Document Type : Geotechnical Earthquake Engineering
Hayward Baker Inc., Nashville, USA
California State Polytechnic University, Pomona
Shiraz University of Technology
Texas A&M Univ., College Station
Seismic design of an embankment dam is a vital step in the design procedure of this important infrastructure. Deterministic approaches such as quasi-static and Newmark method have been employed to evaluate slope stability of embankmentdams. However, the variables required for a slope stability analysis, e.g. soil strength, pore pressure and loading parameters involve uncertainties which cannot be handled in the traditional deterministic methods. As an alternative, reliability analysis might be conducted to assess reliability indexes and the related failure probability of embankment dams. In this study, based on probability theories, a reliability analysis is performed to evaluate the seismic stability of an embankment dam (i.e., Gotvand dam) constructed in Iran. The probability of failure under seismic loading is considered for different sources of uncertainties involved in the problem, including uncertainty of loading, and the friction angle of core material as a strength parameter. Employing some statistical parameters, dynamic analysis is performed to determine the influence of friction angle variation on seismic slope stability. Significant pore pressure may build-up during cyclic loading, especially, when mixed clay (mixed clay and gravel) constitutes the dam core. Also, an undrained behavior of core materials has a great importance. Therefore, to estimate the effect of pore pressure build-up during seismic loading, two types of core materials (pure clay and mixed clay) are considered in this research. The results of dynamic analysis by finite element method are used to obtain the critical surface and acceleration in the embankment. Then, Newmark approach is employed to calculate the permanent displacement of the dam. Finally, reliability analysis is conducted and seismic performance of Gotvand dam during the earthquakes is investigated.