Impact of Metro Shield Interval Mechanical Method Connecting Passage Construction in Water-rich Sandy Stratum

Objective There is limited research on the impact of mechanical method connecting passage construction on mainline tunnels and surrounding soil of metro shield interval in water-rich sandy stratum. Method Taking a metro shield tunnel interval project with mechanical method connecting passage construction in water-rich sandy stratum as example, a numerical model is established using ABAQUS finite element software to simulate and analyze the entire process of this engineering. The effects of mechanical method connecting passage construction on mainline tunnels and surrounding soil are investigated. The calculation results are compared with actual engineering monitoring data to verify the reliability of the proposed numerical model. Result & Conclusion Land subsidence along the longitudinal direction of the mainline tunnel and connecting passage caused by mechanical method connecting passage construction exhibits a U-shaped curve, with a maximum land subsidence value of 4.60 mm. The effects of the construction on mainline tunnel deformation are mainly vertical deformation and horizontal deformation along the mainline tunnel. The maximum vertical deformation of the mainline tunnel is 1.08 mm, and the maximum horizontal deformation is 1.28 mm. During construction, the maximum stress in the mainline tunnel suddenly increases with the breakthrough of the connecting passage portal, reaching 52.54 MPa upon completion of the construction. Actual monitoring data show that the fitted land subsidence monitoring data aligns with the trend of numerical calculation results, validating the reliability of the numerical calculations.