Discrete element simulations of two wetting effects on granular materials

To explore the microscopic responses of granular materials to wetting, the inter-particle lubrication effect and particle breakage in an odometer were simulated using a two-dimensional discrete element method. The lubrication effect was modeled by reduction of the inter-particle friction coefficient and particle breakage was initiated by decreasing the particle strength. Once the strength of the particles decreased to a threshold value, the particles began to break so that new contacts could be established to transfer the external loads. Numerical simulations successfully reproduced the additional compaction of the material and the intensification of the horizontal stress in addition to the microscopic responses of the granular assemblies. The microscopic interpretation of the earth pressure coefficient at rest and the evolution of the grain number distribution during particle breaking were also investigated.