Solutions of axisymmetric transient response of lined tunnel in transversely isotropic saturated soil under explosive loading

Existing studies on the dynamic response of tunnel linings and surrounding soil under explosive shocks primarily treat the soil as isotropic, however, it is actually a transversely isotropic medium. To investigate the axisymmetric dynamic response of transversely isotropic soil under explosive loading, we derive the governing equations for the lining and the surrounding transversely isotropic saturated soil based on Biot’s theory and the theory of transversely isotropic elastic mechanics. The potential function was introduced and Laplace transform and Fourier transform were performed to obtain the general solution. The results indicate that as the transversely isotropic parameter ξ increases, both the radial displacement and the peak effective circumferential stress of the soil decrease. The peak values of radial stress, circumferential stress, and pore water pressure in transversely isotropic soil occur almost simultaneously at the moment of the explosion. In the axial direction of the tunnel, these responses decay exponentially as the distance from the explosion source increases. When the axial distance reaches six times the tunnel radius, the transient response of the soil approaches zero.