Analysis of longitudinal stress and deformation characteristics of shield tunnel under faulting dislocation

Fault dislocation seriously threatens the structural security of cross-fault tunnels during operation. Regarding the mechanical response of the tunnel across faults, the tunnel was equated as the Timoshenko beam on the Vlasov foundation in the present study, and the mechanical analytical model of the cross-fault tunnel was established and solved by the finite difference method. Published cases were utilized to validate the reasonableness of the analytical model. The influence law of critical parameters of the model on the response of the tunnel was investigated by parameter sensitivity analysis. Finally, the mechanical properties of the tunnel under the non-homogeneous foundation conditions were discussed. The calculation results of the proposed analytical model were similar to the existing model test monitoring data, and the trend was the same, demonstrating the correctness of the analytical model. The tunnel-fault distance, foundation reaction coefficient, foundation shear stiffness, and effective factor of bending stiffness changed the maximum tunnel bending moment, while the fault inclination changed the position where the maximum bending moment occurred. For the non-homogeneous foundation, the difference of adjacent foundation parameters significantly affected the response law of tunnel longitudinal internal forces, and the maximum tunnel bending moment presented a particular nonlinearity with the change of foundation parameters.