Responses of a cylindrical lined tunnel due to internal dynamic load in two distinct mediums: Ideal elastic and saturated porous medium

The dynamic responses of a lined tunnel subjected to dynamic loading is one of the key issues that needs to be addressed prior to the design and construction of tunnels. While the tunnel lining and surrounding soil are commonly designed in ideal explosion-proof engineering as ideal elastic media to simplify the problem, in reality; soils are porous geo-materials. Therefore, the concern is whether this practice is more conservative or close to the reality, in contrast to the scenario where the surrounding soil is assumed as a saturated porous medium. This study investigates the differences and relationships between the dynamic responses of the lining structures in two immensely disparate media: ideal elastic medium and porous saturated medium. Firstly, to avoid the complexity of 3D numerical studies, 3D analytical solutions for the responses of the lined tunnel in both the ideal elastic medium and porous medium due to internal dynamic loading are derived using Fourier and Laplace transforms. Also, the differences between the dynamic responses (e.g., the radial displacement, radial effective stress, and hoop effective stress) of the lining structures in two media are determined to assess the rationality of assuming that the soil around the lined tunnel is an infinite elastic compressible medium. Finally, the influence of the porosity on the dynamic response of a cylindrical lined tunnel subjected to dynamic loads is examined.