石首长江公路大桥北边跨主梁施工关键技术

Key Techniques for Construction of Main Girder of North Side Spans of Shishou Changjiang River Highway Bridge

石首长江公路大桥主桥为主跨820m的双塔非对称混合梁斜拉桥,大桥中跨与南边跨主梁采用PK断面钢箱梁结构,北边跨主梁采用PK断面预应力混凝土箱梁结构(长251.5m)。受粉细砂地质条件影响,大桥北边跨主梁采用"1+1桥位短线法"进行工厂化预制、胶拼施工。施工时,首先采用大型组合式移动模板进行预应力混凝土箱梁节段预制施工,然后利用1 100t特种龙门吊机将箱梁节段提升至墩顶滑移支架,最后进行预应力混凝土箱梁节段匹配、胶拼,并张拉纵向预应力钢筋进行体系转换,完成北边跨主梁施工。

The main bridge of Shishou Changjiang River Highway Bridge is a double-pylon asymmetric hybrid girder cable-stayed bridge with the main span of 820 m.The main girder of the main span and the south side spans of the bridge is the steel box girder of the Pasco-Kennewick（PK）Bridge section while that of the north side spans is the prestressed concrete box girder（251.5 min length）also of the PK section.Affected by the geological conditions of the fine silty sand at the bridge site,the segments of the main girder of the north side spans were precast in a factory production way,using the 1＋1 bridge site short-line match method and were assembled and connected,using the epoxy resin.In the construction,the segments of the prestressed concrete box girder were firstly precast,using the large-size combined slide shuttering,were then lifted onto the launching truss on the piers,using the 1 100 tspecial gantry crane and were matched,assembled and connected,using the epoxy resin.Finally,the longitudinal prestressing bars of the girder were tensioned and the system transferring was carried out.At this stage,the construction of the main girder of the north side spans was completed.