武汉青山长江公路大桥主桥施工方案

Construction Schemes for Main Bridge of Qingshan Changjiang River Highway Bridge in Wuhan

武汉青山长江公路大桥主桥为主跨938 m的双塔双索面全飘浮体系斜拉桥,主墩采用钻孔灌注桩基础、哑铃形承台,桥塔采用A形混凝土结构,主跨主梁采用整体式钢箱梁、边跨主梁采用钢-混凝土结合梁。针对该桥结构特点及水文、地质条件,南主墩钻孔桩采用“吹填筑岛+旋挖钻机”方案施工、承台采用锁口钢管桩围堰方案施工;北主墩基础采用双壁钢套箱围堰平台一体法施工;塔柱采用液压爬模分节施工,在两塔肢间设13道临时横撑,并采用新型超高压地泵和特制超高压泵管一次将混凝土泵送到位;边跨结合梁采用先顶推架设钢槽梁,再安装预制混凝土桥面板,最后浇筑湿接缝的方案施工;主跨钢梁采用500 t架梁吊机悬臂架设方案施工;主跨合龙段采用顶推辅助合龙方案施工。

The main bridge of Qingshan Changjiang River Highway Bridge in Wuhan is a two-pylon cable-stayed bridge of a full-floating system.The bridge has a main span of 938 m,with stay cables fanned out in double cable planes.The main piers stand on dumbbell-shaped pile caps that are mounted on bored pile foundations.The pylons are A-shaped concrete structures.The main span consists of the integral steel box girders,and the side spans comprise steel-concrete composite girders.Given the structural characteristics of the bridge as well as the hydrological and geological conditions,the bored piles for the south main pier were constructed by reclaiming an island from the river and using rotary drilling rigs,and the pile cap was cast with the assistance of cofferdam made up of interlocked steel tubular piles.For the foundation of the north main pier,the double-walled steel cofferdam was employed to aid the construction of bored piles,which also functioned as the formwork for the pile cap casting.Pylon columns were constructed using hydraulic climbing formwork,and during the construction process of which,a number of 13 temporary lateral bra-cings were installed between the two columns of each pylon.A new type of ultra-high pressure pumps together with the ultra-high pressure tubing deployed was able to pump the concrete to the specified locations,with just one-time pumping.For the side spans,the steel trough girders were first incrementally launched,then,the precast concrete slabs were installed,and the stitches were filled with concrete.The steel girders in the main span were hoisted and erected by the 500 t-capacity girder erection crane,and the closure section in the central span was erected and tuned into position by pushing.