Railway Ballast Bed Mechanical Property Based on Discrete Element Method

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.

Key words:discrete element method; cluster; contact force; coordination number; dynamic response