| Subway tunnel construction will disturb the layer of the earth around itself inevitably, and cause settlement of the ground surface. When the settlement achieves a certain stage, it will affect the safety of buildings overground and the utilization of pipelines underground. To reduce the damages, which are induced by tunnel construction, to the buildings overground and the facilities underground, analyzing the regularity of ground surface settlement exactly and forecasting are necessary. Sequentially, optimal construction techniques could be chose and perfect measures could be established to insure the safety of buildings and pipelines in construction area.In this paper, the metro tunnel excavation mechanics and settlement of the ground surface theory was expounded and analyzed first. Then it introduced the numerical analysis methods and related software, which are more commonly used in analysis of current underground engineering. A real soft soil tunnel pilot construction by both sides heading method was simulated by FLAC3D simulation software in engineering and the surface subsidence caused by construction rules were summarized, which are in agreements with an accepted more mature Ground Settlement unanimously presently. By analysis we can know that the upper part of the tunnel face is the most dangerous areas and the horizontal and vertical displacement are quite large on front of the tunnel face. The sample of transversal deformation of the settlement of ground deformation is similar to normal distribution. The modified Peck Tunnel formula can be applied in analysis of the ground surface settlement by shallow mining method. In the both sides heading method, the excavation of the middle hole has quite obvious effect on the surface subsidence, besides the one lateral lead hole which is excavated at the beginning. At last, some advices which are good for controlling surface subsidence effectively are given in the paper.
|
PDF Full Text Request