软土地层盾构隧道结构整体抬升实践

An uplifting practice of shield tunnel in soft ground

软土地层盾构施工易沉降过大导致轴线偏差,出现调坡困难,甚至影响后期列车运行速度,注浆抬升是轴线偏差治理的一种方法。宁波轨道交通某区间在施工过程中因对地层变化理解不彻底,导致沉降过大,调坡困难,为了不造成结构破坏,不影响工程工期,使隧道线型得到改善,对隧道结构整体抬升进行了实践。通过对地质情况分析,结构验算,注浆工艺研究,提出了下部注浆,内部支撑,实时监控,即时调整的思路,在注浆过程及时调整浆液。经过精细化管理,该区间最大稳定抬升量达3 cm。工程实践表明,注浆工艺和内部支撑对抬升阶段通用环管片结构安全起到重要作用,浆液的选择对后期稳定非常重要。该工程探索了软土地层盾构隧道不均匀沉降治理、控制措施,可为其他盾构隧道沉降治理提供参考和抬升设计提供依据。

Axis deviation easily occurs during shield tunneling in soft clays due to the overlarge settlement, while adjusting the slope ratio of tunnel difficulty, even affecting the running speed of trains during the operation period. Grouting uplift is a solution to axis deviation. In order to not cause structural failure, not affect construction period, and improve the tunnel line shape, a case of uplifting practice for overall tunnel structure in an inter zone with overlarge settlement of Ningbo metro construction is studied in this paper. Through the analysis of the geological condition, structure calculation, grouting process research, lower part of tunnel structure grouting, internal support, real-time monitoring, real-time ideas adjustment, the process of grouting slurry adjustment timely; and the fine management, the integral structure of tunnel is uplifted about 3cm without causing any damage; so that the tunnel line shape is improved effectively. The engineering practice shows that the grouting process and internal support play an important role to uplift stage general ring structure safety; slurry choice is very important to late stability. And by the practice, control measures for uneven subsidence of tunnel construction in soft clays are explored to provide references for other similar engineering and shield tunnel uplift designing. © 2016, Science Press. All right reserved.