Statistic Analysis And Prediction For Ground Surface Settlement Due To Tunnel Construction In Beijing Metro

Metro tunnel construction will disturb rock mass inevitably, and the ground surface settlement is likely to influence the buildings and the existing pipelines. 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.Based on actual data of ground surface settlement from several construction areas of Beijing metro and Beijing electric power tunnel, this paper adopts statistic analysis method which includes multinomial regression, nonlinear regression, subsection function regression and so on, the regularities of ground surface settlement due to underground cut with shallow burden and shield methods are studied. According to the research results of ground surface settlement, principal technique measures to control ground surface settlement due to construction of underground cut with shallow burden and shield are introduced severally. And then, Grey Model is built up based on data of ground surface settlement, and it forecasts the regularity of ground surface settlement. After contrast analysis, it is showed that modeling Grey Model to forecast ground surface settlement is successful.Some chief conclusions in this paper are elicited as follow:1. Values of ground surface settlement during upper bench cutting occupy total settlement values among 60%～70% in the construction of bench cut method;2. Values of ground surface settlement during side cavern cutting occupy total settlement values more than 50% in the construction of CRD method;3. When the spans of tunnel increase, the values of ground surface settlement and widths of settlement tank enlarge either, and the relationship between them is nonlinear;4. When the buried depths of tunnel increase, the values of ground surface settlement decrease, and the widths of settlement tank enlarge;5. When the distance between double track tunnels is lesser, the curve of settlement tank is single-peaked; and when the distance is large enough, the curve is double-peaked.