西江特大桥钢箱提篮拱架设施工技术

Construction Techniques for Erection of Steel Box Basket Handle Arch of Xijiang River Bridge

新建南广铁路西江特大桥主桥为（41.2＋486＋49.1）m中承式钢箱提篮拱桥,拱肋为变高度钢箱结构。拱肋G0～G3节段利用500t浮吊安装;G4～G21节段采用“缆索吊机＋扣挂法”悬臂拼装施工。为确保拱肋顺利吊装、架设及精确就位,缆索吊机采用扣缆塔合建方案;G4～G9节段吊耳布置在拱肋上翼缘板和上横断面处,G10～G21节段吊耳布置在拱肋上翼缘板;拱肋拼装到位后,采用连接件和限位牛腿临时连接;扣索扣点系统采用双向铰座方式,由扣耳、锚箱、销轴组成;锚索锚点布置于两侧的锚碇上;扣、锚索张拉端均设置于扣塔上。为保证成桥后线形和受力与设计状态一致,拱肋采用了“6＋1”的半长线法制造工艺,预埋段采取了精确空间立体定位技术,3个节段拼装后进行一次精确线形调整,合龙过程中采用了扣索索力调整和合龙温度控制等措施。该桥合龙后,主拱长、宽、高及对角线误差均在±2mm以内,满足设计要求。

The main bridge of the Xijiang River Bridge on the newly-built Nanning-Guangzhou Railway is a half-through steel box basket handle arch bridge with span arrangement （41.2＋486＋ 49.1） m and the arch ribs of the bridge are the steel box structures of variable depth. In the con- struction of the bridge, the segments G0～G3 of a arch rib were erected by the 500-t capacity float- ing earne and the segments G4～G21 were cantileveredly assembled and erected by the ＂cable crane ＋fastening stay method＂. To ensure that the segments of the arch rib could be smoothly lifted, e- rected and accurately set in place, the scheme of constructing the towers for support of both the ca- ble crane and fastening stays was adopted. The lifting ears for the segments G4～G9 were arranged on the upper flange plates and upper cross section of the arch rib and for the segments G10～G21 were arranged on the upper flange plates. At the time the arch rib was well assembled, the seg- ments were temporarily connected by the connecting pieces and limiting corbels. The fastening point system for a fastening stay was the two-way hinge and was comprised of the fastening ear, anchor box and pin. The anchor points of the anchor cables were arranged in the anchorage on both sides and the jacking ends of the fastening stays and anchor cables were all arranged on the towers. To ensure that the geometric Shapes and force conditions of the completed bridge could be accord- ant with those in the design, the segments of the arch rib were manufactured by the workmanship of the ＂6＋1＂ semi-long line match method and the pre-embedded segments of the arch rib were po- sitioned by the accurate spatial positioning technique. The geometric shapes of the arch rib were accurately adjusted for one time after every 3 segments were assembled. In the process of closure of the arch rib, the fastening stay forces were adjusted, the closure temperatures were comtrolled and after the closure of the bridge, the errors of the length, width, height and diagonal lines of the main arch were all controlled within ±2 mm and could meet the design requirements.