Study On Construction Method Of Tunnel Crossing Subway

With the accelerated process of urbanization in China,the degree of urban motorization is constantly improving,and the contradictions of urban road construction land are becoming more and more prominent.Many large and medium cities will start to reduce the number of urban roads(urban tunnels)The ground cross,but also to the ground left a good landscape space.The underground space of the big city is the priority of the urban rail transit(subway).Therefore,in the construction of the subway section of the urban road,it is often close to or across the existing urban rail line.The normal operation of the subway is very sensitive,too large deformation and even affect the safe operation of the subway.How to ensure the safety of the subway operation in the process of urban tunnel construction is the subject that city builder must face.As one of the common methods of tunnel construction,the excavation method plays an important role in the construction of urban tunnels.This paper introduces the general situation and main points of the construction method of the excavation method,and puts forward the main flow and the main points of the construction of the excavation tunnel.Digging,construction MJS construction pile,steel support construction,structural construction,earth backfill and so on.In this paper,the finite element software Midas GTS is used to calculate the influence of the distance between the new urban tunnel and the existing subway tunnel on the deformation of the subway tunnel,and the deformation mechanism of the existing tunnel caused by excavation is studied.The finite element model is established for the different working conditions,whether the protective measures are taken,whether or not the excavation is carried out,the deformation is simulated and the excavation sequence of the foundation pit is optimized.Evaluation of the effectiveness and rationality of different protective measures(soil reinforcement,pouring floor and anti-floating pile to form a "protective hoop" and block excavation block load back pressure)Taking the subway line 2 of Suzhou North Road tunnel as an example,the research results provide a basis for the design and construction.