• Journal of the Korean Geosynthetics Society
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• v.6 no.2
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• pp.9-15
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• 2007

Bedding zone in CRFD (Concrete Faced Rockfill Dam) requires bearing capacity to support the concrete face slab uniformly. Also, shear strength which is a key factor in slope stability and impermeability which is to prevent a loss of soils in case of leakage of concrete slab face are needed. In this study, trial prototype construction for bedding zone in CRFD was performed to investigate the compaction characteristics of bedding zone according to the frequency of compaction, water contents and so on. As a results of series of field test, the compaction characteristics of bedding zone in CRFD was affected considerably by the depth of compaction layer and frequency of compaction.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.278-287
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• 2009

This thesis studied effect of zoning on seepage flow in concrete faced gravel-fill dam (CFGD) designed to have selected main rockfill or gravel-fill zone, Zone 3Bs with higher permeability to enhance the safety against accidental water infiltration into the dam. For this purpose, centrifuge model tests with two cases, with and without Zone 3Bs, were performed in order to investigate the necessity and the function of Zone 3Bs. Model dams were made by soil samples with modified coefficients of permeability and concrete faced slab was simulated with aluminum alloy. Water infiltration was simulated by rising water table over cracks on the facing. Behaviors of model dams were measured by LVDTs, strain gages, pore water pressures and cameras. Form the results of centrifuge tests, it was found out that the Zone 3Bs acts as a protection of main gravel-fill zone by inducing flow paths for infiltrated water into it as well as by draining off the infiltrated water out of the dam in a short time.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.679-682
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• 2005

The effects of substituting cement with fiber addition(poly vinyl alcohol), fly ash and Expansive Additive on the control of microcrack and enhanced durability performance of face slab concrete in concrete-faced rockfill dam was studied experimentally The laboratory test results shown that the mixture of fiber containing concrete and of fly ash replacement of concrete to be more effective than expansive additive concrete in the crack control and mechanical performance.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.713-716
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• 2006

The main purpose of this research was to enhance the durability in both the design and construction of dams. Especially, in case of rockfill dams, the durability of tunnel concrete in a concrete-faced rockfill dam(CFRD) is achieved by optimizing the fly ash replacement for cement and application of steel fiber. The effect on durability and thermal property corresponding to the increasing replacement of fly ash and application of steel fiber was evaluated, and the optimum value of fly ash replacement and steel fiber application was recommended. The results show that 15% of fly ash replacement and $20kg/m^3$ of steel fiber application was found to be an optimum level and demonstrated excellent performance in durability and thermal property.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.1017-1022
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• 2001

Dam concrete for pumped storage power plants should have sufficient durability in repetitive wet and dry conditions and abrasion due to water level fluctuation and also in freezing and thawing resistance as well as permeability capacity. This study presents various experimental results to enhance the durability of face slab concrete in CFRD(concrete faced rockfill dam) by varying the fly ash substitution such as 0%, 15%, 20% and 25% and polypropylene such as 0%, 0.1%. The effect on durability of concrete corresponding to the increasing amount of fly ash and polypropylene was evaluated and the optimum quantity of fly ash and polypropylene substitution was recommended. The results show that 20% of fly ash substitution and 0% of polypropylene were found out to be an optimum quantity to achieve excellent performances in durability for face slab concrete in CFRD.

• Journal of the Korean Geosynthetics Society
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• v.8 no.2
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• pp.31-39
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• 2009

The purpose of present study performed 27 CFRD cases analyses to predict and effectively use post-construction crest settlement, face slab deformation, and leakage as indexes for the maintenance and management of concrete faced rockfill dams(CFRD). The results showed that the range of post-construction crest settlement suggested by Sherard and Cooke (1987), and Clements (1984) had a good agreement in the case analyses using rockfills with very high intact strength, but it had a trend which underestimated crest settlement in the cases using rockfills with medium to high intact strength. The leakage case analyses showed that leakage is mainly caused by face slab deformation due to the water load, the maximum leakage in general was observed during the first reservoir filling, and leakage was rapidly increasing when the dam height exceeds 125m.

• Journal of the Korean GEO-environmental Society
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• v.8 no.6
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• pp.77-83
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• 2007

In this study, deformation behavior of existing concrete face rockfill dam, which is raised to a certain height to enhance storage capacity or to improve hydraulic and hydrologic stability, is examined using numerical analysis method. The results obtained from FEM analysis show a possibility that additional fill at downstram slope of existing CFRD dam body may lead undesirable deformations and stresses in existing dam body, especially in face concrete, such as settlements in upper part and bulging in lower part, excessive bending moments, and eventualy tensile cracks. Therefore, in designing multi-staged raising construction of CFRD, it is essential to consider deformations and stresses to be developed within and between exisiting dam body and added parts due to additional fill, and to prepare a proper measure to prevent abnormal deformations and stresses in the dam body including added parts.

• 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.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.784-793
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• 2006

As the number of CFRD constructions increases, the necessity of an accurate assessment on its behavior also has been increasing accordingly. The performance of concrete faced rockfill dam (CFRD) under different water levels is greatly concerned by dam engineers and designers in the world. However, domestic research on CFRD design and construction has yet been insignificant. This study deals with three centrifuge model tests, mainly investigates the deformation of the concrete faced slabs with different face slab stiffness under different water levels. The prototype of a centrifugal model dam is half size of domestic CFRD dam. Detailed material preparation, model design, model set-up, model instrumentation and testing procedures are presented. In order to simulate the prototype concrete faced slab, three kinds of thin fiberglass plates with different thickness was adopted in the three model tests. The water level control facility was specially designed for this experiment to control the water level rise and drawdown during centrifuge flight. Although most of the results from the three model tests are satisfactory, it is also required that the centrifuge test results should be compared with those of numerical analysis and field measurements to analyze the centrifuge test results more in detail.

• The Journal of Engineering Geology
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• v.19 no.4
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• pp.493-499
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• 2009

Recently, the construction of Concrete Faced Rockfill Dam (CFRD) is increasing because rock material resources are plenty in Korea. Bedding zone in the CFRD is necessary enough bearing capacity to support the concrete face slab uniformly and enough impermeability to prevent the loss of fine soils in case of leakage from the concrete slab face. Therefore, cut-off the water leakage in bedding zone securely is the key factor influencing the safety of CFRD. Tested materials satisfied with the specification of particle size distribution at the Bedding Zone area are chosen for conducting permeability tests, which are done to evaluate the property of cut off the materials. Based on the test results, the effects of cut off the materials are investigated by considering the coefficient of permeability, the soil particle distribution, and the dry unit weight. Especially, the relationships between coefficient of permeability with effective size(D10), dry unit weight, and weight passing percent the No.4 sieve are suggested, and also the variation of coefficient of permeability with time are proposed.