Scattering Of Elastic Waves By 3D Canyon And Cavity In Layered TI Saturated Medium

Study of dynamic response induced by complex topography due to elastic waves is a hot research topic in many fields,such as seismic engineering.Note that existing studies are almost based on the isotropic material.However,because natural weathering and sedimentation,soil shows obvious transversal isotropy(TI).Moreover,the real sites are always solid-liquid two-phase material,namely porous saturated media.Therefore,great theoretical meaning and value should be attached to the study of 3D scattering problem of elastic waves induced by irregularities in layered TI saturated medium.The indirect boundary integration equation method(IBIEM)is adopted.The main contents are listed as follow:1.Based on the precise dynamic stiffness matrix of 3D porous saturated TI layered medium,the dynamic Green's function of the concentrated load is derived in cylindrical coordinate using direct stiffness method.Then,degenerated parametric calculation verifies the correctness of adopted method by comparing with published results.Next,more parametric calculations are performed.2.Using obtained dynamic Green's function,the scattering field of a semispherical canyon is established.IBIEM is then utilized combing the free field response,and boundary condition to solve the scattering problem of qP1,qSV and SH waves due to a semi-spherical canyon.Degenerated parametric calculation verifies the correctness of adopted method by comparing with published results.Subsequently,parametric calculations and analysis are illustrated concerning the scattering problem of elastic waves due to a semi-spherical canyon.3.Combining the scattering field and free field response as well as the zero stress boundary condition,the scattering problem for a buried cavity is presented.Comparing the degenerated results with the existing literature vincidate the accuracy of adopted method.Then few detailed parametric calculations are given regarding the the scattering problem of elastic waves due to a spherical cavity.Parametric calculation indicates that the change of horizontal and vertical moduli can exert tremendous influence on the dynamic behavior of the TI saturated site.Moreover,the frequency and types of seismic waves or concentrated load,the presence of bedrock as well as the porosity of the TI saturated medium are also very significant in deciding the dynamic response.