Numerical Analysis of the Effect of the Rock Particle Size on the Macroscopic Mechanical Properties Under Uniaxial Compression and Shearing

When the distribution characteristics of rock particles are unknown, obtaining reasonable particle size parameters through trial-and-error methods is time-consuming. Therefore, identifying a set of particle size parameters that can accurately reflect the macro-mechanical properties of rock is crucial. In this study, a series of uniaxial compression and direct shear tests were conducted on standard rock models with varying particle sizes and particle size ratios using the discrete element method (DEM). The results indicate that the uniaxial compressive strength, elastic modulus, and shear stiffness increase with decreasing particle size. Conversely, the uniaxial compressive strength, elastic modulus, and shear stiffness decrease as the particle size ratio increases. Based on the simulation results, the accuracy and reliability of numerical simulations can be ensured when the relative average particle size exceeds 50 and the particle size ratio is greater than 1.5. These findings can be applied to other similar numerical studies, thereby reducing the time required for parameter matching and enhancing the efficiency of scientific research.