Parameters used in the simulations.

Particle morphology and size are fundamental characteristics that significantly influence the mechanical behavior of granular materials. This study introduces key parameters—aspect ratio (Ω), sphericity (S), and equivalent diameter (Dₑ)—into a modified Hertz-based contact model to conduct a multiscale study using contact mechanics theory and the discrete element method (DEM). A series of two-particle tests and triaxial compression simulations were performed. The results show strong agreement between numerical simulations and theoretical predictions at the particle scale, validating the modified contact model. At the sample scale, the peak deviatoric stress increased by approximately 15–40% as aspect ratio decreased from 1.00 to 0.33 and sphericity decreased from 1.00 to 0.11. Similarly, increasing the equivalent diameter from 3.78 mm to 8.82 mm led to a 20–35% rise in peak stress. At the particle scale, both normal and tangential contact forces increased with larger equivalent diameters but exhibited complex dependencies on morphology due to varied contact patterns. These findings enhance the understanding of how particle-scale characteristics influence macroscopic mechanical properties.颗粒形貌与尺寸是显著影响散粒材料力学行为的核心特征。本研究将长径比（aspect ratio）、球形度（sphericity）与等效直径（equivalent diameter）等关键参数引入改进的基于赫兹理论的接触模型（Hertz-based contact model），结合接触力学理论与离散元法（discrete element method, DEM）开展多尺度研究。本研究开展了一系列双颗粒试验与三轴压缩仿真，结果表明：颗粒尺度下数值仿真与理论预测结果高度吻合，验证了所改进的接触模型的有效性。在试样尺度下，当长径比从1.00降至0.33、球形度从1.00降至0.11时，偏应力峰值提升约15%~40%；同理，将等效直径从3.78 mm增至8.82 mm可使峰值应力升高20%~35%。颗粒尺度下，法向与切向接触力均随等效直径增大而提升，但由于接触模式存在差异，其与颗粒形貌呈现复杂的依赖关系。上述发现深化了对颗粒尺度特征如何影响宏观力学性能的认知。