武汉汉江湾桥连续钢桁拱架设关键技术

Key Erection Techniques for Continuous Steel Truss Arch of Hanjiangwan Bridge in Wuhan

武汉汉江湾桥主桥为(132+408+132)m三跨连续钢桁系杆拱桥,边跨为变高度钢桁梁,中跨为钢桁系杆拱,横向设2片主桁,主桁采用变高度N形桁式,采用Q370qD、Q500qE、Q690qE钢。该桥钢桁拱采用先边跨后中跨,中跨“先拱后梁”、“拱上爬坡吊机+吊索塔架”方案架设。在该桥施工中,汉口侧边跨架设时,采用扩大基础+千斤顶补偿支架和横跨龙门吊机方案,克服了地面施工条件的限制;中跨钢桁拱架设时,采用边跨锚索避开平面曲线段、分3次边跨压重并设扣锚索、增设尾部平衡梁、边支点与边墩承台锚拉等措施,解决了悬臂架设抗倾覆的难题;采取边支点预降低、整体纵移一侧钢桁拱和设置合龙口顶拉装置实现中跨钢桁拱快速、精确合龙;采用了一系列加热、保温、防风和焊接工艺措施,解决了Q500qE、Q690qE高性能桥梁钢焊接控制难题;研制了吊重100 t、爬坡角30°、覆盖2个节间作业的拱上爬坡吊机,实现了钢桁拱安全、快速架设。

The main bridge of Hanjiangwan Bridge in Wuhan is a half-through tied arch bridge with three continuous spans of 132,408 and 132 m.The steel truss arch consists of two variable-depth N-shape lateral trusses made of Q370qD,Q500qE and Q690qE steel.The side spans take the form of variable-depth steel truss girders,the central span is a steel truss tied arch,and the construction of the side spans were carried out ahead of the central span.In the central span,the erection of the arch was conducted ahead of the girder,by the combined utilization of the arch-mounted climbing crane and a cable-stayed cantilever assembly supporting system.The Hankou-side arch seat was supported on spread foundation,the steel trusses in the side span were erected by using the jack-complimented scaffolds and gantry crane,which overcame the limitations of construction space.The steel trusses in the central span were erected by a cable-stayed cantilever assembly system.To address the overturning of arch,anchor cables were added to the side spans to avoid the curved section,the side spans were counterweighted by three times and correspondinglly,the fastening stays were installed and tensioned by three times.balance beams were installed at the ends of the arch,and the side supports and pile caps of the side piers were stabilized by anchor cables.To ensure the rapid and accurate closure of the central span arch,the elevation of the side supports were pre-lowered,the entire half steel truss arch on each side was longitudinally moved,and jacking and pushing devices were set at the closure gap.A series of measures were taken to facilitate the welding control of the Q500qE and Q690qE high-performance steel,such as heating,thermal insulation,wind resistance and welding techniques.The 100 t-capacity arch-mounted climbing crane with a climbing angle of 30°was developed,which could assembly the elements of two arch panels at a time,ensuring the safe and rapid erection of the steel truss arch.