Analysis Of Factors Affecting Surface Subsidence In Construction Of Double - Track Tunnel

With the rapid development of urban economy and the increase of urban population, resulting in urban ground traffic congestion, in order to alleviate or fundamentally solve this problem, the development of urban underground space is imperative. The subway,convenient and public transport, arises at the historic moment. However,in recent years,in the urban subway tunnel construction process, double parallel tunnels to the simplicity of its high flexibility and construction gradually become common forms of subway tunnel excavation, the surface subsidence of double parallel tunnels excavation increasingly attracted people’s attention. Based on Beijing Metro Line 7 Jiulongshan- Dajiaoting interval double line tunnel, using the numerical simulation software to analyze the lane tunnel construction of rock and soil dynamic construction mechanics theory, in double line tunnel bench excavation and reservation core soil excavation of finite element numerical simulation analysis of.The study work is summarized as follows:(1) Numerical simulation In practical engineering background,due to the complex excavation model, so use Midas simulation to establish the basic model, then the use of software programming the Midas in mesh through a form into FLAC3 D, used FLAC3 D simulation actual excavation steps of operation, analysis of double line tunnel construction of rock soil dynamic construction mechanics theory and the numerical simulation results and the actual monitoring results were compared, in order to verify the reliability of the accuracy of numerical simulation model and results, and draw the different stages of excavation settlement nephogram and final settlement nephogram.(2) The construction of the core soil with different step length is used to study the construction of the double track tunnel model, and the influence of the reserved core soil excavation on the ground surface settlement is studied.(3) Using the Bench method construction of the double line tunnel, draw the different stages of excavation profile tunnel soil displacement nephogram, and reservation core soil excavation method are compared, put forward two kinds of tunnel excavation, reserved for the core of indigenous excavation of tunnel face extrusion deformation, tunnel in front of the soil stability and the stability of the tunnel structure of the utility.