# Shape or friction? Which of these characteristics drives the shear strength in granular systems?

Emilien Azéma21 (Institut Universitaire de France)

Estimated H-index: 21

Emilien Azéma21 (Institut Universitaire de France)

Estimated H-index: 21

References31

Influence of the rolling-resistance-based shape of coarse particles on the shear responses of granular mixtures

#1Yangui Zhu (CSU: Central South University)H-Index: 3

#2Zhihong Nie (CSU: Central South University)H-Index: 8

Last. Jian Gong (CSUST: Changsha University of Science and Technology)H-Index: 2

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Abstract Shear responses of dense granular mixtures of spherical coarse particles with the rolling resistance and spherical fine particles are studied via triaxial compression tests using the discrete element method. The macroscale responses (shear strength and dilatancy) are examined. Comparing the results with those in the literature indicates that granular mixtures with a rolling resistance coefficient of 0.5 have similar macroscale responses to those of gravel-shaped coarse particle mixtures...

Combined effects of contact friction and particle shape on strength properties and microstructure of sheared granular media

#1Theechalit BinareeH-Index: 2

#2Emilien AzémaH-Index: 21

Last. Itthichai PreechawuttipongH-Index: 6

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We present a systematic numerical investigation concerning the combined effects of sliding friction and particle shape (i.e., angularity) parameters on the shear strength and microstructure of granular packings. Sliding friction at contacts varied from 0 (frictionless particles) to 0.7, and the particles were irregular polygons with an increasing number of sides, ranging from triangles to disks. We find that the effect of local friction on shear strength follows the same trend for all shapes. St...

New insights into the effect of interparticle friction on the critical state friction angle of granular materials

#1Jian Gong (CSU: Central South University)H-Index: 8

#2Jin-feng Zou (CSU: Central South University)H-Index: 10

Last. Zhihong Nie (CSU: Central South University)H-Index: 8

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Abstract This letter examines the effect of interparticle friction (μ) on the critical state friction angle (φcs) of granular materials via the discrete element method. A series of drained triaxial tests are conducted on multisphere ellipsoids. The results indicate that φcs first increases with μ and then reaches a plateau when μ ≥ 0.3. Anisotropic analysis provides new insights into the underlying mechanisms of the φcs evolution from two perspectives. First, the initial increase of φcs results ...

The intertwined roles of particle shape and surface roughness in controlling the shear strength of a granular material

#1Kieran A. Murphy (U of C: University of Chicago)H-Index: 4

#2Arthur K. MacKeith (U of C: University of Chicago)H-Index: 1

Last. Heinrich M. Jaeger (U of C: University of Chicago)H-Index: 78

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Both the shape of individual particles and their surface properties contribute to the strength of a granular material under shear. Here we show the degree to which these two aspects can be intertwined. In experiments on assemblies of 3D printed, convex lens-shaped particles, we measure the stress–strain response under repeated compressive loading and find that the aggregate’s shear strength falls rapidly when compared to other particle shapes. We probe the granular material at mm-scales with X-r...

Re-recognizing the impact of particle shape on physical and mechanical properties of sandy soils: A numerical study

#1Zhichun Lu (China University of Geosciences)H-Index: 2

#2Aiguo Yao (China University of Geosciences)H-Index: 1

Last. Shan Dong (CDUT: Chengdu University of Technology)H-Index: 1

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Abstract The particle shape created by geological processes is an essential characteristic that determines the physical and mechanical properties of sandy soils. However, the nature of the arbitrary shape and the individual volume of particles in natural sand have been given scant regard. In this study, we constructed a particle flow code (PFC) model using a number of clumps with random irregular shapes (called “Irreg-Sam”), and simulated direct shear tests on silica sand. Further, particle shap...

#1K. Michael Salerno (ARL: United States Army Research Laboratory)H-Index: 12

#2Dan S. Bolintineanu (SNL: Sandia National Laboratories)H-Index: 15

Last. Leonardo E. Silbert (Central New Mexico Community College)H-Index: 23

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The packing and flow of aspherical frictional particles are studied using discrete element simulations. Particles are superballs with shape {|x|}^{s}+{|y|}^{s}+{|z|}^{s}=1that varies from sphere (s=2 to cube (s=\ensuremath{\infty}, constructed with an overlapping-sphere model. Both packing fraction, \ensuremath{\phi} and coordination number, z decrease monotonically with microscopic friction \ensuremath{\mu} for all shapes. However, this decrease is more dramatic for larger s..

#1Frédéric DuboisH-Index: 35

#2Vincent AcaryH-Index: 22

Last. Michel Saint Jean (AMU: Aix-Marseille University)H-Index: 14

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When velocity jumps are occurring, the dynamics is said to be nonsmooth. For instance, in collections of contacting rigid bodies, jumps are caused by shocks and dry friction. Without compliance at the interface, contact laws are not only non-differentiable in the usual sense but also multi-valued. Modeling contacting bodies is of interest in order to understand the behavior of numerous mechanical systems such as flexible multi-body systems, granular materials or masonry. These granular materials...

#1Deshan Cui (China University of Geosciences)H-Index: 5

#2Wei WuH-Index: 56

Last. Jinge Wang (China University of Geosciences)H-Index: 8

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Consolidated undrained triaxial compression tests are conducted on standard cylindrical samples of nearly monodisperse glass beads, initially assembled in a dense state by a funnel pouring technique. Deviator stress, volumetric strain and induced pore air pressure are measured as functions of vertical strain under different confining stress and vertical strain rates. We find that in stick phase the glass beads accumulate energy and regain strength, which can lead to slow sliding in volumetric st...

Periodic boundary conditions of discrete element method-lattice Boltzmann method for fluid-particle coupling

#1Min Wang (Swansea University)H-Index: 10

#2Y.T. Feng (Swansea University)H-Index: 31

Last. T. T. Zhao (Swansea University)H-Index: 1

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This paper presents a periodic boundary condition for the coupled discrete element and lattice Boltzmann method for simulating fluid-particle systems. Detailed implementation of this special boundary condition is given. Besides, the detailed procedure of immersed moving boundary scheme for fluid–solid coupling is proposed. The accuracy and applicability of the proposed periodic boundary condition are well demonstrated by two benchmark tests, i.e. single particle transport and multiple particle m...

#1Yucang Wang (Central Queensland University)H-Index: 16

#2Fernando Alonso-Marroquin (USYD: University of Sydney)H-Index: 19

Last. Jun Xie (CSIRO: Commonwealth Scientific and Industrial Research Organisation)H-Index: 12

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It has long been recognized that the rotation of single particles plays a very important role in simulations of granular flow using the discrete element method (DEM). Many researchers have also pointed out that the effect of rolling resistance at the contact points should be taken into account in DEM simulations. However, even for the simplest case involving two-dimensional circular particles, there is no agreement on the best way to define rolling and sliding, and different definitions and calc...

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