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Jotaki, Tomosada; Moriyama, Ryuichi

doi:10.4164/sptj.16.184

Cited by 39 publications

(16 citation statements)

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“…When confronted with the experimental data [1,2] one sees a serious drawback of this explanation: the data show a scaling behaviour which the model cannot support. The observed scaling (called RSF scaling, see Sec.…”

Section: Related Modelling Workmentioning

confidence: 99%

“…Some of the simplest questions one can ask about this system concern the distribution of stresses in the pile. Specifically, it is possible experimentally to measure the downward force on the supporting surface at different positions under the pile [1,2]. (Throughout the paper we assume this to be a high friction surface so that slip does not occur at it.)…”

Section: Introductionmentioning

confidence: 99%

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Stress propagation and Arching in Static Sandpiles

1997

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We present a new approach to the modelling of stress propagation in static granular media, focussing on the conical sandpile constructed from a point source. We view the medium as consisting of cohesionless hard particles held up by static frictional forces; these are subject to microscopic indeterminacy which corresponds macroscopically to the fact that the equations of stress continuity are incomplete -no strain variable can be defined. We propose that in general the continuity equations should be closed by means of a constitutive relation (or relations) between different components of the (mesoscopically averaged) stress tensor. The primary constitutive relation relates radial and vertical shear and normal stresses (in two dimensions, this is all one needs). We argue that the constitutive relation(s) should be local, and should encode the construction history of the pile: this history determines the organization of the grains at a mesoscopic scale, and thereby the local relationship between stresses. To the accuracy of published experiments, the pattern of stresses beneath a pile shows a scaling between piles of different heights (RSF scaling) which severely limits the form the constitutive relation can take; various asymptotic features of the stress patterns can be predicted on the basis of this scaling alone. To proceed further, one requires an explicit choice of constitutive relation; we review some from the literature and present two new proposals. The first, the FPA (fixed principal axes) model, assumes that the eigendirections (but not the eigenvalues) of the stress tensor are determined forever when a material element is first buried. (This assumes, among other things, that subsequent loadings are not so large as to produce slip deep inside the pile.) A macroscopic consequence of this mesoscopic assumption is that the principal axes have fixed orientation in space: the major axis everywhere bisects the vertical and the free surface. As a result of this, stresses propagate along a nested set of archlike structures within the pile, resulting in a minimum of the vertical normal stress between the apex of the pile, as seen experimentally ("the dip"). This experiment has not been explained within previous continuum approaches; the appearance of arches within our model corroborates earlier physical arguments (of S. F. Edwards and others) as to the origin of the dip, and places them on a more secure mathematical footing. The second model is that of "oriented stress linearity" (OSL) which contains an adjustable parameter (one value of which corresponds to FPA). For the general OSL case, the simple interpretation in terms of nested arches does not apply, though a dip is again found over a finite parameter range. In three dimensions, the choice for the primary constitutive relation must be supplemented by a secondary one; we have tried several, and find that the results for the stresses in a three dimensional (conical) pile do not depend much on which secondary closure is chosen. Three dimensional result...

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Section: Related Modelling Workmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stress propagation and Arching in Static Sandpiles

1997

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“…In deposits formed under the action of gravity, this particular stress transmission leads to characteristic phenomena such as the pressure dip below the apex of a pile [5,6], or the Janssen effect [7], i.e., pressure saturation in silos. Moreover, it is well known [8][9][10] that these phenomena strongly depend on the packing formation history.…”

Section: Introductionmentioning

confidence: 99%

Influence of the feeding mechanism on deposits of square particles

et al. 2013

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In a previous paper [Hidalgo et al., Phys. Rev. Lett. 103, 118001 (2009)] it was shown that square particles deposited in a silo tend to align with a diagonal parallel to the gravity, giving rise to a deposit with very particular properties. Here we explore, both experimentally and numerically, the effect on these properties of the filling mechanism. In particular, we modify the volume fraction of the initial configuration from which the grains are deposited. Starting from a very dilute case, increasing the volume fraction results in an enhancement of the disorder in the final deposit characterized by a decrease of the final packing fraction and a reduction of the number of particles oriented with their diagonal in the direction of gravity. However, for very high initial volume fractions, the final packing fraction increases again. This result implies that two deposits with the same final packing fraction can be obtained from very different initial conditions. The structural properties of such deposits are analyzed, revealing that, although the final volume fraction is the same, their micromechanical properties notably differ.

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“…Point sources are interesting because they appear often in industrial settings and in experiments dealing with, for example, the stress distribution under the pile [3][4][5][6][7][8][9]11,12]. Obviously, since point source is a limiting case of area source, it can be used as an additional check of the geometrical picture given in Figure 2.…”

Section: Point Source Density and Contact Number Of Monodisperse Heapsmentioning

confidence: 99%

“…One may easily list a series of complex granular phenomena that have attracted recurring interest over the years, e.g. studies addressing major effects like the characterization of the stress dip under the pile [3][4][5][6][7][8][9][10][11][12], avalanching behavior [13][14][15][16], segregation by size [17][18][19], creep motion deep in the pile [20] and the remarkable properties discovered in the growth of grain piles by revolving rivers [21][22][23][24][25][26], and many others [27][28][29][30][31][32]. The majority of studies presently available mainly explores properties of twodimensional (2D) heaps of grains.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of large three-dimensional heaps of particles produced by ballistic deposition from extended sources

Topić

Gallas

Pöschel

2013

Philosophical Magazine

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This paper reports a detailed numerical investigation of the geometrical and structural properties of three-dimensional heaps of particles. Our goal is the characterization of very large heaps produced by ballistic deposition from extended circular dropping areas. First, we provide an in-depth study of the formation of monodisperse heaps of particles. We find very large heaps to contain three new geometrical characteristics: they may display two external angles of repose, one internal angle of repose, and four distinct packing fraction (density) regions. Such features are found to be directly connected with the size of the dropping zone. We derive a differential equation describing the boundary of an unexpected triangular packing fraction zone formed under the dropping area. We investigate the impact that noise during the deposition has on the final heap structure. In addition, we perform two complementary experiments designed to test the robustness of the novel features found. The first experiment considers changes due to polydispersity. The second checks what happens when letting the extended dropping zone to become a point-like source of particles, the more common type of source.

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Cited by 39 publications

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Stress propagation and Arching in Static Sandpiles

Stress propagation and Arching in Static Sandpiles

Influence of the feeding mechanism on deposits of square particles

Characteristics of large three-dimensional heaps of particles produced by ballistic deposition from extended sources

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