软土狭长形基坑“跳仓式”取消换撑施工技术

"Skip-bay"Construction Technique of Cancelling Strut Replacement for Long and Narrow Foundation Pit in Soft Soil

深基坑工程中,为保障底部钢支撑拆除后基坑变形这一问题,在常规深基坑围护图纸中都会设计钢支撑换撑工艺,但换撑工艺存在着施工工程量大、施工难度大、施工成本高等诸多问题,现场实施过程中较为困难。通过在上海软土狭长形基坑项目中开展的取消换撑试验,从地下连续墙测斜与钢支撑轴力角度,分析了取消换撑后基坑变形增量数据,总结了换撑施工段与取消换撑段的变形差异,提出了“跳仓式”取消换撑施工技术,节省了施工工期,也节约了工程成本支出。

In deep foundation pit projects,to ensure the deformation stability of the foundation pit after the removal of the bottom steel struts,the steel strut replacement process will be designed in the conventional deep foundation pit enclosure drawings,but there are many problems in the replacement process,such as large amount of construction work,difficult construction,high construction cost and so on,which are difficult to be adopted on-site.Through an experiment conducted on a long and narrow soft soil excavation project in Shanghai,the incremental data of foundation pit deformation after canceling replacement struts is analyzed from the angle of diaphragm wall inclination measurement and steel struts axial force,and the deformation difference between the replacement strut construction section and the cancelled replacement strut section is summarized.The construction technique of"Skip-bay"cancellation of strut replacement is put forward,which saves the construction period and project cost.