Scattering of plane waves by a 3D canyon in a transversely isotropic fluid-saturated layered half-space

Scattering of plane waves by a three-dimensional (3D) irregularity in a transversely isotropic (TI) fluid-saturated layered half-space is investigated for the first time. The derived exact stiffness matrix is applied to solve the dynamic response of free fields. The scattered fields, which arise from the presence of canyon irregularity, are described by applying dynamic Green's functions for uniformly distributed loads and pore pressure acting on an inclined plane, that is, the special indirect boundary element method (IBEM). The accuracy of the proposed method is verified via the comparison between the calculated results and those of published literature. By taking a semi-spherical canyon cut in a homogeneous, single-layered, and three-layered TI saturated half-space as examples, the influences of material anisotropy, boundary drainage condition, and sedimentary sequence on dynamic response are investigated. The results show that the material anisotropy and boundary drainage conditions all have a significant impact on the seismic responses, which is highly dependent on the waves type, incident angle, and frequency. For the layered medium, the displacement amplification is affected by the soil layer properties and sedimentary sequence.