Seismic Damage Response Analysis of the Daliang Tunnel on the Lanzhou-Xinjiang High-Speed Railway Crossing a Reverse Strike-Slip Fault

Taking the Daliang Tunnel of the Lanzhou–Xinjiang High-speed Railway crossing a reverse strike-slip fault as the engineering background, seismic damage investigations of the Daliang Tunnel and other cross-fault tunnels under earthquake action were conducted. Using 1:50 meso-scale model tests, experimental analyses were carried out on the lining strain response, internal crack development and failure, and surrounding rock pressure variation during fault dislocation. The failure modes and mechanisms of tunnels crossing reverse strike-slip faults were thoroughly explored. Meanwhile, a three-dimensional numerical model of the Daliang Tunnel was established to investigate the influence of dislocation modes with structural zonation within the fault zone on the surrounding rock response. The results indicate that the damage and strain response of the tunnel lining are mainly distributed within the fracture zone, predominantly characterized by combined oblique shear and compression failure. Due to the displacement of the lining induced by strong surrounding rock movement, surrounding rock pressure exhibits considerable variation at the boundaries of the fracture zone, accompanied by certain void detachment phenomena. The overall deformation of the tunnel crossing the reverse strike-slip fault presents an “S”-shaped pattern, which is consistent with the numerical simulations. The compression and dislocation morphology of the sidewalls within the rupture surface is in good agreement with the point cloud plan view. The compressive deformation and strain of the surrounding rock are most significant within the rupture surface. Meanwhile, the soft-to-hard transition segments between the new fracture zone and the rupture surface, as well as between the rupture surface and the influence zone, exhibit a trend of first decreasing and then increasing.