Research On Risk Control Measures Of Beijing Subway Shield Undercrossing The Existing Subway In Short Vertical Distance

As the rail transit network continues to expand and ground buildings become more intensive, the utilization rate of ground and underground space tends to be saturated, so a growing number of crossing projects come up, especially project of shield tunnel undercrossing the existing subway section in short vertical distance, with great difficulty and high risk. Therefore, it is necessary to analyze the deformation regularity in the project of shield tunnel undercrossing the existing subway section in short vertical distance, so as to put forward reasonable construction parameters and optimize risk control measures in order to guarantee the safety of the existing subway operation. With the rapid development of rail transit, crossing projects are increasing, this research is instructive to the development of urban subway and underground engineering.The project of Beijing subway shield undercrossing the existing subway in short vertical distance is taken as the research object, in this project, the vertical distance between shield tunnel and the existing subway section is2.1m, the horizontal distance between shield tunnel and the existing bridge-pile is3.6m, so the surrounding environment is very complicated; the shield construction parameters are difficult to control, because the crossing is adjacent to shield origin and receiving side.The main research contents are as follows:(1) Use finite element software ANSYS to establish three-dimensional stratum structure model, to analyze the influence on the existing subway section caused by shield construction in short vertical distance.(2) Through the analysis of monitoring data in the construction process and comparing with simulation results, to verify the accuracy of simulation, then to conclude the influence regularity on the existing subway caused by pre grouting and shield construction.(3) Focus on optimizing the risk control measure of pre grouting, then propose reasonable suggestions to construction based on the analysis conclusion, in order to instruct construction of the similar project and guarantee the safety of subway operation in the future.