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。本文总结分析了国内盾构管片发生上浮的现象和特征,指出了承压水对诱发管片上浮的重要作用。依托北京地铁17号线香西区间盾构隧道,开展了盾构穿越富水承压地层的理论分析和数值模拟。结果表明,仅考虑浆液浮力和地层回弹的作用,难以解释该工程管片发生较大上浮的现象,考虑承压水作用后,提供了一种合理解释。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。

During the subway shield construction, the problem of shield segment lifting is very common. In some cases, it may even lead to the deviation of tunnel axis that exceeds the limit and hence affects the design and planning of the entire line. This paper summarizes and analyzes the phenomenon and characteristics of shield segment lifting in China, pointing out the important role of confined water in inducing segment lifting. Based on investigating a shield tunnel in Beijing metro line 17, we accomplished 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, it is difficult to explain the large lifting of segments in this project. When the effect of confined water is further taken into account, a reasonable explanation is obtained. Shortening the coagulating time of synchronous grouting and supplementing secondary grouting are measures specific for dealing with grouting buoyancy, while radial grouting around the tunnel can reduce the segment lifting induced by stratum rebound as well as confined water.

U231