盾构法重叠隧道施工过程中施工顺序及施工间隔对土体变形的影响研究

Influence of Construction Sequence and Lagging Distance on Ground Movements Induced by Two Overlapping Shield Tunnels

随着我国地下工程的持续开发建设,城市地下空间变得愈发拥挤.城市地铁上下行双线隧道在面对狭窄的地下空间环境限制时,有时需要采取重叠隧道的形式进行施工.由于双线隧道重叠布置,施工引发的土体变形产生叠加效应,因此重叠隧道施工引发的地表沉降更难控制和预测.同时,由于双线隧道重叠一般是为了应对狭窄的空间,因此重叠隧道通常会临近其他结构物施工,如建筑基础、管线和其他隧道.本文以天津地铁5号线程津段重叠隧道工程为背景,建立了精细化模拟的有限元数值模型,考虑了盾构掘进过程中掌子面支撑、盾构摩擦、盾构推力、盾尾注浆和台车重量等施工因素.计算结果与实测数据行了对比验证,证明了数值模型的可靠性.借助该数值模型对重叠隧道施工顺序与盾构施工参数的关系展开研究,优化了已有研究得出的简单定性结论.对重叠隧道双线隧道同步施工时不同施工间隔进行评估,从地表沉降、沉降发展速率、隧道位移和收敛等方面进行了分析,结合统计学方法和施工实际情况给出了推荐的重叠隧道施工间隔方案,应用该结论可以帮助重叠隧道施工节省近一半工期成本.

The urban underground space in China has become increasingly crowded due to underground construction projects.Because of the space constraints in a narrow underground environment,urban subway twin tunnels must occasionally be constructed as overlapping tunnels.Since the soil deformation caused by the construction has a super-imposing effect because of the overlapping arrangement of tunnels,the surface settlement caused by the construction of overlapping tunnels is difficult to control and predict.Moreover,since overlapping tunnels are designed to fit into narrow spaces,they are usually constructed near other structures,such as building foundations,pipes and other tunnels.In this study,a detailed finite element method simulation model is proposed based on the construction of overlapping tunnels for Tianjin Metro Line 5.Construction parameters such as face support,shield friction,shield thrust,tail grouting,and trailer weight were considered in the simulation.The calculation results of the proposed model were compared and verified with the measured data,demonstrating the reliability of the numerical model.In this study,ground settlements due to tunneling were investigated using different construction sequences of overlap-ping tunnels and the construction parameters of shield tunnels.Simple qualitative conclusions derived from existing studies were perfected.Various lagging distances during the simultaneous construction of overlapping tunnels were evaluated,and the surface settlement,settling rate,tunnel displacement,and tunnel convergence were analyzed.Moreover,a construction plan was proposed using a statistical method and construction conditions.The results can aid in reducing the construction time limit cost of overlapping tunnels by 50%.