Scattering of elastic waves by a 3-D inclusion in a poroelastic half space

Abstract

Using the indirect boundary element method (IBEM) and Biot's theory, surface displacement associated with the field scattered by a 3-D inclusion in a two-phase poroelastic half space under plane SV waves has been studied. According to single-layered potential theory, scattering waves are constructed by the introduction of uniform loads and fluid sources distributed over the surface of the half space and on the interface between the inclusion and the half space. The magnitudes of these loads and sources are obtained by establishing a boundary integral equation based on continuity boundary conditions. The accuracy of this method is verified by comparing the results of degradation with existing results of cavities in elastic media. The scattering of plane waves due to a 3-D inclusion is investigated from several aspects. Numerical results show that the dynamic coupling effect between the solid frame and pore water and the permeability condition of the poroelastic soil boundary result in a generally larger surface displacement amplitude for dry soil than poroelastic soil when the porosity is n = 0.3. By contrast, the surface displacement amplitude of poroelastic soil is larger than that of dry soil when the porosity is n = 0.36. As the depth of burial decreases and as the inclusion becomes wider and thicker, the scattering effect increases. The peak value of the displacement spectrum curve usually appears near the incident frequency η = 1.