Ground Motion Response and Energy Partitioning in 3D Saturated Porous Media: Coupled Effects of Porosity and Poisson's Ratio under P and SV Wave Incidence

Abstract

Understanding the dynamic behavior of saturated porous media is critical for seismic hazard assessment and geotechnical engineering, particularly due to the complex interaction between the solid skeleton and pore fluid. This study numerically investigates the seismic wave propagation and subsequent energy partitioning within a three-dimensional saturated porous medium subjected to incident P-wave and SV-wave excitation. A comprehensive parametric analysis is conducted to quantify the isolated and coupled influence of key material properties, namely porosity (?) and Poisson's ratio (?), on the system's dynamic response. The analysis focuses on comparing the resultant reflection coefficients, the full-field displacement components across various directions, and the detailed energy distribution (including reflected, refracted, and dissipated energy) within the ground. The results demonstrate that both porosity and Poisson's ratio exert a significant and complex influence on wave conversion efficiency at the interface. Specifically, variations in these parameters lead to distinct, non-linear changes in surface and subsurface displacement magnitudes and critically control the total seismic energy distribution, dictating the proportion of energy lost through damping and scattering versus that carried by propagating waves. The findings provide essential insights into the poroelastic dynamic characteristics of ground and are vital for the accurate simulation of earthquake-induced ground motions on saturated soil sites.