A refined nonlinear theoretical model for mechanical analysis of tunnels subjected to strike-slip faulting with multiple fault planes

During strike-slip fault dislocation, multiple fault planes are commonly observed. The resulting permanent ground deformation can lead to profound structural damage to tunnels. However, existing analytical models do not consider multiple fault planes. Instead, they concentrate the entire fault displacement onto a single fault plane for analysis, thereby giving rise to notable errors in the calculated results. To address this issue, a refined nonlinear theoretical model was established to analyze the mechanical responses of the tunnels subjected to multiple strike-slip fault dislocations. The analytical model considers the number of fault planes, nonlinear soil‒tunnel interactions, geometric nonlinearity, and fault zone width, leading to a significant improvement in its range of applicability and calculation accuracy. The results of the analytical model are in agreement, both qualitatively and quantitatively, with the model test and numerical results. Then, based on the proposed theoretical model, a sensitivity analysis of parameters was conducted, focusing on the variables such as the number of fault planes, fault plane distance ( d ), fault displacement ratio ( η ), burial depth ( C ), crossing angle ( β ), tunnel diameter ( D ), fault zone width ( W f ), and strike-slip fault displacement ( Δf s ). The results show that the peak shear force ( V max ), bending moment ( M max ), and axial force ( N max ) decrease with increasing d . The V max of the tunnel is found at the fault plane with the largest fault displacement. C , D , and Δf s contribute to the increases in V max , M max , and N max . Additionally, increasing the number of fault planes reduces V max and M max , whereas the variation in N max remains minimal. • The nonlinear soil-tunnel interaction, geometric nonlinearity, and fault zone width are introduced within the governing equation. • The proposed theoretical model is applied across various scenarios encompassing diverse numbers of fault planes, varying fault plane distances, and distinct fault displacement ratios. • The tunnel response computed by the theoretical model exhibits excellent agreement with the model test and numerical model. • The impact of crucial parameters, including numbers of fault plane, fault plane distance, fault displacement ratio, buried depth, crossing angle, tunnel diameter, fault zone width, and strike-slip fault displacement, on tunnel response are investigated.