武汉青山长江公路大桥主桥中跨合龙施工技术

Mid-Span Closure Techniques for Main Bridge of Wuhan Qingshan Changjiang River Highway Bridge

武汉青山长江公路大桥主桥为主跨938 m的双塔双索面斜拉桥,主梁采用混合梁结构。其中,边跨主梁采用钢箱结合梁;中跨主梁采用整体式钢箱梁,钢梁宽48 m、高4.5 m。中跨钢箱梁共59个节段,其中合龙段长11.4 m,重约305 t,节段间采用栓焊组合连接。大桥先施工边跨钢箱结合梁,再施工中跨钢箱梁,最后采用顶推辅助合龙方案施工中跨合龙段。合龙段在工厂精确匹配制造后运至桥位处,将合龙口一侧主梁往边跨侧顶推15 cm,利用2台500 t桥面吊机抬吊合龙段嵌入合龙口;完成合龙段与一侧钢梁的栓焊连接后,再将钢梁往跨中顶推复位;利用预设的三向偏差调整装置调整合龙口偏差并锁定,先栓后焊完成合龙,解除临时锁定,实现大桥体系转换。

The main bridge of Wuhan Qingshan Changjiang River Highway Bridge is a two-pylon cable-stayed bridge with a main span of 938 m. The stay cables are fanned out in double cable planes. The main girder adopts the hybrid girder structure, with steel box composite girder in the side spans and integral steel box girder in the central span. The steel girder is 48 m wide and 4.5 deep. The steel box girder in the central span consists of 59 sections, with a closure section of 11.4 m in length and weighing about 305 t. The girder sections are connected by the combined use of bolting and welding. During the construction, the steel box composite girder in the side spans was installed ahead of the steel box girder in the central span, and the final step was to erect the closure section into position by the pushing-aided closure scheme. The closure section was accurately matched and manufactured in the workshop and delivered to the bridge site. The main girder on the one side of the closure gap was pushed 15 cm towards the side span, and then two girder erection cranes with a capacity of 500 t each were employed to lift the closure section and allow the closure section to be embedded into the closure gap. When the bolting and welding connection of the closure section and the steel girder on one side was completed, the steel girder was pushed towards the mid-span to return to its original position. The prepared three-directional deviation adjusting devices were used to adjust the deviation at the closure gap and lock the closure gap. After the bolting and welding connection of the closure gap, the temporary locking was relieved, and the systematic transformation of the bridge was realized.