Numerical evaluation of topographic effects on seismic response of single-faced rock slopes

This paper investigates the seismic responses of homogenous single-faced rock slopes subjected to vertically propagating shear waves by numerical simulations in order to explore the topographic amplification of ground motion. The horizontal and vertical topographic amplification factors both on the free surface and in the slope are evaluated using parametric studies focusing on slope geometry, rock material, and input motion with the two-dimensional finite element code LS-DYNA. Comparison of the results obtained in this study with those of previous numerical analyses available in the literature and with the provisions of the existing seismic codes shows good agreement. Both qualitative and quantitative insights into the topographic amplification effects on the seismic responses of single-faced slopes are presented in this study. The results show that both slope geometry and rock material have great influences on the horizontal and vertical amplification factors. As for input motion, the magnitude and duration have negligible effects on the amplification factors when rock materials are homogeneous and elastic. However, the frequency extent of input motions has great impact on the amplification factors. It is also indicated that the modern seismic codes may underestimate the amplification effects of ground motion. Nevertheless, modification of the provisions of the codes may require more convincing evidence from reliable field experiments.