Research on anti-dislocation technologies for tunnels crossing active faults considering fault heterogeneity

Active faults are widely distributed in China and severely restrict the construction and safe operation of transportation tunnels, as fault dislocation easily induces uneven deformation, stress concentrations and structural damage to tunnel linings. Most existing relevant studies oversimplify fault zones as homogeneous rock mass, which fails to reflect real geological conditions and reduces the accuracy of tunnel mechanical responses. Taking fault heterogeneity into consideration, this study established a refined numerical model to investigate the mechanical response of tunnels subjected to fault dislocation, as well as the mitigation effects of over-excavation and articulated designs. The main results show that the over-excavation design can effectively reduce the horizontal convergence of the lining, mitigate lining deformation, and decrease the peak internal forces of the lining; as the over-excavation thickness increases, the horizontal convergence of the lining gradually decreases, and the reduction in peak internal forces gradually increases. The articulated design can effectively reduce the peak internal forces of the lining; as the lining segment length decreases, the peak internal forces gradually decrease, although excessive shortening of the segment length may increase convergence deformation. The research provides a reference for the structural design and safety protection of tunnels crossing active faults.