软土地区邻近既有建筑半盖挖深基坑变形特征

Deformation Characteristics of Semi-covered Deep Foundation Pit Adjacent to Existing Buildings in Soft Soil Area

为研究邻近既有建筑的半盖挖深基坑变形特性及环境效应,以南京地铁5号线山西路站的软土地区半盖挖深基坑工程为例,将基础形式、支护形式等作为变量,设计了8种数值模拟工况进行分析。研究结果表明:既有建筑使基坑一侧产生偏压导致地连墙侧移曲线整体向基坑内移动,盖板与地连墙的刚性连接使其顶部发生翘曲,地连墙嵌入岩层限制了底部侧移量,改变了地连墙下端侧移曲线形状;坑外地面沉降曲线受建筑及基础形式影响较大,受盖板和地连墙深度影响较小;基坑开挖主要影响墙后2倍深度以内三角形区域的土体沉降,既有建筑地下室和桩基础能有效控制建筑靠近基坑一侧土体的沉降大小及范围。

To study the deformation characteristics and environmental impact of semi-covered deep foundation pit adjacent to existing buildings,taking the foundation pit engineering in soft soil area of Nanjing Metro Line 5 Shanxi Road Station as example,and adopting foundation form and support form as variables,8 groups of numerical simulation working conditions are designed and analysed.Research results show that existing buildings cause eccentric loads on one side of the foundation pit,leading to the overall movement of diaphragm wall lateral curve into the pit.The rigid connection between cover plate and diaphragm wall makes the wall top warp,and the embedment of diaphragm walls into rock stratum limits the lateral movement of the bottom and changes the shape of diaphragm wall bottom lateral curve.The land subsidence curve outside the pit is greatly influenced by the form of building and its foundation,and has little relation with cover plate and depth of diaphragm walls.The foundation pit excavation mainly affects soil settlement in the triangular area within 2 times of depth behind the wall,and the existing building basement and pile foundation can effectively control the soil settlement size and scope on the side of the building close to foundation pit.