软土中超大面积深基坑逆作法设计与实践

上海铁路南站北广场基坑为超大面积深基坑工程,周边环境保护要求极高;为了控制基坑的变形和达到经济合理的设计目的,采用了主体结构与支护结构相结合的逆作法设计方案,其中包括地下室外墙与围护墙体相结合,结构水平构件与基坑内支撑相结合,结构竖向构件与临时立柱(立柱桩)相结合.实施结果表明本基坑工程设计创造了较好的经济效益,确保了周边环境的安全,同时也为软土地区超大面积深基坑的设计提供了借鉴.

Design and Practice of a Super Large Excavation Using Top- down Method in Soft Deposit

The foundation pit of the North Square of Shanghai South Railway Station is a super large excavation. The requirement for protection of its adjacent properties is quite strict. In order to control the displacement of the wall and posses good economic effect, a top-down method is adopted to excavate the pit. In the design scheme, the diaphragm wall is used as retaining wall as well as the outside wall of the basement. Horizontal members of the main structure are used as horizontal struts. Moreover, the vertical members of the main structure are used as vertical props of the supporting system. The implementation results of this project indicate that the design of this excavation is very successful. It is also provides some useful reference for the design of super large excavation in soft deposit.