摘要
新建安九铁路鳊鱼洲长江大桥南汊航道桥为主跨672 m交叉索钢箱混合梁斜拉桥,4号主墩承台施工采用双壁套箱围堰,设计最大水头差37.5 m,入土深度16.0 m。围堰尺寸为59.4 m×40.6 m×36.5 m,壁厚2.0 m,双壁舱混凝土高16 m;设置4层内支撑,采用“对撑+斜撑+圈梁”布置形式;采用锅底状封底,以减少围堰下沉深度;设置双壁+单壁可调组合底隔舱,以解决锅底状封底混凝土分次浇筑难题。围堰分节分块加工,在钻孔平台上组拼;底节围堰提升下放最大总重1852 t,利用钢护筒设置六吊点同步下放,下放过程中分次浇筑底隔舱刃脚、双壁舱刃脚和底隔舱剩余混凝土,下沉过程中采用分舱一次浇筑14 m高双壁舱混凝土;围堰采用空气吸泥配合射水下沉,终沉姿态满足要求;封底施工前进行单壁底隔舱下放并堵漏,抽水后封底混凝土止水效果良好。
The south branch navigation channel bridge of Bianyuzhou Changjiang River Bridge of the newly-built Anqing-Jiujiang Railway is a hybrid girder cable-stayed bridge with a main span of 672 m,featuring the cross-over stay cables at the midspan of main span.A double-walled box cofferdam was employed for the construction of the pile cap of pylon pier No.4.The cofferdam measures 59.4 m(length)by 40.6 m(width)by 36.5 m(height),with wall thickness of 2.0 m,inside which,four layers of inner supports that consist of cross bracings,diagonals and ring beams are installed.The space between the inner and outer layers of cofferdam walls is filled with 16 m-deep concrete.The cofferdam is designed to be rooted 16 m-deep in the river bed,and the maximum design drop-in head is 37.5 m.The cofferdam is sealed with concrete to have a pan-like bottom,to reduce the sinking depth.To facilitate the phased concreting of the pan-like bottom of the cofferdam,the cells at the base of the cofferdam are formed of double layers of walls and/or single layer of walls,which are quite flexible for adjustment.The components of the cofferdam were manufactured in a plant and assembled on the boring platform at the bridge site.The total hoisting and lowering weight of the base lift of the cofferdam reached 1852 t.Steel casings were driven to carry out six-point simultaneous lowering of the cofferdam.During the lowering process,the cutting edges of the base cells,the cutting edges stretching from the base of the double layers of walls,and the remaining concrete of the base cells were cast in phases.The space between the two layers of the cofferdam walls were divided into zones to ease the concreting,and in the first phase,14 m-high concrete was cast.The cofferdam was laid down by air suction and water injection,and the final position of the cofferdam met the requirements.Before the bottom sealing,the bottom cells with single layers of walls were lowered and blocked.When water inside the cofferdam was pumped out,the watertight effect of the bottom sealing
作者
张小川
汪芳进
ZHANG Xiao-chuan;WANG Fang-jin(China Railway Major Bridge Engineering Group Co. ,Ltd. ,Wuhan 430050,China)
出处
《世界桥梁》
北大核心
2022年第4期54-60,共7页
World Bridges
基金
中国中铁股份有限公司科技研发计划项目(2018-重点-08)。
关键词
斜拉桥
深水区
双壁套箱围堰
内支撑
可调组合底隔舱
锅底状封底
围堰设计
施工技术
cable-stayed bridge
deep water area
double-walled box cofferdam
inner support
adjustable bottom cell
pan-like bottom
cofferdam design
construction technique
