Development of image analysis tools to evaluate in-situ evolution of the grain size distribution in sand subjected to breakage

Abstract

Grain crushing is a phenomenon of pivotal importance in the inelastic deformation of granular materials. The progressive evolution of the grain size distribution is known to play a major role in a number of geotechnical engineering problems. There is, however, a lack of experimental work tackling the quantification of the three dimensional evolution of the grain size distribution of materials undergoing grain crushing. The technological advancements in X-ray computed tomography now allow in situ, 4 dimensional (3D + time) images of geomaterials to be obtained as they evolve. While recent investigations of the kinematics of persistent grains have allowed a deeper experimental understanding of some inelastic micro-mechanisms to be obtained, a further effort is required when interpreting tomographic images in which grains are not persistent (i.e., they can break). In this contribution, a novel image-analysis technique under development is proposed to quantify the evolution of the grain size distribution as grain crushing proceeds in an experiment. This technique is applied to the analysis of 3D tomographic images of sand sheared at high confinement.