Puzzling behaviors concerning the flow of granular media have been reported, such as large fault slippage during earthquakes, the unexpected apparent viscosity during crater formation by meteorite impacts, or landslides with unusually large runouts. These observations have been attributed to frictional softening due to self-induced vibrations or noise by the material flow. To investigate the physical origin of the sensitivity of these systems to vibrations, we study the dynamics of avalanche angles in a granular material model subjected to external vibrations. The experiment is performed in a rotating drum, subjected to tiny horizontal vibrations. The role of vibration frequency and amplitude on avalanche onset angles and angle of repose is investigated. Experiments suggest that there exists an energy scale associated to the particle asperities controlling avalanche triggering. Some applications of granular avalanches and flows in chilean copper mining are presented.
Accès Salle des séminaires FAST-LPTMS (Bât. 530, salle C.120, 1er)