大跨径钢筋混凝土拱桥悬臂浇筑施工控制

分析了拱桥主拱圈斜拉扣锚悬臂浇筑施工体系的结构特点, 总结了拱桥悬臂浇筑施工扣、锚索力的确定方法, 分析了零位移法、定长扣索法、影响矩阵法与零弯矩法的优缺点与适用性。基于净跨径为180m的钢筋混凝土拱桥——马蹄河大桥的设计与施工方案, 分析了大跨径钢筋混凝土拱桥主拱斜拉扣锚悬臂浇筑施工的全过程, 采用零弯矩法进行索力求解, 并在最大悬臂施工阶段采用以拱圈弯曲能量为目标函数的影响矩阵法对索力进行了优化。分析结果表明: 在拱桥斜拉扣锚悬臂浇筑施工中采用零弯矩法是最直接有效的控制方法; 整个施工过程中拱圈截面由部分受拉逐渐进入全截面受压, 拱圈线形与应力满足设计要求; 拱圈上、下缘拉应力不超过1.5MPa, 压应力不超过7.0 MPa, 拱圈位移不超过10mm; 对最大悬臂施工阶段进行索力优化可以进一步调整拱圈线形, 并改善主拱圈受力状态, 通过调整可以使拱脚接近"零"应力状态; 悬臂浇筑施工阶段的稳定性与扣、锚索系统的关系密切, 合理的扣、锚索系统同时控制拱圈的内力、线形与施工阶段的稳定性; 扣、锚索拆除顺序的不同对合龙后的拱圈应力影响较大, 因此, 施工时应注意对扣、锚索系统拆除程序进行优化。研究成果成功解决了国内悬臂浇筑施工的最大跨径钢筋混凝土拱桥的施工方案设计与施工控制问题, 并可供大跨径拱桥结构设计与施工控制参考, 以期推动大跨径钢筋混凝土拱桥悬臂浇筑技术的发展。

Construction control of cantilever casting of long span reinforced concrete arch bridge

The structure characteristics of cable-stayed and anchored cantilever casting construction system for the main arch ring of arch bridge were analyzed.The methods to determine the forces of anchored cables in cantilever casting construction were summarized.The advantages, disadvantages, and applicabilities of the zero displacement method, the fixed length jacking cable method, the influence matrix method, and the zero moment method were analyzed.The design and construction schemes of Matihe Bridge being a reinforced concrete arch bridge with net-span of 180 m was taken as engineering background, and the main construction process of long span arch bridge built by using cable stayed cantilever casting method was analyzed.Thecable forces were calculated by using the zero moment method, the cable forces at the maximum cantilever construction stage were optimized by using the influence matrix method with the objective function of bending strain energy.Analysis result shows that the zero moment method is determined to be the most direct and effective control method for the cable-stayed and anchored cantilever casting construction of arch bridges.The stresses in the arch ring section change gradually from partially tensile state to completely compressive state, and both the alignment and stress of arch ring satisfy the design requirements in whole construction process.The tensile stresses of arch ring at the top and bottom sides do not exceed 1.5MPa, the compressive stresses are no more than 7.0 MPa, and the displacements of arch ring are no more than 10 mm.As the cable forces at the maximum cantilever construction stage are optimized, the alignment of arch ring can be adjusted, and its stress state is improved, thus the stress state of arch foot can be closed to "zero" state.The stability of arch ring at cantilever casting construction stage is closely related to the stayed and anchored cable system, and the internal forces, alignment, and stability during construction process are simultaneously dominated by a reasonable stayed and anchored cable system.The stress of arch ring is deeply influenced by the different removal procedures of stayed and anchored cable system, thus the removal process of stayed and anchored cable system should be optimized during construction process.The research results have been successfully applied to the design of the construction scheme and construction control of cantilever casting of the longest span reinforced concrete arch bridge in China, and can be taken as a reference for the design and construction control of other long span arch bridges, which has a practical significance in promoting the development and application of cantilever casting technology of long span reinforced concrete arch bridges. 2 tabs, 10 figs, 29 refs.