X-ray observation of micro-failures in granular piles approaching an avalanche

Alexandre Kabla (1) , Georges Debregeas (2) , Jean-Marc Di Meglio (3, 1) , Tim Senden (1)

1 ANU - Australian National University
2 LPMC - Laboratoire de Physique de la Matière Condensée
3 MSC - Matière et Systèmes Complexes

An X-ray imaging technique is used to probe the stability of 3-dimensional granular packs in a slowly rotating drum. Well before the surface reaches the avalanche angle, we observe intermittent plastic events associated with collective rearrangements of the grains located in the vicinity of the free surface. The energy released by these discrete events grows as the system approaches the avalanche threshold. By testing various preparation methods, we show that the pre-avalanche dynamics is not solely controlled by the difference between the free surface inclination and the avalanche angle. As a consequence, the measure of the pre-avalanche dynamics is unlikely to serve as a tool for predicting macroscopic avalanches.

Mots clés: granular matter

Mots clés: avalanche

Domaines: Matière Molle [cond-mat.soft]; Systèmes désordonnés et réseaux de neurones [cond-mat.dis-nn]

Alexandre Kabla, Georges Debregeas, Jean-Marc Di Meglio, Tim Senden. X-ray observation of micro-failures in granular piles approaching an avalanche. EPL - Europhysics Letters, 2005, 71 (6), pp.932. ⟨10.1209/epl/i2005-10165-4⟩. ⟨hal-00003464⟩