Manifestation of particle morphology on the mechanical behaviour of granular ensembles

Kandasami, Ramesh Kannan; Murthy, Tejas G.

doi:10.1007/s10035-017-0703-z

Cited by 36 publications

(8 citation statements)

References 43 publications

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“…The steady value of repose angle is close to 42 0 . By comparing with the hollow cylinder experiments [6] carried out for a 'b'(intermediate principal stress ratio) value of 0.4 (which corresponds to plane strain conditions) on the sand used in our experiments, we observe that the repose angle of the pile is very close to the critical state friction angle obtained using the hollow cylinder tests under similar boundary conditions.…”

Section: Resultssupporting

confidence: 58%

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An experimental study on shear bands in sand using the orthogonal cutting setup

Hegde

Murthy

2021

EPJ Web Conf.

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We study the evolution of shear bands in granular media subjected to very large deformations using the orthogonal cutting geometry. We perform our cutting experiments on Cauvery Delta sand with d50 of 0.45mm. We also capture images of the cutting process which allows us to perform a PIV analysis to determine the deformation in material around the cutting tool. In our experiments we observe that the dynamic angle of repose of the pile that forms in-front of the tool as cutting progresses, approaches the critical state friction angle of the material. We observe a flow bifurcation around the tool as the material begins to slip along planes which are oriented at an angle of π/4 – θ/2, θ being the dynamic angle of repose, to the cutting direction. This leads to formation of shear bands/velocity jumps which contain around 14 particles. A measurement of dilation angle within the shear bands indicate that material is in a critical state of deformation.

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Section: Resultssupporting

confidence: 58%

“…In this paper, we have performed experiments on Cauvery Delta sand with a d 50 of 0.45mm. The physical as well as mechanical properties of this granular material has been studied extensively by [6]. The sand grains are angular with a roundness(R) value of 0.17.…”

Section: Materials Usedmentioning

confidence: 99%

An experimental study on shear bands in sand using the orthogonal cutting setup

Hegde

Murthy

2021

EPJ Web Conf.

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“…However, along with grain size, the strength properties of the granular media are strongly linked to the shape of grains. It has been shown in both numerical and experimental studies that grain shape has a nontrivial effect upon packing and shear properties of granular materials [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. For instance, the grains presenting the more angular shapes (in opposition to rounded) do not show the highest shear strengths as one could expect.…”

Section: Introductionmentioning

confidence: 99%

Microstructural analysis of sheared polydisperse polyhedral grains

2020

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This article presents an analysis of the shear strength of numerical samples composed of polyhedra presenting a grain size dispersion. Previous numerical studies using, for instance, disks, polygons, and spheres, have consistently shown that microstructural properties linked to the fabric and force transmission allow granular media to exhibit a constant shear resistance although packing fraction can dramatically change as a broader grain-size distribution is considered. To have a complete picture of such behavior, we developed a set of numerical experiments in the frame of the discrete element method to test the shear strength of polydisperse samples composed of polyhedral grains. Although the contact networks and force transmission are quite more complex for such generalized grain shape, we can verify that the shear strength independence still holds up for 3D regular polyhedra. We make a particular focus upon the role of different contact types in the assemblies and their relative contributions to the granular connectivity and sample strength. The invariance of shear strength at the macroscopic scale results deeply linked to fine compensations at the microstructural level involving geometrical and force anisotropies of the assembly.

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“…The nonconvergence of compression paths (NCLs and CSLs) has been acknowledged when describing the constitutive behavior of sand, and the published literature has introduced the term transitional to describe this mode of behavior (Nocilla et al 2006). Several studies have demonstrated that the transitional behavior of sand is caused by particle breakage (Altuhafi and Coop 2011;Shipton and Coop 2012;Xiao et al 2015), inherent effects of a specimen's initial density state (Coop 2015;Shipton and Coop 2012;Xiao et al 2016;Xu and Coop 2017), the complex morphology of natural sand particles (Alshibli and Cil 2018;Kandasami and Murthy 2017;Santamarina and Cho 2004;Yang and Luo 2015), influences of grain size distribution (Altuhafi et al 2010;Altuhafi and Coop 2011), variation in the mineralogy of sand-fine mixtures (Ponzoni et al 2017;Shipton and Coop 2015), and the percentage of fine content in sand specimens (Kwa and Airey 2016;Zuo and Baudet 2015). The transitional behavior of sand has also been attributed to the strong forms of microscale fabric that are difficult to break even at high applied strains.…”

Section: Introductionmentioning

confidence: 99%

Discrepancy in the Critical State Void Ratio of Poorly Graded Sand due to Shear Strain Localization

Imseeh

Alshibli

Al-Raoush

2020

J. Geotech. Geoenviron. Eng.

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The critical state (CS) concept is a theoretical framework that models the constitutive behavior of soils, including sand and other granular materials. It supports the notion of a unique postfailure state, where the soil ultimately experiences continuous shearing with no change in the plastic volumetric strain. However, the published literature has frequently noted the nonconvergence of sand specimens with different initial densities to a unique CS in the compression plane due to many factors such as specimen fabric, particle morphology, breakage, and grain size distribution. This paper examines the CS for poorly graded (uniform) glass beads and 3 different types of silica sands using 50 conventional triaxial compression (CTC) experiments, 12 oedometer tests, and in situ synchrotron microcomputed tomography (SMT) scans for 10 CTC experiments. The results of the 50 CTC experiments revealed a diffused CS zone in the compression plane, which was further examined using the in situ SMT scans. A thorough three-dimensional image analysis of the SMT scans accurately quantified the evolution of the local void ratio (e local ) versus axial compression within zones of intensive shearing toward the center of the specimen. The evolution of the void ratio was also measured using the entire volume of the specimen (e global ). At the CS, the e local =e global ratio was assessed to be ∼1.25 when a single shear band developed within the scanned specimens and ∼1.1-1.15 for specimens that failed via external bulging that was internally manifested by the development of multiple shear bands. This finding suggests that the CS zone in the compression plane can be attributed to the common wrong consideration of e global evolution in lieu of e local within the developing shear bands. Furthermore, the lack of shear band development in uniaxial compression has made the results of the oedometer test reliable in quantifying the CS parameters in the compression plane.

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Manifestation of particle morphology on the mechanical behaviour of granular ensembles

Cited by 36 publications

References 43 publications

An experimental study on shear bands in sand using the orthogonal cutting setup

An experimental study on shear bands in sand using the orthogonal cutting setup

Microstructural analysis of sheared polydisperse polyhedral grains

Discrepancy in the Critical State Void Ratio of Poorly Graded Sand due to Shear Strain Localization

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