千米级混合梁斜拉桥双目标控制施工监控体系

摘要

为确保千米级混合梁斜拉桥施工监控的高效性、高精度以及安全性,以鄂东大桥为背景,通过理论分析、有限元数值计算,在充分考虑结构非线性效应,并结合现场实际及工程面临问题的基础上,开展了特大跨度混合梁斜拉桥施工监控理念、监控方法及监控内容研究,构建了适用于该复杂结构的监控体系.首先,根据千米级混合梁斜拉桥施工控制特点及面临的问题和挑战,基于几何控制理论,构建了双目标监控体系;其次,根据双目标控制系统关键问题,重点针对初始无应力状态量的确定、关键构件计算分析、制造浇筑及安装控制、施工期安全稳定等问题进行深入研究,得到了其计算分析及安装控制方法;最后,利用建立的监控体系,对鄂东桥进行了全过程控制.研究结果表明:采用的监控系统,制造阶段误差梁顶最大为16 mm,轴线误差2.7 mm,累计梁长误差10.8 mm;非线性稳定安全系数最小2.5,满足要求;边跨混凝土线形最大误差11 mm,中跨钢箱梁最大误差157 mm;塔偏相对误差为L/12 434,混凝土梁单根拉索索力最大误差为4.50％,钢梁索力最大为6.30％,全桥应力合理,监控各项指标均满足规范要求.%To ensure the construction control of thousand-meter-scale hybrid girder cable-stayed bridges for high efficiency,precision,and safety,taking the Edong Yangtze River Bridge as a case study,research on the construction monitoring concept,monitoring method,and monitored parameters of the super-long-span hybrid girder cable-stayed bridge was carried out,and the construction control system for this complicated structure was built.The research and the system were based on theoretical studies,finite element numerical calculations with full consideration of the structural nonlinear geometrical effects,and the issues faced at the construction site.First,according to the construction control characteristics,problems,and challenges of thousand-meter-scale hybrid girder cable-stayed bridges,the double target control system was built based on the geometry control method.Then,focusing on the key aspects of this control system,some important issues such as the determination of the initial unstressed state amount,calculations pertaining to key construction members,fabrication and cast-in-site control stage,erection stage,and safety control in the construction stage were extensively studied,and the calculation and installation control methods were obtained.Finally,the entire construction control procedure for the Edong Yangtze River Bridge was carried out using this control system.The results show that the maximum alignment error at the top of girder is 16 mm,the axis error is 2.7 mm,and the cumulative girder error is 10.8 mm during the manufacturing stage.The minimum value of the nonlinear stability safety factor is 2.5 and meets the specifications.Meanwhile,the maximum alignment error of concrete girder in the side span is 11 mm,and the maximum alignment error of the steel box girder in the middle span is 157 mm.The relative error of the pylon deviation is L/12434.Furthermore,the maximum cable force error of a single cable located in the concrete girder is 4.5％,and the maximum cable force error of a single cable located in the steel girder is 6.30％.All the analyses show that the stress condition in the entire structure is reasonable,and all the monitoring indexes meet the specifications.