Abstract The impact of crushing on the macroscopic mechanical characteristics of granular materials from a microscopic perspective has recently been revealed using the discrete element method (DEM). The influence of the self-organized, mass conservation and volume conservation of daughter particles in the fragment replacement method (FRM) on particle breakage is complex and crucial. In this paper, 14-ball Apollo directly filling method (DFM) and expansion method are combined to keep balance among particles before and after crushing, considered to establish DEM to simulate granular material. By considering the influence of volume loss on the micro-fracture condition of the samples, the macro-responses of mechanical and deformation characteristics, the gradation change and the critical state are studied. The effect of inter-particle interaction on macroscopic properties is also analyzed from the microscopic perspective. The rationality of the volume expansion method is verified. The comparisons of samples with volume conservation and volume loss show that the stress development process and the volumetric strain are affected. The existence of the balance point of volume effect is related to the stress level which lead to the difference in stress and strain. Through analysis of relative breakage index (Br) and the statistical number of microscopic particles, it can be seen that the gradation deviation comes from the two-way influence of the volume loss on the crushing of particles. The volume loss has no effect on stress ratio in the critical state, but has a significant effect on stress change during shearing process, and results in the critical state void ratio to decrease with increasing confining pressure. The rationality of daughter particles’ volume conservation are analyzed from the motion, displacement development and force chain evolution.
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