ABSTRACT
Contrary to the dry granular material and suspensions on which a great number of studies have been carried out for years, there are few works related to the direct study of the influence of moisture on the static and dynamic properties of a granular material (Ranaivoson 1988; Fraysse et al. 1997). However the presence of moisture can notably modify the mechanical properties of granular media: adsorbed liquid film on the surface of the grains and capillary liquid bridges at the contact points between the grains strongly affect their interactions compared to the dry case governed by the solid friction law. Capillary forces result in particular in cohesion of the medium (Biarez et al. 1989 & 1993). Effects of lubrication may also intervene. Moisture effects play an important role in many industrial applications based on granular materials. The paper presents an experimental work carried out on an experimental 2D hopper model, developed to allow the observations of the kinematics of glass balls gravity flow under different moisture conditions. The observations were compared with the results derived from a Discrete Elements Method code (PFC 2D, developed by Itasca Consulting Group Inc.), in which the capillary contact forces are taken into account.
