深水裸岩大直径双壁钢围堰水上拼装与浮运就位工艺

Large-diameter and Double-wall Steel Cofferdam Water Assembling and Floating Transportation Under Deep-water and Uncovered-rock Conditions

杨梅洲特大桥主跨658m,为双塔双索面半漂浮体系斜拉桥,其23号主墩位于江中,采用双壁钢围堰作为挡水围护结构。钢围堰直径41. 4m,高23. 0m,总重1 180t,竖向分为5节。因岸阶坡度陡,不具备气囊下水条件,本工程提出利用平板驳搭设水上浮式拼装平台完成首节围堰拼装,采用500t起重船整体吊装入水后,通过水上悬浮拼装完成其余围堰安装。围堰浮运就位后,其安装偏差只有10cm,且具有工效高、成本低、安全系数高等特点。

Yangmeizhou Bridge is a cable-stayed bridge with double pylons,double cable-planes and semi-floating system,and its main span is 658 meters.The No.23 pier locates in Xiangjiang River,which leads to a double-wall steel cofferdam as a retaining structure.The cofferdam with diameter of 41.4 meters and height of 23.0 meters is divided into five parts and the total weight is 1180 tons.Considering the slope shoreside,the cofferdam can not launch through air bags.Thus,a new method is improved,which assembles several flat barges into a floating platform to finish the first part of the cofferdam.Then,the first part is craned into water by a craned ship with the maximum lifting weight of 500 tons.The rest of parts are assembled into a whole by using suspension assembly on water.Results show that the deviation between design and construction place is only 10 centimeters,and this method has obvious advantages such as high efficiency,low cost and adequate safety.