• Structural Engineering and Mechanics
• /
• 제28권4호
• /
• pp.411-442
• /
• 2008

Ground motions in near source region of large crustal earthquakes are significantly affected by rupture directivity and tectonic fling. These effects are the strongest at longer periods and they can have a significant impact on Engineering Structures. In this paper, it is aimed to determine near-fault ground motion effects on the nonlinear response of dams including dam-reservoir-foundation interaction. Four different types of dam, which are gravity, arch, concrete faced rockfill and clay core rockfill dams, are selected to investigate the near-fault ground motion effects on dam responses. The behavior of reservoir is taken into account by using Lagrangian approach. Strong ground motion records of Duzce (1999), Northridge (1994) and Erzincan (1992) earthquakes are selected for the analyses. Displacements, maximum and minimum principal stresses are determined by using the finite element method. The displacements and principal stresses obtained from the four different dam types subjected to these nearfault strong-ground motions are compared with each other. It is seen from the results that near-fault ground motions have different impacts on the dam types.

• 한국지반환경공학회 논문집
• /
• 제15권6호
• /
• pp.41-48
• /
• 2014

본 연구에서는 현장응력상태 및 수위변동을 재현한 원심모형실험을 통하여 속도변화를 고려한 지속적 수위승강에 따른 제체의 거동을 검토하였으며, 기후변화에 따른 기습적 폭우 상황을 상정한 월류 시 제체의 파괴거동을 모사하였다. 실험 결과, 제체내의 간극수압 및 변위는 수위상승 및 하강속도에 비례하여 증감하며, 제정부 및 제체 하류측 사면부의 변위증분은 수위승강속도에 대하여 독립적임을 알 수 있었다. 또한 반복적이고 지속적인 수위변동은 변위의 누적을 통해 제체의 변형을 진행시키는 요인이 되며, 월류에 의해 저수지 제체의 안정성이 급격히 저하됨을 확인하였다. 따라서 호우 등으로 수위가 급상승하는 경우 간극수압, 변위 등을 실시간으로 감시하고, 이상 발생 시 수문개방 등을 통해 저수지의 수위를 조절하는 조치를 강구할 필요가 있다.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2005년도 학술발표회 논문집
• /
• pp.3-10
• /
• 2005

In this study, 1-g shaking table tests on the model of CFR(Concrete-Face Rockfill) type "D" dam in operation and the model of virtual ECRD(Earth Core Rockfill Dam) of which static stability is about the same compared to the model of CFRD were carried out. The purpose of this study is to compare the seismic performance of CFRD and ECRD from the analysis of model test results. Displacement response behavior of the dam was examined through the measurement of vertical and horizontal displacement of model dam crest. Also, amplification characteristics of accelerometers installed with dam height were examined through the measurement of acceleration with dam height. Also, in the case of ECRD, patterns of excess pore pressure generation with dam height were examined. From the test results, it was found that accelerations of dam crest of CFRD and ECRD were amplified about 1.52 times and 2 times compared to the accelerations of dam bottom, respectively. amplification was outstanding at three quarters of dam height from the bottom of dam. This phenomenon was outstanding in case of ECRD. And it was estimated that vertical and horizontal displacement of prototype dam of CFRD were 6.8cm (0.1% of dam height) and 12.3cm (0.2% of dam height), respectively. Also, it was estimated that vertical and horizontal displacement of prototype dam of ECRD were 4.3cm (0.1% of dam height) and 5.5cm (0.11% of dam height), respectively.

• Structural Engineering and Mechanics
• /
• 제22권3호
• /
• pp.351-370
• /
• 2006

In this study, the earthquake damage response of the concrete arch dams was investigated including dam-reservoir interaction. A continuum damage model which is a second-order tensor and includes the strain softening behavior was selected for the concrete material. Fluid-structure interaction problem was modeled by Lagrangian approach. Sommerfeld radiation condition was applied to the truncated boundary of reservoir. The improved form of the HHT-${\alpha}$ time integration algorithm was used in the solution of the equations of motion. The arch dam Type 5 was selected for numerical application. For the dynamic input, acceleration records of the 10 December 1967 Koyna earthquake were chosen. These records were scaled with earthquake acceleration scale factor (EASF) and then used in the analyses. Solutions were obtained for empty and full reservoir cases. The effects of EASF and damping ratio on the response of the dam were studied.

• Structural Engineering and Mechanics
• /
• 제48권1호
• /
• pp.17-39
• /
• 2013

In the present paper, a coaxial rotating smeared crack model is proposed for mass concrete in three-dimensional space. The model is capable of applying both the constant and variable shear transfer coefficients in the cracking process. The model considers an advanced yield function for concrete failure under both static and dynamic loadings and calculates cracking or crushing of concrete taking into account the fracture energy effects. The model was utilized on Koyna Dam using finite element technique. Dam-water and dam-foundation interactions were considered in dynamic analysis. The behavior of dam was studied for different shear transfer coefficients considering/neglecting fracture energy effects. The results were extracted at crest displacement and crack profile within the dam body. The results show the importance of both shear transfer coefficient and the fracture energy in seismic analysis of concrete dams under high hydrostatic pressure.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2008년도 추계 학술발표회
• /
• pp.836-841
• /
• 2008

CFRD (Concrete Faced Rockfill Dam) has been world-widely constructed due to a lot of advantages compared with rockfill dam and recently, sand/gravel materials, instead of crushed rock materials, are also utilized as a main rockfill material to overcome geological and environmental problems. In this paper, the process of water infiltration into the originally unsaturated sand/gravel-fill dam is studied using two-dimensional saturated-unsaturated seepage theory. According to the results of seepage analysis, if the effective drainage zone is installed in the dam, the reservoir water infiltrate into the dam along a downward flow path towards the lower drainage area. The main body constructed with sand/gravel materials, therefore, remains unsaturated.

• Structural Engineering and Mechanics
• /
• 제91권2호
• /
• pp.123-133
• /
• 2024

The assessment of seismic behavior and seismic performance of ageing Sarıyar concrete gravity dam constructed on Sakarya River in Türkiye is the main focus of this paper. For this purpose, the impact of sediment domain, ageing of concrete material under the impact of chemical and mechanical actions, and dam-water-sediment interaction are included in the two-dimensional (2D) finite element (FE) model developed in FORTRAN 90 environment. In the FE model, the dam and age dependent sediment domains are modeled by solid elements, while reservoir domain is modeled by Lagrangian fluid elements. The radiation of reflected waves to the unbounded water domain is modeled by infinite Lagrangian fluid elements, while unbounded sediment domain is modeled by infinite solid elements. The coupled system was assumed to be under the simultaneous impact of Vertical (V) and Horizontal (H) ingredients of 1976 Koyna earthquake and the coupled system was analyzed in Laplace domain by direct method. Due to the deterioration of the concrete, the H and V displacement responses together with the fundamental period of the body, elongate throughout the lifetime and this reduce the seismic safety of the dam. It was deduced that the ageing dam body will not experience major damages under the Koyna earthquake both at the earlier and later ages. Furthermore, at the heel of the dam, the hydrodynamic pressure responses are decreased by rising the sediment domain depth.

• 콘크리트학회논문집
• /
• 제19권1호
• /
• pp.11-18
• /
• 2007

댐 안전성 평가를 위한 내진성능평가는 지속적으로 실시하였으나, 댐에서 취약부로 알려진 여수로 피어부에 대한 거동 분석에 대한 연구는 거의 이루어지지 않았다. 실제 지진발생시 여수로 피어가 국부 손상을 받기에 취약한 부분으로 추정되어 본 연구에서 댐의 내진성능 평가를 위한 기초 실험으로서 정적 시험을 수행하였다. 본 연구에서는 댐의 여수로 피어부에 대한 축소된 철근콘크리트 모형을 통한 강도모델을 구성하여 정적 모형 시험을 실시하고, 시험 결과의 분석, 구조해석을 통한 실제 구조물의 거동 및 균열하중, 극한하중에 대한 분석을 실시하였다. 대상 시험체에 대한 모형 시험 결과와 수치해석 결과는 서로 다른 파괴 거동을 나타내어 파괴하중이 서로 다르게 추정되었으나, 모형 시험체의 파괴 거동을 고려하는 경우에는 정적 시험과 해석을 통하여 실제 구조물의 균열 발생 하중과 극한하중을 추정할 수 있는 것으로 사료된다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2006년도 춘계 학술발표회 논문집
• /
• pp.784-793
• /
• 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.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 1999년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall
• /
• pp.113-120
• /
• 1999

When we design the large rockfill dams the safety of dams against the quake must be considered. Generally pseudostatic analysis method has been used for slope stability and evaluation of safety but the case of dynamic response analysis of earthquake was not in general in Korea. Therefore we need to perform the dynamic response analysis of rockfill dams from these results we analyze the dynamic behavior of dam body such as response displacement and response acceleration. consequently we analyse the selected model of rockfill dam using the FLAC-2D (FDM) program.