基于动态映射关系的桥梁附加变形对高速行车安全影响机理与评价准则

Under special territory and complicated environment, high-speed railway bridges are inevitably subjected to additional deformation that can affect the track regularity and running safety. However, there is lack of understanding on how the accumulated deformation affects the track regularity and running safety. This research for the first time presents the influence mechanism of vehicle’s dynamic behaviors in time-frequency domain and the evaluation criteria of running safety, from the perspective of the dynamic mapping relationship between the bridge additional deformation and running safety. By introducing contact constraint modulus coefficient and time sequence variation index of connection layer, the main mapping path of track geometry will be determined, and universal mapping models between bridge additional deformation and track geometry will be established, considering interlayer deformation transfer mechanism and connection failure effects. Based on model test of the deformation mapping, the variation tendency, development law and spectrum characteristics of track geometry will be quantitatively investigated, which caused by the key parameters including deformation change, structural discontinuity and uneven stiffness. Finally, the quantitative relationship between bridge additional deformation and change amounts of vehicle dynamic indices will be obtained，using the dynamics of coupled system in high-speed trains and fundamental structures. On this basis, evaluation criteria of bridge additional deformation for running safety will be suggested, considering the safety requirements of high-speed railway. The investigation results of this research would lay the foundation for the intelligent system of running safety for high-speed railway. And the corresponding research findings will contribute to the improvement of the operation safety, intelligence and maintenance of high-speed railway.

受特殊地域与复杂环境影响，不可避免产生的高速铁路桥梁附加变形，随时空变换长期存在且持续发展，势必影响轨道平顺性与行车安全，而目前对该问题的映射影响机理尚不明确。本项目首次从桥梁附加变形与行车安全的动态映射关系角度，提出车辆时频域动力性能影响机理与安全评价准则研究。引入接触约束模量系数和连接层时序演化指数，掌握轨面几何形状的主要映射路径，构建反映层间变形传递机制和联结失效长时影响的桥梁－轨道通用映射模型；结合变形映射模型试验，量化分析形位变化、结构不连续、刚度不均匀等引起的轨面几何形态变化趋势、发展规律和频谱特性；利用高速列车－基础结构系统动力学的研究方法，揭示车辆动力学指标变化量与桥梁附加变形的定量映射关系，依据高速列车安全性要求，提出基于桥梁附加变形指标体系的行车安全评价准则。研究成果可为高速铁路行车安全智能化系统的建立奠定理论基础，对于保障高铁安全运营、提升智能化运维水平具有重要意义。

我国高铁运营里程已达4.2万公里，桥梁平均占比58%。针对高铁桥梁，更应关注轨道上运行列车的安全性和舒适度。尤其影响桥上列车安全舒适运行的轨道“形”和“位”是高铁安全运维领域重点攻克的焦点难题。由于高铁桥梁不可避免地产生桥墩沉降、梁端转角、梁体错台和徐变上拱等多种附加变形，加之轨道结构产生的离缝、脱空、上拱等病害现象，若不掌握桥梁-轨道层间变形协调、逐层映射传递机理，势必导致轨道几何状态恶化和结构“动力型”不平顺，进而通过轮轨动力作用影响列车安全舒适运行。因此，本项目创建了含接触非线性和联结失效长时影响的桥梁-轨道变形映射通用解析模型，阐明了桥梁-轨道变形协调性和跟随性规律，定量化揭示了形位变化、结构不连续和刚度不均匀对轨道平顺性的影响机制；发展了含基础结构长期演变时序性的车-轨-桥耦合振动分析方法，厘清了车体垂向加速度和轮轨垂向力时频响应特征，阐明了典型桥梁附加变形、基础结构性能演变对高速列车时频域动力性能影响规律，揭示了桥墩沉降以及徐变上拱等典型桥梁附加变形与行车安全的动态映射关系；明确了基础结构性能演变对桥梁附加变形阈值的影响规律，细化了不同运行速度等级和层间联结情况下桥墩沉降、梁端转角、梁体错台和徐变上拱等桥上行车安全限值，实现从桥梁变形的角度，提出了一套较完善的多指标桥上行车安全评价准则。研究结果表明：变形映射解析模型能更好地刻画层间界面状态演变对映射路径和变形协调效应的时序影响规律，可供列车-基础结构动力耦合系统使用，大幅降低了计算分析规模；基于动态映射关系和车辆动力学评价指标，提出了桥梁服役安全阈值，桥墩沉降为22.6mm，梁端转角为0.092%rad，梁体错台为7.8mm，徐变上拱为17.2mm；层间联结失效对桥梁变形阈值有显著影响，计算时不可忽略。研究成果促进了高铁桥上行车安全运维理论及方法的逐步形成，有力保障了桥梁-轨道系统的安全服役。