天兴洲长江大桥3号主塔墩钢吊箱围堰施工

Steel wall cofferdam construction of the No.3 main tower pier for Tianxingzhou Yangtze River Bridge

大型钢吊箱围堰在工厂整体制造成型、整体下水并浮运至墩位进行定位,是现代特大型桥梁深水基础施工的发展方向,可以提高钢吊箱围堰的制造精度,减少在墩位处现场拼装的水上作业量。整体制造浮运的钢吊箱围堰集钻孔桩施工平台、钢护筒插打导向结构及承台施工挡水围堰等多种功能于一身,可以大大缩短钻孔桩施工完毕后至开始承台施工的工序转换时间,缩短整个基础的施工时间。但围堰整体制造成型后结构庞大,对锚碇系统投设及围堰的精确定位标准等均有特殊的要求,并给围堰浮运拖带及定位等带来一系列的困难。以天兴洲长江大桥3号墩为例,介绍了大型钢吊箱围堰锚碇系统抛设及对拉预绞的施工方法,简述了双壁钢吊箱围堰浮运拖带方案的选择及围堰精确定位的方法。

Manufacturing the large - scale steel box wall cofferdam in the factory and locating it through floating - transport to the pier is the development direction of the deep water foundation construction of modem super bridge, which can increase the manufacturing accuracy of the steel box wall cofferdam and decrease the aquatic workload of assembling work on the spot of the pier. The whole manufactured and float - transported large - scale steel box wall cofferdam integrates various functions together, such as being a construction platform for drilling a hole for piles, the oriented structure of steel protecting tube in the putting homework, the cofferdam to block the water for construction of pile caps etc. It can consumedly shortens the conversation time between the end of drilling construction and the beginning of pile caps construction, and so shortens the whole foundation construction time. However, the structure scale of cofferdam is huge after it was wholly manufactured to the shape, it has special requirement for hurling anchorage block system and the standard of the accurate location for cofferdam etc., and brings a series of difficulties for cofferdam floating - transport drag and locating etc. Talking the No. 3 pier of Tianxingzhou Yangtze River Bridge as an example, this paper describes the cast- anchor and taking construction methods of anchorage block system for the large - scale steel wall cofferdam, and meanwhile it gives a brief introduction to the selection of floating - transport scheme and accurate location method for double steel wall cofferdam.