Abstract:A series of Discrete Element Method (DEM) simulations of triaxial compression tests of rockfill materials (RFM) were presented to investigate the mechanical and deformation properties of rockfill,and the sensitivity of some related parameters were also studied.Two different DEM simulation approaches were employed,namely,the spherical-particle model and the sphere-clump model，and particular attention was given to the variation of RFMs strength due to the use of sphere-clumps.For the sphere-clumps model,the influence of microscopic properties of RFMs,such as Young’s modulus and friction angle,had also been examined.According to the deviator stress-axial strain and volumetric strain-axial strain curves,the peak/residual strength,strain,Young’s modulus,and the shear compression/dilation properties were analyzed.This study described how modeling parameters could influence the granular properties.According to the numerical results,as the confining pressure increased from 300 kPa to 1 000 kPa,the peak deviator stress of the spherical-particle model increased from 500 kPa to 1 700 kPa,while for the sphere-clump model,it increased from 1 400 kPa to 3 500 kPa.This trend showed apparent enhancement of shear strength when the sphere-clump model was used in the simulations.As the friction angle increased from 10° to 50°,the peak deviator stress of the sphere-clump model varied from less than 1 000 kPa to 3 250 kPa and the max volume strain increased from 6.5% to 20%.As the Young’s modulus increased from 10⁷ Pa to 10⁹ Pa, the shear strength increased from 1 350 kPa to 2 575 kPa,and the volumetric deformation of the granular sample transformed from shear contraction to dilation.