张靖皋长江大桥南航道桥北锚碇地下连续墙槽壁稳定控制技术  

Slurry Trench Stability Control Techniques for North Anchorage Diaphragm Wall Foundation of South Navigation Channel Bridge of Zhangjiagang-Jingjiang-Rugao Changjiang River Bridge

作　　者：关健 王瑞 李奔琦 GUAN Jian;WANG Rui;LI Benqi(Jiangsu Traffic Engineering Construction Bureau,Nanjing 210004,China;The Second Engineering Co.,Ltd.,China Railway Major Bridge Engineering Group,Nanjing 210015,China)

机构地区：[1]江苏省交通工程建设局,江苏南京210004 [2]中铁大桥局集团第二工程有限公司,江苏南京210015

出　　处：《世界桥梁》2024年第5期37-42,共6页World Bridges

基　　金：国家重点研发计划项目(2022YFB3706700)。

摘　　要：张靖皋长江大桥南航道桥为主跨2300 m的双塔双跨吊钢箱梁悬索桥,北锚碇位于长江下游民主沙岛上,地下水水位高,地层以粉砂层和粉质黏土层为主,粉质黏土层力学性能及稳定性差。北锚碇为重力式锚碇,采用双层回字形支护转结构复合地下连续墙基础。地下连续墙共划分为214个槽段,最大深度69.5 m,槽段类型有一字形、L形、T形和十字形。根据地下连续墙结构特点和地质、水文情况,采用液压铣槽机成槽,施工前利用有限元软件模拟分析,确定控制槽壁稳定的关键指标。施工中通过采用三轴水泥搅拌桩加固上部槽壁、分阶段控制泥浆关键指标、填高场地并设置降水井控制槽内泥浆和周围地下水之间的水头差、双重控制成槽垂直度和钢箱(钢筋笼)吊装垂直度,以及优化槽段施工顺序等措施,降低了槽壁失稳的风险,保障了地下连续墙施工质量。The south navigation channel bridge of Zhangjiagang-Jingjiang-Rugao Changjiang River Bridge is a suspension bridge featuring two suspended spans,where the length of the longer suspended span reaches 2300 m.The bridge has two towers,and the superstructure consists of steel box girders.Considering the north gravity anchorage is located at the Minzhusha sandbank downstream of the Changjiang River,a composite diaphragm wall foundation is selected to better address the high groundwater level,silty sand and silty clay dominated ground,and the weak bearing capacity and stability of the silty clay layers.The foundation constitutes an exterior and an interior rectangular layers of diaphragm walls,and the gap between the two layers is filled with concrete to create a composite structure to improve the entirety of the foundation and ensure the safe excavation during the construction.The diaphragm walls,on the one hand,serve as a shoring system during the foundation pit excavation and on the other hand,become the permanent load bearing components after the completion of the bridge.To facilitate the construction,the diaphragm wall foundation was divided into 214 trenches,with a maximum depth of 69.5 m,and the trenches were categorized in accordance with their sections,including the I-section,L-section,T-section and crisscross-section trenches.Considering the characteristics of the diaphragm walls as well as the hydrogeological conditions,hydraulic milling machines were deployed for trench formation.Numerical modelling was performed ahead of the construction to determine the key indicators of the slurry trench stability.During the construction,the upper slurry trench was strengthened by triaxial cement-soil mixed piles,and the key indicators of the slurry were controlled in stages,the ground was filled higher and dewatering wells were deployed to control the waterhead between the slurry inside the trench and the subsurface water,The perpendicularity of the completed trenches and the verticality of the concrete-filled steel box

关 键 词：悬索桥 锚碇 支护转结构 地下连续墙 槽壁稳定 施工控制 

分 类 号：U448.25[建筑科学—桥梁与隧道工程] U443.24[交通运输工程—道路与铁道工程]