Volume 110, Number 5, June 2015
|Number of page(s)||6|
|Section||Interdisciplinary Physics and Related Areas of Science and Technology|
|Published online||29 June 2015|
Shear bands as bottlenecks in force transmission
1 Department of Mathematics and Statistics, University of Melbourne - Parkville, Victoria 3010, Australia
2 School of Earth Sciences, University of Melbourne - Parkville, Victoria 3010, Australia
3 Department of Civil Engineering, School of Engineering, University of Portland - Portland, OR 97203, USA
4 Université Grenoble Alpes, 3SR - F-38000 Grenoble, France
5 CNRS, 3SR - F-38000 Grenoble, France
6 Department of Civil and Environmental Engineering, University of Tennessee - Knoxville, TN 37996, USA
Received: 20 December 2014
Accepted: 5 June 2015
The formation of shear bands is a key attribute of degradation and failure in soil, rocks, and many other forms of amorphous and crystalline materials. Previous studies of dense sand under triaxial compression and two-dimensional analogues from simulations have shown that the ultimate shear band pattern may be detected in the nascent stages of loading, well before the band's known nucleation point (i.e., around peak stress ratio), as reported in the published literature. Here we construct a network flow model of force transmission to identify the bottlenecks in the contact networks of dense granular media: triaxial compression of Caicos ooid and Ottawa sand and a discrete element simulation of simple shear. The bottlenecks localise in the nascent stages of loading —in the location where the persistent shear band ultimately forms. This corroborates recent findings on vortices that suggest localised failure is a progressive process of degradation, initiating early in the loading history at sites spanning the full extent, yet confined to a subregion, of the sample. Bottlenecks are governed by the local and global properties of the sample fabric and the grain kinematics. Grains with large rotations and/or contacts having minimal load-bearing capacities per se do not identify the bottlenecks early in the loading history.
PACS: 81.05.Rm – Porous materials; granular materials / 05.10.-a – Computational methods in statistical physics and nonlinear dynamics
© EPLA, 2015
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