Mechanical Response and deformation mechanism of the utility tunnel crossing earth fissure

Abstract

The structural safety of the utility tunnel is adversely affected when it passes through an area with earth fissures. Using the comprehensive tunnel project at the f7 earth fissure site in Xi'an as the engineering prototype, finite element simulation was employed to investigate the mechanical responses and deformation laws of the utility tunnel under different relative positions of earth fissures and deformation joints. Simultaneously, the deformation mechanism of a utility tunnel crossing an earth fissure was explored by using theoretical analysis. The results show that the influence of the earth fissure on the surface deformation of the hanging wall is greater than that of the footwall, and the main deformation is near the earth fissure. In addition, because the rigidity of the utility tunnel greatly exceeds that of the soil, the surface deformation at the earth fissure does not show a sudden change in form as dislocation generated by the hanging wall and footwall. Earth fissure movement mainly affects the stress change in the utility tunnel in the crossing ground fissure section. Moreover, the void area will be generated by the dislocation of the earth fissure near the earth fissure position at the bottom of the utility tunnel, which is not conducive to the stress of the utility tunnel. The research results contribute to optimizing the design of utility tunnel projects and enhancing the structural safety of tunnels. Additionally, they provide important reference points for the maintenance and management of comprehensive utility tunnels, enabling timely identification and resolution of the impacts of earth fissures on tunnel structures, thus ensuring the long-term stable operation of the tunnels.