青藏铁路列车行驶冻土场地路基振动荷载研究

基于青藏铁路现场振动监测成果检验自编列车-轨道耦合动力学仿真程序的正确性，并研究在实测里程高低不平顺与宽轨缝脉冲性激扰条件下的青藏铁路客车行驶引起冻土场地路基振动的振动荷载特性。研究表明，自编程序仿真结果与青藏铁路现场监测成果吻合良好，程序理论正确结论可信；列车行驶振动荷载随路基阻尼的增大而略微减小，随路基模量、列车行驶速度的增大而增大，随轨缝的增宽而线性增大；振动荷载优势频段主要在移动轴重作用率内，转向架作用率处振动能量最大，轨枕振动对列车行驶振动荷载影响较小；路基的冻融状态、轨缝宽度与列车行驶速度对冻土路基振动荷载影响不能忽略；并定量给出青藏铁路路基振动荷载最大值与列车行驶速度之间的函数关系。此项研究对于列车行驶引起冻土场地环境振动分析与振陷预测具有重要意义，且为轨道交通工程设计和铁路运营安全分析提供可靠的理论依据。

The investigation of train-induced vibratory load exerted on the permafrost subgrade along Qinghai-Tibet Railway

Based on the filed monitoring of subgrade structure vibration along Qinghai-Tibet Railway, the self-programming software of the train-track coupled dynamic interaction was validated, and simultaneously the characteristics of permafrost subgrade vibration induced by passenger trains were investigated in view of the observed track profile irregularity and the impulsive excitation of broad rail gap. The researches show that, the simulation results of the self-compiling program are in accord with the field monitoring data, and the theory of the procedure is proper; the train-induced vibratory load is in inverse proportion to the subgrade damping, and increases with the raising of the subgrade modulus and vehicle velocity, at the same time increases linearly with the rise of the rail gap; the dominant frequency bands are mainly within the action rate of shifting axle load, the vibratory energy reaches the maximum at the bogie action rate, and the sleeper vibration makes little different to the vibratory load induced by passing trains; the effects of the freeze thawing status, rail gap width, and the train speed can not be ignored on the subgrade vibration. Moreover, the function relationship of the subgrade vibratory maximum value versus train velocity is given quantificationally. The research has great significance on the train-induced ambient vibration analysis and subgrade subsidence prediction in permafrost site, furthermore, provides the rational theoretical foundation for the rail traffic engineering design and railway operation safety analysis.