ABSTRACT
Rockfill behaviour is known to be strongly influenced by water action. Collapse settlements typically occur in rockfill dams, in which the upstream shell is flooded during reservoir filling. Moreover, it seems that in some cases collapse deformations were related to heavy rainfall. With the aim of studying the behaviour of rockfill in non-saturated condition under variable water content, oedometer test were performed on a rockfill-type-material, a quartzitic slate, with control of relative humidity. The main conclusion of this work is that it is enough to impose a 100% relative humidity atmosphere within the rockfill voids in order to get the same collapse strain magnitude as obtained by flooding the specimen. Experimental results are interpreted and a basic mechanism of rockfill volumetric deformation, which is based on some fracture propagation mechanisms, is proposed.
