Simulating elastic wave propagation in 3-D layered transversely isotropic half-space using a special IBEM: Hill topography as an example

This paper provides an indirect boundary element method (IBEM) to elaborate elastic wave propagation in a layered anisotropic medium (simplified as transversely isotropic, TI) with three-dimensional (3-D) irregular free surfaces. The present method using a modified dynamic Green's function for point loads acting on an internal inclined plane as its kernel function, which has the merits of handling perfectly the stratification, without the problem of singularity and fine adaptability to complex models with surface irregularities. Accuracy of the IBEM solution is verified through comparison with existing results, and then a computer program combining parallel computation is developed to achieve numerical evaluation of the methodology. By taking the Gaussian, parabolic, and semi-ellipsoidal shaped hill topography in a TI half-space subjected to qP-, qSVand SH-waves as examples, numerical studies are performed to demonstrate the influence of the TI parameters and hill's shape on the seismic ground motion. It is found that both the TI parameters and hill's shape have significant impacts on the surface responses, and the surface displacement amplitudes dependent heavily on the type of incident wave, frequency of excitation and incident angle.