Dense flows of cohesive granular materials

Rognon, Pierre; Roux, Jean‐Noël; Naaïm, Mohamed; Chevoir, François

doi:10.1017/s0022112007009329

Cited by 157 publications

(187 citation statements)

References 82 publications

(140 reference statements)

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“…Chaudhuri et al, 2006;Sarkar and Wassgren, 2010) or environmental applications such as avalanche dynamics (e.g. Rognon et al, 2008;Faug et al, 2009). However, to our knowledge, discrete elements have never been used to model crack propagation in layered systems or to describe slab avalanche release processes.…”

Section: Motivation and Objectivesmentioning

confidence: 99%

Modeling of crack propagation in weak snowpack layers using the discrete element method

Gaume¹,

Herwijnen²,

Chambon

et al. 2015

The Cryosphere

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Abstract. Dry-snow slab avalanches are generally caused by a sequence of fracture processes including (1) failure initiation in a weak snow layer underlying a cohesive slab, (2) crack propagation within the weak layer and (3) tensile fracture through the slab which leads to its detachment. During the past decades, theoretical and experimental work has gradually led to a better understanding of the fracture process in snow involving the collapse of the structure in the weak layer during fracture. This now allows us to better model failure initiation and the onset of crack propagation, i.e., to estimate the critical length required for crack propagation. On the other hand, our understanding of dynamic crack propagation and fracture arrest propensity is still very limited.To shed more light on this issue, we performed numerical propagation saw test (PST) experiments applying the discrete element (DE) method and compared the numerical results with field measurements based on particle tracking. The goal is to investigate the influence of weak layer failure and the mechanical properties of the slab on crack propagation and fracture arrest propensity. Crack propagation speeds and distances before fracture arrest were derived from the DE simulations for different snowpack configurations and mechanical properties. Then, in order to compare the numerical and experimental results, the slab mechanical properties (Young's modulus and strength) which are not measured in the field were derived from density. The simulations nicely reproduced the process of crack propagation observed in field PSTs. Finally, the mechanical processes at play were analyzed in depth which led to suggestions for minimum column length in field PSTs.

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Section: Motivation and Objectivesmentioning

confidence: 99%

Modeling of crack propagation in weak snowpack layers using the discrete element method

Gaume¹,

Herwijnen²,

Chambon

et al. 2015

The Cryosphere

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“…Discrete Element Method (DEM) simulations are used to investigate the system at micro (partial) and macro level. In order to quantify the intensity of cohesion, a variation of the granular Bond number [50,54,55] is introduced. We find that this dimensionless number very well captures the transition from a gravity/shear-dominated regime to the cohesion-dominated regime.…”

Section: Introductionmentioning

confidence: 99%

Effect of cohesion on shear banding in quasistatic granular materials

et al. 2014

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It is widely recognized in particle technology that adhesive powders show a wide range of different bulk behavior due to the peculiarity of the particle interaction. We use Discrete Element simulations to investigate the effect of contact cohesion on the steady state of dense powders in a slowly sheared split-bottom Couette cell, which imposes a wide stable shear band. The intensity of cohesive forces can be quantified by the granular Bond number (Bo), namely the ratio between maximum attractive force and average force due to external compression. We find that the shear banding phenomenon is almost independent of cohesion for Bond numbers Bo < 1, but for Bo ≥ 1 cohesive forces start to play an important role, as both width and center position of the band increase for Bo > 1. Inside the shear band, the mean normal contact force is always independent of cohesion and depends only on the confining stress. In contrast, when the behavior is analyzed focusing on the eigen-directions of the local strain rate tensor, a dependence on cohesion shows up. Forces carried by contacts along the compressive and tensile directions are symmetric about the mean force (larger and smaller respectively), while the force along the third, neutral direction follows the mean force. This anisotropy of the force network increases with cohesion, just like the heterogeneity in all (compressive, tensile and neutral) directions.

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“…The present communication investigates those phenomena by discrete element simulations in quasistatic conditions. Such a situation, with loose systems, has hardly been addressed by numerical means, as the recent literature rather explored dynamic compaction [4,5], gravity deposition [6], steady flows [7], or denser materials [8,9]. We introduce a simple model material and report on its consolidation properties, in relation to its microstructure, thus presenting a brief account of studies published in two recent papers [10,11], to which a section with new results on the resistance to tension is added.…”

Section: Introductionmentioning

confidence: 99%

Discrete simulation of model, loose cohesive powders: plastic consolidation, fractal microstructure and tensile strength

Gilabert¹,

Roux²,

Castellanos³

2009

AIP Conference Proceedings

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Abstract. Isotropic packings of cohesive disks in 2D are studied by discrete, stress-controlled numerical simulations. Depending on the assembling process and on whether contacts possess rolling resistance (RR), configurations form under low pressure P with varying solid fraction Φ and fractal dimension d F describing small scale correlations below some blob size ξ . The gradual collapse observed under growing P is described as a linear relation between ln P and 1/Φ within some range, once the influence of initial conditions has faded out, and until a maximum density is approached. This corresponds to a decrease of ξ that is compatible with the fractal blob model. The isotropic tensile strength is always considerably smaller than the naive Rumpf estimate, and grows with consolidation. Coordination numbers in systems with small RR change little while density increases by large amounts in consolidation.

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Dense flows of cohesive granular materials

Cited by 157 publications

References 82 publications

Modeling of crack propagation in weak snowpack layers using the discrete element method

Modeling of crack propagation in weak snowpack layers using the discrete element method

Effect of cohesion on shear banding in quasistatic granular materials

Discrete simulation of model, loose cohesive powders: plastic consolidation, fractal microstructure and tensile strength

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