基于分布式宏应变影响包络线的铁路桥梁刚度快速评估方法研究

Stiffness of railway bridges directly affects the track smoothness of railways, which will lead to deterioration of the track conditions and endanger the safety of train operation. The existed railway bridge verification specification is mainly used for the traveling trains with the maximum speed less than 200km/h, and there are no relevant regulations for the operation and performance evaluation of high-speed railway bridges. Aiming at the shortcomings of existing high-speed railway bridge stiffness and deflection verification, the distributed long gauge strain sensing technology is applied in this project to evaluate and verify the stiffness of bridge superstructure under high-speed train load. Study the method of extracting the distributed macro-strain influence envelope of the bridge under the high speed train loads; On this basis, the mechanical relationship between the macro-strain influence envelope and the bridge stiffness will be studied, and put forward the theory of stiffness verification for bridge superstructure. Study on the rapid detection method of bridge deflection based on distributed macro-strain influence line; give the threshold range of the early earning of the stiffness and deflection of the bridge superstructure through the numerical simulation and experimental study; realize the rapid and automatic evaluation, verification and early warning of the stiffness and deflection of the superstructure of the high speed railway bridge. The research results will provide a new method for rapid detection of superstructure stiffness of high speed railway bridges, and improve the automation level of railway bridge maintenance, which has both value of theory and practice.

铁路桥梁刚度直接影响轨道平顺性，桥梁刚度退化将造成桥梁受很大冲击力，危及列车运行安全。现有铁路桥梁检定规范适用于最高车速小于200km/h的旅行客车既有桥梁检定，缺乏针对高速铁路桥梁运营性能测试评定相关规定。针对现有高速铁路桥梁安全评估存在的不足，本项目拟采用分布式长标距应变传感监测技术，对铁路桥梁上部结构刚度状况进行快速安全评估。研究高速列车荷载作用下桥梁分布式宏应变影响包络线提取方法；在此基础上，研究宏应变影响包络线幅值和桥梁纵向刚度之间的力学关系，提出基于此方法的桥梁上部结构刚度快速评定理论；研究基于分布式宏应变影响线的桥梁挠度快速检定方法；通过数值分析和试验研究，给出桥梁上部结构刚度和挠度预警的阈值，实现对高速铁路桥梁上部结构刚度和挠度的快速、自动化评估及预警。研究成果将为高速铁路桥梁上部结构刚度快速安全评估提供新方法，提高铁路桥梁管养自动化水平，具有理论和实际应用的双重价值。

桥梁结构为高铁路线上的重要组成结构物，如何保证其在运营期间保持良好的健康状态，对保障高铁运输安全畅通具有重要的意义。尤其是在高速铁路桥梁至今已服役10年的背景下，面对大量高速铁路桥梁，快速、有效的进行桥梁的安全监测评估具有重要的工程意义。.针对于传统电阻应变计过于局部、难以捕捉桥梁结构的整体信息和易受电磁干扰等问题，采用高速列车荷载作用下桥梁宏应变影响包络线直接监测评估桥梁刚度以及识别损伤。首先，为了解决监测过程中长标距应变传感器受温度影响的问题，本项目建立了BFRP材料封装的长标距光纤光栅传感器中心波长与环境温度之间的数值模型关系，分析了BFRP材料封装的长标距光纤光栅传感器的灵敏度，并与一般长标距光纤光栅传感器的灵敏度进行了对比，提出了该传感器温度补偿方法，该方法可用于传感器在工程实际监测运用中，排除环境温度变化对传感器长标距应变提取的影响；其次，提出了高速列车荷载下铁路桥梁的分布式宏应变影响包络线的快速提取方法，通过数值模拟，研究了高速列车荷载作用下的桥梁损伤位置、损伤数量对宏应变时程曲线及其时程面积的影响；研究了列车速度对宏应变时程曲线及其时程面积的影响规律，提出了损伤定量分析指标，建立了高速列车荷载作用下基于分布式长标距光纤光栅传感器的刚度监测与损伤识别的方法。最后开展现场实桥测试试验，验证了本文所提方法的可行性。本项目研究成果丰富了现有高铁桥梁安全评估的方法，且光纤光栅技术与应变影响线理论的结合，可实现快速有效的对封闭运营状态下的高铁桥梁精准的刚度监测。

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