Dynamic validation of a discrete element code in modeling rock fragmentation

A discrete element code has been developed to simulate dynamic behavior of rock materials, particularly rock fragmentation upon impact in rock-fall analysis. Dynamic compression tests at a lower strain rate regime ((epsilon) over dot < 0.2s(-1)) and Split Hopkinson Pressure Bar tests at a higher strain rate regime ((epsilon) over dot > 10.0s(-1)) have been performed to validate the discrete element code. The dynamic strength and fragment size distribution of the tested granite showed clear strain rate dependence; the dynamic strength of granite increases with strain rate and a higher strain rate loading tends to produce more fragments. It has been found that the developed discrete element code can reasonably simulate the dynamic behavior in terms of strain rate dependent dynamic strength but not fragment size distribution. The strain rate dependent dynamic strength of granite can be explained as an inertial effect, in which material inertia inhibits crack propagations. The experimental fragment size distribution can be well represented by a two-parameter Weibull distribution. (C) 2011 Elsevier Ltd. All rights reserved.