软土地区深基坑施工对邻近地铁隧道的影响

Influence of deep foundation pit construction on adjacent subway tunnels in soft soil

为改善软土地区深基坑施工引起邻近地铁隧道变形的问题,结合现场监测数据,利用有限元软件PLAXIS3D建立深基坑-地铁隧道数值模型分析深基坑施工引起邻近地铁隧道的变形。研究了基坑与隧道间水平距离和地连墙嵌固深度的影响。研究结果表明,在一定范围内,增加基坑与隧道间的水平距离和地连墙嵌固深度可以有效控制隧道结构和基坑的变形,确定本工程基坑与地铁隧道的安全水平距离为8 m和合理地连墙嵌固深度为7 m;本工程的支护结构和施工方案能有效控制隧道结构变形在规范限制要求,但地铁荷载对基坑开挖引起邻近隧道竖向位移的影响不可忽视。

In order to improve the problem of deformation of adjacent subway tunnel caused by deep foundation pit construction in soft soil area,a deep foundation pit and subway tunnel numerical model is established.Using the finite element software PLAXIS 3 D,the deformation of adjacent subway tunnel caused by deep foundation pit construction is analyzed and compared with the field monitoring data.The effects of horizontal distance between the foundation pit and the tunnel,and the embedded depth of diaphragm wall are studied.The results show that the deformation of tunnel structure and foundation pit can be effectively controlled by increasing the horizontal distance between the foundation pit and the tunnel and the embedded depth of the diaphragm wall within a certain range.It is founded that the safe horizontal distance between the foundation pit and the subway tunnel is about 8 m and the reasonable embedded depth of diaphragm wall is about 7 m.The supporting structure and construction scheme of this project can control effectively the deformation of tunnel structure in the standard limit requirements,but the influence of subway load on the vertical displacement of adjacent tunnels caused by foundation pit excavation can not be ignored.