Motion at the Surface of a Double-Porosity Thermoelastic Layer Excited by Plane P- and SV-Waves

Wave modelling in stratified marine environments involves multi-physics interactions between different media, as well as the complex wave attenuation properties of porous seabeds. This study elucidates the wave motion in a porous seabed employing the double-porosity thermoelastic (DPT) model. We explore the motion at the surface of a DPT layer induced by the incidence of plane P- and SV-wave. This coupled system consists of a DPT layer of fixed width embedded between seawater and an elastic solid (bedrock). Two instances of incidence have been examined: incident P-wave and SV-waves originating from bedrock. The amplitude ratios of all existing waves are derived in closed form. Amplitude ratios are used to compute the horizontal and vertical displacements and their amplification coefficients. A parametric study is performed to investigate the effects of wave incidence angle, wave frequency, inclusion radius, temperature, fluid types, local fluid flow, and the thickness of the embedded DPT layer on site displacement and amplification coefficients. The findings demonstrate that it is crucial to account for the effects of fluid types and LFF variations in site response analysis. Increasing layer thickness elevates both horizontal and vertical amplification coefficients and raises natural frequencies, with the most significant effects occurring on both displacements and amplification coefficients. The site reaction is additionally influenced by temperature, inclusion radius, and the properties of the incident wave. Ultimately, these elements significantly influence site dynamics and must be meticulously evaluated in subsurface engineering.