Compaction of confined mono-sized spherical particle systems under symmetric vibration: a suspension model

Abstract

This paper presents a simulation study on the compaction of confined mono-sized spherical particle systems under symmetric vibration. In the model used, a random loose packing is confined between two fixed random granular boundary conditions and is submitted to symmetric vibrations of constant amplitude until complete transformation into a “suspension”. The granular system is then compacted by letting particles settle down until an equilibrium of minimum potential energy is reached. The influence of the vibration amplitude on the final packing density is studied. The increase in the vibration amplitude leads to an increase in the final packing density. Packing densities ranging from 0.57 up to 0.67 are obtained. For small vibration amplitude a linear relation is found between the final packing density and the vibration amplitude. For large vibration amplitude high packing densities are obtained and an order appears amongst the system. A suspension model is then presented which considers that, in the “suspension”, all the particles can move symmetrically upwards and downwards independently of the displacements of other particles in the system. It is shown that in these conditions, and for random systems, the vibration amplitude can be considered as a homogeneous contraction of the system during sedimentation. A relation is found between the final packing density, initial packing density and vibration amplitude. A very good agreement is obtained between the simulation results and this suspension model as long as the packing is random.