崔家营汉江特大桥主梁合龙控制分析

Closure Control for Main Girder of Cuijiaying Hanjiang River Bridge

汉十高铁崔家营汉江特大桥主桥为(135+2×300+135)m四跨连续刚构拱桥。为实现该桥的精确合龙,考虑混凝土收缩徐变效应、温度效应、合龙段钢束荷载作用,采用MIDAS Civil建立该桥有限元模型,并结合施工现场试顶实测数据,研究主梁合龙时桥墩墩顶偏位及对顶力,进行合龙控制。结果表明,混凝土收缩徐变效应、降温效应、合龙段钢束荷载作用对桥墩墩顶偏位的影响方向一致,叠加后对墩身受力较为不利;对顶过程实测墩顶偏位约为理论计算值70%,需对控制偏位、对顶力进行修正;考虑结构实际刚度偏大,最终对顶控制墩顶偏位取理论计算值的80%以进行合龙控制,对比可知,墩顶实测偏位与控制偏位最大偏差为3.6%,成桥线形与预期吻合较好。

The main bridge of Cuijiaying Hanjiang River Bridge on Wuhan-Shiyan High Speed Railway is a continuous rigid-frame arch bridge with four spans of 135,2×300 and 135 m.The piers are reinforced concrete structures.The software MIDAS Civil was used to build the model of the bridge,taking into account the effect of concrete shrinkage and creep,temperature effect,load effect of the reinforcement in the closure section.Based on the calculated data and the measured data,the pier-top offsetting and two-way jacking forces were studied,and the closure process was controlled.The results show that the concrete shrinkage and creep,falling temperature,loads of reinforcement in close section incur pier-top offsetting in the same direction,and when all these effects appear together,the pier shafts would be in unfavorable loading condition.During the two-way jacking process,the measured pier-top offsetting is about 70%of the calculated amount,indicating that the controlled offsetting and two-way jacking force should be modified.Given that the actual stiffness of the structure is relatively big,the pier-top offsetting during the two-way jacking process takes 80%of the calculated amount for the closure control.The results of the comparison show that the maximum difference between the measured pier-top offsetting and the controlled offsetting is 3.6%,suggesting that the geometry of the completed bridge agrees well with the expected one.