基于离散元法的铁路道床力学特性

Railway Ballast Bed Mechanical Property Based on Discrete Element Method

摘要:

道砟外形复杂，其几何形态对道床力学行为有显著影响，为揭示道砟模拟方法对道床力学行为的影响规律，针对道砟外形极不规则、咬合作用强的特点，采用自编算法建立了能模拟真实道砟外形的颗粒簇.基于离散元法，分别建立了基本球道砟和颗粒簇道砟的三维道床轨枕空间模型，分析循环荷载下两种道床的接触力、配位数、道床应力和振动加速度的差异.结果表明,相同循环荷载下，颗粒簇道床比基本球道床最大接触力小769 N，平均接触力小10 N，说明颗粒簇接触力幅值范围更小，分布更均匀；基本球配位数在1.0～3.2范围内周期变化，颗粒簇配位数在5.3～6.1范围内周期变化，说明颗粒簇间的接触点更多，接触状态更稳定；颗粒簇道床顶部振动加速度和应力比基本球道床的分别小0.26g，16 kPa，说明颗粒簇能反映道砟间的咬合作用，保持道床的整体受力性.

Abstract:

Shape of ballast is complex. The irregular shape affects the dynamic characteristic of ballast bed significantly. In order to reveal the effects of simulation methods on railway ballast bed mechanical property, a program is compiled to generate cluster to model real ballast according to the characteristics of ballast irregular shape and interlock behavior. Based on discrete element method, the 3 dimenson models of ballast bed and sleeper are established by using sphere ballast and cluster ballast. The paper presents an analysis of the differences of two kinds of ballast bed model under cyclic load on contact force, coordination number, ballast bed stress and acceleration. The results indicate that the maximum contact force of cluster ballast is 769 N smaller than the sphere ballast and the average contact force is less than 10 N, which shows that magnitude contact force of cluster is smaller and its distribution is more uniform. The coordination number of sphere varies within 1.0~3.2 and that of cluster is between 5.3 and 6.1, which suggests that contact point of cluster is larger and its contact state is more stable. The acceleration of the cluster ballast bed top is 0.26g smaller than the sphere and the stress is less than 16 kPa, which proves that cluster can simulate the interlock behavior and maintain the ballast bed integrity.