1 research outputs found
Arches and contact forces in a granular pile
Assemblies of granular particles mechanically stable under their own weight
contain arches. These are structural units identified as sets of mutually
stable grains. It is generally assumed that these arches shield the weight
above them and should bear most of the stress in the system. We test such
hypothesis by studying the stress born by in-arch and out-of-arch grains. We
show that, indeed, particles in arches withstand larger stresses. In
particular, the isotropic stress tends to be larger for in-arch-grains whereas
the anisotropic component is marginally distinguishable between the two types
of particles. The contact force distributions demonstrate that an exponential
tail (compatible with the maximization of entropy under no extra constraints)
is followed only by the out-of-arch contacts. In-arch contacts seem to be
compatible with a Gaussian distribution consistent with a recently introduced
approach that takes into account constraints imposed by the local force balance
on grains.Comment: 7 pages, 7 figures, major revisio