复杂富水地层地铁深大基坑渗漏治理技术研究

Research on Leakage Treatment Technology for Deep and Large Foundation Excavation of Subway in Complex and Water Rich Strata

由于青岛地区濒临海岸线,地下水丰富,地铁深大基坑开挖遇到软硬复合地层、构造破碎带的复杂地层时,易发生地下水渗漏。依托青岛地铁7号线周村站基坑工程,基于工程调研、现场试验和现场监测,研究了穿越不良地质段深大基坑开挖渗漏特点,提出了CSM止水帷幕下坑外注浆+坑内注浆的系统注浆工艺。研究结果表明:构造破碎带是地下水的良好通道,基坑开挖侧壁易发生渗漏。分段注浆、地表与坑内注浆结合的注浆工艺可有效处理地下水大范围渗漏的问题,弥补CSM止水帷幕的工艺缺点。注浆全过程地表最大注浆量为410.5m^(3),桩体水平位移最大值为26.4mm,发生在断层破碎带与基坑围护桩相接的位置。基坑再次开挖,基坑侧壁无渗水点,实际注浆止水效果良好。

Qingdao is close to the coastline,and its groundwater is abundant;therefore,the deep and large foundation excavation of the subway is prone to groundwater leakage problems when it encounters complex strata such as soft and hard composite strata and tectonic fracture zones,etc.Based on the foundation excavation project of Zhoucun Station of Qingdao Metro Line 7,in accordance with engineering investigation,field testing,and field monitoring,the characteristics of water leakage in deep and large foundation excavation through unfavorable geological sections are studied,and the system grouting process of external grouting+in⁃excavation grouting under a CSM waterproof curtain is proposed.The results show that the structural fracture zone is a good channel for groundwater,and the side wall of the foundation excavation is prone to water leakage.The grouting process of segmented grouting and the combination of surface and in⁃excavation grouting can effectively deal with the problem of large⁃scale leakage of groundwater and make up for the shortcomings of the CSM waterproof curtain.The maximum grouting amount of the surface in the whole process of grouting is 410.5m^(3),and the maximum horizontal displacement of the pile is 26.4mm,which occurs at the position where the fault fracture zone is connected with the foundation pit retaining pile.When the foundation excavation is re⁃excavated,there is no seepage point on the side wall of the foundation excavation.The actual grouting water stop effect is good.