石首长江公路大桥柔性缓移合龙关键技术  

Key Techniques of Flexible and Slow-Moving Closure of Shishou Changjiang River Highway Bridge

作　　者：张斌 彭文渊 ZHANG Bin;PENG Wen-yuan(CCCC Second Highway Engineering Co.,Ltd.,Wuhan 430056,China)

机构地区：[1]中交二公局第一工程有限公司,湖北武汉430056

出　　处：《世界桥梁》2021年第3期28-33,共6页World Bridges

基　　金：湖南省教育厅资助项目(18A202);湖南省科技厅资助项目(2019JJ40301)。

摘　　要：石首长江公路大桥为主跨820 m的双塔单侧混合梁斜拉桥,南边跨和中跨采用钢箱梁,北边跨采用混凝土箱梁,钢箱梁塔区梁段利用浮吊直接吊装于塔区支架上安装,其余梁段利用桥面吊机起吊安装,主桥于中跨合龙。针对主桥中跨悬臂长、合龙气温较高且操控时间短等难点,为保证合龙后的成桥状态与设计吻合,在几何控制法基础上,提出了一种柔性缓移合龙技术。柔性缓移装置由南塔梁间纵向限位拉索、张拉千斤顶和撑脚组成,通过合龙时纵向缓移行程和纵向缓移拉力,确定纵向限位拉索采用1860 MPa高强镀锌钢丝,索体规格为211∅7 mm,主跨、边跨侧各布置2台750 t千斤顶。合龙时,在钢箱梁存梁高支架上搭设操作平台,利用千斤顶张拉纵向限位拉索,带动钢箱梁整体移动,进行合龙口宽度调节;合龙段配切好后,起吊安装合龙段,实现了主桥钢箱梁中跨高精度合龙。The Shishou Changjiang River Highway Bridge is a two-pylon cable-stayed bridge with a main span of 820 m,featuring its single-side hybrid girder,specifically steel box girders in south side span and central span and concrete box girders in north side span.The steel box girder segments in the pylon region were hoisted onto the scaffolds in the pylon region using floating crane,and the remaining segments were erected using deck crane.The closure gap of the main bridge was reserved in the central span,and the closure faced challenges of long cantilevers,high temperature and short control time.To ensure that the geometry of the completed bridge could be in consistent with the design geometry after closure,a flexible and slow-moving closure technique was proposed,based on the conventional geometry control method.The flexible and slow-moving system consists of the longitudinal restraint cables,jacks for tensioning and outriggers.As per the longitudinal slow-moving track and pulling force during closure,it was determined that the longitudinal restraint cable be made of high-strength galvanized steel wires with tensile strength of 1860 MPa.Each restraint cable consists of 211 steel wires of 7 mm diameter.Two 750 t-capacity jacks were set at the sides of both main and side spans.During closure,an operation platform was installed on the steel box girder storage scaffolds,the jacks were used to tension the longitudinal restraint cables so as to move the whole steel box girder,and consequently to adjust the width of the closure gap.After matching and cutting,the closure segment was hoisted and lowered into position.The closure of the steel box girders in the central span of the main bridge was performed with high accuracy.

关 键 词：斜拉桥 钢箱梁 柔性缓移装置 缓移行程 缓移拉力 合龙段配切 合龙 施工技术 

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]