Numerical modeling of seismic ground response considering the coupled effect of slope and soil layering

Abstract

Seismic waves change as they pass through the soil layers. This change can be due to soil layering or existence of surface topography, which is estimated by ground response analysis. In this study, the coupled effect of soil layering and topographic irregularity is considered to evaluate the interaction of these two factors. In the first part, using two-dimensional finite element method (FEM) and viscous boundaries, the Gilroy region is simulated and one of the devastating earthquakes in this area, Loma Prieta (1989), applied to the model as an incident wave. The results are compared with those of recorded data to evaluate the performance of the model. In the second part, different slopes are assumed to exist in the Gilroy region and the seismic site response considering the coupled effect of soil layering and topographic irregularity is estimated using a nonlinear approach. In this part, characteristics of the soil layers are considered as same as the Gilroy region. Obtained results show that the amplification generally increases with increasing the slope angle. Comparing the results of free field condition with those of slope region reveals that the coupled effect of soil layering and topographic irregularity cannot be ignored and should be evaluated using accurate and practical approach.