SEISMIC RESPONSE ANALYSIS OF MULTI-LAYERED TI SATURATED SITE SUBJECTED TO OBLIQUE INCIDENT SEISMIC WAVE

Under long-term weathering and deposition, the horizontal modulus of natural soil in coastal areas is often greater than its vertical modulus, showing obvious transverse isotropic (TI) saturation characteristics. However, there are few studies on the dynamic response of TI saturated site. Haskell-Thomson transfer matrix method is extended to a layered TI saturated half space. First, Biot dynamic equilibrium equation and the pore fluid motion equation of two-phase medium in a rectangular coordinate system are solved. Then a layered TI saturated half-space transfer matrix is established. Finally, the time domain response of the free field of a layered TI saturated site under the oblique incidence of seismic waves is solved in combination with surface boundary conditions. The paper verifies the correctness of the proposed method, and then takes CNTWGXE wave (0.3 g) as input ground motion to study the influence of soil TI properties and saturation characteristics on the acceleration time history and the response spectrum of the site. Analytical results show that:the dynamic response of the layered TI saturated site and that of the isotropic saturated site are different, and changes in TI parameters cause the site to have different filtering and amplification effects on seismic waves. The saturation characteristics of the site have an important influence on the dynamic response of the surface, and the solid-liquid coupling of saturated porous media has a weakening effect on seismic wave. The peak values of surface acceleration and response spectrum are less than those of the oblique incidence, and the incident angle has more obvious impact on the site for qP1 wave.