PARTIAL PRESSURES SUPPORTED BY GRANULOMETRIC CLASSES IN POLYDISPERSE GRANULAR MEDIA

A packing of particles subjected to an cedometric compression displays a large distribution of interparticle contact forces. The latters are correlated with the particle size. Using the principle of virtual wor k, we relate the ''partial'' pressure supported by a granulometric cla ss of particles to a purely geometrical problem, namely, the solid fra ction of a polydisperse granular medium as a function of its granulome try. We apply in particular this result to the case of bimodal packing s and we show that the partial pressure is larger for the small partic les in three dimensions, whereas a size independence is predicted in t wo dimensions. Two-and three-dimensional numerical simulations confirm these results.