超千米级公铁两用斜拉桥斜拉索安装关键技术

Key Techniques for Stay Cable Installation on Rail-cum-Road Cable-Stayed Bridge with Main Span Length over 1 000m

沪通长江大桥主航道桥主跨1 092m,斜拉索采用双塔三索面、扇形密索体系,最长索长576.2m,最大索重83.5t,超长、超重斜拉索安装难度大。斜拉索采用先塔端挂设,再梁端牵引,最后塔端张拉的总体施工方案。短、中索采用常规的先塔端挂设后脱空展索的方式施工,长索采用斜拉索桥面整体运输及展索技术,按照先桥面展索后塔端挂设的步骤施工。短索采用卷扬机牵引系统完成斜拉索梁端牵引。中、长索采用梁端卷扬机快速牵引技术,加大卷扬机牵引力,将梁端锚杯向锚固位置牵引一段距离。中索、中跨长索梁端作业空间有限,采用钢绞线软牵引系统和梁端反压牵引技术完成梁端牵引;边跨长索采用常规的钢绞线软牵引系统完成梁端牵引。斜拉索张拉时,采用防扭转装置。为加快施工进度,29号墩斜拉索采用同步智能张拉系统,同步完成2层共12根斜拉索张拉。

The main navigational channel bridge of Hutong Changjiang River Bridge is a cablestayed bridge with a main span of 1 092 m.The bridge has two pylons,the stay cables are densely fanned out in three cable planes,with the longest cable measuring 576.2 mand the maximum cable weight reaching 83.5 t,and the super long and heavy stay cables pose great challenges to installation.During the construction process,the stay cables were first hung on anchorages in the pylons,then unreeled to reach the girder,after anchored to the girder,the cable forces were adjusted from the anchorages in the pylons.The short and medium-sized stay cables were erected following the conventional procedure,by which the stay cables were first hung on the anchorages in the pylons and then unreeled to reach the girder.But for the long stay cables,the transportation and unreeling were integrated,in specific operation,the stay cables were unreeled on the deck and then hung on to the anchorages in the pylons.The stay cables were dragged to the anchoring location in the girder by winches.The medium-sized and long stay cables were rapidly dragged by winches on the girder,the traction force of the winches was scaled up to drag the sockets in the girder a distance to the anchoring location.Due to the limited operation space on the girder,the medium-sized and long stay cables were dragged into the final position in the girder using the steel strand soft traction system and the counter-pressure traction system,with the long stay cables in side spans dragged by the conventional steel strand soft traction system.During the tensioning of the stay cables,torsion-protection devices were used.To expedite the construction,the stay cable No.29 was tensioned by the synchronized intelligent tensioning system,with 12 stay cables in two layers tensioned in parallel.