Abstract:

  3D model is established and analysis is made on the influence on the existing bridge imposed by the construction of a subway tunnel crossing a ground fissure, and the site monitoring data and the simulation results are analyzed, with a section of Xi’an Metro line 2 crossing Chang’an overpass and f6 ground fissure as an example. The conclusions drawn are as follows: 1) The construction of the Metro tunnel crossing the ground fissure has some influence on the existing bridge piers, especially on the settlement of the third row of the bridge piers; 2) The influence of the ground fissure on the excavation of the Metro tunnel in short term is not obvious, therefore longterm monitoring should be made for the tunnel structures near the ground fissure. Meanwhile, 2D model of different distances from the Metro tunnel to the ground fissure is established, analysis is made and the minimum fortification distance to excavate Metro tunnels near ground fissures in Xi’an area is proposed to be at least 3 times of the tunnel diameter.

Key words: Metro tunnel, ground fissure, existing bridge, numerical simulation