Study On Safety Clear Distancebetween Subway Shield Tunnel And Foundation Pitin The Sand On The Rock Layer

Affected property development along the periphery of cities around the country the workhas faced great challenges from the excavation to protect the structural safety of rail trafficfrom the subway tunnel side. On the one hand, Metro Shield Tunnel in the city subway linetunnel proportion is growing due to its advantages; on the other hand, its severe disease inci-dents are common because of the impact of construction excavation by side. In order to solvethe security protection of shield tunnel on the side of the pit due to the construction of exter-nal operations, required to limit minimum safety Structure level net distance between excava-tions outside line and shield tunnel wall structure in the land planning and preliminary tech-nical review of security of subway shield tunnel on the side of excavation can be to one prac-tical solution which can achieve rational use of land along the subway tunnel while makingstructural safety on land planning. However, it is less in the research about how to designate areasonable security clear level net distance at present.Aiming at subway shield tunnel maximum displacement control objectives， the authorcalculates the safety level net distance under the control of5mm and10mm displacementbetween the subway shield tunnel and the foundation pit using the3-d numerical simulationanalysis method from the aspect of the subway security protection technology in light of thedeep foundation pit engineering which in the typical conditions of the sand on the rock layer.The author illustrates the practicability and rationality of the net from the security level ac-cording to an engineering case.This paper conducts the following studies:(1) Make a brief description of current theory and research status and problems of influ-ence of excavation close to the subway tunnel structure and subway tunnel structure securitybased on safety level net distance.(2) Summarise the research on displacement effect for the tunnel. The means ofthree-dimensional numerical experiments is carried out to research Systematic the safety levelnet distance under the control of5mm and10mm displacement between the subway shieldtunnel and the foundation pit in the sand on the rock layer of the excavation depth, tunnelslocated stratigraphic and depths and different properties of rock layers. (3) Analysis the influence on safety level net distance between subway shield tunnel andfoundation pit in the sand on the rock layer in respect of factors such as the groundwater im-pact, the depth of the tunnel structure and longitudinal stiffness, the deformation control offoundation pit, the size effect of pit, and correction and instructions the safety level net dis-tance influenced on the related factors.(4) Make a preliminary applied in practical engineering for research results.