盾构近接施工对既有构筑物的影响

Research on the Influence of Shield Driving on Adjacent Existing Structures

以北京轨道交通新机场线盾构区间下穿既有高压管道及侧穿桥桩为工程背景,使用FLAC 3D软件建立三维数值模型。模拟分析表明,在未采取加固措施时,桥桩最大累计竖向位移达17.5 mm,超出控制值。掘进前选取100 m试验段,总结出盾构机穿越该类土层的最佳参数,选择合适参数进行穿越南六环的施工,选取合适注浆压力与注浆量避免浆液损失。根据现场实际监测所得数据经过高斯曲线拟合,计算该地段沉降槽宽度系数,为盾构施工提供参考和指导。

In this paper,FLAC3D was used to establish a three-dimensional numerical model based on the engineering background that the shield interval of Beijing Rail Transit New Airport Line passes through the existing high-pressure pipeline and side crossing bridge pier.The simulation analysis showed that the maximum cumulative vertical displacement of the bridge pier is 17.5 mm,which is beyond the control value.It was proposed to select 100m test section before tunneling,to sum up the best parameters for the shield machine to cross this kind of soil layer,to select the appropriate parameters for the construction of crossing the South Sixth Ring Road,and to select the appropriate grouting pressure and amount to avoid slurry loss.According to the actual monitoring data,through Gaussian curve fitting,the width coefficient of settlement trough in this section was calculated,which provides reference and guidance for shield construction.