Effect of realistic shape on grain crushing for rounded and angular granular materials

The deformation characteristics of granular materials in the field of geotechnical engineering largely depends on particle breakage behavior, which remains unresolved to date due to complex grain morphology. In this paper, a combination of experimental and numerical study was conducted to investigate the effect of realistic shape on grain crushing behavior for two groups involving rounded and angular rock grains. A shape library was established after acquirement of grain morphology via three-dimensional scanner, in addition, statistical analysis of grain shape indicates that four indices including sphericity, convexity, inscribed circle sphericity and volume sphericity, are useful for distinguishing shape characteristics of two rock grain groups. The experimental results exhibit a marked difference in force–displacement curve, fragmentation mode and Weibull survival probability for the two rock grain groups, moreover, these results were reproduced by discrete element method (DEM) simulation of grain crushing considering realistic shape. Finally, on the basis of DEM simulation method, deeming the grain shape as the sole variable, its influence on strength distribution was explored by modifying realistic complex shape of grains without altering microscopic mechanical parameters of DEM simulation. A conclusion can be reached that realistic irregular shape enhances grain crushing strength variability, and more angular edges (indicating higher degree of shape irregularity) leads to greater variability of grain crushing strength. Meanwhile, the role of particle microstructure in weakening or strengthening the effect of grain shape was also confirmed. These findings provide a deeper insight into the effect of morphological features on grain crushing behaviours.