Fine Modelling of Ballast Grains and Influence on Mechanical Properties of Track Bed

The track bed was simulated with the discrete element method.The model of bonded ballast particles clumps was established to model real ballast particles.The ballasts box model was built for the track bed composed of ballasts of diversified gradation and different grain shapes.The influence of gradation and grain shapes on the mechanical properties of the track bed was analyzed.The results show as follows:The reasonably graded track bed has better mechanical properties than a track bed of single-size grains;under the condition that ballast grain shapes are the same,a track bed of a wider range of gradation has better mechanical properties but has a lower porosity;grain shapes affect the mechanical properties of the track bed significantly,regular grain shapes degrade the mechanical properties of the track bed obviously.