Stress–dilatancy and force chain evolution

Tordesillas, Antoinette; Shi, Jingyu; Tshaikiwsky, Timothy

doi:10.1002/nag.910

Cited by 58 publications

(33 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These force chains are supported laterally by a complimentary weak network of particles [13]. Prior to collapse force chains accumulate stored potential energy and this process continues until the force chains reach their peak load, after which buckling occurs and the force chains experience a loss in load-carrying capacity [14]. Furthermore, Tordesillas & Muthuswamy [15] showed that force chain buckling can be elastic or plastic depending on the state of the contact points.…”

Section: Simulation Parameters and Specimen Generationmentioning

confidence: 99%

“…On the other hand, at low friction some of the strong force chains can yield while others have not reached the limiting value for sliding, hence yielding is more gradual. Earlier research [14] has showed that void spaces are created between the particles in the buckling chain and their laterally supporting neighbours and Only a limited amount of information is provided by scalar measures of the material fabric such as Z. A deeper understanding can be gained using orientation data that can be quantified using the fabric tensor, defined by Satake [11] as:…”

Section: Simulation Parameters and Specimen Generationmentioning

confidence: 99%

See 1 more Smart Citation

The influence of inter-particle friction and the intermediate stress ratio on soil response under generalised stress conditions

2012

View full text Add to dashboard Cite

Previous research studies have used either physical experiments or discrete element method (DEM) simulations to explore, independently, the influence of the coefficient of inter-particle friction () and the intermediate stress ratio (b) on the behaviour of granular materials. DEM simulations and experiments using photoelasticity have shown that when an anisotropic stress condition is applied to a granular material, strong force chains or columns of contacting particles transmitting relatively large forces, form parallel to the major principal stress orientation. The combined effects of friction and the intermediate stress ratio upon the resistance of these strong force chains to collapse (buckling failure) are considered here using data from an extensive set of DEM simulations including triaxial and true triaxial compression tests. For all tests both  and b affected the macroand micro-scale response, however the mechanisms whereby the force chain stability was improved differ. While friction clearly enhances the inherent stability of the strong force chains, the intermediate stress ratio affects the contact density and distribution of orthogonal contacts that provide lateral support to the force chains.

show abstract

Section: Simulation Parameters and Specimen Generationmentioning

confidence: 99%

Section: Simulation Parameters and Specimen Generationmentioning

confidence: 99%

The influence of inter-particle friction and the intermediate stress ratio on soil response under generalised stress conditions

2012

View full text Add to dashboard Cite

show abstract

“…Dilatancy implies that the shear strength partly stems from the work against pressure that is necessarily spent in order to shear the granular material. The idea is often invoked to justify * emilien.azema@univ-montp2.fr † franck.radjai@univ-montp2.fr ‡ jean-noel.roux@ifsttar.fr semiempirical stress-dilatancy relations [4] between ϕ and ψ, which numerical and micromechanical investigations [5][6][7][8][9] sought to support and to relate to internal state characteristics (such as fabric or force chains). In dense granular assemblies subjected to quasistatic shear under constant normal stress σ yy , ϕ, as a function of growing shear strain γ , first increases to a maximum (the peak deviator stress, typically reached for strain γ peak of the order of 10 −2 ), and then decreases to a final plateau (in the so-called critical state of soil mechanics [4]).…”

mentioning

confidence: 99%

“…The properties of frictionless grains might be correctly described by constitutive models involving numerically measured relations between stresses and microscopic variables such as coordination and fabric [46]. They are nevertheless expected to set an important constraint to first-principle approaches attempting to predict internal friction and dilatancy properties from microscopic rheophysical mechanisms [5,8,9] (see [42] for more comments).…”

mentioning

confidence: 99%

Internal friction and absence of dilatancy of packings of frictionless polygons

2015

View full text Add to dashboard Cite

By means of numerical simulations, we show that assemblies of frictionless rigid pentagons in slow shear flow possess an internal friction coefficient (equal to 0.183 ± 0.008 with our choice of moderately polydisperse grains) but no macroscopic dilatancy. In other words, despite side-side contacts tending to hinder relative particle rotations, the solid fraction under quasistatic shear coincides with that of isotropic random close packings of pentagonal particles. Properties of polygonal grains are thus similar to those of disks in that respect. We argue that continuous reshuffling of the force-bearing network leads to frequent collapsing events at the microscale, thereby causing the macroscopic dilatancy to vanish. Despite such rearrangements, the shear flow favors an anisotropic structure that is at the origin of the ability of the system to sustain shear stress. One of the most basic properties of slowly deformed solidlike granular materials is their dilatancy, i.e., their propensity to change volume under shear strain (or, more generally, deviatoric strain). In particular, initially dense granular assemblies will dilate under shear, and since its introduction by Reynolds in 1885 [1], this property is regarded as stemming from steric constraints [2], as one may expect from the naive image of Fig. 1, often relied upon in pedagogical documents.In simple shear (see Fig. 1), with the convention that shrinking strains are positive, this property is conveniently expressed by dilatancy angle ψ, defined through the ratio of normal expansion rate −˙ yy to shear rateγ :This angle may be regarded as the kinematic dual of the friction angle ϕ or friction coefficient μ * , defined as the ratio of shear stress to normal stress (coordinates are defined as in Fig. 1):An alternative definition of a friction angle ϕ relies on principal stresses σ 1 > σ 2 , mean stress p = (σ 1 + σ 2 )/2, and deviator q = (σ 1 − σ 2 )/2:Definitions of ϕ in (2) and (3) coincide within the MohrCoulomb model (which does not exactly apply to granular materials [3]). Dilatancy implies that the shear strength partly stems from the work against pressure that is necessarily spent in order to shear the granular material. The idea is often invoked to justify * emilien.azema@univ-montp2.fr † franck.radjai@univ-montp2.fr ‡ jean-noel.roux@ifsttar.fr semiempirical stress-dilatancy relations [4] between ϕ and ψ, which numerical and micromechanical investigations [5][6][7][8][9] sought to support and to relate to internal state characteristics (such as fabric or force chains). In dense granular assemblies subjected to quasistatic shear under constant normal stress σ yy , ϕ, as a function of growing shear strain γ , first increases to a maximum (the peak deviator stress, typically reached for strain γ peak of the order of 10 −2 ), and then decreases to a final plateau (in the so-called critical state of soil mechanics [4]). Meanwhile, ψ, often negative in a small initial strain interval, increases to a positive maximum (reached near γ peak ), and then decreases...

show abstract

“…Many numerical studies employ the discrete element method (DEM) for this particular problem (e.g., Ferdowsi et al, 2013;Morgan, 2004;Tordesillas et al, 2011), a numerical technique that is ideally suited to investigate the behavior of aggregates with a large number of degrees of freedom. By implementing the appropriate physical interactions between particles, DEM can be employed to simulate 10.1029 and generalize the complex behavior observed in the laboratory, and test hypotheses regarding the mechanisms of stick-slips.…”

Section: Introductionmentioning

confidence: 99%

Time-dependent compaction as a mechanism for regular stick-slips

Ende¹,

Niemeijer²

2018

Preprint

View full text Add to dashboard Cite

Owing to their destructive potential, earthquakes receive considerable attention from laboratory studies. In friction experiments, stick-slips are studied as the laboratory equivalent of natural earthquakes, and numerous attempts have been made to simulate stick-slips numerically using the discrete element method (DEM). However, while laboratory stick-slips commonly exhibit regular stress drops and recurrence times, stick-slips generated in DEM simulations are highly irregular. This discrepancy highlights a gap in our understanding of stick-slip mechanics, which propagates into our understanding of earthquakes. In this work, we show that regular stick-slips emerge in DEM when time-dependent compaction by pressure solution is considered. We further show that the stress drop and recurrence time of stick-slips are directly controlled by the kinetics of pressure solution. Since compaction is known to operate in faults, this mechanism for frictional instabilities directly relates to natural seismicity. Plain Language SummaryEarthquakes have a big impact on the society and are therefore intensively studied in laboratory settings. The study of laboratory-scale earthquakes, the so-called stick-slips, generates new insights into the origin and behavior of earthquakes in nature. At present, computer simulations of stick-slips have not been able to reproduce prominent laboratory observations, which shows that the origin of stick-slips, and of natural earthquakes, is not yet fully understood. In this work, we present computer simulations that succeed to reproduce the laboratory observations, thereby revealing that time-dependent compaction is of great importance to stick-slips and natural earthquakes. These results help to further understand the complex behavior of earthquakes in nature.

show abstract

Stress–dilatancy and force chain evolution

Cited by 58 publications

References 53 publications

The influence of inter-particle friction and the intermediate stress ratio on soil response under generalised stress conditions

The influence of inter-particle friction and the intermediate stress ratio on soil response under generalised stress conditions

Internal friction and absence of dilatancy of packings of frictionless polygons

Time-dependent compaction as a mechanism for regular stick-slips

Contact Info

Product

Resources

About