Breakage in quasi-static discrete element simulations of ice rubble

Abstract

Breakage of particles plays a key role in force transmission in granular materials. Discrete element method (DEM) simulations are often used to model granular materials, but modeling particle breakage in them remains a challenge. Models for breakage of non-spherical particles are scarce and often the existing models are computationally heavy to be used in simulations with large numbers of particles. To address this, the present study develops a particle breakage model for quasi-static DEM simulations of non-spherical particles that fail due to shear. The model is novel, since it is based on experimental observations and high resolution modeling. Breakage models based on experimental evidence are rare as it is often virtually impossible to gain detailed data on the mechanisms related to breakage. The developed particle breakage model was integrated into a DEM code and direct shear box experiments on ice rubble, a granular material consisting of ice particles, were then simulated. Accounting for particle breakage in DEM simulations improved their accuracy: simulations were compared to experiments and the results were found to be in better agreement when particle breakage was taken into account. The effect of particle breakage on the shear strength of a granular material was found to be independent of particle size, decreasing fast with increasing particle strength. The combined effect of shear box length and breakage was also studied. The results showed that the strength of a granular material may be determined reasonably well with a shear box that has a box to particle length ratio greater than 60.