高速铁路碎石道砟振动的离散元模拟

A discrete element simulation of high-speed railway ballast vibration

道砟振动对其磨损、破碎和道床累积变形有显著影响,为揭示高速车辆移动荷载作用下道砟动态响应特性,建立有砟道床离散元模型,开展车辆-轨道耦合动力学计算得到离散元模型输入荷载,模拟分析高速车辆以不同速度通过时有砟道床的振动响应,并与车辆-轨道耦合动力学计算结果进行对比分析。结果表明,轨枕、道砟和道床块振动位移波形相似,位移幅值沿道床深度方向减小,道床块振动位移与轨枕底面以下0.3m处道砟的振动位移相当;轨枕、道床块振动速度与加速度随行车速度提高而增大;受道砟颗粒间复杂相互作用的影响,道砟振动加速度会出现突变。道床离散元模型能合理反映道砟颗粒的振动响应特性,道床块模型体现了道床层在有砟轨道结构中的动力传递与减振特性,两种道床模型的计算结果具有一定的相似性。

Ballast vibration has remarkable impact on its wear,breakage and the ballast bed cumulative deformation.In order to reveal dynamic response characteristics of railway ballasts under the high-speed vehicle moving loads,firstly,a ballasted track discrete element model was built,and the input loads was obtained from railway vehicle-track coupled dynamic simulation.Then,vibration responses of the sleepers and ballast particles were calculated considering various vehicle travel speeds,meanwhile,the discrete element simulated results were compared to those of the railway vehicle-track coupled dynamics.Numerical results show that the vibration displacement responses of the sleepers,the ballast particles and the ballast-bed blocks present similar curve shape;the corresponding displacement amplitudes decrease gradually along the track depth direction.The vibration displacement of the ballast-bed block is very close to that of the ballast particle 0.3 m below the sleeper bottom.The vibration velocities and accelerations of the sleepers,the ballast-bed blocks increase with the vehicle travel speed, but the ballast vibration acceleration occurs unpredicted change due to the complex interplay among the ballast particles.The ballast discrete element model can reflect reasonably the particle vibration characteristics,while the ballast-bed block model does embody the force transfer and vibration attenua-tion characteristics of the ballasted track structure,so the calculation results from both models are consistent with each other.