Memories in sand: Experimental tests of construction history on stress distributions under sandpiles

Abstract

We report experiments on piles of cohesionless granular materials showing the effect of construction history on static stress distributions. Stresses under piles are monitored by sensitive capacitive techniques. The piles are formed either by pouring granular material from a funnel with a small outlet (localized source), or from a large sieve (homogeneous rain). Localized sources yield stress profiles with a clear stress dip near the center of the pile; the homogeneous rain profiles have no stress dip. We show that the stress profiles scale linearly with the pile height. Experiments on wedge-shaped piles show similar but weaker effects.

Force dynamics in weakly vibrated granular packings

“…In contrast, our tube/sensor assembly is effectively a solid container since the maximal deflection of the piezo is less than 1 nm, which ensures that the measured force variations are intrinsic to the granular medium [7,8,9].…”

Powder Flow Testing with 2D and 3D Biaxial and Triaxial Simulations

“…In both experiments and simulations, the plastic behavior of powder samples depends on the applied strain and on the history of the material [9]. Under bi-or tri-axial deformation, the response of the system is characterized by elastic behavior for very small deformations, softening, plastic yield and critical state flow at large strain.…”

Stress Transmission and Isostatic States of Non-Rigid Particulate Systems

“…Recalling that theories for ideal rigid particles predict stresses that propagate nonuniformly along arches [12,20,25], this explains why such force chains are also observed in packings of compliant particles [3][4][5][6][7][8][9][10][11]. Moreover, since the trajectories of force chains can be predicted in ideal packings [25] then the above suggests that these predictions can be extended to systems of compliant particles.…”

“…Much attention has been given lately to particulate systems both due to their overwhelming technological importance and the fundamental theoretical challenges that they pose [1,2]. In particular the micro-and macro-mechanics have focused research activity following experimental [3][4][5][6][7] and numerical [8][9][10][11] observations of nonuniform stress fields [12]. Specifically, stresses frequently appear to be supported by arch-like regions, termed force chains, that cannot be straightforwardly described by conventional approaches [13][14][15].…”

“…Moreover, since the trajectories of force chains can be predicted in ideal packings [25] then the above suggests that these predictions can be extended to systems of compliant particles. It would be interesting to compare these predictions with the actual trajectories observed in realistic systems, such as those of references [3][4][5][6][7]. Three dimensions.…”