Mesoscopic Analysis of the Compaction Characteristics of Rockfill Materials Considering Gradation and Shape

The development of high rockfill dams has imposed greater demands on the compaction quality of rockfill materials. However, because rockfill particles are subjected to crushing under the compaction of a high-powered roller, the rockfill compaction characteristics might be affected. In this paper, a 3D discrete element model of the rockfill compaction process under vibration force was established to investigate the compaction characteristics and the mesoscopic mechanism of rockfill, considering gradation, shape, and particle breakage. The results showed that the geometric accuracy of rockfill particles is well maintained with 30-surface polyhedrons based on SHAPE simplification. The rockfill material with larger aspect ratios showed a larger final cumulative settlement ratio, while those with larger d50 showed a smaller ratio. Due to the combined effects of compaction and particle breakage, the porosity of the surface rockfill particles decreased more rapidly. As the settlement ratio increased and the porosity decreased, the coordination number of the rockfill material increased. In general, the average velocity of particle movement increased with decreasing particle size during compaction.