长沙南湖路湘江隧道岸上段基坑围护结构选型分析

为减少城市中复杂周边环境下明挖隧道基坑因围护结构选型不合理造成的施工事故和经济浪费,在总结前人研究成果的基础上,以长沙市南湖路湘江隧道岸上段明挖基坑为例,对周边建筑物和管线密集道路下的深基坑、相互交错且不同深度的隧道基坑及相互临近基坑的围护结构选型和设计进行了较为详细地介绍,并得出以下结论:1)对于城市道路下明挖基坑,特别是对于路下管网和建筑物密集地段,建议采用防止侧向变形较好的排桩(或连续墙)+内支撑的围护结构形式,可以有效地控制基坑变形;2)对于基坑深度差别不大,且具有一定距离的临近基坑,建议采用互不影响的共用对拉围护结构;3)对于复杂线路、深度差别较大,且基坑之间夹层较薄的交错基坑,建议采用共用基坑短桩及有限放坡的围护结构形式。

Case Study on Selection of Proper Retaining Structures for Different Types of Foundation Pits of Nanhulu Xiangjiang River Crossing Tunnel in Changsha,China

The on-shore section of Nanhulu Xiangjiang river crossing tunnel in Changsha has different types of foundation pits.Proper retaining structures should be selected for these different types of foundation pits so as to avoid accidents during construction and,on the other hand,to minimize the construction cost.In the paper,the selection and design of proper retaining structures for these different types of foundation pits are presented.Conclusions drawn are as follows：1 ） For open-cut foundation pits under urban roads,especially for foundation pits interfered with concentrated utility lines and buildings,retaining structures consisting of rowed piles （or diaphragm walls）and internal bracing should be adopted so as to control the lateral deformation;2）For neighboring foundation pits with almost the same depths and some distance in between,tying retaining structures should be adopted;3 ） For alignment-complex foundation pits with great depth difference and small spacing,retaining structures with common short piles and open cutting should be adopted.