铜陵长江大桥整体拼装低温焊接技术

Integral Assembling and Low-Temperature Welding Techniques Used for Tongling Changjiang River Bridge

铜陵长江大桥主桥为五跨连续三索面钢桁梁斜拉桥,上层公路桥面系采用正交异性钢桥面板,下层铁路桥面系采用正交异性钢箱桥面,钢桁梁的桁片采用大型整体焊接式结构。为保证整体拼装低温焊接质量,针对桥面系板单元和桁片部位的整体拼装对接焊缝进行低温焊接试验,并对试件进行无损检测和力学性能检测。结果表明,在采取低温防护措施后,试件无冷裂纹等缺陷产生,接头的各项力学性能均满足技术条件要求,焊接过程中未产生淬硬组织。在实际生产中,采用减少焊缝中的扩散氢含量、减缓焊缝冷却速度、加强人员及设备防护等措施后,焊缝质量良好,力学性能均满足设计要求,有效地降低了低温对整体拼装焊接的影响,保证了工程的质量和进度。

The main bridge of Tongling Changjiang River Bridge is a five-span continuous steel truss girder cable-stayed bridge with three cable planes. The upper highway deck adopts the ortho- tropic steel deck, the lower railway deck uses the orthotropic steel box deck, and the trusses of the steel truss girder are the large-scale integral welded structures. To ensure the low-temperature welding quality of the integral assembly, the low-temperature welding test was carried out for the butt joints of the bridge deck plate elements and the trusses, and non-destructive test and load bearing capacity test were done for the samples. The results indicated that after the low-tempera- ture protection measures were taken, no defects, like cold cracks were found in the samples, the load bearing capacity of the joints could meet the requirements of the technical condition, and no quench hardening lumps were produced during the welding process. In the actual application, when the measures such as reducing the quantity of the diffusible hydrogen in the welding joints, slowing down the cooling speed of the welding joints and strengthening the protection for the per- sonnel and the equipment were taken, the quality of the welding joints was proved to be good, the load bearing capacity could meet the design requirements, and the adoption of these measures helped effectively reduce the impact of low temperature on integral assembling and welding and ensure the quality and progress of the project.