Impact Research Of A Large-diameter Shield Tunnel Crossing The Existing Subway Bridge Structure In Beijing

Subway as a major force in the urban transport system, responsible for most of the city traffic flow, operation safety of which is directly related to the safety of passengers. To satisfy the demand of urban rail transport networking, Subway line network structure become more complicated, various types of crossing engineering occur frequently, due to the existence of project risk and the effects on the existing structure result from crossing engineering, it’s increasingly becoming an important part of the focus in traffic engineering.Shield construction with many advantages such as better intelligence, construction safety, leakproof, seepage-proofing, small impact on the surrounding environment, easy to control the subsidence and so on, has become the mainstream construction method of a subway tunnel project at home and abroad. But As one of the difficult points:for large diameter shield tunnel crossing subway bridge structure in Beijing is the first time that its similar regularity research is very little. During the construction of a new large shield tunnel project, in addition to the structural safety, the key objective is to ensure that construction minimize impact degree of the existing bridge. Therefore, how to assess project risk of large diameter shield crossing the existing subway bridge and accurate analysis deformation law of shield tunnel construction on the existing bridge and track structure, put forward reasonable protection measures and analyzes its effects, in turn guide the project construction, to ensure the safety of both the structure and operations of the subway. In the future similar engineering like large diameter shield crossing project is particularly important.In this paper, taking Beijing subway large diameter shield tunnel project as the research object, another difficult point is that the deformation control standard of the existing subway is high than others. By considering the above two difficult points to analyze and summarize the deformation laws of the existing subway bridge and track structure, put forward reasonable protection measures for the large shield tunnel crossing the bridge construction project to provide reference in the future. The main research works of this paper are as follows:(1) On the basis of extensive research on the related literature at home and abroad, to explore the deformation mechanism of shield tunnel crossing project. According to practical engineering, using numerical simulation-finite element software ANSYS, analyze the deformation of large diameter shield tunnel construction influence on existing subway bridge and track structure. Comparing three different conditions:Under unreinforced conditions, drilled grouting piles program and composite rockbolt piles program on existing subway bridges and track structures, and summarizes the best program.(2) According to the third-party monitoring measurement data of practical engineering, compare with the results of numerical simulations to test the correctness of numerical simulation and possible problems, and summarize the deformation laws of the existing bridge structure and track structure, put forward risk management measures of large diameter shield crossing project construction for future similar large diameter shield crossing bridge engineerings construction providing references.