Exploring the effects of gravel shapes on vibration compaction behaviours of coarse-grained mixtures via DEM simulations

Abstract

ABSTRACT Coarse-grained mixtures composed of coarse gravels and fine sands are widely used in subgrade constructions, coarse gravels of which contain rubbles and pebbles with different roundness (R d). To investigate the effect of gravel shapes on the compaction behaviours of subgrades, the real-shaped gravel particles with varying R d (0.2–0.5) were selected to establish coarse-grained mixtures models via the discrete element method (DEM). The contact parameters in DEM models were determined through a series of calibration tests, and the reliability of models was verified by vibration compaction tests with rubble-grained and pebble-grained mixtures. The evolutions of porosity, particle motion, and contact relationship affected by R d were revealed from the macro-and mesoscales, and the influence of R d on the stability of skeleton structures is discussed. As R d decreases, the contact number tends to increase and the distribution of strong contacts is more uniform, the skeleton structure in which can effectively inhibit the motion of fine particles and the sliding between coarse particles. Conversely, the increase in R d will cause the concentration of strong contacts, which further results in the sliding damage of skeleton structures and the improvement of compaction deformation.