Analysis on Safety Range of Supporting Force at Excavation Face of Shield Tunneling in Xi’an Metro

Abstract

Based on the tunnel engineering of Xi’an metro, according to the specific geological conditions, used FLAC3D numerical simulation software, the paper determine the minimum supporting force of the excavation face by two monitoring points’ settlement as the standard. The point at the surface above the excavation face and the other at the top of excavation face. When buried depth of tunnel is greater than 1.5 times the diameter of hole, the surface point cannot effectively reflect the deformation of soil around the tunnel, it should monitor and control the deformation of soil by the top point. The paper determine the maximum supporting force of the excavation face by the analysis of the settlement at the top points in different buried depth of tunnel. Obtain the safety range of supporting force in shield machine excavation face. According to the surface uplift larger phenomenon in shallow tunnel, put forward corresponding countermeasure. It is of great significance to apply reasonable supporting force at excavation face and prevent the surface subsidence and uplift crossing the locations that tunnel depth have large changes.