Numerical Simulation of Curvature and Confining Pressure Effect on Progressive Failure of Surrounding Rock in Arch Tunnel with Straight Wall

Considering the influence of tensile plastic strain of intact rock on tensile strength and elastic modulus. The influence of arch curvature and height of the straight wall on the progressive failure of surrounding rock under different confining pressures are simulated based on the Mohr-Coulomb constitutive model and the nonlinear CWFS criterion of friction strengthening and cohesion weakening. The results show that when λ ₁ = 0.2, the difference between vertical load and horizontal load is large, the buckling failure of rock burst and slab cracking is obvious, and the sectional curvature effect is obvious. When λ ₃ = 0.5, the buckling failure of rock burst and slab cracking is very limited, the sectional curvature effect is reduced, and the confining pressure effect of rock burst and slab cracking is obvious. The shear yield localization of the surrounding rock is sensitive to sectional curvature, and the sectional curvature effect of shear failure under different lateral pressure coefficients is obvious. The numerical calculation results are consistent with the failure law of surrounding rock obtained from field and laboratory tests, which can provide a reference for tunnel excavation and support design.