Reasearch On Deformation And Stability Under The Influence Of Excavation On Adjacent Metro Tunnel

With the rapid development of national economy,the increasing of the underground pipeline,routes and the structures,phenomenon of excavation nearby the existing operation tunnel gradually becomes the norm.The settlement of soil around caused by the foundation pit excavation,the deformation of the retaining structure and the uplift of soil at the bottom of the foundation pit all will,at different extent,influence the stability of the tunnel,increases the additional stress of soil surrounding tunnel and tunnel structure are produced by different degree of deformation.The damage of the stability of tunnel structure may cause heavy losses to public property security.It is necessary to study the effect on the deformation and the stability of the adjacent tunnel caused by foundation pit excavation and put forward reasonable construction measures.Combined with the project that high-rise building foundation pit near the terminal tunnel in Xian,using finite element analysis software MIDAS/GTS to study the influence of deformation and stress of whole process of excavation on existing adjacent tunnel.The effect of distance and influence depth caused by excavation on the adjacent tunnel and the corresponding protection measures is put forward.The main research of this paper can be summarized as follows:Combined with the research results of scholars at home and abroad,the factors that affect the excavation of tunnel deformation and the deformation characteristics of the tunnel be analysis.The vertical and horizontal spacing span of the foundation pit and the tunnel,the reinforcement scheme of foundation pit soil,the construction sequence,the drainage and precipitation measures are summarized as classification.Set excavation engineering with a adjacent existing tunnel on typical geological conditions in xi’an area as an example,through the finite element software MIDAS/GTS NX,deformation calculation model of the existing tunnel near excavation is established.Considering the whole project of the initial stress analysis,drawing the deformation of the tunnel and the influence of foundation pit excavation in depth and scope,effective measures to protect the stability of the tunnel structure is put forward.On the basis of the analysis of the engineering example,by changing the thickness of the excavation,the depth and the level of excavation.Under the conditions of different pit excavation depth,spacing,dimensions,thickness.Analysis of the deformation and stress of the tunnel structure.Comparing and designing the scheme of the protection of the existing tunnel near foundation pit excavation,through the different construction measures and solutions to control the deformation of foundation pit and the subsidence of surrounding soil effectively,adopting different construction technology method to reduce the deformation of the tunnel on purpose,the security and stability of the tunnel is protected.