粉砂性土体中基坑开挖工程实践

本文介绍了某大厦基坑工程实例。该基坑位于粉砂性地基中，平均开挖深度12m，围护结构采用钻孔灌注桩，结合高压旋喷桩止水和止土，基坑内外共布置三级井点降水。基坑开挖表明该围护结构设计安全经济，为粉砂性地基中类似工程设计施工提供了借鉴。

Case Study of Excavation of a Deep Foundation Pit in Silty Sand

In this paper,the excavation of a deep foundation pit in silty sand is introduced.The pit is located at permeable silty sand with high water level.There are a number of pipelines and fragile structures around the pit that are sensible to soil deformation.The pit is designed to be excavated to a depth of more than 12 meters.The rows of cast-in-place piles are employed to support the pit with rows of chemical churning piles behind them to hold back underwater.At the same time,well-point-system is used to dewater inside and outside the pit.During excavation of the pit,the monitoring of normal force of bracing system,the water level inside and outside the pit,and the deformation of soil around the pit have been worked out.The monitoring work shows that the design of the retaining structure is successful.It provides a practical experience for the design and construction of similar project on permeable silty sand ground with high water level.