The grain effect of intact rock modelling using discrete element method with Voronoi grains

A comprehensive investigation of grain effect (size and distribution) in discrete element modelling of intact rock is carefully conducted through simulating Brazilian disc and uniaxial compressive tests on an intact rock using Universal Distinct Element Code. All the investigations are performed based on the same group of material parameters. Six sizes of Voronoi tessellation grains ranging from 1 to 6 mm are investigated. To investigate the influence of grain assemblage distribution, five different polygonal grain assemblages are created and tested for uniaxial compression and Brazilian disc tests. The simulation results demonstrate that grain size and assemblage distribution play a significant role in the numerical modelling of intact rock using discrete element method. It is found that larger particle size produces higher stiffness and strength. It is also observed that a more homogeneous model can produce higher strength (compressive strength, tensile strength). The modelled Young’s modulus and Poisson’s ratio have been demonstrated to be dependent on the grain effect.