Stability Analysis Of Changchun Metro Line No.2 Tunnel In Yitong River

As the acceleration of urbanization,the traditional traffic supply can't meet the requirements of traffic demand.Constructing underground rail transport is becoming an effective way for some of the larger cities to ease traffic pressure.In the domestic construction of the tunnel project,the subway tunnel through rivers and lakes under construction by shield is more common.Changchun Metro Line No.2 tunnel under the crossing zone of Yitong River is mud interbed,which is with high strength,disintegration dehydration,water softening,and prolonged exposure can cause flaking;The deformation of the tunnel and construction is difficult to control,a slightest mistake will result in collapse.To ensure the stability of tunnel is the key of shield construction,so it is necessary to study it.This thesis takes the tunnel from Nanguan station to Yanchang station in Changchun Metro Line NO.2 as a study subject and uses FLAC^3D numerical software with the embedded FISH language to analyse rock displacement,plastic zone,inside deformation and the main stress changes of concrete lining,considering how Seepage influences tunnel on stability under Fluid-Structure Interaction,contrasting the conditions which ignores the impact of groundwater seepage,using ORIGIN and EXCEL software to discuss the stability of the tunnel.The research shows that under the same shield excavation situation,vault settlement,dome uplift is positively correlated with tunnel depth.The deformation of hole increases as the covering earth thickens;the surface subsidence decreases as the depth increases;the strength of tunneling pressure bears relatively big impacts on lining deformation the and main stress;as the greater is the excavation force,the vault subsidence is smaller,the greater is the principal stress,the greater the stability of the tunnel within a certain scope;under the same excavation,the greater grouting pressure is,the greater is the horizontal displacement,the larger is the main stress,and stress is proportional to the grouting pressure;under fluid-structure interaction the lining will go up,segment' stress diameter increases,and is easier to reach the yield limit evendamage.