Volume 104, Number 4, November 2013
|Number of page(s)||6|
|Section||Condensed Matter: Structural, Mechanical and Thermal Properties|
|Published online||11 December 2013|
Crossover from quasi-static to dense flow regime in compressed frictional granular media
1 Institut des Sciences de la Terre, CNRS-Université Joseph Fourier, Grenoble - 1381 rue de la Piscine, BP 53, 38041 Grenoble Cedex 9, France
2 Laboratoire de Glaciologie et de Géophysique de l'Environnement, CNRS-Université Joseph Fourier, Grenoble 54 rue Moliere, BP 96, F-38402 Saint- Martin d'Hères Cedex, France
3 Seismological Laboratory, California Institute of Technology - 1200 E. California Blvd., Pasadena, CA 91125, USA
Received: 6 May 2013
Accepted: 15 November 2013
Being ubiquitous in a large variety of geomaterials, granular assemblies play a crucial role in the mechanical stability of engineering and geophysical structures. For these applications, an accurate knowledge of the processes at the origin of shear localization, i.e. faulting, in frictional granular assemblies submitted to compressive loading is needed. Here we tackle this problem by performing discrete-element numerical simulations. A thorough analysis of the evolution of multi-scale mechanical properties as approaching sample macroscopic instability is performed. Spatial correlations operating within the shear stress and strain fields are analyzed by means of a coarse-graining analysis. The divergence of correlation lengths is reported on both shear stress and strain fields as approaching the transition to sample instability. We thus show that the crossover from a quasi-static regime where the sample deforms infinitely slowly to a dense flow regime, where inertial forces play a significant role, can be interpreted as a critical phase transition. At this transition, no shear band of characteristic thickness can be defined.
PACS: 62.20.-x – Mechanical properties of solids / 64.60.De – Statistical mechanics of model systems (Ising model, Potts model, field-theory models, Monte Carlo techniques, etc.) / 91.60.Ba – Elasticity, fracture, and flow
© EPLA, 2013
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