Objective The construction conditions in water-rich soft soil strata are unfavorable, and the construction of metro shield tunnel link passages may significantly affect the integrity of the existing tunnel structure and the stability of the surrounding strata. To enhance the construction safety, it is necessary to study a construction scheme that combines the freezing method with prestressed support.
Method Based on the link passage and pump station project in Pingxi Station-Low Carbon City Station interval of Shenzhen Rail Transit Line 3, a construction scheme utilizing freezing method + prestressed support is proposed. The freezing parameters and construction steps are described. Finite element simulations are conducted to systematically analyze the bearing performance of the frozen wall and the prestressed support system, while field monitoring is performed to evaluate the effectiveness of construction disturbance control.
Result & Conclusion According to the finite element simulation results, the maximum tensile, compressive, and shear stresses of the frozen wall are 0.07 MPa, 1.31 MPa, and 0.50 MPa, respectively, all meeting the safety factor requirement of 2.0. The maximum deformation of the frozen wall in the regular link passage section is 21.0 mm, approximately 3.9 times that of the frozen wall in pump-station section. Under uniform and non-uniform working conditions, with prestress load of 500 kN at the nodes, both the strength stress ratio and the stability stress ratio of the support structure remain below 0.7, indicating excellent spatial stability and load-bearing performance. Field monitoring results show that adopting the freezing method + prestressed support can effectively control the link passage construction induced disturbance to the ground structures and existing segmental lining.
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