Theoretical and numerical investigations of the mechanical responses and damage characteristics of segmental tunnels under reverse faulting

Previous analytical models of fault-crossing tunnels have predominantly been based on the assumption of the tunnel being continuous, which is barely present in practical engineering projects. In this study, a theoretical model for the mechanical analysis of segmental tunnels subjected to reverse fault dislocation is proposed, wherein the interactions between the segmental lining and joints are incorporated, significantly improving the application range. A numerical concrete damaged plasticity (CDP) model is subsequently developed, which incorporates both the segmental lining and joints, to investigate the damage characteristics of the segmental tunnel under reverse faulting. Compared with the experimental and numerical results, the proposed theoretical model not only precisely captures the segmental character of the mechanical response of the segmental tunnel under reverse fault dislocation but also has a high degree of computational accuracy, with a maximum error of approximately 7.2 %. Drawing upon the theoretical and numerical models, a parameter analysis is conducted on the segment length (L_seg), distribution range of the segmental lining (W_seg), and fault displacement (R_fd). The results show that the L_seg value should not exceed 20 m and that the W_seg value should be no less than the fault zone width.