北京某基坑承压水截水帷幕工程实例分析

The Analysis of an Engineering Example about Curtain for Cutting of Confined Water in a Foundation Excavation in Beijing

基坑工程长约190 m,宽约98~195 m,呈"L"形,基底标高不一(主体深10.4 m,部分地段深6.48 m),东部中段存在下沉绿地(深5.88 m),整个基坑分2期施工;采用"φ600排桩+桩顶土钉墙"进行基坑支护;潜水及承压水对基坑开挖构成影响,在支护排桩之间设置φ1200旋喷搅拌桩,使其与支护排桩进行搭接咬合形成截水帷幕,并对帷幕内的潜水进行疏干,对基底以下附近的承压水进行疏干或基本疏干,以保证主体基坑在开挖过程中的槽底、电梯井坑底、集水坑坑底不发生承压水突涌。

The foundation pit is about 190 m long,98~195 m wide, and presenting the shape of ＂L＂. The base burying depth is different（the depth of the main body is 10. 4 m,the depth of the sections is 6. 48 m）. Existing sinks greenbelt in the middle part of the east（5. 88 m deep）,the project is divided into phase 2 construction. The foundation pit will be protected by using ＂φ600 soldier pile wall ＋ soil nailing wall above the pile＂.The foundation pit excavation are influenced by diving water and confined water, using ＂φ1200 mm rotary jet and mixing cement-soil pile＂ between the adjacent pile of foundation pit protection. That will be biting with the pile of foundation pit protection to form a curtain for cutting off drain, and the diving water will be drainaged to clean within the curtain, the confined water below the basement nearby will be drainaged to clean within the curtain. In order to ensure that groove bottom of the main body foundation pit,and the elevator well bottom, and the sump pit are not to be outburst flood during excavation.