超深圆形基坑逆作法“两墙合一”地下连续墙设计

上海世博500kV全地下变电站工程基坑直径130m，开挖深度34m，工程地处高水位软土地层，周边环境条件复杂，没有现成的工程经验可以借鉴，其设计和施工都遇到了全新的挑战。采用超深圆形基坑逆作法设计体系，基坑围护体系采用“两墙合一”地下连续墙。针对超深圆形基坑逆作法“两墙合一”地下连续墙设计：从施工能力、计算分析以及类似工程实践经验等方面对地下连续墙的厚度、入土深度的确定进行了分析；结合工程特点对超深地下连续墙槽段接头和成槽方法进行了专项设计；并对高地下水压力作用下的深埋圆筒形“两墙合一”地下连续墙的防水节点进行了设计。工程实施的结果表明，“两墙合一”地下连续墙所采取的一系列针对性的技术措施是成功的。

Design of diaphragm wall of an ultra-deep cylindrical excavation constructed by top-down method

The scale and excavation depth of the Shanghai 500kV World Expo Underground Transmission and Substation(SWEUTS) are rarely seem both in Shanghai urban area and in China.The SWEUTS project is situated in soft soils with high groundwater level,meanwhile,the environmental condition in its vicinity is very complicated.The design and practice met brand new challenges since there is no established engineering experience that can be referred to.Diaphragm wall was used as retaining wall as well as outside wall of t...