山区桥梁钢梁“后驱式”滚动架设关键技术

Key Techniques of"Rear-Driven"Rolling-Erection of Steel Girders in Mountainous Area

川滇金沙江特大桥引桥为2×40 m钢-混组合梁桥,分左、右幅布置,单幅主梁采用4片工字钢梁。针对引桥地势艰险、施工难度大、风险高等特点,通过施工方案比选,提出“后驱式”滚动架设方法,利用牵引卷扬机驱动钢梁在固定滚轮上滚动行走,实现钢梁快速架设;对钢梁滚动架设全过程进行仿真模拟,结果表明结构受力安全。施工时,在钢梁端部设置前、后导梁;在顺桥向共布设5处固定滚轮;在中间墩柱、桥塔横梁支墩上架设钢梁临时支架;采用10 t卷扬机形成“后驱式”牵引动力牵引钢梁向桥塔侧前进,同时设置反拉制动卷扬机;前导梁过孔时,将前导梁预抬高20 cm并滞后安装固定滚轮的方式以实现过孔;采取在横向设置刚性限位装置主动导向及点接触滚动纠偏的被动方法进行钢梁偏位控制;钢梁牵引到位后,采用“小步距、低落差、同步降”的方法进行同步落梁,顺利实现钢梁架设。

The approach bridge of Chuandian Jinshajiang River Bridge consists of two steel-concrete composite superstructures arranged in two spans of 40 m,each comprising 4 steel I girders.A"rear-driven"rolling construction method is selected to address the challenging terrain at the bridge site,high construction complexities and hazards.The steel girders were driven to roll on fixed rollers by winches to accelerate the construction.The numerical simulation of the whole rolling erection process of the steel girders indicated that the loading condition of the structure was safe.During construction,the front and rear ends of the steel girders were fitted with guide beams.Along the bridge length,five fixed rollers were distributed.Temporary scaffolds were installed on the center pier and the supports of the pylon cross-beams.The 10 t-capacity winches were employed to create a"rear-driven"system to push the steel girders towards the pylons,at the same time,the anti-tension brake winches were installed.The front guide beam was pre-raised 20 cm and the installation of the fixed rollers was delayed to achieve the smooth crossing of the span.The alignment bias of the steel girders was controlled by the active method of using rigid restrainers along the bridge width and the passive method of using contacting rollers.Once pushed into places,the steel girders were lowered simultaneously with small steps and lowering increments,to complete the erection.