Influence Law of Foundation Pit Excavation on Stress of Surrounding Tunnel Bolt

Abstract

Due to the existence of a tunnel next to the foundation pit, the soil surrounding the foundation pit deforms into the foundation pit due to the excavation unloading during the process of foundation pit excavation, which causes the deformation of the tunnel. The supporting structure of the tunnel can ensure the deformation stability of the tunnel, so it is necessary to study the stress of the tunnel bolt supporting structure caused by the excavation of the foundation pit. In this paper, the numerical simulation method was adopted to study the influence of the distance between the foundation pit and tunnel and the width and depth of foundation pit excavation on the stress of the tunnel bolt, and the following results were obtained: (1) When the distance between the tunnel and the foundation pit changes, the axial force of the bolt changes accordingly. The axial force of the left bolt first increases and then decreases, and the largest axial force is located in the middle of the bolt. (2) With the increase in the excavation width of the foundation pit, the stress of the left bolt does not change much. For the left bolt, with the increase in excavation depth, the stress of the left bolt does not increase monotonically but shows a trend of increasing first and then decreasing. When the excavation depth exceeds a certain value, the influence of excavation depth on lateral soil displacement gradually decreases. With the increase in excavation depth, the axial force of the top bolt decreases first and then increases.