Research on Floor Deformation of Shield Tunneling Through Existing Stations Under Horizontal MJS Construction
In order to reasonably determine the impact of horizontal MJS(Metro Jet System)construction in cohesive soil layers on existing stations and ensure the safety of the project,this study is based on the project that a new subway tunnel in Suzhou close crossing through the existing station,and explains the design and construction parameters of horizontal MJS reinforcement and the arrangement of monitoring points.A numerical simulation method for horizontal MJS is proposed to study separately the influence of its construction on the deformation of existing structures and the deformation of the station when the shield tunnel cuts through the diaphragm wall after reinforcement completion,and it is verified in the supported project.The results indicate that the area where shield tunneling through the station is reinforced using a full-cavity method with downward 180° swing-jetϕ2.0 m horizontal MJS piles,the simulation predicts that the horizontal MJS grouting will cause a maximum uplift of 2.77 mm on the station's floor(actual monitored value of 3.7 mm).The influence of cutting through the diaphragm wall is generally less than 0.5 mm,and the maximum influence from the shield tunneling through is 1.5 mm.The engineering practice shows that the construction disturbance of horizontal MJS is small,which can meet the deformation control requirements of existing railway stations.The relevant experience is valuable and worth referencing.
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