既有简支钢桁梁桥抬升施工关键技术

Key Lifting Construction Technique for Existing Simply-Supported Steel Truss Girder Bridge

某简支钢桁梁桥为24×48 m的单线铁路桥,根据线路功能提升需求,采用牵引拖拉方式将钢桁梁更换为钢箱梁,在换梁施工前需对钢桁梁进行抬升。针对该铁路桥钢桁梁抬升需求,结合现场施工条件,对常规梁体同步顶升方案和逐跨梁体整体提升方案进行比选,最终选取逐跨梁体整体提升方案完成钢桁梁抬升工作。根据既有轨道尺寸及起吊重量需求,设计一种走行式提升吊架,主要由主梁、支腿、走行装置、吊挂系统及配重等组成,配套有同步液压系统。施工中,在待提升桥跨两端相邻钢桁梁顶面各布置1台提升吊架,通过吊挂系统与梁体形成可靠连接,借助同步液压系统实现连续提梁施工。

A simply-supported steel truss girder bridge is a single-track railway bridge with 24 spans of 48 m.Due to that the functions of the railway would be upgraded,the steel truss girder of the bridge was planned to be replaced by box girder.And before the replacement,the steel truss girder had to be lifted up.Two lifting schemes,the conventional synchronized jacking up of the girder from multiple points and the span-by-span integral lifting,were compared,taking into account the lifting requirements of the steel truss girder railway bridge and the construction conditions at the bridge site.The span-by-span integral lifting scheme was finally selected.In accordance with the dimension of the existing track and the lifting weight,a self-propelled lifting frame was designed,which consisted of main beam,legs,propelling device,hanging system and counterbalance,together with a tailored synchronous hydraulic system.During construction,a lifting frame was arranged on the top of steel truss girder in each adjacent span of the operated span,which could have a reliable connection to the girder body via the hanging system,and realize continuous lifting of steel truss girders with the assistance of the synchronous hydraulic system.