Study On Tunnel Characteristics Of Double Shield Tunneling With Continuous Curve Of Small Curvature Radius

In recent years,small radius of curvature continuous curve double shield tunnel construction of metro tunnel engineering is becoming more and more.The domestic engineering community has accumulated some engineering experiences through several example projects.In order to solve the engineering problems such as difficult to control the construction axis of shield tunnel,large surface settlement,shield measurement and attitude control,shield tunnel construction parameter selection,shield deformation correction and shield tail and tube segment,the research of small curvature radius curve characteristics of shield tunnel construction provides a solution.This paper relies on Wuhan Metro Line 11,to carry out the research of the construction parameters such as the choice of the shield tail clearance,shield posture and segment attitude control as well as tunnel convergence deformation,specific research content and results are as follows:(1)"S" type curve of continuous interval of shield construction simulation,to analysis the influence of small curvature radius of turn period of shield tunnel construction on the surface and tunnel segment.Through the study of formation deformation and tunnel characteristics,to explore the continuous curve excavation section of the shield machine construction parameters(such as shield tail clearance,soil pressure,grouting parameters,etc.)of rationality,especially in the small shield tail gap although the control of surface subsidence is better,but the construction of tunneling and segmentation brings difficulty,as the key points and difficulties of this article.(2)Based on field monitoring and numerical simulation results.Focus on analysis of numerical simulation and deformation monitoring of tunnel convergence,a comprehensive comparison and analysis to evaluate its security and stability.(3)Analysis of shield attitude and segment pose attitude control,segment quality control measures analysis.In view of the phenomena of segment damage and shield attitude drift caused by small radius of curvature shield tunnel excavation,the control of the axis of acute curve tunnel and the large deviation of shield excavation during excavation,by shield themselves from the control and construction technology in combination with the actual construction experience for attitude control of some specific control measures are summarized.(4)This article relies on the Wuhan Metro Line 11,the use of active shield machine shield to 35 mm shield tail gap construction,compared to the 75 mm shield tail clearance which is usually used,effectively controls the surface deformation,but increase the difficulty of construction and the control of the attitude of shield machine.By using shield measurement,effective combination of shield jack and "hinge" device,the difficulty of construction is reduced,which is the main innovation of this paper.