Granular dynamics at the approach of the critical state
type: Dataset
description: The granular dynamics leading to the avalanche is of interest in understanding the destabilization conducting to one. Its study implies a good train of throught in the understanding of more complex mechanisms such as geophysical disasters (earthquakes, landslides, rockslides). Thus, when a three-dimensional granular medium under gravity is quasi-statically tilted, precursors are observed from the tilt of ten degrees before the avalanche. These precursors correspond to collective rearrangements of grains observed on the free surface which appear pseudo-periodically with the angle of inclination. In order to understand this phenomenon, the thesis presents an experimental characterisation of the precursors detected on the surface by optical method and in the bulk by acoustic methods (linear and nonlinear). Firstly, good correlations were found between the surface and bulk rearrangements which led to extending the study with a non-exhaustive list of parameters affecting the precursors properties. The surface features of the grains have appeared to be particularly crucial in the precursors dynamics. Finally, an attempt at a description of the destabilization is approached with the measurement of the variation of the elastic parameters revealing that precursors of avalanches correspond to successive loss of rigidity of the system, followed by hardening of the latter.
identifier: NNT: 2013REN1S128
issued: 2026-05-05T15:13:02.189340
language: fr
modified: 2026-05-05T15:13:02.189345
contact point: Organization
  fn: CCSD
keyword: acoustics
keyword: acoustique
keyword: avalanche
keyword: critical-state
keyword: destabilisation
keyword: destabilization
keyword: etat-critique
keyword: etat-de-surface
keyword: granular-medium
keyword: infoeu-reposemanticsdoctoralthesis
keyword: milieu-granulaire
keyword: physcondcm-genphysics-physicscondensed-matter-cond-matother-cond-matother
keyword: precurseur
keyword: precursor
keyword: stick-slip
keyword: surface-features
keyword: theses
keyword: unjamming
landing page: https://theses.hal.science/tel-00977530

Granular dynamics at the approach of the critical state
type: Distribution
format: HTML
issued: 2026-05-05T15:13:02.201852
modified: 2026-05-05T15:13:02.173569
access URL: https://theses.hal.science/tel-00977530

test_moissonnage_selune
type: Agent