Influence of the rolling-resistance-based shape of coarse particles on the shear responses of granular mixtures
Shear responses of dense granular mixtures of spherical coarse particles with the rolling resistance and spherical fine particles are studied via triaxial compression tests using the discrete element method. The macroscale responses (shear strength and dilatancy) are examined. Comparing the results with those in the literature indicates that granular mixtures with a rolling resistance coefficient of 0.5 have similar macroscale responses to those of gravel-shaped coarse particle mixtures. We quantify the microscale responses including the percentage contributions of contact types, partial coordination number, average particle rotation, average degree of interlocking, and local structural properties. A detailed analysis of the force–fabric anisotropy reveals the mechanisms of the variations in the shear strength with the rolling resistance coefficient and the fines content. The mechanism of the variation in the shear strength with the fines content for granular mixtures with a rolling resistance coefficient of 0.5 is different from that for gravel-shaped coarse particle mixtures. Finally, we find that a rolling resistance linear model weakens the linear relationship between the stress ratio and the fabric anisotropy of strong and non-sliding contacts when the fines content is 30% and 40%.
Keywords: Granular mixture, Rolling resistance, Particle shape, Fines content, Macroscale and microscale responses, Anisotropy