临港长江公铁两用大桥3号墩组合围堰施工技术  

Construction Techniques for Composite Cofferdam of Pier No.3 of Lingang Changjiang River Rail-cum-Road Bridge

作　　者：张程然 祝兵[1] 张振[1] 赵雨佳 ZHANG Cheng-ran;ZHU Bing;ZHANG Zhen;ZHAO Yu-jia(Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]西南交通大学,四川成都610031

出　　处：《桥梁建设》2020年第4期101-106,共6页Bridge Construction

基　　金：四川省应用基础研究重大前沿项目(2017JY0003);高铁联合基金重点支持项目(U1834207)。

摘　　要：川南城际铁路临港长江公铁两用大桥主桥为主跨522 m的公路与高铁共建平层斜拉桥,3号主墩采用66根φ2.5 m钻孔桩基础,承台为矩形,尺寸67.0 m×35.75 m×7.0 m。大桥3号主墩基础位于长江江心,地质条件复杂,岩面起伏变化差异大,采用哑铃形钢-混组合结构围堰(由下部混凝土咬合桩、中部冠梁、上部双壁钢围堰组成)方案施工。主墩基础施工期间,咬合桩采用旋挖钻机成孔,将咬合桩打入底部基层以下4 m,同时在加工厂内进行双壁钢围堰水平分块、竖向分节制作;咬合桩施工后进行冠梁施工;最后通过预埋板和剪力钢筋将下部咬合桩和上部双壁钢围堰连接成整体,形成组合围堰。为保证施工期间的组合围堰安全,对其应力、变形进行了现场监测。结果表明:组合围堰结构状态表现良好,满足现场施工安全要求。The main bridge of Lingang Changjiang River Rail-cum-Road Bridge on the Inter-city Railway of Southern Sichuan is a cable-stayed bridge with a main span of 522 m,accommodating highway and high-speed railway on the same deck.The main pier No.3 rests on a rectangular pile cap measuring 67.0 m×35.75 m×7.0 m,beneath which is the foundation containing 66,φ2.5 m bored piles,located in center of the water course of Changjiang River.Restricted by the complicated geological condition at the bridge site and the wild steeps of bedrock surface,the pile cap was constructed with the aid of the dumbbell-shaped steel-concrete composite cofferdam that consists of the lower concrete interlocking piles,intermediate capping beams and upper double-walled steel cofferdam.In the construction period of the main pier foundation,the holes for the interlocking piles were drilled by rotary drilling rigs,and the piles were driven to 4 m below the bedrock.At the same time,the double-walled steel cofferdam was manufactured in the factory,block by block horizontally and lift by lift vertically.The construction of the capping beams was carried out after the completion of interlocking pile construction.The lower interlocking piles and upper double-walled steel cofferdam were connected into an integral composite cofferdam via the embedded plates and shear reinforcement.The on-site stress and deformation monitoring was conducted to ensure the safety of the composite cofferdam in the construction process.The results show that the structural condition of the composite cofferdam was good and met the safety requirements of field construction.

关 键 词：公路铁路两用桥 斜拉桥 钢-混组合围堰 咬合桩 双壁钢围堰 组合式结构 施工技术 施工监测 

分 类 号：U448.27[建筑科学—桥梁与隧道工程] U445.4[交通运输工程—道路与铁道工程]