基坑施工对紧邻地铁出入口影响分析

Influence analysis of foundation pit construction on the adjacent subway entrance

基坑工程及结构施工对邻近地铁结构产生扰动影响,依托合肥某邻近地铁的商业中心基坑工程,建立了基坑与地铁出入口结构的三维有限元模型,分析了基坑开挖、地下室施工及上部建筑物施工3个主要施工阶段下出入口结构位移情况。研究结果表明:基坑及结构施工对敞开段远大于暗挖段;敞开段以向基坑方向的水平位移为主,且呈层状分布特征;基坑开挖引起的出入口结构位移超过总位移的2/3,是位移控制的关键阶段;紧贴基坑的地铁最大位移未超过控制值,结构处于安全状态,但已超过预警值,需通过信息化监测实时反馈施工。

The construction of foundation pit has a disturbing effect on the adjacent subway structure.Based on one foundation pit project adjacent to metro structure in Hefei,a three-dimensional finite element numerical model,which includes foundation pit and subway entrance,has been built.The entrance displacement during the three main construction stages of foundation pit excavation,basement construction and upper building construction are calculated and analysed.Some conclusions have been drawn.Firstly,the impact of pit excavation and structural construction on the open section is much greater than that on the excavation section.Secondly,the displacement of open section is mainly horizontal displacement towards the excavation direction.And the displacement has a layered distribution characteristic.Thirdly,the entrance displacement caused by foundation pit excavation exceeds 2/3 of the total displacement.Thus,pit excavation is a key stage of displacement control.Finally,the maximum displacement of the subway close to the foundation pit is smaller than the control value,and the structure is in a safe state.But the maximum displacement has exceeded the warning value.Therefore,it necessary to carry on-site monitoring for information construction.