Micromechanical modelling of granular materials: Effect of confining prcssure on mechanical behaviour, Mechanics or Materials (accepted with revision

Abstract. In this paper the effects ofmaximum particle size, particle gradation/sorting and fabric on bulk mechanical behaviour of granular materials such as coarse grained soils and rockfilIs are investigated from micromechanical considerations starting from the grain scale level, using numerical simulations based on Discrete Element Modelling (DEM). Hydrostatic compaction and biaxial tests on 2-dimensional assemblies of discs with varying particle sizes and gradations were modelled using DEM. An examination of the constitutive behaviour of granular media considering the particulate nature of the medium has been attempted to explain the effect of particle size and gradation. Simul,\tio!1 results on perlcctly parallel graded assemblies indicate that with increase in the size of the particles, a m,\rginal increase (or no increase) in the angle of internal friction is observed during biaxialloading co!1ditio!1s. A change to a wider grad,\tion ( keeping the minimum grain size the same) results in a decrease in the angle or internal friction and an incre,\se in volumetric strain to a considerable exte!1t. Based On micromech,lnical force a!1dfilbric paramctcrs. the basis f()r the physical bl:haviour was I:stablishl:d. This hl:lps in under-standing the physics or parallel grad,\tion techniqul:s. nent Modelling, micromechanics,Kcy words: granular materials. particle size. Discrl: microstructure. induct:d anisotrop