Analysis Of Formation Deformation And Driving Parameters Caused By Shield Tunneling In Soft Soil

With the rapid development of urbanization in China,large diameter earth pressure balance shield tunneling is widely used in the construction of subway tunnels,crossing river tunnels or deep water storage tunnels.As the shield passes through the saturated soft soil layer,the self-stability of the soil in front of the shield face gradually decreases,especially in complicated geological conditions and engineering environment,so the construction of shield tunneling is confronted with many difficulties.Still many unsolved geotechnical engineering problems in city subway tunnel,due to construction of shield tunnel in soft soil to many complex factors,shield tunnel and related theoretical research lags behind engineering practice,many involving the calculation theory and has not yet been solved,therefore,has important theoretical and practical significance study on strata deformation caused by excavation and excavation parameters of shield tunnel construction.Based on this,this paper is based on finite element software,the fine simulation method of shield construction on soft soil area,shallow analysis of shield tunnel construction on the ground deformation,and the finite element analysis of the simulation results comparing the measured data,the calculation and analysis of shield tunneling induced ground displacement field and the stress field distribution(some single soil,normal buried deep under the condition of shield construction caused by stress,strain and displacement fields).On this basis,analysis of shield tunneling construction process caused by ground subsidence and longitudinal transverse settlement trough trend,according to the actual construction of Shield Crossing the soft soil layer,the construction parameters of the statistical results,the optimal parameters of shield construction(advancing speed,chamber pressure,volume,and synchronous grouting)numerical model calculation results and field the monitoring data were verified.The main research work is as follows:(1)The earth pressure has little effect on the transverse settlement trough,with the increase of the earth pressure,the transverse settlement trough width decreases,the earth pressure increases,the maximum settlement of clay decreased gradually,and decreases with the increasing amplitude.In different earth pressure under the maximum settlement of the gap is not large.(2)The main deformation of the tunnel structure is vertical displacement,and the vertical downward displacement of the tunnel increases as the support pressure of the excavation face increases.The change of the support pressure of the excavation face has little influence on the newly installed lining.With the increase of the support pressure of the excavation face,the deformation of the lining decreases.(3)In the process of excavation in soft soil stratum,the driving speed is small and unstable,the driving speed change and demand is not stable,in sand stratum,shield posture adjustment difficulties,so we must constantly adjust the driving speed,ensure the driving efficiency,in order to control the front of the excavation face of surface settlement and excavation,the surrounding rock of soft soil different physical and mechanical properties of the required cutter speed rather than changes in demand is stable.(4)Soft soil surrounding rock loose structure,physical and mechanical properties of different excavation parameters shown are not the same,in order to control the front of the excavation face of surface settlement and excavation,the demand of soft soil surrounding rock in different physical and mechanical properties of the tunneling parameters rather than changes in demand is stable,the performance of the shield tunneling parameters demand also different.