南叶公路桥主桥施工过程中两个关键技术问题的探讨

Discussion on Two Key Technologies of Nanye Highway Bridge in Construction of Its Main Bridge

南叶公路桥主桥为一跨径127 m的钢管混凝土系杆拱桥,采用先拱后桥的施工方法。主桥施工过程中,在系梁没有张拉预应力之前,拱肋拱脚的水平力由临时水平拉索以及拱脚处水平止推装置共同承受,然后通过分批张拉系梁预应力钢束来替换。临时水平拉索与水平止推装置的共同受力与系梁预应力的张拉控制是主桥施工过程的两个关键技术问题。结合实际施工情况并通过详细的结构分析,合理控制了临时水平拉索与水平止推装置所承受的水平力;通过分析对系梁预应力钢束张拉顺序进行了优化,实现了水平力的替换并有效控制了系梁的混凝土压应力水平,确保了主桥施工的顺利完成。

The main bridge of Nanye Highway Bridge is a one-span 127 m concrete filled steel tube bowstring arch bridge, and is constructed by the pre-arch and post-beam method. In the construction of main bridge and before the straining beam is not tensioned and pre-stressed, the horizontal force of arch rib and arch foot is supported together by the temporary horizontal stayed cable and the horizontal thrust device at arch foot, and then is replaced by the pre-stressed steel cables of tensioned straining beams in batches.The common stress of the temporary horizontal stayed cable and horizontal trust device, and the pre-stressing tension control of straining beam are two key technical issues in the construction of main bridge.Combined with the practical construction situation and through the detailed structure analysis, the horizontal force supported by the temporary horizontal stayed cable and horizontal thrust device is reasonably controlled. Through the analysis on the optimization of pre-stressed steel strand tension sequence of straining beam, the replacement of horizontal force is realized, and the concrete pressure stress level of straining beam is effectively controlled to ensure the smooth completion of main bridge construction.