新建福厦高铁乌龙江特大桥施工关键技术

Key Construction Techniques for Wulongjiang River Bridge of Newly-Built Fuzhou-Xiamen High-Speed Railway

新建福厦高铁乌龙江特大桥为主跨432 m的四线铁路高低塔双索面混合梁斜拉桥,主梁为非对称布置的混合梁。桥位处于乌龙江瓶颈处,水文地质地形条件复杂,且跨越、临近既有道路和桥梁。针对河床覆盖层浅或无覆盖层的情况,主墩基础采用基岩面管桩稳定锚固技术和整体框架式栈桥及平台施工;钻孔桩采用大冲击气举反循环钻机成孔施工,提高了钻进效率和成孔质量;为解决坚硬岩层及岩层倾斜、硬度不均等成孔难题,采用气动潜孔钻机进行预处理;主墩承台采用少支撑拆装式双壁钢吊箱围堰施工,方便水中围堰拆除和倒用。桥塔采用液压爬模法施工,上横梁顶、底面均为弧面,采用整体大跨拱形托架施工。边跨及次边跨混凝土梁采用支架现浇,福州侧次边跨钢梁采用组拼式大型水上浮吊分段吊装并利用支架滑道拖拉滑移就位,中跨钢梁采用大吨位桥面吊机单悬臂分段安装。

The Wulongjiang River Bridge of newly-built Fuzhou-Xiamen High-speed Railway is a cable-stayed bridge with a main span of 432 m.The bridge accommodates four railway tracks and features its two pylons of different heights and the asymmetrical steel-concrete hybrid superstructure.The bridge site is located at the bottleneck of the Wulongjiang River,where the complex hydrological and geological conditions as well as the nearby existing roads and bridges impose great challenges on the construction.At the pier sites with shallow overburden or without overburden,a technique to stabilize and anchor pipe piles in the bedrock is used in the foundation construction,additionally,an integral framed trestle and platform were erected to facilitate the construction.The boreholes were made by a large-impact reverse circulation drilling system,with good drilling efficiency and borehole formation quality.Due to the existence of hard and inclined rock layers as well as the uneven hardness of rock layers,the boreholes were pretreated using the pneumatic DTH drilling rigs.The pile caps supporting the main piers were cast in place with the detachable double-wall steel boxed cofferdam,and the cofferdam could be cyclically used.The pylons were constructed by the hydraulic climbing formwork,the top and bottom of the upper cross beams of the pylons are curved,to fit up,the integral large-span arch-shaped corbels were used.The concrete girders in the side and secondary side spans were cast in situ on scaffolds.The steel girders in the Fuzhou-shore secondary side spans were assembled segment by segment using the floating crane with great lifting capacity,and then towed and slid into position along the tracks on scaffolds.The steel girders in the central span were assembled segment by segment using large-tonnage deck crane in a one-way cantilever manner.