Packing geometry and statistics of force networks in granular media

Abstract

The relation between packing geometry and force network statistics is studied for granular media. Based on simulations of two-dimensional packings of Hertzian spheres, we develop a geometrical framework relating the distribution of interparticle forces P(f) to the weight distribution P}(w), which is measured in experiments. We apply this framework to reinterpret recent experimental data on strongly deformed packings, and suggest that the observed changes of P(w) are dominated by changes in contact network while P(f) remains relatively unaltered. We furthermore investigate the role of packing disorder in the context of the q-model, and address the question of how force fluctuations build up as a function of the distance beneath the top surface.