江津白沙长江大桥浅覆盖层桥塔承台无封底组合围堰设计  

Design of Base-Sealing-Free Cofferdam for Pile Cap in Shallow Overburden for Pylon of Baisha Changjiang River Bridge in Jiangjin

作　　者：刘晓敏 强伟亮 于海力 石怡安 谢朋林 LIU Xiao-min;QIANG Wei-liang;YU Hai-li;SHI Yi-an;XIE Peng-lin(Tech Center, China Construction Sixth Engineering Bureau Co. , Ltd. , Tianjin 300451, China;China State Construction Bridge Co. , Ltd. , Tianjin 300451, China)

机构地区：[1]中国建筑第六工程局技术中心,天津300451 [2]中建桥梁有限公司,天津300451

出　　处：《世界桥梁》2021年第5期9-14,共6页World Bridges

基　　金：中建股份科技研发课题(CSCEC-2020-Z-21)。

摘　　要：江津白沙长江大桥为两跨悬吊地锚式悬索桥,桥梁全长1300 m。西桥塔紧邻成渝铁路既有线,边坡陡峭且位于浅覆盖层,其承台结构为2个独立的正方形结构,尺寸为17.0 m×17.0 m×5.0 m。综合考虑桥址所在长江水域的地质、水文等,设计了适用于浅覆盖层的无封底钢-混组合围堰。围堰结构平面布置形式为“E”形结构,分为迎水面壁体、侧壁、中隔壁及内支撑系统,迎水面壁体长度为72.0 m,壁体平均高度为16.5 m;侧壁长度为25.5 m,壁体高度为5~17 m,随边坡面变化。围堰竖向分为2层,下部结构为混凝土挡墙基础,采用桩基与冠梁的组合形式,上部结构采用双壁钢围堰,壁体厚度为1.5 m。采用花管注浆技术对浅覆盖层区域土体进行加固,可节省混凝土用量且便于后期钢围堰回收。通过有限元法对壁体、内支撑及基础的强度、变形进行计算,并对壁体进行屈曲分析,结果表明无封底钢-混组合围堰各项技术指标均满足要求。The Baisha Changjiang River Bridge in Jiangjin is a two-span earth-anchored suspension bridge,containing a 1300 m-long river-crossing part.The west pylon stands next to the existing Chengdu-Chongqing Railway.Challenged by the steep slopes and shallow overburden,the pile cap is designed as two independent square structures,each with dimension of 17.0 m by 17.0 m by 5.0 m.To accommodate the geological and hydrological conditions of the bridge site,a kind of base-sealing-free cofferdam that can be constructed in shallow overburden is proposed.The cofferdam is an E-shaped structure in plan,consisting of upstream walls,side walls,bulkheads and inner bracings.The upstream walls measure 72 m long and have an average depth of 16.5 m.The sidewalls are 25.5 m long and 5 m to 17 m deep,varying along with the slope.The cofferdam is composed of two parts vertically,the lower part is the concrete retaining wall foundation that comprises piles and cap beams,while the upper part is a double-wall steel cofferdam with wall thickness of 1.5 m.The soil in the shallow overburden zone is strengthened by grouting via perforated pipes,and the method can save the concrete used and facilitate the recycling of the cofferdam.The finite element method was used to calculate the strength and deformation of the cofferdam walls,inner bracings and the foundation,and the buckling of the cofferdam walls was analyzed.The results show that all the technical indexes of the base-sealing-free steel-concrete composite cofferdam can meet the requirements.

关 键 词：悬索桥 承台 浅覆盖层 无封底钢-混组合围堰 混凝土挡墙 双壁钢围堰 花管注浆 结构设计 

分 类 号：U445.556[建筑科学—桥梁与隧道工程] U442.5[交通运输工程—道路与铁道工程]