富水地区溶洞对深基坑开挖稳定性影响

在富水岩溶地区进行深基坑的开挖,往往会遇到基坑侧壁或底部突涌水的工程问题,轻则影响工程进行、花费人力物力、耽误工期,重则破坏基坑支护结构、淹没基坑,甚至威胁工程人员人身安全。依托广州新白云国际机场第二高速公路北段明挖隧道工程,采用有限差分软件FLAC^3D对富水地区溶洞对深基坑开挖稳定性进行研究,分别改变溶洞直径、溶洞埋深、溶洞内承压水头3个参数,研究富水地区溶洞对基坑土体变形、灌注桩侧移以及水平支撑轴力的影响。结果表明,当开挖至基底时,溶洞顶板厚度较小,溶洞参数的变化对基坑土体及支护结构影响较大。最后,提出现场应对基坑突涌水的方案,研究结果可为富水岩溶地区深基坑工程的设计与施工提供参考。

Influence of Karst Caves on the Stability of Deep Foundation Pit Excavation in Rich Water Area

When deep foundation pit excavation is carried out in water-rich karst area, water gushing from the sidewall or bottom of the foundation pit is often encountered, which may affect the progress of the project, waste human and material resources, delay the construction period, destroy the supporting structure of the foundation pit, flood the foundation pit, and even threaten the safety of the engineers. Based on the tunnel engineering of the northern section of the second highway of Guangzhou Baiyun international airport, the finite difference software FLAC^3D is adopted to study the stability of deep foundation pit excavation in the water-rich area. The influences of the size, buried depth and water head height of karst cave on foundation pit soil deformation, filling pile and horizontal axial force were studied. The results showed that when excavating to the basement, the roof thickness of the cave is small, then the change of cave parameters affects a lot to foundation pit supporting structure and soil. In the end, a scheme to deal with the sudden water gushing from the foundation pit on site was put forward. The research results can provide references for the design and construction of deep foundation pit in the water-rich karst area.