Failure of geomaterials assessed using an extended discrete element method

Abstract

Strength and failure of geomaterials is investigated using an extended discrete element method (DEM). A rock material is modelled using spherical particles bonded by breakable force elements. An inflation procedure to generate dense sphere packings which is based on the particle's current coordination number is proposed. The particle bonds are enhanced by a progressive failure model that reproduces the effects of singular stress concentrations near crack tips, which are normally not present in DEM, by successive weakening of bonds. The material model is investigated in uni- and triaxial compression, where an efficient approach for simulation of flexible confining is applied, and calibrated to granite yielding wide agreement in strength and failure. A procedure to model shape and angularity of ballast particles is proposed. The strength of ballast stones made from bonded particles is subjected to statistical evaluation and compared to published experiments. Different measures for single particle strength are investigated with respect to the loading state which causes failure. © 2010 Civil-Comp Press.