IBEM simulation of seismic wave scattering by valley topography with fluid layer

Combined with the dynamic Green’s function of single-phase medium and the Green’s function in the fluid domain, the indirect boundary element method is developed to solve the scattering of valley topography with fluid on plane P and SV waves, and the parameter analysis is carried out in combination with specific examples. The results show that the seismic response of valley topography with fluid layer to plane P and SV waves is controlled by many factors, such as incident wave frequency, incident wave angle and the depth of fluid. Generally speaking: ① In the low frequency domain, the frequency spectrum characteristics of the valley bottom and the nearby surface are basically the same in the valley with or without water. ② When P wave incidents, at the resonance frequency of this aquifer system, the displacement at the bottom of the valley decreases significantly, but the displacement of fluid surface reaches the maximum. ③ The fluid layer has the function of absorbing seismic wave energy. The larger the fluid depth is, the smaller the ground motion displacement of the valley surface and nearby ground is. The results can provide a theoretical basis for the evaluation of the ground motion effect near the valley terrain and the work of earthquake prevention and mitigation.