横琴二桥主桥钢桁拱架设施工关键技术

摘要

珠海横琴二桥主桥为主跨400 m的三跨连续中承式钢桁系杆拱桥,边跨钢桁梁采用架梁吊机悬臂法吊装,中跨钢桁拱采用斜拉扣挂悬臂法、先拱后梁法架设.施工中对结构体系进行多次转换,并在边、中支点设置了三向调位装置,以确保施工过程中结构受力满足要求;斜拉扣挂系统扣锚索张拉采用“等值法”控制索力,以确保索力的均匀性;中跨主拱合龙采用预偏位移补偿+顶落梁法,避免了复杂调索和整体大吨位移梁施工;刚性系杆合龙采用限位中支座法,避免了架设临时系杆,合龙方便快捷;采取了栓孔重合度控制、拱度控制、轴线偏差控制等线形控制措施,以确保拼装拱度和轴线满足要求.实践表明,该桥施工采取的关键技术有效解决了一系列施工难题、确保了大桥施工安全、缩短工期和节约成本.%The main bridge of the Second Hengqin Bridge in Zhuhai is a three-span halfthrough continuous steel truss tied arch bridge with a main span of 400 m.In the construction of the bridge,the side span steel truss girders were erected by the deck cranes by the cantilever method while the central span steel truss arch was erected by the fastening stay cantilever method in the sequence of erecting the arch first and the steel truss girder late.The structural system of the bridge was transformed several times in the process of the construction.The three-way position adjusting devices were arranged at the side and intermediate supports in order to ensure that the force conditions of the structure could meet the requirements in the construction.The forces of tensioning of the fastening stays and anchor cables of the fastening stay system were controlled by the "equivalent value method" in order to ensure the uniformity of the forces of the stays and cables.The main arch of the central span was closed by the method of the pre-offsetting compensation+jacking-up and-down of the girder.In such a way,the complicated adjustment of the fastening stay forces and the integrally shifting of the heavy load girder were avoided.The rigid tie members were closed by the limit intermediate bearing method,the erection of the temporary tie members was thus omitted on the one hand and on the other hand,the closure of the rigid tie members was convenient and fast.The geometric shape control measures of the bolt hole coincidence control,camber control and the axial line offsetting control were taken in order to ensure that the installation camber and axial line could meet the requirements.Practice proves that all these key techniques applied to the construction of the bridge can provide effective solution to a series of the construction problems,ensure the construction safety,shorten the construction time schedule and can save the construction cost of the bridge.