Study on Characteristics of Rayleigh Waves in Media Containing Shallow Rectangular Cavities

Abstract

Numerical simulations of Rayleigh wave with a source on the free surface are achieved by using FEM(finite element method). Artificial viscous boundary conditions are used to weaken boundary reflections. Modeling results are proved by comparison between analytic and numerical solutions in homogeneous half-space and layered media. Surface wave field of homogeneous half-space with rectangular cavities are modeled and analyzed. The results show that the velocity of converted wave above cavity is less than which in homogeneous media and energy is concentrated obviously in the area when the depth of cavity is relatively smaller than surface wave length. The cavity can be located by characteristics in time domain and frequency domain of surface wave. Dispersion characteristics of waves above cavity are mainly influenced by the top depth of the cavity instead of bottom depth and consistent with Lamb wave of slab with corresponding height and same media.