富水承压地层盾构管片上浮规律及控制措施探讨

Upward Lifting Characteristics and Treatments of Shield Segments in Water-Rich and Confined Strata

在地铁盾构施工过程中,隧道管片上浮问题十分普遍,严重时甚至会造成隧道轴线偏差超限,影响整个线路的设计规划。总结分析国内盾构管片发生上浮的现象和特征,指出承压水对诱发管片上浮起重要作用。依托北京地铁17号线香西区间盾构隧道,开展盾构穿越富水承压地层的理论分析和数值模拟。结果表明:导致该工程管片发生较大上浮现象的原因不应仅考虑浆液浮力和地层回弹的作用,还应考虑承压水作用的影响。缩短同步注浆凝结时间和补充二次注浆是针对浆液浮力的措施,而在隧道周边径向注浆则可同时减少地层回弹和承压水的影响,径向注浆对减小管片上浮效果明显。

The shield segment lifting problem commonly arises when constructing subway shields.In some cases,it can lead to the deviation of a tunnel axis that exceeds the limit and then affects the design and planning of the entire line.This study summarizes and analyzes the shield segment lifting phenomenon and characteristics in China,noting the important role of confined water in inducing segment lifting.By investigating a shield tunnel in Beijing Metro line 17,we conducted theoretical analyses and numerical simulations of shield tunneling in a water-rich stratum with confined water.The results show that,if only the effects of grouting buoyancy and stratum rebound are considered,explaining the large lifting of segments in this project is difficult.When the effect of confined water is further considered,a reasonable explanation is obtained.Shortening the coagulating time of synchronous grouting and supplementing secondary grouting are viable measures for handling grouting buoyancy,and radial grouting around the tunnel can reduce the segment lifting induced by the stratum rebound and confined water.