Research On The Ground Deformation Characteristics And Control Of Shallow-buried Undercut Tunnel With Groundwater Seepage In Water-rich Soft Stratum

In recent years,with the development of urban rail transit in China,shallow buried excavation method is increasingly applied to the urban weak and rich strata.Compared with the dry stratum,it is not clear that the formation deformation and its influencing factors are caused by the construction of tunnel in the weak and rich stratum,and the effective control measures can not be taken to prevent the formation deformation.This paper relies on changchun metro line 1 satellite plaza station and existing station interchange channel project.Through theoretical analysis,field monitoring and numerical simulation,this paper deeply analyzes the deformation characteristics,relevant influencing factors and control measures of shallow buried tunnel construction in weak and rich water stratum.The main work and analysis results are as follows:(1)This paper theoretically analysis of weak water stratum deformation mechanism,and summarize the influence factors of formation deformation and the method of surface subsidence budgeting,to provides a theoretical basis for the analysis and numerical analysis of practical engineering.(2)Based on the monitoring data of the project site,combining with the specific situation of the site construction,This paper classifies and compares the ground deformation of underground water seepage tunnel in the early stage and the control measures.The influence of groundwater seepage on formation deformation of tunnel construction is revealed.(3)This paper describes the principle of fluid-solid coupling,determines the solution method of fluid-solid coupling,and clarifies the boundary conditions and initial conditions of the tunnel excavation.This paper analyzes the deformation timeliness of the tunnel excavation flow,and determines the type of full fluid-solid coupling analysis.This paper discusses and selects the modified Cambridge model suitable for the analysis of weak water stratum and calculates the corresponding parameters.(4)Compared with the factors of different water level and different grouting effect,the mechanism of formation deformation caused by the release of surrounding rock stress and the effect of water loss consolidation in the groundwater seepage stratum during the tunnel construction was analyzed in the two angles of the surface and the vault settlement.(5)Released from surrounding rock stress and groundwater seepage stratum dewatering consolidation two aspects to carry on the different excavation sequence,pipe roof + deep hole grouting combined support analysis,and compared with the actual engineering situation,for the weak tunnel excavation deformation of control strata water stratum to provide theoretical and technical basis.