The Mechanical Analysis Of The Metro Station Expanded Under Shield Running Tunnels By Shallow Tunneling Method

As shield method is widely applied in running tunnel construction while the shallow tunneling method is more and more used in metro station construction in domestic, the different construction time limit between metro station and running tunnel comes to be a serious problem. It is very important for the technique development of metro construction to find out a new construction method by combination of Shield and shallow tunneling method.Based on a large number of reference documents, the construction schemes of the expanded subway station under shield running tunnel were studied in this paper. CRD method is used in the construction on running tunnel, station tunnel and the passage tunnel.Focus on the constructing time of secondary lining in station tunnel, two construction schemes were brought forward in this paper. In scheme 1, the secondary lining in station tunnel is constructed when the excavate step of station tunnel is done. In scheme 2, the secondary lining in station tunnel is not constructed until the excavation of passage tunnel is finished.A comparative study is made via numerical simulation of scheme 1 and scheme 2 by software FLAC^3D , which contrast the deformation and displacement of the tunnel structure and environment, and the internal force of structure. The numerical compute result shows that scheme 1 is superior to scheme 2 in different research contents previously mentioned.A 1:10 large-scale model test was also studied in this paper to carry out the construction steps of scheme 1. In this test, surface settlement and the convergence of shield segment were studied to prove the feasibility of the construction schemes of the expanded subway station under shield running tunnel.In this new construction method of the construction schemes of the expanded subway station under shield running tunnel, the step of moving out the shield segment is the key step in the whole construction. Based on the 1:10 large-scale model test, further numerical compute was done to analysis the deformation and the internal force of shield segment. The most unfavorable position of shield segment was found out in this paper to provide a theoretical basis for the shield segment design and construction.