Granular structure and heterogeneous deformation preceding avalanches
Abstract
Granular packings undergo intermittent rearrangements, known as precursors, before avalanche onset. Using grain-scale tracking in an inclined granular layer, we show experimentally that the number and recurrence of precursors change with the compatibility between the anisotropic structure inherited from preparation and the subsequent loading direction. Preparation also modifies the propagation of the mobility front, defined as the region in which the packing undergo measurable displacement: frequent precursors produce small progressive advances, whereas rare precursors involve larger extensions. By contrast, several features remain unchanged across protocols. The ensemble-averaged displacement always decays exponentially with depth over approximately four grain diameters, while the local shear-strain variance follows a common quadratic scaling with the mean strain. A two-state model suggests that, regardless of the packing structure, local strain heterogeneities affect approximately one quarter of the elementary cells, superimposed on the exponential strain profile. The reported results separate preparation-dependent precursor activity from the robust spatial features of the deformation preceding avalanches.
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BibTeX
@misc{awada2026granular,
title = {{Granular structure and heterogeneous deformation preceding avalanches}},
author = {Ibrahim Awada and Michel Bornert and Vincent Langlois and Julien Léopoldès},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.21531},
eprint = {2609.21531},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.21531},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Granular structure and heterogeneous deformation preceding avalanches
AU - Ibrahim Awada
AU - Michel Bornert
AU - Vincent Langlois
AU - Julien Léopoldès
PY - 2026
DA - 2026/09/18
PB - arXiv
DO - 10.48550/arxiv.2609.21531
UR - https://arxiv.org/abs/2609.21531
AB - Granular packings undergo intermittent rearrangements, known as precursors, before avalanche onset. Using grain-scale tracking in an inclined granular layer, we show experimentally that the number and recurrence of precursors change with the compatibility between the anisotropic structure inherited from preparation and the subsequent loading direction. Preparation also modifies the propagation of the mobility front, defined as the region in which the packing undergo measurable displacement: frequent precursors produce small progressive advances, whereas rare precursors involve larger extensions. By contrast, several features remain unchanged across protocols. The ensemble-averaged displacement always decays exponentially with depth over approximately four grain diameters, while the local shear-strain variance follows a common quadratic scaling with the mean strain. A two-state model suggests that, regardless of the packing structure, local strain heterogeneities affect approximately one quarter of the elementary cells, superimposed on the exponential strain profile. The reported results separate preparation-dependent precursor activity from the robust spatial features of the deformation preceding avalanches.
ER -