Study On Construction Mechanics Effect Of Shallow-buried City Light Rail Station Tunnel With Large Span

The exploitation city underground space is very necessary for Chinese urbanization, and railroad traffic system which is city's basic urban establishment and recovery disaster establishment is the most important part of urban underground utilization.With the development of economy, large span and shallow-buried tunnel in the center of city will appear more and more.The article firstly handles the data for monitor and control of Chongqing light rail Daping station tunnel, secondly analyses stress distribution of surrounding rock and expatiates construction methods of large span and shallow-buried tunnel. By making simulation and analysis to several construction methods for large span and shallow-buried tunnel through ANSYS software, educes the most reasonable method by comparing the surface subsidence and stress convergence. By comparison, the data of monitor and control is consistent with the data of numerical simulation.Through study, conclusions are as follows.1.Through ground surfacehrough the data processing of Chongqing light rail large Daping station tunnel's monitor and control,anlyses tunnel' headroom, ground surface, vault and shoring structure stress,get clearly terrene, vault and shoring structure's change in value curve,fits tunnel's headroom convergence regression curve.2.To several cavities,such as circular cavity,oval cavity and olivary cavity, anlyses surrounding rock stability,and expatiates major factors which impact tunnel surrounding rock stability and determinant gists by considering the chacteristics of large span and flat tunnel.3 Tunnel's numerical simulation, from vault sedimentation and horizontal convergence, shoring structure stress, surrounding rock plastic zone distribution aspects, optimizes the fittest construction method.4.3D numerical simulateion of arch shows the trend of wall rock secondd afresh distributing and timbering shoring stress movement. Skew back stresss reaches maxima when tunnel heading heads 6 m. The vault sedimentation maximizes behind tunnel heading reaching 9m,So 6m construction throat is necessary.