L形地铁车站超深大基坑分区开挖施工技术研究

Study on Construction Technology of Partition Excavation of Super Deep and Large Foundation Pit of L-shaped Subway Station

随着城市轨道交通的快速发展,地铁车站设计越来越趋向于多样化、复杂化,对基坑施工安全的要求越来越高。本文基于福州地铁5号线洪塘路站“L”形地铁换乘车站开挖工程,对L形基坑的封堵墙、支撑体系、降水方案和开挖顺序等进行设计,在确保周边环境和安全质量的前提下,攻克了富水砂层和临江36.2m超深基坑开挖的难题,形成了一套切实可行的施工方法。实际施工中,基坑周围5m范围内地表最大沉降为13.7mm;地连墙最大水平位移为22.6mm;支撑最大轴力为8027kN,均满足规范要求。本项目采用的施工方法可为类似的工程提供借鉴和参考。

With the rapid development of urban rail transit,the design forms of subway stations are diversified,and the environment is complicated.Especially the transfer station in urban traffic network,the requirements for foundation pit safety are higher and higher.Based on the excavation project of L-shaped subway transfer station of Hongtang Road Station of Fuzhou Metro Line 5,this paper designs the plugging wall,supporting system,reducing water scheme and excavation sequence of L-shaped foundation pit.On the premise of ensuring the surrounding environment and safety quality,it overcomes the problems of excavation of 36.2m deep foundation pit in water rich sand layer and riverside,and forms a set of feasible construction methods.In actual construction,the maximum ground settlement within 5m around the foundation pit is 13.7mm;The maximum horizontal displacement of diaphragm wall is 22.6 mm;The maximum axial force of the support is 8027kn.All of them meet the safety requirements of the specification.