SIMULATION OF THE QUASI-STATIC MECHANICS AND SCALAR TRANSPORT-PROPERTIES OF IDEAL GRANULAR ASSEMBLAGES

The current article reports on the further development of a new techni que for the computer simulation of the quasi-static mechanics and scal ar transport properties of sphere assemblages. In an extension of a pr evious 2D simulation to 3D, we have developed an improved computation based on several innovations: a shuffling algorithm to rapidly generat e random loose-packed configurations of particles; a microcell-adjacen cy method to accelerate particle-contact search; a relaxation method t o overcome singularities in the static transport equations; and a simu lated mechanical compression to generate dense random initial states. The improved algorithm allows for 3D simulations on a workstation plat form. As major results, the dilatancy (volume expansion) computed for random dense-packed assemblages is found to depend on interparticle fr iction, contrary to the classical Reynolds hypothesis. Also, the use o f linear-elastic contacts is found to be valid near the rigid-particle limit of interest here. Experimental data from (''triaxial'' compress ion) tests agree well with the simulations of both the shear strength and the electrical conductivity of sphere assemblages, when proper acc ount is taken of the actual electrical contact resistance between stee l balls as a function of load. One major conclusion is that scalar tra nsport can serve as a useful macroscopic probe of particle-contact top ology in granular media. (C) 1995 Academic Press, Inc.