孟加拉帕德玛大桥铁路连接线简支钢桁梁顶推架设技术

Incremental Launching Erection Technology of Simply-Supported Steel Trusses of Padma Bridge Rail Link Project in Bangladesh

帕德玛大桥铁路连接线是孟加拉国连通首都达卡与西南部地区客货运输重要的交通干线,新建铁路正线全长168.6 km,正线上有8座桥,共35孔单孔跨度100 m的简支钢桁梁,其中12孔钢桁梁采用顶推法架设。采用顶推法架设的钢桁梁在桥位或过渡墩后混凝土箱梁区设拼装支架,在临时墩和各墩旁滑移支架顶设置顶推滑移系统,拼装第1孔钢桁梁和前端导梁,小节点竖杆设临时加固杆件,运用多点同步控制技术完成第1孔钢桁梁顶推;拼装第2孔钢桁梁,相邻孔跨间设置临时连接,将简支结构变为可顶推的连续结构;循环作业直至完成所有孔跨顶推;运用体系转换及高位落梁技术完成钢桁梁架设。已完成的首座钢桁梁桥成桥线形及结构受力满足设计要求。

Padma Bridge Rail Link Project is a passenger and freight traffic arterial route which connects the capital city Dhaka with the south-western region of Bangladesh.The newly built rail main line stretches 168.6 km,consisting of 8 simply-supported steel truss bridges,totally 35 simply-supported steel truss spans of 100 m each.Of them,3 bridges totally 12 spans are erected by incremental launching method.For the incrementally launched steel trusses,the assembly scaffolds are installed in the concrete box girders bay at the bridge site or behind the transition piers,the launching sliding system is supported on the top of the temporary piers and the permanent-pier-side sliding brackets.The steel trusses in the starter span and the launching nose were assembled first,temporary reinforcing members were added to the vertical members at the minor joints,and the multi-point synchronized control technique was used to complete the incremental launching of the steel trusses.The steel trusses in the second span were sequentially assembled,and the adjoining spans were temporarily connected to transform the simply-supported structure to be a continuous structure available for incremental launching.This process was cycled until the completion of the incremental launching of all the spans.The system transformation and overhead lowering of trusses are the key techniques to ensure the completion of the steel trusses erection.It is shown that the geometry and load bearing capacity of the first steel truss girder bridge after completion can meet the design requirements.