Effects of particle shape on triaxial compression behaviours of realistic ballast particles based on M-A-V-L particle shape evaluation system

The particle shape has a significant influence on the mechanical behaviour of granular materials. Based on a new particle shape evaluation system M-A-V-L, this paper studies the effect of the M-value (a particle shape index) on the macro and micro triaxial compression behaviours of granular material via DEM modelling. Firstly, 1500 digital models of realistic ballast particles were obtained by white-light scanning. Then, the M-values of all the particles were calculated, and five groups of particles with different M-values (M = 1.5, 2.0, 2.5, 3.0, 3.5) were selected. There are five particles in each group. Subsequently, the evolution of macro and micro mechanical behaviours (such as void ratio, deviatoric stress ratio, coordination number, etc.) for samples with different M-values were analysed based on triaxial compression tests. Moreover, the relationship between M-values and mechanical behaviours for samples at both peak state and critical state were studies. Finally, by analysing the stress-force-fabric (SFF) relationship, the origin of shear strength related to M-values was revealed from the perspective of the fabric anisotropy.