武汉二七长江大桥主桥桥塔施工关键技术

针对武汉二七长江大桥主桥桥塔施工工期紧、大体积混凝土构件裂缝控制及高空作业难度大、施工风险高等问题,该桥塔柱采用爬模施工,横梁采用满堂支架法施工,上塔柱采取塔梁同步施工技术.塔柱采用改进的液压自爬模系统和大节段模板、分竖向6 m大节段施工;为控制裂缝,下塔柱第1节与塔座混凝土同时灌注,横梁分2层施工,中塔柱合龙段施工时增设水平联结系以锁定两肢中塔柱；采用接力泵、振捣坐标化管理及有针对性的养护措施确保高空混凝土施工及质量；塔梁同步施工阶段,根据塔形变形曲线精确定位索道管,并设置高空防护平台、封闭液压自爬模系统等措施确保施工安全.

Key Techniques for Construction of Pylon of Main Bridge of Wuhan Erqi Changjiang River Bridge

In view of the facts that the construction time schedule of the pylon of the main bridge of Wuhan Erqi Changjiang River Bridge was tight,the crack control of the massive concrete components and the work high above the ground were difficult and the risk of the construction was high,the columns of the pylon of the bridge were constructed by the self-climbing formwork,the cross beams of the pylon were constructed by the staging method and the upper columns of the pylon were constructed by the technique of concurrent construction of the pylon and girder.The climbing formwork used for the construction of the pylon had the improved hydraulic self-climbing system and large segment formwork and a column was constructed in each 6 m large segment in vertical direction.To control the cracks in the massive concrete components of the pylon,the first segment of a lower column was concreted together with the pylon footing and a cross beam was concreted in two layers.At the time the closure sections on the middle columns were constructed,the horizontal bracing systems were arranged to lock the two middle columns.The relay pump,vibrating coordinate management and the targeted curing measures were taken to ensure the smooth construction and construction quality of the concrete high above the ground.At the stage of the concurrent construction of the pylon and girder,the cable ducts were accurately positioned in terms of the measured deformation curves of the pylon.The safety protection platform and the closed hydraulic self-climbing system were also provided to eventually ensure the construction safety.