Inversion Analysis of Mechanical Parameters of Surrounding Rock in High-speed Railway Tunnel

Research purposes: The surrounding rock of tunnels is a kind of heterogeneous and discontinuous geological body. The determination of its mechanical parameters directly affects the accuracy of numerical simulation results. To solve the problem that it is difficult to obtain the mechanical parameters of the surrounding rock of the tunnel, based on the Yangshan high-speed railway tunnel, FLAC3D is used to simulate the construction process of the tunnel. According to the support vector machine (SVM) optimized by the genetic algorithm (GA), the inversion method of the mechanical parameters of the surrounding rock of the high-speed railway tunnel is investigated. On this basis, the finite difference model of the tunnel is established to analyze the deformation, stress distribution and failure mode of surrounding rock under different bench length construction. Research conclusions: (1) The simulation of the vault settlement of the surrounding rock is basically consistent with the measured values, which verifies the feasibility of the inversion model of the mechanical parameters of the surrounding rock. (2) When the length of the construction steps is greater than 6 m, the stability of the surrounding rock of the tunnel decreases dramatically, which is not conducive to the safety of personnel and the orderly construction of the tunnel. (3) The research results can provide a reliable basis for the follow-up construction and a reference for the stability analysis of tunnel construction. © 2020, Editorial Department of Journal of Railway Engineering Society. All right reserved.