道砟非均匀分布对道床力学特性的影响

Effect of Uneven Ballast Distribution on Mechanical Characteristics of Ballast Bed

铁路道床机械清筛作业中,分次回填道砟颗粒会导致道砟分层,出现非均匀分布现象。为了解道砟非均匀分布对道床力学特性的影响,基于离散单元法基本原理,生成有砟道床仿真模型,模拟道砟均匀分布、“上大下小”分层分布、“上小下大”分层分布等3种道床工况,分析3种道床工况在捣固作业和稳定作业中的力学特性变化。结果表明:道砟非均匀分布对道床力学特性产生影响,其中道床密实度特性受道砟分布状态影响较小,而道床垂向刚度和横向阻力特性则受道砟分布状态影响较大。在捣固作业中,道砟“上小下大”分层分布最有利于道床垂向刚度提升。在稳定作业中,道砟“上大下小”分层分布最有利于道床横向阻力提升。道砟颗粒流动则是使得道床垂向刚度和横向阻力提升的重要因素。

During the mechanical cleaning operation on ballast bed,backfilling ballast in batches would lead to a layered and uneven ballast distribution.To reveal the effect of uneven ballast distribution on the mechanical properties,the simulation model of ballast bed was generated based on the basic principle of discrete element method.Then three kinds of ballast layering distributed conditions were simulated in the model,the uniform distribution,"large upper and small lower"distribution and"small upper and large lower"distribution,respectively.And the mechanical characteristics of ballast bed during the tamping operation and the stabilizing operation were analyzed.The results show that the uneven ballast distribution has impact on the mechanical properties of ballast bed.The compactness of ballast bed is less affected,while the vertical stiffness and the lateral resistance are obviously affected.During the tamping operation,the"small upper and large lower"ballast distribution is most conducive to improve the vertical stiffness.While during the stabilizing operation,the"large upper and small lower"ballast distribution is most conducive to improve the transverse resistance.The flow of ballast particles is an important factor to improve the vertical stiffness and the lateral resistance of ballast bed.