Research On Tunnel Settlement Control Technology In Backfill Soil

The development and utilization of underground space engineering has become an effective way to solve the urban traffic development,this paper takes the settlement control technology in the tunnel construction of the four km-channel road in Chongqing Rail Transit loop as the research object,through collecting the existing data,the field investigation and analysis,The mechanical properties of the backfill soil and the surrounding rock mass after grouting are obtained in the laboratory test.By means of numerical simulation analysis,firstly,the deformation and stress of the surrounding rock and ground of the backfill tunnel are analyzed,and the stress and deformation in the surrounding rock are found to be large,which leads to the instability of the surrounding rock and the ground cracking.In order to strengthen the surrounding rock and reduce the settlement of the surrounding rock and the ground by using grouting technology,the influence of different grouting thickness on the surrounding rock and ground deformation and the stress of the first lining of the tunnel is analyzed and discussed,thus the grouting thickness of surrounding rock suitable for this project is put forward.On this basis,the influence of the ratio of the release load of the surrounding rock and the first lining on the deformation of surrounding rock and the stress of lining is further discussed,the control values of the main parameters of the comprehensive construction scheme for controlling the surrounding rock and ground subsidence of the backfill tunnel(grouting thickness releasing load ratio)are put forward,and the theoretical calculation is correct by the field monitoring.The surrounding rock and ground subsidence are controlled effectively.The main contents and achievements of the thesis are as follows:1.Consult the Geological Survey data to master the topography,geological structure,hydrological conditions and the physical parameters of the surrounding rock of the backfill tunnel.The mechanical properties(stress-strain)curves of backfill soil and the surrounding rock mass after grouting were obtained by laboratory test by sampling in situ backfill soil(including test grouting soil).2.Using the numerical analysis software to simulate the tunnel construction condition of Midas GTS NX,the deformation of surrounding rock of backfill tunnel and the regularity of initial lining stress and the change of ground with excavation progress are predicted,the stress and deformation in the surrounding rock are large,which leads to the instability of the surrounding rock and the ground cracking,and puts forward the grouting reinforcement measures of the backfill soil.3.The paper calculates and analyzes the influence of different grouting thickness on the surrounding rock deformation,initial lining stress and ground subsidence of the tunnel,and through comparative analysis,determines the grouting thickness of the backfill tunnel on the basis of safety,reliability and economic rationality.4.The paper further discusses the influence of the proportion of 5 different rock and the initial lining release load on the surrounding rock deformation and the initial lining stress of the tunnel,and determines the proportion of the surrounding rock and the initial lining release load.5.Through the comparison and analysis of different(grouting thickness,the proportion of surrounding rock and initial release load),the implementation plan is confirmed,and the field monitoring shows that the theoretical calculation is correct,and the surrounding rock and ground subsidence are effectively controlled.