双主跨高墩连续刚构桥合龙方案优化研究

Optimization Study on Closure Scheme of Double Main Span High Pier Continuous Rigid Frame Bridge

高墩大跨连续刚构桥成桥后在混凝土收缩徐变作用下会引起主梁下挠和主墩水平偏移,对成桥线形和主墩受力都会产生影响,合龙方案的确定对成桥阶段和运营阶段结构的变形与受力十分重要。文中依托黔川古金高速公路清池特大桥,针对双主跨高墩连续刚构桥不同合龙工序和是否顶推拟定四种合龙方案开展对比分析。结果表明,顶推对改善主墩内力与水平偏位有利,但会增加边跨挠度;相较于先中跨后边跨合龙,先边跨后中跨合龙更利于主梁长期变形。

Main beam will deflect downward and the main pier will shift horizontallyunder the action of concrete shrinkage and creep after the completion of a long-span rigid frame bridge with high piers,which will affect alignment of the completed bridge and stress on the main pier.Closure scheme is very important for the deformation and stress of structure in the bridge completion stage and operation stage.Relying on Qingchi super Bridge of Gujin expressway in Guizhou Province,four closure schemes of double-main-span high pier continuous rigid frame bridge are proposed for different procedures and whether to consider pushing technique.The research results show that the jacking is beneficial to improve the internal force and horizontal deflection of the main pier during closure process,but it will also increase the deflection of the side span;compared with closing middle span first and then side span,closing side span first is more conducive to the long-term deflection of the main beam.