泥石流冲击下山区铁路车-轨-桥系统动力学行为特性研究

Dynamic behavior characteristics of a train-track-bridge system on mountain railway under debris flow impact

随着全球极端降雨事件愈发常见,复杂艰险山区泥石流灾害发生频次大幅增加,研究泥石流冲击作用下车-轨-桥系统动力学行为特性对保证桥上列车行车安全性具有重要意义。基于光滑粒子流体动力学(smoothed particle hydrodynamics,SPH)理论,建立泥石流冲击桥墩精细化模型,模拟泥石流冲击桥墩动态演化过程,获取泥石流冲击荷载,构建考虑泥石流冲击作用影响的车-轨-桥系统动力学模型,研究泥石流冲击桥墩作用下车辆和桥梁动力学响应变化趋势,探讨泥石流冲击强度和行车速度对桥上列车行车安全性的综合影响,明确桥上列车行车安全阈值。结果表明:SPH方法可以较好地模拟泥石流冲击桥墩动态过程,冲击过程中出现了明显的浆体爬高、回淤等现象;泥石流冲击作用引起桥梁在横向自振频率附近更剧烈的振动,可能加剧桥梁结构的损伤破坏;当泥石流荷载强度超过4.4 MN时,行车速度200 km/h列车的脱轨系数和轮重减载率均超出安全限值;当泥石流荷载强度超过6.2 MN时,行车速度160 km/h列车的轮重减载率超出安全限值,列车运行中可能面临脱轨的风险。研究成果旨在为泥石流灾害发生时桥上列车走行性能评估提供理论依据。

As global extreme rainfall events become increasingly common,the frequency of debris flow disasters in complex and difficult mountainous areas have significantly increased,and it is of great importance to study the dynamic behavior characteristics of a train-track-bridge system under debris flow impact for ensuring the running safety of trains moving on bridge.Based on the theory of smooth particle hydrodynamics(SPH),a refined model of debris flow impact on bridge piers was established to simulate the dynamic evolution process of the debris flow impact,and the debris flow impact loads were obtained.Then,a train-track-bridge system dynamics model considering the effect of debris flow impact was constructed.The changing trends of vehicle and bridge dynamic responses under the debris flow impact were studied,and the comprehensive influences of debris flow impact intensity and train speed on the running safety were investigated,and the safety threshold of trains running on bridge was clarified.The results show that the SPH method can better simulate the process of the debris flow impact on bridge piers,and the obvious phenomena such as slurry climbing and siltation occurring during the impact process.The more severe vibration of the bridge near the lateral natural frequency excited by the impact loads may aggravate the bridge structure damage.When the impact intensity exceeds 4.4 MN,the derailment factor and wheel unloading rate will both exceed the standard safety limit at the trains speed of 200 km/h,and when the impact intensity exceeds 6.2 MN,the wheel unloading rate may exceed the standard safety limit at the trains speed of 160 km/h,the trains passing over the bridge may face derailment risk.The research results aim to provide a theoretical basis for the evaluation of the running performance of trains moving on bridge during debris flow disasters.