The Effect of Contact Generation on the Elastic Properties of a Granular Medium

Abstract

Previous models for the elastic properties of a granular medium have assumed that all grain contacts are established in its undeformed configuration. Experimental data for the change in elastic properties as a function of confining pressure cannot be explained by these models. Contact creation is cited as one possible cause for this discrepancy. In this paper a model for a granular material is derived that allows for the creation of grain contacts during hydrostatic compression. This formulation allows for the use of general contact microphysics and a general statistical distribution of gap widths at the near-contact points. Numerical results show that for very small values of the average near-contact gaps (approximately 1/1000 of a sphere radius), there can be significant effects occurring in the range of confining pressures between 106 to 107 Pa. The results of this contact generating model are consistent with published experimental measurements.