摘要
为研究大跨径混合梁斜拉桥中跨合龙施工技术,以主跨340 m的重庆高家花园轨道环线专用桥为工程背景,借助Midas/Civil2015有限元软件对其施工过程进行了仿真模拟,并对合龙顶推位移量和合龙顶推力的两个关键合龙参数的计算方法进行了系统研究。首先提出基于刚性支承连续梁法,对合龙前斜拉桥最大悬臂结构进行等效简化,利用结构温度作用位移公式计算出不同温差下的梁体伸缩量,进而确定出合龙顶推位移量,并将其与有限元软件计算值进行对比,吻合程度较高。又将现场监测的实测值与之对比,误差较小,验证了合龙顶推量数值计算方法的可靠性。其次,通过对影响主梁顶推各个因素进行分析,得出了顶推力计算公式,并利用影响矩阵和Matlab软件有效计算出不同合龙顶推位移量的顶推力数值,确定了两者变化关系。将现场监测的顶推力实测值与其对比,实测值呈台阶式增长关系,理论值呈线性增长关系,实测值均匀地分布在理论值两侧,一定程度上验证了顶推力数值计算方法的可行性。最后,介绍了缝接合龙法的现场施工过程,并依次从成桥后的斜拉索附加索力、主梁附加应力、主梁线形变化及主塔偏移方面对成桥状态进行了对比验证分析,成桥状态良好。
To research the central span closure technique for long span hybrid girder cable-stayed bridge, taking the Chongqing Garden Gao Rail Link Bridge with 340 m main span as an example, the closure process is simulated by using the Midas/Civil2015 FE software, and the calculation method of the 2 key closure parameters(jacking displacement and jacking force) is systematically studied.First, the continuous girder method based on rigid support is proposed, the maximum cantilever structure of the cable-stayed bridge before closure is equivalent simplified, and the stretching amounts of the girder body under different temperature differences are calculated by structure temperature acting displacement formula, and the jacking displacement for closure is determined accordingly, which is compared with the calculated value of FE software, showing the high degree of coincidence.It is also compared with the measured value of field monitoring, showing the small deviation, which verified the reliability of the numerical calculation method of the jacking displacement.Second, through the analysis of the influencing factors of girder jacking, the jacking force calculation formula is obtained.Combining the influence matrix and the Matlab software, the jacking force values under different jacking displacements are calculated effectively, and the relationship between jacking force and jacking displacement is identified.The comparative analysis shows that the measured values have a stepwise growth relationship, while the theoretical values show a linear growth relationship.The actual values are evenly distributed on both sides of the theoretical values, which verified the feasibility of the jacking force numerical calculation method to some extent.Finally, the construction process of the seaming closure method is introduced, and the completion state of the bridge is compared and verified from the additional cable force of the cable, the additional stress of the main girder, the change of the main girder geometric shape and the deviation of the main pylon, which shows the bridge is in good condition.
引文
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