Analysis on Surface Settlement of Pipe Jacking Method for Construction of Contact Channel in Water-rich Silty Fine Sand Layer
In order to study the influence of pipe jacking method on surface settlement of subway contact channel in water-rich silty sand layer,the surface settlement of contact channel with 15 m depth and 7.5 m length in 08 work area of Zhengzhou Metro Line 12 during pipe jacking construction was monitored,and the spatial and temporal evolution law of surface settlement during pipe jacking construction was analyzed in combination with 3D numerical simulation of " stratum-main tunnel-inner support-contact channel " system. The surface settlement increased gradually with the pushing of pipe jacking machine,and reached the maximum settlement value after pushing in place,in which the settlement increment produced in the stage of trolley positioning,starting hole breaking and receiving hole breaking was obviously larger than that in other excavation stages. After the equipment was dismantled,the stratum would rebound a certain amount due to unloading effect,and the settlement value would decrease. The surface settlement curve was funnel-shaped,symmetrical along the direction perpendicular to the center line of the contact channel,asymmetrical along the direction parallel to the center line,and the maximum settlement value was located 3 m away from the center of the contact channel and close to the starting end in the longitudinal direction. The horizontal influence range of the contact channel pipe jacking method on the surface was larger,and the concentrated area of the surface settlement was approximately elliptical,and its long axis was perpendicular to the axis of the contact channel.
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