富水砂层地铁盾构侧穿桥梁桩基影响分析及控制研究

Analysis and control study of the influence of metro shield tunneling on bridge pile foundations in water-rich sand stratum

依托郑州地铁12号线区间隧道盾构工程实例,结合盾构试验段参数,构建一套精细化数值模拟计算模型。在此基础上,将仿真计算数据与现场监测数据相互对照解析,研究在富水砂层环境下盾构侧穿现有桥梁结构时,对桥梁桩基变形的影响及其控制措施的效果。研究表明:在盾构掘进过程中穿越群桩基础区域时,随着盾构掌子面与桩基位置间距的减小,桩基的横向及纵向变形会显著增大,尤其在盾构经过桩基所在位置时,桩基变形达到峰值,之后随着盾构远离,桩基变形逐渐恢复至稳定状态。在隧道挖掘方向的垂向剖面上,桩基上部表现出向远离隧道开挖方向的位移趋势,而桩基下部则发生与之相反的位移现象。在盾构穿越过程中,由于受到前排桩基的遮拦效应,后续排桩的位移特征值呈逐排减弱趋势。针对地层以及桩基的变形提出控制措施,并通过比较实施措施前后现场实测数据与模拟预测数据的一致性,验证控制措施的有效性,以期为同类相关工程提供参考。

Based on the case study of the shield tunneling section in the Zhengzhou metro line 12 project,and by integrating parameters from the shield tunneling trial section,a refined numerical simulation computation model was established.On this basis,through comparative analysis between the simulation data and field monitoring data,this research investigates the impact on bridge pile foundation deformation and the effectiveness of the control measure when a shield passes lateral to an existing bridge structure in a waterrich sand stratum environment.The findings indicate that during the shield tunneling passes through a cluster pile foundation area,as the distance between the shield's tunnel face and the pile position decreases,both lateral and longitudinal deformations of the pile foundation would significantly increase.Notably,deformation peaks when the shield passes directly beneath the pile foundation,and then gradually recovers to a stable state as the shield moves away.In the vertical cross-section along the tunnel excavation direction,the upper part of the pile foundation exhibits a displacement trend moving away from the tunnel excavation direction,while the lower part experiences an opposite displacement phenomenon.During the process of shield crossing,due to the shielding effect of the front row of piles,the displacement characteristics of subsequent rows show a diminishing trend.Control measure was proposed to address the deformation of the soil stratum and pile foundations,and the feasibility of the control measure was validated by comparing the consistency between field measured data before and after implementation with simulated predicted data,so as to provide reference for similar relevant projects.