关键词: 场地效应, 失稳机制, 高陡斜坡, 放大系数

Abstract: The Jiguanshanliangzi high-steep slope is taken as a typical case study in Wudongde hydropower station near Chin-sha River. Based on seismic monitoring of the slope surface, firstly, after inputting horizontal and vertical Ricker wavelets at the elastic slope model bottom, it is found that the low modulus of rock mass materials at the slope top is easily amplified after the excitation of the horizontal Rick wavelet. The surface convex topography is easy to produce resonance amplification when the vertical Rick wavelet is excited. The predominant frequencies of the top surface are consistent with the measured values. Secondly, comparative analysis of the slope stability and dynamic response characteristics are performed when inputting the real Wenchuan and Ludian earthquake acceleration records. It can be found that the slope may have three different potential slip surfaces at different locations under the static condition. However, when inputting the above two seismic waves, the deformation and failure occur only at the slope top position. When inputting the Wenchuan seismic wave, the shear strain increment of the top slip surface is significantly greater than that when inputting Ludian seismic wave. The tension failure zone is observed at the slip surface and the horizontal and vertical residual deformation is not convergence. The slope is at the state of instability after the earthquake. When inputting the Ludian seismic wave, there is no tensile failure zone observed at the slip surface and the residual deformation is convergence, which means that the slope is stable after the earthquake. The slope of horizontal and vertical acceleration at the slope top surface appears significantly enlargement due to a low modulus material, showing obvious site effect. In addition, the surface acceleration is generally greater than the corresponding values within the slope, especially at the location of convex topography. The amplification factor of horizontal acceleration at the slope top after inputting the Wenchuan seismic wave is greater than that after inputting the Ludian seismic wave, but the vertical acceleration amplification factors are essentially the same.

Key words: site effect, failure mechanism, high-steep slope, amplification factor