五峰山长江大桥主缆架设施工关键技术

Key Techniques for Main Cable Construction of Wufengshan Yangtze River Bridge

主缆架设施工是悬索桥建设中的关键工序之一,其成缆质量与线形直接影响大桥长期的受力与线形。为实现主跨1092 m的连镇铁路五峰山长江大桥1.3 m大直径主缆的顺利、精准架设,开展大桥主缆架设施工关键技术理论分析研究。根据大桥特点及施工条件,主缆架设采用预制平行索股法(PPWS),索股采用双线往复式牵引系统进行架设,先进行基准索股架设,架设完成后对其进行精细化垂度调整;根据调整后的基准索股进行一般索股架设并对其进行垂度调整。索股架设中,分别在上下游边跨跨中,中跨L/4,L/2,3L/4处布置几何测点,进行几何位置连续监测。主缆架设时监控结果表明,主缆基准索中跨、边跨误差,中跨跨中上下游高差均满足限值要求。空缆成缆误差均值在-95~22 mm,精度良好。往复式牵引架索、基准索监控与垂度调整、非基准索相对调索等关键技术为大桥主缆的精确架设提供了有力支撑。

Construction of main cable of suspension bridge is one of the key procedures in bridge construction because its cable quality and line shape directly affect the long-term stress and profile of the bridge.Theoretical analysis on key technologies of bridge main cable erection construction are carried out to realize smooth and accurate erection of main cables with a diameter of 1.3 m in Lianzhen Railway Wufengshan Yangtze River Bridge with a main span of 1092 m.According to the bridge characteristics and construction conditions,the main cable is erected by prefabricated parallel wire rope strand method(PPWS).Main cable units of the bridge are erected by the double-line reciprocating traction system.The erection of the reference cable units shall be carried out first.The general strand is set up and its sag is adjusted according to the adjusted datum strand.After the adjustment of the datum cable sag,measuring points are arranged at the middle of side-span,mid-span L/4,L/2,3L/4 of the upstream and downstream sides respectively,and continuous observation is conducted.The results of main beam erection and monitoring measurement show that the error of middle span and side span of main cable reference cable,height difference of upper and lower reaches of middle span,and middle span all meet the requirement of limit value.The average error of the empty cable is within the range of -95~22 mm,and the accuracy is good.Such key technologies as reciprocating towing frame cable,reference cable monitoring,sag adjustment and non-reference cable relative adjustment provide strong support for the accurate erection of the main cable of the bridge.