Dynamic Response of a Circular Lined Tunnel in Unsaturated Porous Media Under Cylindrical P‐ and SV‐Waves

Tunnels are frequently subjected to blast‐induced waves from adjacent construction activities, making their dynamic analysis critically important. However, the conventional plane‐wave assumption adopted in many studies is often inadequate for near‐field source scenarios, where the curvature of the incident wavefront cannot be neglected. This study investigates the scattering of cylindrical P‐ and SV‐waves by a circular lined tunnel embedded in an unsaturated porous medium with an imperfect interface. By using the wave function expansion method, analytical solutions are derived for the stress and displacement fields in the unsaturated substrate and elastic lining. Numerical examples are presented to examine the effects of incident‐wave frequency, degree of saturation, wave‐source distance, and interfacial stiffness on the dynamic stress concentration factor (DSCF). The results show that saturation strongly affects the DSCF under a high‐frequency P‐wave, whereas its influence under an SV‐wave is limited. These findings provide a theoretical basis for evaluating lined tunnels subjected to near‐field blast‐induced waves in partially saturated ground.