Tunnel Stability and Deformation Analysis under Excavation Load

Based on the finite element model of the tunnel influenced by approaching excavation of foundation pit, influence laws of excavation depth and distance on the tunnel stability are studied. The results show that the largest settlement occurs in the left lining, and the maximum uplift occurred in the right lining. The displacement values of the various monitoring section of tunnel structure on the left side are more closer, and the displacement values near the tunnel bus present obvious negative peak displacement. When the excavation distance is increasing, the settlement displacement of the tunnel increases obviously. Local uplift effect caused by unloading of soil gradually disappeared. With the increasing of the approaching distance, the bottom of the foundation pit bears all or part of the passive earth pressure, which makes the active area earth pressure and passive earth pressure area produce greater deformation.