Risk Control of Shield Tunneling Undercrossing the Operational Station in Water-rich Soft Strata
To minimize disturbances to an existing metro station during shield tunneling in a water-rich soft stratum,this study focuses on the construction of a T-type transfer station where shield tunneling passes through an operational station.The study examines the cutter configuration and tunneling parameters for shield tunneling through a diaphragm wall without glass fiber reinforcement using theoretical analysis and field measurements.Key risk control measures for shield tunneling through the operational station are also proposed.The results indicate that the shield can safely cut through the diaphragm wall by using high-strength shell cutters with varying heights,reducing the tunneling speed and shield thrust,and increasing the cutter head torque.Disturbances to the station floor can be reduced by considering the interaction force between the station floor and the surrounding stratum as an additional load during the underpass construction.Setting the chamber pressure at 1.2 times the static soil pressure at the shield's center further minimizes floor disturbance.Effective settlement control of the existing structure is achieved by filling the gap between the shield shell and the surrounding stratum with clay shock and using a combination of synchronous grouting,secondary grouting,and radial grouting to fill gaps behind the segments.The primary deformation caused by tunneling beneath the operational station is settlement,while shield cutting through the diaphragm wall leads mainly to horizontal displacement,accounting for over 75％of the total horizontal movement.
rail transitwater-rich soft stratumshield constructionundercrossing operation stationcutting diaphragm wallrisk control
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