复杂组合线形钢桁梁顶推轨迹线拟合技术研究

Research on Fitting Technique of Incremental Launching Trajectory of Complex Composite Linear Steel Truss Girder

摘要:

顶推法施工属于异位安装，即钢桁梁安装位置与成桥位置不同，在顶推施工过程中，需将钢桁梁整体抬高，沿着合适的顶推轨迹线进行顶推，最后整体落梁至成桥线形。合适的顶推轨迹线对顶推施工至关重要。以浙江永宁大桥项目为工程背景，针对该项目大纵坡+复杂竖曲线的组合线形，通过采用抛物线、椭圆曲线、圆曲线三种形式进行顶推轨迹线线形拟合，最终确定顶推轨迹线为半径15 670 m的单圆曲线，将顶推施工由刚性转动+平动转变为绕固定的圆心转动旋转，有效地降低了施工难度和风险，为后续复杂组合曲线顶推施工提供相关经验。

Abstract:

The construction of incremental launching method belongs to the ectopic installation, that is, the installation position of the steel truss girder is different from that of the finished bridge. During the incremental launching construction, the steel truss girder should be raised as a whole and pushed along the suitable incremental launching trajectory. Finally, the whole girder falls to the alignment of the finished bridge. The proper incremental launching trajectory is very important to the incremental launching construction. Based on the background of the Yongning Bridge Project in Zhejiang Province, aiming at the composite alignment of large longitudinal slope + complex vertical curve of the project, three forms of parabola, elliptic curve and circular curve are used to fit the incremental launching trajectory. Finally, the incremental launching trajectory is determined as the single circle curve with a radius of 15 670 m. The incremental launching construction is changed from the rigid rotation + translation to rotation around the fixed center of the circle, which effectively reduces the construction difficulty and risk, and provides the relevant experience for the incremental launching construction of subsequent complex composite curves.