Experimental breakage mechanics of confined granular media across strain rates and at high pressures

Abstract

Many constitutive models employed for modeling granular materials have recently incorporated the evolution of the particle size distribution (PSD) using a relative breakage variable. While these models have been successful in many applications, data to validate them across strain rates and at pressures exceeding several hundred megapascals remains scarce. In this paper, we therefore use confined uniaxial strain experiments performed in an oedometer, a drop tower, and a split-Hopkinson bar to study the compaction of Ottawa sand across strain rates and at high pressures. We provide some of the first data quantifying particle breakage up to several gigapascals. We also use in-situ acoustic emissions measurements to study deformation mechanisms active throughout the compaction process during low strain-rate experiments. Our results indicate the presence of three stages of compaction, within which the granular material exhibits a distinct breakage rate and lateral pressure coefficient. The transition pressures between the three stages vary as a function of strain rate. Finally, we show that a well-known breakage mechanics constitutive model can capture material response up to several hundred megapascals, but is unable to capture higher-pressure responses.