Discrete element modelling of yielding and normal compression of sand

McDowell, G. R.; Harireche, Ouahid

doi:10.1680/geot.52.4.299.41018

Cited by 30 publications

(18 citation statements)

References 13 publications

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“…3.7.4). Furthermore, both McDowell and Harireche [23] and Cheng et al [24] obtained qualitatively valid compression curves, without introducing any 'size-hardening law' for the fragments in their simulations. Based on this, but notwithstanding the improper size effect on grain strength, the use of the same 3 macrograins (D macro = 2 − 3 − 4 mm) multiple times-as a module-in the oedometer was deemed appropriate.…”

Section: Size Effect On Grain Strengthmentioning

confidence: 89%

“…(Oedometer dimensions of D oed ≥ 10 · D max and h oed ≥ 5 · D max are suggested for representative results in real tests. In contrast, Cheng et al [24] simulated the crushing of silica sand with an oedometer of D oed = h oed = 6.66 · D max , while McDowell and Harireche [23] arrived at qualitatively valid results even with D oed = h oed = 2.5 · D max ). The oedometric test comprised 2 main phases: the specimen preparation phase and the compression phase.…”

Section: Evolution Of Grain Crushing Under Oedometric Compressionmentioning

confidence: 96%

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Grain crushing and high-pressure oedometer tests simulated with the discrete element method

Laufer¹

2015

Granular Matter

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The present paper investigates the influence of microstructural inhomogeneities of brittle grains on grain crushing in cohesionless, frictional granular materials, using the discrete element method. Macrograins are modelled as assemblies of bonded micrograins of different sizes and bond strengths to simulate crushed sandstone. A method is suggested to incorporate fracture mechanical properties in the model through the selection of bond properties. Normal distribution of bond strengths, as well as degraded bonds are assumed to simulate bond defects. Their effects are first examined through single macrograin crushing tests. Then monotonic oedometer compression tests on macrograin ensembles are simulated for a wide range of pressures and different initial void ratios. The paper also explores the applicability of Bauer's macroscopic compression law to the results of simulations of monotonic, oedometric compression tests. Correlations between the properties of individual macrograins, such as crushing strength and bonding defects, and the properties of the grain ensemble, such as granular hardness and grain size distribution are investigated.

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Section: Size Effect On Grain Strengthmentioning

confidence: 89%

Section: Evolution Of Grain Crushing Under Oedometric Compressionmentioning

confidence: 96%

Grain crushing and high-pressure oedometer tests simulated with the discrete element method

Laufer¹

2015

Granular Matter

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“…A number of authors argued that the existence of asymptotic states is directly linked to particle crushing [2,7,8,[43][44][45]65]. Using DEM simulations, the existence of normal compression lines was explained by particle crushing in references [2,7,8,44,65].…”

Section: Introductionmentioning

confidence: 99%

“…Using DEM simulations, the existence of normal compression lines was explained by particle crushing in references [2,7,8,44,65]. Cheng et al [7,8] predicted both critical states and normal compression lines, using the same parameter sets, creating a more complete picture of the granular material behaviour.…”

Section: Introductionmentioning

confidence: 99%

Asymptotic behaviour of granular materials

Maš́ın

2012

Granular Matter

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The concept of the asymptotic behaviour of particulate materials is described, including its enhancement by considering asymptotic states in extension. A 3D discrete element model with elastic spherical particles and the granulometry of a real sand is set up. The numerical sample is stretched from different initial states, and the influence of the strain rate direction on the final state is studied within the stress ratio, void ratio and mean stress space. Asymptotic behaviour is clearly observed, although the grains remain intact (no grain crushing is considered). The extension asymptotic states are observed, and the notion of a normal extension line is introduced. The extension asymptotic states coincide with the peak states observed in the shear tests with constant stress path direction in dense samples.

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“…Discrete element models (Cundall and Strack, 1979), wherein the particles are modelled as discrete bodies interacting via contact relations are likely to be more appropriate for modelling the deformation of cermets. These approaches have been successfully used to predict the yielding and dilation of soils during confined compression (McDowell and Harireche, 2002;Powrie et al, 2005) as well as the uniaxial deformation of asphalt (Cai et al, 2013;Collop et al, 2007;Wu et al, 2011). However, there have been no reported attempts of discrete element models for cermets.…”

mentioning

confidence: 99%

Deformation mechanisms of idealised cermets under multi-axial loading

Bele

Goel

Pickering

et al. 2017

Journal of the Mechanics and Physics of Solids

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The response of idealised cermets comprising approximately 60% by volume steel spheres in a Sn/Pb solder matrix is investigated under a range of axisymmetric compressive stress states. Digital volume correlation (DVC) analysis of X-ray microcomputed tomography scans (μ-CT), and the measured macroscopic stress-strain curves of the specimens revealed two deformation mechanisms. At low triaxialities the deformation is granular in nature, with dilation occurring within shear bands. Under higher imposed hydrostatic pressures, the deformation mechanism transitions to a more homogeneous incompressible mode. However, DVC analyses revealed that under all triaxialities there are regions with local dilatory and compaction responses, with the magnitude of dilation and the number of zones wherein dilation occurs decreasing with increasing triaxiality. Two numerical models are presented in order to clarify these mechanisms: (i) a periodic unit cell model comprising nearly rigid spherical particles in a porous metal matrix and (ii) a discrete element model comprising a large random aggregate of spheres connected by non-linear normal and tangential "springs". The periodic unit cell model captured the measured stress-strain response with reasonable accuracy but under-predicted the observed dilation at the lower triaxialities, because the kinematic constraints imposed by the skeleton of rigid particles were not accurately accounted for in this model. By contrast, the discrete element model captured the kinematics and predicted both the overall levels of dilation and the simultaneous presence of both local compaction and dilatory regions with the specimens. However, the levels of dilation in this model are dependent on the assumed contact law between the spheres. Moreover, since the matrix is not explicitly included in the analysis, this model cannot be used to predict the stress-strain responses. These analyses have revealed that the complete constitutive response of cermets depends both on the kinematic constraints imposed by the particle aggregate skeleton, and the constraints imposed by the metal matrix filling the interstitial spaces in that skeleton.

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Discrete element modelling of yielding and normal compression of sand

Cited by 30 publications

References 13 publications

Grain crushing and high-pressure oedometer tests simulated with the discrete element method

Grain crushing and high-pressure oedometer tests simulated with the discrete element method

Asymptotic behaviour of granular materials

Deformation mechanisms of idealised cermets under multi-axial loading

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