基坑围护结构技术方案经济性分析

On Economy Analysis of Technique Plan for Foundation Pit Envelop Structure

轨道交通、越江隧道等地下空间工程的基坑具有深、大、安全等级高等特点。基坑围护结构基本采用地下连续墙、灌注桩排桩围护墙、型钢水泥土搅拌墙、水泥重力式围护墙等。各类围护方案受周边环境、地质条件影响,适用于一定的基坑深度范围。当2种围护结构均能适用时,如何在经济性方面决定选择的方案,须作围护结构经济性分析。主要分析了各类围护结构的经济指标,从水泥土搅拌桩直径、内插H型钢布置形式、施工周期、钢筋含量、基坑开挖深度(插入比)等分析了影响围护结构造价的主要因素。最后,对合理确定围护方案提示了应关注的问题。

Underground space engineering foundation pit such as rail transit,crossriver tunnel is of characters such as deep,large and high safety level.Envelop structure of foundation pit will adopt several structures as follows: diaphragm wall,bored concrete pile piling enclosure wall,steel cement-soil mixing wall and cement gravity enclosure wall,etc.Different enclosure plan may suit different foundation pit's depth scale influenced by the surroundings and geological conditions.When 2 kinds of enclosure structures are suitable,the economy analysis must be made to choose the more suitable plan.Economic indicators of different enclosure structures are introduced mainly,and the main factors influencing the price of enclosure structure are analyzed including diameter of cement soil mixing pile,interpolating H-steel layout,construction period,reinforcing steel bar content and depth of foundation pit excavation(insertion ratio),etc.Finally,some attentions are provided for deciding reasonable enclosure plan.