How disorder can diminish avalanche risks: effect of size distribution.
Résumé
We study the behavior of disk assemblies with a variable disorder distribution. The packing is first consolidated and then continuously tilted very slowly. The amount of displaced disks for each tilted angle is recorded. Large displacements of the disks can occur due to some local or global mechanical instabilities. The definition of neighboring disks is based on radical (extension of Voronoï) tessellation rules to decompose, in a unique and perfectly defined manner, the two-dimensional space for polydisperse disks. In this way, by comparing the characteristics of stability for one disk to the neighboring ones for local ordered cluster, we can predict the global amount of displaced disks. Some tilting cycles have been performed to check the correlation between the instability of the packing structure (collective displacements) with micro and macro order parameters.