Dynamic Response of Tunnels Surrounded by Thawing Permafrost with Anisotropic Frost Heave in Cold Regions: Considering the Movement of the Frozen Interface

This paper considers the anisotropic frost heave that occurs in frozen soils during thawing and investigates the dynamic response of tunnel systems in such regions to a uniformly distributed load. The phase change of ice to water is assumed to cause the layers of frozen and unfrozen soil to move relative to one another. Analytical solutions were obtained for the displacements and stresses of the tunnel lining, layer of frozen soil, frozen surface, and layer of unfrozen soil under loading during thawing. The boundary conditions and continuity conditions of contact surfaces made from different media were used to obtain the unknown parameters. Through parametric analysis, the dynamic response of the tunnel system under various thawing circumstances was determined. The results demonstrated that the thawing of frozen soil surrounding the tunnel lining can reduce the influence of the load at various positions of the soil under different conditions without affecting the structural stability. Many factors affect the dynamic response of cold-region tunnel systems when the surrounding frozen soil starts to thaw and exhibits anisotropic frost heave. The safe construction and operation of tunnel projects under such conditions can be achieved through the adjustment of the medium parameters.