A stepwise artificial boundary condition for wave propagation in elasto-plastic media

Abstract

Wave propagation in elasto-plastic media is often encountered in earthquake geotechnical engineering. However, dynamic boundary conditions in the numerical simulation of wave propagation problems are often developed based on linear elastic assumptions. In this study, the method of characteristics is utilized to propose a novel stepwise artificial boundary condition (S-ABC) for wave propagation in elasto-plastic media. The numerical implementation of S-ABC within a finite element procedure in time domain is developed. Typical numerical examples are chosen to verify the efficiency of this ABC, including: 1) a semi-infinite soil column model subjected to impulse load, where the influence of unloading wave front in elasto-plastic media is discussed; 2) an infinite and a finite soil column model under cyclic seismic wave input, where the proposed S-ABC is compared with the traditional viscoelastic artificial boundary condition (V-ABC). Numerical results demonstrate the significantly higher accuracy and robustness of the proposed S-ABC for nonlinear and elasto-plastic media compared to traditional V-ABC. The influence of unloading wave front on artificial boundary condition for elasto-plastic media is also revealed, which has not been reported previously.