群井验证性抽水试验在敏感环境下基坑工程中的应用

Application of group well pumping test in foundation pit engineering under sensitive environment

以周边环境较为敏感的上海某深基坑工程为例,分析基坑正式开挖之前,进行群井验证性抽水试验的必要性。通过抽水试验发现,在坑内水头降至安全水位时,坑外局部观测井水位下降异常,下降幅度最大约5.58 m。分析表明,该区域隔水帷幕出现了渗漏,采用RJP超高压旋喷桩进行了注浆止水。注浆后又进行了抽水试验,试验结果表明注浆有效解决了帷幕渗漏问题。

Taking a deep foundation pit project in Shanghai,which is extremely sensitive to the surrounding environment as an example,this paper analyzes the necessity of group well pumping test before the foundation excavation is formally implemented. Through the pumping test,it is found that when the head of the pit falls to the safe water level,the partial well logging water level outside the pit is abnormally decreased,the largest decrease is about 5. 58 m. The analysis shows that the water separation curtain in this area has leakage,in order to eliminate the hidden danger of safety,the RJP ultra high pressure jet grouting pile is used for grouting to stop water. After pumping test,the maximum water level outside the pit is only about 0. 17 m,which effectively solves the problem of curtain leakage.