Analysis Of Surface Subsidence And Numerical Simulation By The Shield Construction Through Existing Railway

With the continuous improvement of the city modernization, the underground railtraffic presents a fast development trend. The shield method is a kind of importantconstruction method for the current domestic urban subway tunnel construction. Asother construction method, the surface subsidence and the influence to the peripheryenvironment caused by construction have has become one of the important problems forshield method.In this paper, taking Tianjin Metro Line no.3Rail Road Station to North Station asthe background, the surface subsidence caused by shield construction across the existingrailway, deep soil displacement and stress distribution are studied. According to theconstruction characteristics of the shield method, a reasonable monitoring program isdeveloped, the surface subsidence for the construction site and deep soil displacementare measured, effective measured data is obtained; On this basis, combining with themonitoring data and the construction parameters Settings, the construction process ofthe tunnel beneath the existing railway is simulated dynamically using ANSYS.Through the comparative analysis of numerical simulation and measured data, theresults show: The surface subsidence along the tunnel axis direction of the measuringpoints is the biggest, when the shield machine gets through the measuring points, thesurface settlement reaches the maximum. The surface subsidence of horizontal directionmeasuring points decreases with increasing distance from the tunnel axis, for the two-lane tunnel construction, the tunnel built later has great influence on the tunnel soil builtbefore; The effect on the deep rock mass displacement by excavation is divided intoclose to, through and away from the measurement point three stages, soil displacementincreases with the measuring point depth, the biggest displacement change of the soil isaround the tunnel; For the deeper soil stress changes, in the shield close to and throughmonitoring section stage tunnel vaults and arched bottom soil stress value changegreatly, the corresponding soil mass displacement of deep buried tunnel is larger, deep soil stress from top to bottom is gradually increasing.