大型软土基坑中心岛法施工中土台预留宽度的研究

Study on mound width remained during the construction of central island for large foundation pits in soft soils

以铁路上海南站南广场大型软土基坑采用中心岛结合预留土台逆作法施工为背景,分析了预留土台的作用机理;通过离心模型试验对比研究三种不同土台预留宽度及其加固与否对地下连续墙的变形控制作用,得出了土台预留宽度及土台加固与否对连续墙变形的影响规律;在此基础上,采用有限元模拟计算多组土台宽度下地下连续墙的变形,得出了根据变形减小率来确定合理的土台预留宽度。

Based on the central-island and athwart construction method for excavation of large foundation pit of Shanghai South Railway Station of South Square in soft soil, the active mechanism of remain mound was analyzed; the deformation of underground diaphragm wall under the condition of three different remained mound width with or without consolidation was contrasted through centrifuge model test, the effect of remained mound width with or without consolidated on the deformation of diaphragm wall was acquired; then the deformation of underground diaphragm wall with several different widths of mound was calculated by FEM, finally it was presented that the reasonable mound width could be determined according to the diminishing ratio of deformation.