润扬大桥南汊北锚碇深基坑开挖工程实践

Case study on excavation of deep foundation pit for the north concrete anchor of south branch of Runyang Bridge

介绍了润扬大桥南汊北锚碇深基坑工程开挖实例。该基坑的地层条件为二元结构 ,平均开挖深度为 48m。围护结构采用1.2m厚的地下连续墙和 12道内支撑及 3 2根立柱桩 ,结合地连墙底的双排注浆帷幕来挡土和止水 ,在距离地连墙 2 3m处进行了水平高喷形成了外部封水帷幕。基坑内共布置有 6口深井 ,基坑外布置有双排降水井进行坑内外降水。深基坑工程施工监测表明 ,该基坑设计合理 。

In this paper, the excavation work of deep foundation pit for the north concrete anchor of south branch of Runyang Bridge is introduced. The pit is located at double stratums with the upper clay layer(16 m) and the lower sand layer(32 m).The depth of the pit is more than 48 meters. The diaphram walls with 12 inner braces and 32 piles are employed to support the pit, together with rows of chemical grouting curtain under them to hold back groundwater. At the same time, six deep well inside and two rows of deep well between the diaphram walls and outside chemical grouting are used to dewater the pit. During excavation of the pit, the forces in bracing system, the water level inside and outside the pit, and the deformation of walls have been monitored.It is shown that the design of the retaining structure is successful. It provides a practical reference for the design and construction of similar project.