Scattering of Plane SV Waves by Underwater Tunnel

Accounting for fluid-solid coupling in saturated underwater soils, the scattering problem of underwater tunnel under plane SV-wave incidence is investigated by using the Fourier-Bessel series expansion method of wave function. Numerical examples analyze the effects of incident wave angle, frequency, tunnel burial depth, and porosity on displacement at the water-soil interface and dynamic stress concentration on the tunnel surface. When eta=0.5, increasing the incident angle reduces horizontal displacement by up to 39.3%, increases vertical displacement by up to 96.2%, and raises the Dynamic Stress Concentration Factor (DSCF) on the tunnel surface by 65.6%. Porosity shows minimal impact on stress and displacement. As porosity increases, horizontal displacement decreases by up to 2.1%, vertical displacement increases by approximately 1.23%, and DSCF decreases by 1.2%. As incident frequency increases, displacement and stress distributions become more complex, with more pronounced peaks, and troughs. Maximum horizontal displacement increases by 86.4%, and vertical displacement by 91.2%. Displacement and stress concentration are most pronounced above the tunnel under shallow burial conditions.