长江边高渗透性土层深基坑开挖防渗处理

Anti-seepage Treatment for Excavation of Deep Foundation Pit in High Permeable Soil Layer near Yangtze River

摘要:

以海港引河南闸站工程为例，对基坑开挖过程中透水性土层的防渗处理进行研究。经比选，闸站基坑采用放坡开挖+搅拌桩围封的方案。运用有限元软件，分析不同搅拌桩长度下基坑边坡的出口水力坡降。结果表明，截渗桩穿越中等透水性层，桩底进入相对不透水层进行围封时，基坑边坡出口水力坡降满足规范要求，无逸流出口。同时，基坑施工中应布置相应降水井及监测点，保证基坑防渗安全。

Abstract:

Taking the Haigang Diversion River South Sluice Station Project as an example, the anti-seepage treatment of permeable soil layer in the process of foundation pit excavation is studied. By comparison and selection, the scheme of sloping excavation + mixing pile enclosure is adopted for the foundation pit of sluice station. The finite element software is used to analyze the hydraulic gradient at the outlet of foundation pit slope under the different lengths of mixing piles. The result shows that when the seepage cut-off pile passes through the medium permeable layer and the pile bottom gets into the relatively impermeable layer for enclosure, the hydraulic gradient meets the specification requirements by the outlet of the foundation pit slope, and there is no escape outlet. Meanwhile, the dewatering wells and monitoring points shall be arranged during the construction of foundation pit to ensure the seepage prevention safety of the foundation pit.