“…However, a complete characterization of the constitutive behavior of geological materials necessitates their examination at multi-scales, including the interactions between grains (i.e., micromechanical response) and the influence of these interactions on the bulk behavior of “granular” systems. For example, previous studies on granular materials have shown a strong dependency of their mechanical response as bulk systems, on the interparticle friction [ 29 , 30 , 31 , 32 , 33 ] and the properties/characteristics of individual grains such as roughness, shape and strength/mode of failure, which influence the energy dissipation mechanisms and the resistance against shearing-induced strains [ 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ]. Multi-scale insights of granular systems can provide a framework to understand the load transfer mechanisms and the flow behavior of particulate materials at a fundamental level [ 36 , 37 , 38 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 ], which are strongly linked to the properties at the grain-scale.…”