a dam on leakage was evaluated based on the comparison between apparent permeability estimated and leakage quantity measured. The above method can be concluded to give a good direction for the evaluation of safety on CFRD in maintenance aspects as design and construction technology is improved with the accumulation of leakage data.

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Compaction Management of Fill Materials for Concrete Faced Rockfill Dam Using Standard Void Ratio (표준간극비를 이용한 콘크리트 표면차수벽형 석괴댐 축조재료의 다짐 관리)

  • Kim Yong-Seong
    • Journal of The Korean Society of Agricultural Engineers
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    • v.48 no.4
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    • pp.59-66
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    • 2006
  • In this study, construction modulus, void ratio and settlement characteristics of 38 CFRD in domestic and foreign countries were investigated from monitoring data. The effect of field dry density and void ratio to dam body was analyzed. The standard void ratio of CFRD that can be easily used by dam designers and field engineers was proposed from the monitoring data. It was confirmed that we can get the degree of compaction needed for reasonable compaction of dam body by calculating the field dry density from inverse operation of the standard void ratio. It was thought that the void ratio of CFRD depends on shape coefficient and in case of a high shape coefficient, the void ratio was high with its void ratio 0.17 -0.38.

Effects of Stiffness of Face Supporting Zone on Face Slab Behaviors of CFRD (CFRD 차수벽지지죤 강성이 콘크리트차수벽 거동에 미치는 영향)

  • Ha, Ik Soo;Seo, Min Woo;Kim, Hyoung Soo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.5C
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    • pp.351-358
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    • 2006
  • The purpose of this study is to recommend the simulation method and procedure of behaviors of CFRD(Concrete Faced Rockfill Dam) concrete face slab with impoundment by centrifuge tests, to examine the effects of the flexural rigidity of the concrete face slab on the face slab deformation from the centrifuge tests, and to evaluate the effects of the stiffness of face supporting zone on the displacement and moment of face slab by numerical analysis which is verified by the centrifuge tests. In this study, the centrifuge tests on the two model dams with the concrete face slab of different flexural rigidity were carried out. Also, the centrifuge tests were simulated by numerical analysis of which input material properties were obtained by the triaxial tests on the model materials. The validity of numerical analysis was evaluated by comparison between the results of centrifuge tests and numerical simulation. The deformation pattern of the concrete face slab was examined with the various stiffness of the face supporting zone by numerical analysis. From the results of centrifuge tests, the effects of face slab thickness on the deformation of face slab were negligible. From the results of centrifuge tests and numerical analysis, it was found that the amplitude of the maximum displacement of face slab and the position where the maximum displacement was mobilized with impoundment were affected by the stiffness of face supporting zone rather than the flexural rigidity of concrete face slab.

Sensitivity Analysis of Rockfill Input Parameters Influencing Crest Displacement of CFRD Subjected to Earthquake Loading (지진하중을 받는 CFRD 정상부 변위에 영향을 미치는 사력재료 입력물성에 대한 민감도분석)

  • Ha, Ik-Soo
    • Journal of the Earthquake Engineering Society of Korea
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    • v.11 no.1 s.53
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    • pp.1-9
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    • 2007
  • The purpose of this study is to carry out the quantitative sensitivity analysis on rockfill material influencing the dam crest displacement of CFRD(Concrete-Faced Rockfill Dam) subjected to earthquake loading. The total 105 dynamic numerical analyses (2 input earthquake, 2 magnitudes for each earthquake. 27 rockfill material property combinations obtained from large triaxial tests) on CFR type "D" dam in operation were conducted. The global sensitivity analysis was carried out using the results of numerical analysis. From the results of sensitivity analysis, It was found that the crest settlement of the CFR type dam subjected to earthquake was absolutely affected by the shear modulus of rockfill material irrespective of the input earthquakes and the maximum acceleration of each earthquake. Also, it was found that the horizontal displacement of the dam crest was highly affected by the shear modulus of rockfill material though the extent of effect on that was smaller than the settlement and the extent of effect depended on the input earthquakes and the maximum acceleration of each earthquake. On the contrary, it was found that the effect of friction angle was negligible.

Evaluation of Seismic Fragility of Concrete Faced Rockfill Dam (콘크리트 표면차수벽형 석괴댐의 지진 취약도 평가)

  • Baeg, Jongmin;Park, Duhee;Yoon, Jinam;Choi, Byoung-Han
    • Journal of the Korean Geosynthetics Society
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    • v.17 no.4
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    • pp.103-108
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    • 2018
  • The fragility curves for CFRD dams are derived in this study for probabilistic damage estimation as a function of a ground motion intensity. The dam crest settlement, which is a widely used damage index, is used for minor, moderate, and extensive damage states. The settlement is calculated from nonlinear dynamic numerical simulations. The accuracy of the numerical model is validated through comparison with a centrifuge test. The fragility curve is represented as a log normal distribution function and presented as a function of the peak ground acceleration. The fragility curves developed in this study can be utilized for real time assessment of the damage of dams.

Soil Properties of Bedding Bone for Concrete Faced Rockfill Dam (콘크리트 표면차수벽형 석괴댐 지지층의 토질특성)

  • 배종순;성영두
    • Geotechnical Engineering
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    • v.12 no.1
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    • pp.47-62
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    • 1996
  • The bedding zone which influence directly to the safety of dam is supporting the face slab under hydraulic load in concrete faced rockfill dam. In case that leakage is developed due to various ruptured joint or cracks of face slab and etc., the bedding zone should limit the leakage by low permeability and keep the internal stability. In this study for the proper coefficient of permeability various properties, such as gradation, dry density, performance of embankment work and etc. were analysed. The results from the large scale test of permeability and density are summerized as follows : 1. Coefficient of permeability is decreased clearly by increase of dry density. 2. The particles smaller than the No.4 strive( p,) greatly influences the permeability under dry density of 2.24t 1 m3. 3. In case of C.40 and p,40%, even if dry density decreased to 2.0t/m3, the permeability coefficient is assumed to u x1-scm/s and internal stability is abtained. 4. Generally in dam construction since dry density and uniformity coefficient of bedding zone were higher than 2.2t/m3 and 50 respectively p, of 30~40% is assumed to be suitable and permeability coefficient of below 1$\times$10-3cm l s is expectable.

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Evaluation of the Shear Wave Velocity Profile of Rockfill Zone of CFRD Using HWAW Method (국내 콘크리트 표면차수벽형 석괴댐(CFRD) 사력존의 전단파 속도 분포 결정(I): HWAW 방법을 사용한 CFRD 사력존 전단파 속도 주상도 결정)

  • Hwang, Hea-Jin;Park, Yun-Seok;Park, Hyung-Choon
    • Journal of the Korean Geotechnical Society
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    • v.30 no.5
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    • pp.5-15
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    • 2014
  • Rockfill zone is a main part of the CFRD for safety and it is important to evaluate the status such as shear wave velocity profile of the rockfill zone. A surface wave method can be used to evaluate the rockfill zone but general surface wave method can have a difficulty to be applied for valuation of rockfill zone because of a stiff slope of dam and background noise in the field. In this research, HWAW method is applied to evaluate the shear wave velocity of rockfill zone. The field test of the proposed method is simple and fast and the HWAW method can determine the reliable shear wave velocity profile under severe noise field condition. To show feasibility of the proposed method, numerical simulation and field tests were performed. Through the numerical and field tests, the applicability of the proposed method was shown.

Determination of Representative Shear Wave Velocity Profile for Rockfill Zone of CFRD Considering Uncertainty Caused by Spatial Variation of Material Property (국내 콘크리트 표면차수벽형 석괴댐(CFRD) 사력존의 전단파 속도 분포 결정(II): 물성치의 공간 변동성에 의한 불확실성이 고려된 CFRD 사력존의 1차원 전단파 속도 주상도의 결정)

  • Hwang, Hea-Jin;Park, Hyung-Choon
    • Journal of the Korean Geotechnical Society
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    • v.30 no.5
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    • pp.17-24
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    • 2014
  • This paper determines 1D shear wave velocity (Vs) distribution of rockfill zone of CFRD using Vs profile determined by the surface wave test. There exists uncertainty in the field test result because of a spatial variation of material property. The harmonic wavelet transform is used to evaluate the uncertainty of test result and generate random 1D Vs distributions which may exist in the rock fill zone. Through the statistical analysis of generated random Vs distributions, the representative 1D Vs distribution considering the uncertainty of test results is proposed for the rockfill zone of CFRD in Korea.