郑州市中心区铁路跨线桥为(106+248+106 ) m双塔单索面跨线斜拉桥 ,其上部结构跨越货运铁路、客运铁路、站场专用线等多条铁路.针对该桥结构特点和施工难点 ,将跨线桥主梁分为A、B、C区 :A区位于斜拉桥的两端 ,远离铁路限界 ,采用支架法现浇 ;C区为主跨中央139 m范围 ,位于铁路专用线上方 ,采用挂篮悬浇施工 ;B区为桥塔两侧的对称区段 ,直接跨越铁路运营线 ,通过比选 ,2号塔B区主梁采用挂篮悬浇方案 ,3号塔B区主梁采用转体方案.施工中在铁路上方设置铁路防护屏蔽网 ,采用宽幅全封闭挂篮技术解决了铁路上方施工净空有限的难题 ,将转体分次进行 ,压缩单次"天窗点"时间 ,减少了施工对既有铁路运营的干扰和影响.%A railway-crossing bridge in downtown of Zhengzhou is a two-pylon single cable plane cable-stayed bridge with span arrangement of (106+248+106) m.The superstructure of the bridge spans multiple railways ,including freight lines ,passenger dedicated railways and plant service railways.According to the structural features of the bridge and the construction complexi-ties ,the main girder of the railw ay-crossing bridge is divided into three parts ,designated A ,B , and C ,respectively.Part A includes the two ends of the cable-stayed bridge ,where is far away from the railway reigns ,such that it is cast in situ on scaffoldings.Part C is the 139 m area in the central of the midspan ,over the special railway lines ,thus cast in cantilevers using form travelers. Part B is the sections symmetrically located at the two sides of the pylons ,directly crossing the railw ay operation lines.By comparison and selection ,the Part B main girder in the vicinity of the No.2 pylon is cast in cantilevers with form travelers ,while the Part B main girder in the vicinity of No.3 pylon adopts the rotating construction scheme.During the construction ,protective sheets are placed over the railways.The adaptation of broad fully-closed form travelers resolved the prob-lem of clearance limitation over the railways.The rotating construction was carried out for several stages ,each"window time"period was squeczed to control the influence of construction on the op-eration of the railw ays.
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