Planar collapse of a granular column: Experiments and discrete element simulations

Lacaze, Laurent; Phillips, Jeremy C.; Kerswell, Rich R.

doi:10.1063/1.2929375

Cited by 127 publications

(87 citation statements)

References 30 publications

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“…Both Staron and Hinch [36] and Zenit [44] focused on the final deposition profiles with little insight on the collapse mechanism. Lacaze et al [17] carried out DEM simulations with good agreement with the experimental results, both in terms of flow behaviour and run-out distance. However, the authors commented on the necessity of investigating the influence of multi-sized particles.…”

Section: Simulating the Column Collapsementioning

confidence: 99%

The role of constitutive models in MPM simulations of granular column collapses

Fern

Soga

2016

Acta Geotech.

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The granular column collapse is a well-established experiment which consists of having a vertical column of granular material on a flat surface and letting it collapse by gravity. Despite its simplicity in execution, the numerical modelling of a column collapse remains challenging. So far, much attention has been dedicated in assessing the ability of various numerical methods in modelling the large deformation and little to the role of the constitutive model on both the triggering mechanism and the flow behaviour. Furthermore, the influence of the initial density, and its associated dilatancy and strength characteristics, have never been included in the analyses. Most past numerical investigations had relied on simple constitutive relations which do not consider the softening behaviours. The aim of this study is to illustrate the influence of the constitutive model on the on-set of failure, the flow behaviour and the deposition profile using the material point method. Three constitutive models were used to simulate the collapse of two granular columns with different geometries and for two densities. The results of the simulations showed that the constitutive model had a twofold influence on the collapse behaviour. It defined the volume of the mobilised mass which spread along the flat surface and controlled the dissipation of its energy. The initial density was found to enhance the failure angle and flow behaviours and was more significant for small columns than for larger ones. The analysis of the potential energy of the mobilised mass explained the existence of two collapse regimes.

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Section: Simulating the Column Collapsementioning

confidence: 99%

The role of constitutive models in MPM simulations of granular column collapses

Fern

Soga

2016

Acta Geotech.

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“…The same problem has been also investigated in a two dimensional geometry, the so-called dam-break problem. [8][9][10][11][12][13] In this case the granular material is initially confined by a wall, which is suddenly removed. The observed scaling characterizing the deposit morphology is different from the axisymmetric case but the aspect ratio remains the relevant parameter, as long as the channel is wide enough to prevent additional frictional effects on the side walls.…”

Section: Introductionmentioning

confidence: 99%

“…9 The granular collapse has been also studied using numerical simulations based on discrete element methods, allowing a precise study of the internal structure of the flow. [13][14][15][16] From a theoretical point of view, the spreading has been described using depth averaged equations. [17][18][19] Although the initial stage of the flow does not fulfill the gentle slope approximation dictated by the depth averaged approach, this approach succeeds in predicting the scaling observed for aspect ratio less than one.…”

Section: Introductionmentioning

confidence: 99%

Granular collapse in a fluid: Role of the initial volume fraction

2011

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The collapse of a granular column in a viscous liquid is experimentally investigated. The morphology of the deposits is shown to be mainly controlled by the initial volume fraction of the granular mass and not by the aspect ratio of the column, an observation which differs from dry granular collapse. Two different regimes are identified corresponding to initially loose and dense packings. Loose packings give rise to thin and long deposits, the dynamics being fast. A positive liquid pressure is measured below the column. For dense packings, the runout distance is twice less, the flow is slow, and a negative pore pressure is measured during the flow. These observations suggest that the dynamics of the granular collapse in a fluid is strongly affected by the dilatancy or contractancy behavior of the granular medium.

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“…As a matter of fact, many numerical studies addressed the granular column released problem using typically three different approaches: shallow-type models (Mangeney-Castelnau et al, 35 Kerswell, 27 Larrieu et al, 32 and Doyle et al 12 ), Discrete Element Methods (DEM) (Staron and Hinch, 51 Zenit, 54 Lacaze et al, 29 and Girolami et al 16 ), and complete viscousplastic or elasto-plastic models (Crosta et al, 8 Lacaze and Kerswell, 28 Meruane et al, 40 Lagrée et al, 30 and Ionescu et al 24 ).…”

Section: Introductionmentioning

confidence: 99%

Continuum viscoplastic simulation of a granular column collapse on large slopes: μ(I) rheology and lateral wall effects

et al. 2017

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We simulate here dry granular flows resulting from the collapse of granular columns on an inclined channel (up to 22°) and compare precisely the results with laboratory experiments. Incompressibility is assumed despite the dilatancy observed in the experiments (up to 10%). The 2-D model is based on the so-called μ(I) rheology that induces a Drucker-Prager yield stress and a variable viscosity. A nonlinear Coulomb friction term, representing the friction on the lateral walls of the channel, is added to the model. We demonstrate that this term is crucial to accurately reproduce granular collapses on slopes ≳10°, whereas it remains of little effect on the horizontal slope. Quantitative comparison between the experimental and numerical changes with time of the thickness profiles and front velocity makes it possible to strongly constrain the rheology. In particular, we show that the use of a variable or a constant viscosity does not change significantly the results provided that these viscosities are of the same order. However, only a fine tuning of the constant viscosity (η=1 Pa s) makes it possible to predict the slow propagation phase observed experimentally at large slopes. Finally, we observed that small-scale instabilities develop when refining the mesh (also called ill-posed behavior, characterized in the work of Barker et al. [“Well-posed and ill-posed behaviour of the μ(I)-rheology for granular flow,” J. Fluid Mech. 779, 794–818 (2015)] and in the present work) associated with the mechanical model. The velocity field becomes stratified and the bands of high velocity gradient appear. These model instabilities are not avoided by using variable viscosity models such as the μ(I) rheology. However we show that the velocity range, the static-flowing transition, and the thickness profiles are almost not affected by them.

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Planar collapse of a granular column: Experiments and discrete element simulations

Cited by 127 publications

References 30 publications

The role of constitutive models in MPM simulations of granular column collapses

The role of constitutive models in MPM simulations of granular column collapses

Granular collapse in a fluid: Role of the initial volume fraction

Continuum viscoplastic simulation of a granular column collapse on large slopes: μ(I) rheology and lateral wall effects

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