邻近基坑开挖顺序对既有隧道的变形影响分析

The influence of construction sequence of adjacent foundation pit on the deformation of existing tunnel

以邻近轨道交通2号线鼓外区间隧道的宁波绿地中心项目基坑为案例,研究了基坑开挖对隧道水平位移、结构沉降、道床沉降的影响规律,并利用PLAXIS程序分析了基坑分坑、分块开挖顺序对隧道变形的影响.结果表明:对隧道变形影响较大的是基坑与隧道之间的距离以及基坑分坑面积的大小,两者呈线性关系;开挖面积越大,隧道变形越大;基坑与隧道之间的距离越大,变形越小.邻近轨道交通的基坑开挖时,应先远坑后近坑,先小坑后大坑,并采取跳挖的施工顺序.具体研究成果可以为类似工程提供借鉴.

Based on the foundation pit of Ningbo Greenland Center Project,which is adjacent to the Guwai interval tunnel of Rail Transit Line 2,the influence of foundation pit excavation on the horizontal displacement,structural settlement and roadbed settlement of the tunnel are studied in this paper.The PLAXIS program is employed to analyze the influence of the excavation sequence of foundation pit and block excavation on the deformation of the tunnel.The results show that the distance between the foundation pit and the tunnel and the area of the foundation pit are the most important factors affecting the deformation of the tunnel.There is a linear relationship between the two.The larger the excavation area is,the larger the tunnel deformation is.The greater the distance between the foundation pit and the tunnel,the smaller the deformation.Hence the construction sequence of the adjacent foundation pits should be arranged from far away to near,from small to big,and better adopting jump interval excavation.The results of this paper can be used as a reference for similar projects.