杭绍台铁路椒江特大桥主桥钢桁梁架设关键技术

Key Steel Trusses Erection Techniques for Main Bridge of Jiaojiang River Bridge of Hangzhou-Shaoxing-Taizhou Railway

杭绍台铁路椒江特大桥主桥采用(84+156+480+156+84)m双塔双索面四线高速铁路钢桁梁斜拉桥,纵向为半飘浮体系。钢桁梁采用2片主桁、N形桁式;桥面采用正交异性钢桥面板,与主桁下弦杆结合。由于下游既有椒江大桥通航净高的限制,且主桥台州侧边墩及辅助墩位于陆地上,经研究采用“边跨顶推+主跨悬臂拼装”的总体施工方案,先采用“无浮吊”法完成钢导梁及架梁吊机拼装,再利用架梁吊机完成钢桁梁整节段吊装。边跨钢桁梁施工时,在桥塔墩和辅助墩之间设置临时支墩,在边墩、辅助墩、桥塔墩设置墩旁托架,利用顶推系统将边跨钢桁梁分批次顶推到设计位置;主跨钢桁梁采用架梁吊机悬臂拼装,跨中合龙段采用2台架梁吊机共同起吊,结合温度变化及施加纵向荷载等调整措施实现精确合龙。

The main bridge of Jiaojiang River Bridge of Hangzhou-Shaoxing-Taizhou Railway is a steel truss girder cable-stayed bridge accommodating four high-speed railway tracks.The bridge,which is of a semi-floating system,has two pylons that create a main span of 480 m,two side spans of 156 m and two end spans of 84 m,and the stay cables are arranged in double cable planes.The superstructure consists of two lateral N-shaped trusses and the orthotropic steel deck plates that are connected with the lower chords of the trusses.Limited by the navigation clearance of the downstream existing Jiaojiang River Bridge(a continuous girder bridge)and the span arrangement of the cable-stayed bridge(the side pier and auxiliary pier on the Taizhou side are land piers),the steel trusses in the side spans were incrementally launched into position,while the steel trusses in the main span were cantilver-assembled.During construction,the steel launching nose and the launching gantries were first assembled with no assistance of a floating crane,afterwards the steel truss segments were erected by launching gantries.To erect the steel trusses in the side spans,temporary piers were added between the pylon piers and auxiliary piers,and brackets were installed on top of all the side,auxiliary and pylon piers,the steel trusses were labeled into different groups and incrementally launched into the design position in sequence.The steel trusses in the main span were cantilever-assembled by launching gantries.The midspan closure segment was hoisted by two launching gantries,and the closure reached the required precision requirements by taking advantages of the temperature variation and applying longitudinal loads.