摘要
存在地下承压水的深基坑,当基坑底部承压水层顶部的残留土层不能与承压含水层水头平衡时,处理不当极易造成管涌及坑壁失稳等问题。对相关承压水处理风险源进行分析,针对勘察、设计、施工各阶段都提出具体要求。实例中的基坑临近江面,基坑下承压水与江水存在贯通通道,河道水位变化时会引起承压水头增减,由于设计水头埋深参考值是针对一年观察期而得到的,未考虑到历年水头变化,成为事故埋下隐患,最终因为施工期间河道涨水导致承压水压力超过预期引起了基坑涌水。事故发生后,现场紧急采取堵漏措施,采用灌浆法加固基坑土体,改善土体性质,增加不透水土层的厚度,最终已解决基坑开挖时出现的涌水等现象,保证了工程的顺利安全完成。灌浆法加固是承压水较大情况下基坑安全开挖的有效方式,研究结论对于承压水的风险控制特别是临近江海的工程的设计施工具有较强的指导意义。
Because of the existence of confined water at the bottom of the deep foundation pit soil, when the weight of impervious soil above cannot balance with hydraulic head,improper construction method can easily lead to piping, the instability of foundation pit enclosures and many other problems. In this paper, many risk sources related confined water are analyzed and many specific requirements are put forward for survey, design and construction. Because the foundation pit is near the river and there are penetration channels between confined water and river water, so the change of river water level will cause the rise or fall of confined water head. In view of the design head was reference the change of groundwater level in nearly one year, not considering the head changes throughout the years, which become the hidden danger caused accident. In the end, the river water level rising during construction, confined water pressure exceeded expectations and caused the piping. After the accident, water channel was soon clogged. And then concrete was poured into soil at the bottom of foundation pit. The soil property improved and thickness of impervious soil increased significantly. Piping problem was resolved and the project was completed safety. Grouting method is an effective way to ensure foundation pit excavation safety when confined water head is larger. Research in this paper has a strong guiding role in controlling risk of the pressure water during design and construction, especially engineering near river or ocean.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2014年第S1期353-358,共6页
Rock and Soil Mechanics
关键词
基坑开挖
承压水
风险源
管涌
灌浆法加固
excavation of foundation pit
confined water
risk source
piping
reinforcement with grouting method
