圆砾地层深基坑地下连续墙变形特性分析

地下连续墙作为深基坑围护结构已经用于多种地质情况，但圆砾地层中地下连续墙的变形特性研究甚少。本文依托南宁轨道交通2号线苏卢站基坑工程，采用Midas/GTS对圆砾地层深基坑开挖过程中标准段和盾构收发井段的地下连续墙的变形情况进行数值模拟分析，并结合现场监测结果对圆砾地层基坑变形情况进行理论分析。分析结果表明圆砾地层基坑采用地下连续墙作为围护结构效果良好，侧向位移值较小，整体变形呈“弓”字形。盾构收发井段由于基坑宽度大，地下连续墙侧向位移比标准段侧向位移大。因此在圆砾地层基坑开挖应控制基坑开挖宽度。模型计算结果与现场监测结果均表明侧向位移在0.7H处地下连续墙变形增长最快，因此圆砾地层深基坑开挖采用地下连续墙支护应在0.7H处设置横向支撑。

Analysis on deformation of diaphragm wall in round gravel strata

The diaphragm wall has been used in many geological conditions for the deep foundation pit enclosure structure. But study on deformation of diaphragm wall in round gravel strata is very few. The paper is based on the Nanning metro line 2 Su Lu foundation pit, and make numerical simulation analysis about the deformation of deep foundation pit standard section and shield-construction origination shaft section in round gravel strata by Midas/GTS. In other sides, the paper makes theoretical analysis by monitoring data. The result shows that the diaphragm wall enclosure structure works well, the lateral displacement is small and the whole deformation is similar to the bow. Because the shield-construction origination shaft section lateral displacement is larger than others which is wider than other parts. Therefore, the excavation width should be controlled. Finally, the model calculation results and monitoring results indicate that the deformation of diaphragm wall lateral displacement increases fastest at 0.7H. So the support should be set at 0.7H for the deep foundation pit in round gravel strata.