Tunnel excavation based on FLAC3d numerical simulation

Abstract

 A semi-circular arch straight wall tunnel with a span of 10m, a side wall height of 5m and a buried depth of 500m is excavated in a class IV surrounding rock. Assuming that the surrounding rock is an ideal elastoplastic material, the following problems are analyzed by using finite element or finite difference method: the arch roof subsidence and the horizontal convergence of the side wall after tunnel excavation under the action of gravity stress field and the size of the plastic zone in the surrounding rock. If the lateral pressure coefficient is 0.5-3, the effects of structural stress on the subsidence of the tunnel arch, the horizontal convergence of the side wall and the plastic zone are analyzed. If the bolt support is adopted after excavation, the system bolt shall be laid on the tunnel arch and side wall. The bolt shall be a full-length metal bolt, perpendicular to the tunnel wall, with a spacing of 1.5m, a length of 3.0m, and a diameter of 25mm. The thickness of shotcrete is 100mm, the number is C20, and the supporting effect is analyzed.