渝黔铁路新白沙沱长江特大桥钢桁梁架设技术

渝黔铁路新白沙沱长江特大桥为双层6线铁路钢桁梁斜拉桥,主桥桥跨布置为(81+162+432+162+81)m。主梁采用N形桁架,2片主桁,全桥钢梁总重约4.1万吨,共68个节间,其中重庆侧边跨4个节间钢梁跨越3条铁路线。为顺利跨越既有铁路线,重庆侧钢梁采用“部分顶推+散拼”的架设方案施工,在2号墩主跨侧的支架上一次性拼装完成,分多次请点将7.5个节间钢梁顶推过既有铁路线,剩余节间钢梁采用支架散拼法架设;贵阳侧钢梁采用双悬臂方案架设,在单侧墩旁托架上利用70t架梁吊机架设3号墩墩顶6个节间钢梁后,利用2台70t架梁吊机对称悬臂架设其余节间钢梁;主跨跨中采用适配法合龙。

Erection Technique for Steel Truss Girder of New Baishatuo Changjiang River Bridge on Chongqing-Guiyang Railway

The New Baishatuo Changjiang River Bridge on Chongqing-Guiyang Railway is a cable-stayed bridge with a structure of steel truss girder which consists of double decks and 6 lines of railway, and the arrangement of main bridge spans is (81+162+432+162+81) m. The N-shaped trusses with two main trusses are adopted to construct the main girders. The total weight of the steel girders of the bridge, containing a total of 68 joints, is about 41 000 tons, in which 4 joints of the side-span steel girders at Chongqing side span three existing railway lines. In order to successfully cross the existing railway, the scheme of "partial incremental launching + assembling " is adopted in the construction of steel truss girder at Chongqing side. Steel truss girders are assembled in one time on the bracket of the main span of pier No.2, and 7.5 joints steel girders are incrementally launched over the existing line in several times. The rest joints of steel truss girders are constructed by the bulk assembly method. The double-cantilever scheme is adopted to erect steel truss girders at Guiyang side. A 70 t girder crane is adopted to erect 6 joints steel girders at the top of pier No.3 on the single-side bracket, then two 70 t girder cranes are adopted to erect the rest intersecting steel girders symmetrically. An adaptation method is adopted for closure of main girder in mid-span.