温州瓯江北口大桥缆梁相交区加劲梁吊装关键技术

Key Hoisting Techniques for Stiffening Girder Segments in Cable-Girder Intersection Area of Oujiang River North Estuary Bridge in Wenzhou

温州瓯江北口大桥为主跨2×800 m的三塔双层桥面钢桁梁悬索桥,受航空限高及通航净空影响,两主跨跨中约300 m范围存在缆梁相交区,主缆高度低于上层桥面。由于缆梁相交区梁段的梁面高于主缆,需将其提升到超过主缆所在高度后进行吊索连接,而常规的缆载吊机、浮吊及缆索吊机均难以满足施工需要,因此研发了分体式吊机。该吊机主要由4套临时索夹、4套液压提升油缸组件、2根托梁组成,采用免横梁结构设计,适应性强。针对分体式吊机直接提升钢桁梁时存在托梁安装难度大的问题,提出了“缆载吊机+分体式吊机”接力提升技术,即利用缆载吊机第1次提升钢桁梁后,通过接长吊索将钢桁梁临时悬挂于主缆;安装分体式吊机,由分体式吊机第2次将钢桁梁提升到位。该技术保证了缆梁相交区钢桁梁的顺利吊装,缆梁相交区梁段吊装平均工效可达1片/d。

The Oujiang River North Estuary Bridge in Wenzhou is a three-tower suspension bridge with two equal main spans of 800 m.The stiffening girder consisting of steel trusses accommodates two levels of decks.To address the required aeronautical and navigation clearances,the main cables sag lower beneath the top of the stiffening girder,to create a 300 m-long cable-girder interaction area in each main span.Due to that the main cables in the intersection areas are below the upper bridge deck,the steel trusses in these areas should be lifted higher to surpass the elevation of main cables to facilitate the hanger cables installation.In this case,the conventional construction of using either lifting gantries mounted on main cables,floating cranes or cable-way cranes was not available,and a split-type lifting crane was developed,which was composed of 4 sets of temporary cable clamps,4 hydraulic cylinders and two corbels,and was quite compatible due to the free-of-cross beam design.However,the corbels of the split-type lifting crane were hard to be cycled during the steel truss hoisting,as a result,the combined utilization of the main-cable-mounted lifting crane and the split-type lifting crane was proposed,namely,a steel truss segment was first lifted by the main-cable-mounted lifting crane,then the hanger cables were lengthened to allow the truss segment to be temporarily hung to the main cables.Afterwards,the split-type lifting crane was installed to lift the steel truss segment again and move it into position.The proposed hoisting techniques ensured the smooth installation of steel trusses in the cable-girder intersection areas,with an average installation speed of one steel truss segment per day.