Influence of Anisotropic Parameters of Sedimentary Media on Earthquake Ground Motionin a 3D Alluvial Basin

Natural soil show usually stratification and transverse isotropy(TI) due to deposition and weathering process, but the research on seismic effect of complex site based on TI layered medium model is still in its infancy.The advantage of the indirect boundary element method(IBEM) to simulate the seismic wave field in layered semi-infinite domain was further extended to the case of TI medium, and the scattering of seismic wave by TI 3D sedimentary basin in half space was studied by combining the conjunction technique.First, the exact dynamic stiffness matrix of TI layered site was established, then the dynamic Green's function of uniformly distributed loads on slopes in TI layered half-space was derived, and then the corresponding IBEM was established with the Green's function as the fundamental solution.The correctness of the method was verified by comparison with known literature.Taking the hemispherical TI sedimentary basin in a single soil layer overlying the bedrock as an example, the influence of anisotropic parameters of the sedimentary medium on the seismic response of the sedimentary basin was discussed.The result shows that the seismic response of the TI site can be significantly different from that of the equivalent isotropic case; The influence of TI parameters on seismic wave scattering in 3D sedimentary basins is affected by the incident mode, incident angle and frequency; The change of TI parameters makes the dynamic characteristics of the site change, which significantly affects the dynamic interaction mechanism between sedimentary basin and layered half-space. © 2020, The Editorial Board of Journal of Basic Science and Engineering. All right reserved.