围护结构兼竖向支撑系统在盖挖逆作地下交通工程中的应用

盖挖逆作法基坑两侧的地下连续墙,作为施工期间基坑的围护结构,截水防渗并承受周围水土的侧压力,作为竖向支撑结构,承受着由各层逆作结构板传递的竖向载荷,在使用阶段可以作为工程永久抗浮结构。一级基坑内部的二级基坑地下连续墙,因为墙顶在负一层底板处,不能直接兼顾竖向支撑作用,结合工程实例,对该技术问题进行分析研究,提出采用临时格构柱等措施,永临结合,实现了二级基坑围护结构兼竖向支撑系统在盖挖逆作地下交通工程中的应用。

Application of Retaining Structure Doubling as Vertical Support System in Underground Transportation Project with Covered Top-Down Excavation Method

Underground diaphragm wall on both sides of the foundation pit,as a retaining structure of the foundation pit during construction,dams out water,prevents seepage and withstands the lateral pressure of the surrounding water and soil;and as a vertical support structure,bears vertical loads from structure floors of all layers constructed by top-down excavation method,and functions as a permanent anti-floating structure after the project is put into use.However,underground diaphragm wall of the secondary foundation pit inside the primary foundation pit cannot directly perform the function of vertical support because the top of the wall is at the bottom slab of the basement level one.For this reason,the paper analyzes and studies such a technical problem in combination with project examples,proposes effective measures such as temporary lattice columns,with a combination of permanent and temporary structures.These measures have helped to achieve the application of secondary foundation-pit retaining structure doubling as vertical support system in underground transportation project with covered top-down excavation method.