Abstract:

In order to study the influence of excavation of oblique close doubleline tunnels on surrounding geotechnical environment, the interaction conditions of the oblique close doubleline shield tunneling in Xujiahui StationShanghai Stadium Station on Shanghai Rail Transit Line No. 11 is simulated by MohrCoulomb elastoplastic soil model and finite element numerical simulation method. With the relative position of the tunnels as variables, the surrounding ground deformation caused by tunneling is simulated. The soil deformation induced by tunneling is analyzed under three conditions in oblique alignment. Some conclusions are drawn as follows. (1) The ground surface settlement curve mainly presents single peak when the horizontal distance between doubleline tunnels is small; and the unimodality will be more evident with the increase of vertical distance of the doubleline tunnels; the bimodality gradually appears as the horizontal distance increase. (2) There is greater influence that caused by the construction of the shallower tunnel on ground surface subsidence; and the soil above the centerline of the tunnel is affected much. (3) Larger horizontal displacements take place at the soil surface and near the shallower tunnel in three oblique conditions.

Key words: oblique doubleline tunnels, excavation construction, finite element numerical simulation, soil displacement