Abstract:The problem of slope stability under earthquake is not yet solved because of complexity and nonlinear properties of soil and rock. The earthquake ground motion is of the stochastic nature,and the failure of earth rock dam under earthquake greatly depends on the details of ground motion. Based on definite stochastic seismic response and time-history seismic response analysis,the slope stability of earth-rock dam is studied by finite element method combining with Hook-Jevees searching method. First,based on time-history response analysis of a sand dam model excited by sine wave,the time-history of the limit sliding surface and the minimum safety coefficient of slope are obtained. Then,with input of equivalent power spectrum of the sine wave,the dam model is analyzed with the definite stochastic seismic response method,and the properties of slope stability and the location of sliding surface are determined. The results of the two analyses agree well with those of the dam model test. It can be concluded that the location and the stability of sliding surface are effected by the factors,such as the maximum value of acceleration,the predominant periods and the types of earthquake records. It should be noted that,the location of limit sliding surface of the dam model excited by sine wave is different from that of earth-rock dam under earthquake.