Analysis And Numerical Simulation On Ground Settlements Caused By Shield Driven Method Construction In Hefei Metro

Shield as an important construction methods in the construction of the subway has been widely used, but in the construction process it will inevitably cause surface subsidence. If the surface subsidence is too large,it will affect the shield construction and the surrounding buildings, pipelines safety. Therefor, the study of surface subsidence caused by shield construction is very important.This paper introduces the research status of domestic and foreign scholars on the surface subsidence caused by shield construction and shield construction principle cause soil disturbance and surface subsidence, and then as the background of shield driven tunnel project from East Ring Station to Tongling Road Station in Hefei metro line 2, by analyzing the monitoring data and using MIDAS / GTS software to simulate the construction site by means of surface EPB shield sedimentation due to construction were studied. First, concluded the field monitoring data, and then use the finite element software MIDAS / GTS to establish three-dimensional model based on the actual engineering, the3 D model transfered some variables such as shield tail crevice size, the degree of pouring thick liquid and the scope of disturbance on soil around the tunnel surface etc,close to construction but hard to scale to sotropic, equal thick layer. The method objectively reflects not only the comprehensive influence of some factors that are difficult to quantify on the surface displacement but also the actual situation of project and simplify the computation model. Changing the functions of cell material properties and the stress release, the process of shield tunneling, pouring thick liquid into shield tail and lining supporting are simulated in the numerical simulation. Then in strict accordance with the order to start the construction phase curve calculated surface subsidence caused by shield construction,hydrogeological conditions combined with engineering analysis of the East Central Station to the general rules of Tongling Road Station Interval Surface Shield Settlement.By changing the parameters to simulate different tunnel buried depths, grouting intensities and driving forces of shield tunnel construction process, got different excavation schemes of ground surface settlement curves.By comparing the variation characteristics of the same group settlement curve to analyze the rules influencing tunnel burying depth,Grouting the end of the shield and boring pressure for the ground surface settlement.Finally, the rule of surface subsidence caused by shield construction of subwayconstruction projects put forward effective measures to control surface subsidence.