Analysis of Influence of Shaft Group Excavation and Pipe Jacking Construction on Subway Tunnel During Operation Period
In order to research the impact of the superposition effect of shaft group excavation and pipe jacking construction on the operation of subway tunnels,the vertical and horizontal displacements of the tunnel vault and tunnel bottom caused by shaft group excavation and pipe jacking construction are investigated by numerical analysis using finite elements,taking the example of the excavation of the shaft and pipe jacking construction project,which is close to the shield interval of the subway line and the access tunnels.The results show that when the distance between the tunnel and the vertical shaft group is less than one time the diameter of the shield tunnel,the tunnel structure is in a bulging state vertically,and the vertical displacement is mainly affected by the soil loss and soil rebound caused by the excavation of the shaft group.When the distance between the tunnel and the vertical shaft group is 1～2 times the shield diameter,the tunnel structure is also in a bulging state vertically,and the ver-tical displacement is mainly affected by the soil loss and soil rebound caused by the excavation of the shaft group,and the maximum bulging value is less than the displacement value when the distance be-tween the tunnel and the vertical shaft group is less than 1 time the shield diameter.When the dis-tance between the tunnel and the vertical shaft group is greater than three times the diameter of the shield tunnel,the vertical displacement is mainly affected by the soil loss caused by the excavation of the shaft group,the rock strata around the tunnel structure is in the unloading state horizontally,and the tunnel structure's arch top is settling and the bottom of the tunnel is bulging.The horizontal dis-placement of the tunnel is mainly controlled by the shaft group because the diameter of the roof pipe is small compared with the diameter of the shaft.
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