Arches and contact forces in a granular pile

Abstract

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.

7 pages, 7 figures, major revision

References in corpus (8)

• Entropy maximization in the force network ensemble for granular solids
• The tail of the contact force distribution in static granular materials
• Ensemble Theory for Force Networks in Hyperstatic Granular Matter
• Identification of arches in 2D granular packings
• Towards a relevant set of state variables to describe static granular packings
• Packing geometry and statistics of force networks in granular media
• Master curves for the stress tensor invariants in stationary states of static granular beds. Implications for the thermodynamic phase space
• High intensity tapping regime in a frustrated lattice gas model of granular compaction

Cited by in corpus (5)

• Breaking arches with vibrations: the role of defects
• Structure of force networks in tapped particulate systems of disks and pentagons (Part 1): Clusters and Loops
• Bridges in three-dimensional granular packings: experiments and simulations
• Arch-based configurations in the volume ensemble of static granular systems
• Average outpouring velocity and flow rate of grains discharged from a tilted quasi-2D silo