Reflection and transmission of waves at a porous-medium/water interface

Studying the reflection and transmission characteristics of acoustic waves at the porous medium-water interface is of great significance to the inversion of underwater medium parameters and geotechnical engineering detection. The reflection and transmission problems of longitudinal waves incident on the water-porous medium interface from water have been solved. The theoretical research on the incidence of longitudinal waves and shear waves from the porous medium to the porous medium-water interface is still incomplete. Based on the acoustic theory of saturated porous media, the wave potential function and amplitude relationship of each mode are given. Combining the displacement and stress boundary conditions of the fluid and the porous medium, the calculation formulas for the wave reflection and transmission coefficients of each mode are respectively derived when the two waves are incident from the porous medium to the water interface. Taking the sediment porous medium as the research object, the propagation characteristics of longitudinal waves and SV waves from the sediment incident to the water boundary are calculated. The reflection and transmission coefficients changing with incident angle, frequency and porosity are calculated numerically. The calculation results show that the three parameters have different degrees of influence on the reflection and transmission coefficients.