3D analytical modeling of seismic ground motion and energy partitioning in the marine site subjected to obliquely P-SV waves

This paper presents an analytical solution for seismic wave propagation and ground motion analysis within a three-dimensional marine porous medium, by incorporating critical factors such as pore shape and saturation. The study focuses on understanding the behavior of the seabed surface displacement, dynamic pore pressure, wave velocity, and energy partitioning under various seismic wave incidences. Numerical results are systematically presented to illustrate the dependence of these parameters on the angle of incident waves across a comprehensive range of material properties: porosity ( n ), pore shape parameter ( s ), Poisson ratio ( v ), incident frequency ( f ), saturation ( S r ), and bulk modulus of soil particles ( K g ). A key finding is that the stiffness of the porous medium decreases as the pore shape parameter is reduced and a reduced s leads to a more noticeable fluid-solid coupling effect. Increased porosity lowers the critical angle, leading to greater reflection of SV waves back into the medium and less transmission of P-waves into the water, while also causing specific wave components to vanish at the critical angle due to total internal reflection or severe mode conversion. • 3D analytical solution for analyzing seismic response is proposed in marine terrain. • The analytical solution of energy partitioning is derived in the 3D site. • The sensitivity of the parameters ( α / β , f , n , v , s , S r ) is discussed.