摘要：【中文】本发明提供了一种水上拼装首节钢围堰施工工艺，包括以下步骤：(1)在围堰基槽的下游搭设水上拼装平台，水上拼装平台由两个小平台组成，在两个小平台之间搭设两个钢平台用于连通该两个小平台；(2)在两个小平台上各自完成1/3弧段钢围堰的安装；(3)剩余的一个1/6弧段钢围堰吊装在两个1/3弧段钢围堰的一端，并在悬臂情况下完成两个1/3弧段钢围堰和一个1/6弧段钢围堰的拼装，焊接时两者之间用限位板约束并临时焊接固定；(4)剩余的另一个1/6弧段钢围堰吊装在两个1/3弧段钢围堰的另一端，并在悬臂情况下完成两个1/3弧段钢围堰和一个1/6弧段钢围堰的拼装，焊接时两者之间用限位板约束并临时焊接固定。本发明的围堰基槽的爆破开挖与首节钢围堰的水上拼装同步进行，节约了近2个月工期。 【EN】The invention provides a construction process for assembling a first section of steel cofferdam on water, which comprises the following steps: (1) an overwater assembling platform is erected at the downstream of the cofferdam foundation trench, the overwater assembling platform consists of two small platforms, and two steel platforms are erected between the two small platforms and are used for communicating the two small platforms; (2) the installation of 1/3 arc-section steel cofferdams is respectively completed on the two small platforms; (3) the rest 1/6 arc-section steel cofferdams are hoisted at one end of the two 1/3 arc-section steel cofferdams, the assembly of the two 1/3 arc-section steel cofferdams and the 1/6 arc-section steel cofferdams is completed under the condition of a cantilever, and the two cofferdams are restrained by a limiting plate and are temporarily welded and fixed during welding; (4) and the other residual 1/6 arc-section steel cofferdams are hung at the other ends of the two 1/3 arc-section steel cofferdams, the assembly of the two 1/3 arc-section steel cofferdams and one 1/6 arc-section steel cofferdam is completed under the condition of a cantilever, and the two cofferdams are restrained by a limiting plate and are temporarily welded and fixed during welding. The blasting excavation of the cofferdam foundation trench and the water assembly of the first section of steel cofferdam are carried out synchronously, so that the construction period is saved by about 2 months.