• Structural Engineering and Mechanics
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• v.36 no.4
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• pp.481-497
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• 2010

The shaking table tests were conducted on two small-scale models (Model 1 and Model 2) to examine the earthquake-induced damage of a concrete gravity dam, which has been planned for the construction with the recommendation of the peak ground acceleration of the maximum credible earthquake of 0.42 g. This study deals with the numerical simulation of shaking table tests for two smallscale dam models. The plastic damage constitutive model is used to simulate the crack/damage behavior of the bentonite-concrete mixture material. The numerical results of the maximum failure acceleration and the crack/damage propagation are compared with experimental results. Numerical results of Model 1 showed similar crack/damage propagation pattern with experimental results, while for Model 2 the similar pattern was obtained by considering the modulus of elasticity of the first and second natural frequencies. The crack/damage initiated at the changing point in the downstream side and then propagated toward the upstream side. Crack/damage accumulation occurred in the neck area at acceleration amplitudes of around 0.55 g~0.60 g and 0.65 g~0.675 g for Model 1 and Model 2, respectively.

• Computers and Concrete
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• v.26 no.6
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• pp.483-495
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• 2020

Dams are vital infrastructures that are expected to maintain their stability during seismic excitations. Accordingly, cemented material dams are an emerging type, which are being increasingly used around the world owing to benefiting from advantages of both earth-fill and concrete gravity dams, which should be designed safely when subjected to strong ground motion. In the present paper, the seismic performance of a cemented sand and gravel (CSG) dam is assessed using incremental dynamic analysis (IDA) method by accounting for two failure modes of tension cracking and base joint sliding considering the dam-reservoir-foundation interactions. To take the seismic uncertainties into account, the dam is analyzed under a suite of ground motion records and then, the effect of friction angle for base sliding as well as deformability of the foundation are investigated on the response of dam. To carry out the analyses, the Cindere dam in Turkey is selected as a case study, and various limit states corresponding to seismic performance levels of the dam are determined aiming to estimate the seismic fragilities. Based on the results, sliding of the Cindere dam could be serious under the maximum credible earthquake (MCE). Besides, dam faces are mostly to be cracked under such level of intensity. Moreover, the results indicate that as friction angle increases, probability of sliding between dam and foundation is reduced whereas, increases tensile cracking. Lastly, it is observed that foundation stiffening increases the probability of dam sliding but, reduces the tensile damage in the dam body.

• Journal of the Korean GEO-environmental Society
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• v.16 no.2
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• pp.5-13
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• 2015

In the present study, the prediction methods of the crest settlement after impounding and the maximum internal settlement during dam construction were proposed through the analysis on settlement data at 38 monitored points of 36 Concrete-Faced Rockfill Dams (CFRDs). The results from this analysis provided that the crest settlement and the maximum internal settlement are increased in proportion to the dam height and the void ratio. However, the relationship between internal settlement and dam height for each void-ratio range plotted in semi-logarithmic scale is the nearly same. Also, the prediction of the crest settlement of the CFRD is possible through the maximum internal settlement during dam construction. In addition, it seems that the valley shape highly affects the dense dam body with high construction modulus. The results of this study will provide the useful tool for the design, construction and management of CFRDs.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.846-853
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• 2006

In this study, quantitative sensitivity analysis on rockfill material influencing the dam crest displacement of Concrete-Faced Rockfill Dam(CFRD) was carried out. The purpose of this study is to indicate the most important input parameter and to show the quantitative variation of displacement at the crest of CFR type dam with this input parameter. The rockfill material properties for parametric study were obtained from the results of large scale triaxial tests on 34 rockfill materials in the 22 different sites. From the statistical analysis on these data, some statistical characteristics of rockfill material properties such as property range, distribution characteristics, and correlation between the properties were investigated. based on these characteristics, 27 property combinations were constituted by Latin Hypercube sampling method. Dam crest displacements after construction, impounding, and earthquake loading were evaluated by static and dynamic numerical analysis on each combination. From the sensitivity analysis, it was found that the crest displacement of CFR type dam was absolutely affected by the shear modulus of rockfill material and the effect of friction angle of it was negligible. This relative difference of sensitivity was more outstanding in case of crest settlement than in case of crest horizontal displacement. Also, it was found that the settlement and horizontal displacement of dam crest logarithmically decreased as the shear modulus increased and the difference between the maximum value and the minimum vale amounted to about 9.5 times in case of settlement and about 10 times in case of horizontal displacement.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.869-887
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• 2008

Coffer dam for tunnel type spillway in inflow section of Dae-am dam was originally planned as 2 lines sheet piles with Water Zet method. But, the result of pilot test was caused of some problems that vibration during installation of pile could pollute water and water leakage could the lower part. So, sheet piles was not satisfactory for faculty of coffer dam. Structural instability of sheet pile system need to reinforcement. Characteristic of Dae-am dam was small reservoir capacity but wide drainage area, of which it was judgment that security of leakage and stability was difficult during excavation of inlet part. So, we consider that water curtain method utilized with in site pouring concrete pile method was designed at weir part of spillway. We were known about basement rock that geological boring was carried out in weir part. After taking a deep consideration, PRD method was accepted as a new method. Concrete pile by PRD was installed to below country rock. CJM method was carried out with PRD. After making concrete wall using Top-down method, earth anchors were installed for supporting it. According to the result of numerical analysis, as water level rises, wall is stable.

• Journal of the Korean Society of Safety
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• v.35 no.5
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• pp.30-38
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• 2020

In order to construct a dam, the diversion facility such as cofferdam and a diversion tunnel should be installed in advance. And size of a cofferdam depends on type of a main dam. According to the Korea Dam Design Standard, if the main dam is a concrete dam, design flood of the cofferdam is 1~2 years flood frequency. This means that overflow of the cofferdam occurs one time for 1 or 2 years, therefore, stability of the cofferdam should be secured against any overflow problem. In this study, failure probability analysis for the concrete cofferdam is performed considering the overflow. First of all, limit state function of the concrete cofferdam is defined for overturning, sliding and base pressure, and upstream water levels are set as El. 501 m, El. 503 m, El. 505 m, El. 507 m. Also, after literature investigation research, probabilistic characteristics of various random variables are determined, the failure probability of the concrete cofferdam is calculated using the Monte Carlo Simulation. As a result of the analysis, when the upstream water level rises, it means overflow, the failure probability increases rapidly. In particular, the failure probability is largest in case of flood loading condition. It is considered that the high upstream water level causes increase of the upstream water pressure and the uplift pressure on the foundation. In addition, among the overturning, the sliding and the base pressure, the overturing is the major cause for the cofferdam failure considering the overflow.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.5
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• pp.74-85
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• 2022

The purpose of this paper is to review the applicability of the current standards for the evaluation method of input variables and performance level in seismic performance evaluation by dynamic plastic analysis of the concrete gravity-type dam to which MCE is applied, and to suggest improvements. To this end, a domestic concrete gravity-type dam was selected as a target facility, dynamic plasticity analysis was performed under various conditions, and applicability to input variables such as concrete tensile strength and breaking energy, was reviewed. By analyzing the effect of cracks at the bottom of the gravity dam on the stability of the activity, an improvement plan for the performance level evaluation method required to secure the water storage function was derived. If the proposed improvement plan is applied, it will have the effect of deriving more reasonable evaluation results than the current seismic performance evaluation method to which MCE is applied.

• Journal of the Korean Society of Hazard Mitigation
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• v.4 no.1 s.12
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• pp.1-14
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• 2004

The objective of this study is firstly to frame up the seismic safety of concrete gravity dams. It is necessary to analyze seismic response and evaluate seismic performance of concrete gravity dams during earthquake. In this study, seismic damage and dynamic analysis of concrete gravity dams using structural analysis package such as SAP2000 and MIDAS were performed. Additional dynamic water pressure due to earthquake considered as additional mass for numerical seismic analysis. According detailed analysis, the vibration through the dam structure (transverse to water flow) seems to be very critical depending on the shape of the dam. For more precise evaluation of seismic fragility of concrete gravity dams, further research is still needed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.3
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• pp.39-48
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• 1989

The concrete temperature in mass concrete rises rapidly above the placing temperature owing to the heat given off by the hydrating cement. This temperature rise produces tensile stress and cracks which later become the cause of water leakage in concrete structures. It is essential, therefore, to reduce the interior heat of concrete dam given off by hydrating cement by artificial cooling. The present study aiming to study the temperature variations in mass concrete by pipe cooling, compars the actual measurements of Chungju Dam with the temperature calculated by Finite Difference Method(FDM), and it found that the results closely agree with each other. Based on these results, the analyses are performed simulate the interior temperature history of concerte dam made of type II (moderate heat) portland cement under various coditions.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.1
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• pp.33-41
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• 2002

Recently, the seismic safety evaluation of concrete gravity dams is raised due to the damage or the failure of dams occurred by the 1995 Kobe earthquake, the 1999 Taiwan earthquake, etc. Failre of dam may incur loss of life and properties around the dam as well as damage to dam structure itself. Recently, there has been growing much concerns about 'earthquake-resistance' or 'seismic safety'of existing concrete gravity dams designed before current seismic design provisions were implemented. This research develops three evaluation levels for seismic safety of concrete gravity dams on the basis of the evaluation method of seismic safety of concrete gravity dams in U.S.A., Japan, Canada, and etc. level 1 is a preliminary evaluation which is for purpose f screening. Level 2 is a pseudo-static evaluation on the basis of the seismic intensity method. Finally, level 3 is a detail evaluation by the dynamic analysis. Evaluation results on existing concrete gravity dam on operation showed good seismic performance under the designed artificial earthquake.