A half-space TD-BEM model for a seismic corrugated orthotropic stratum

Abstract

In this paper, the model of a linear corrugated orthotropic stratum above a semi-infinite substratum is elaborated by a half-space time-domain boundary element method (TD-BEM) subjected to oblique incident plane SH waves. The ground surface and the interface are corrugated in a similar ratio using a Gaussian-shaped function. In the used approach, only the corrugated boundaries are required to be discretized. An incremental mesh scheme is applied to reduce the number of boundary elements in the large width of the interface. After developing the algorithm and solving a verification example, the seismic ground response is obtained and compared by assuming three cases of the model based on the isotropy factor, one isotropic case, and two orthotropic cases. Some effective parameters, including the shape ratio of the corrugation, frequency content, and wavefront propagation angle, are also considered to obtain the amplification pattern of the surface. Finally, by developing the method to multi-layered medium, its efficiency is investigated in the analysis of orthotropic heterogeneous models with more degrees of freedom. The results showed that both geometry and material factors were directly affected by the phenomenon of wave propagation so that the corrugation depth and the velocity of the wavefront in different directions could significantly control the response of the ground surface.