Viscoelastic Displacement Solution of Surrounding Rock and Its application for Tri-Central Arch Section Tunnels

Based on the complex function method of elasticity and the elastic-viscoelastic correspondence principle, the surrounding rock area of tri-central arch section on the physical plane (z plane) is mapped to the unit circle outer area on the computing plane (ζ plane), and two stress functions are used to express the stress, displacement and corresponding boundary conditions of the surrounding rock. Considering the space effect of the excavation face and expressing it as stress release rate, the viscoelastic displacement solution of the surrounding rock of the tunnel with tri-central arch section is given by means of power series method and Laplace transform. Compared with the numerical solution, the correctness of the theoretical solution is verified. This method is applied to the Yang Lin Tunnel, the variation of viscoelastic deformation of surrounding rock is analyzed, and the law of the effect of advancing speed, space effect and lateral pressure coefficient on the viscoelastic displacement of surrounding rock is revealed, it has universal application value for viscoelastic deformation analysis of surrounding rock of similar cross-section tunnel.