Micro-morphological changes in granular soils

The idea of relating the mechanical macro-behaviour of granular soils to their micro-mechanics has received increasing attention during the last two decades. The association of the yielding and failure of granular soils to particle breakage has been the principal concept in many of these studies. However, particle breakage is not the only micro change that occurs at the particle scale and changes to shape or surface topography can also occur during compression or shearing. Particle breakage does however contribute to significant changes in the shape of particles or their surface topography either through catastrophic breakage such as splitting or through minor breakage of asperities. In spite of their importance, these micro changes have not been fully examined due to the difficulty of finding a quantitative way to define them. In this paper the micro-morphological changes associated with compression and shearing of a silica sand are monitored. Important shape factors such as the sphericity, aspect ratio, convexity and roughness of particles are monitored. The findings indicate that in addition to stress level effects, different types of loading can lead to distinctive changes at the particle scale, a finding which might need to be considered in future DEM studies. © 2011 Taylor & Francis Group.