Transient wave motion in a cracked, multi-layered geological region by the BEM

A hybrid BEM is developed for investigating ground motion in geological regions with complex geometry, variable material properties, interface cracks, internal cracks, and under plain-strain conditions. Two different aspects of the problem are considered, namely (a) computation of ground motion in the form of synthetic scismogrants at the free surface of the region swept by a seismically-induced pressure (P) wave and (b) evaluation of the crack-tip stress concentration field (SCF) that develops around cracks buried in the deposit for the same loading. The present method combines both displacement and regularized traction BEM in the Laplace transformed domain for the crack-free and cracked states, respectively, while the transient nature of the wave scattering phenomenon is reconstructed through use of the inverse Laplace transformation.