Compaction Localization in Granular Rocks: Modeling Grain-Size Effects

This paper focuses on the simulation of localized compaction in granular rocks. For this purpose, a continuum framework referred to as Breakage Mechanics is used to capture the role of microscopic crushing on the mechanical response of grain assemblies. In particular, grain size dependencies are introduced by connecting the physics of grain-scale fracture to the energetics of collective crushing. It is shown that this approach enables the simultaneous consideration of changes in grain sorting and average grain size, where the role of the latter is modeled via central splitting and contact fracture laws. Using this constitutive framework, the localization potential of Bentheim sandstone has been studied with the purpose to emphasize the role of grain scale characteristics in the inception of compaction banding. The analyses show that the model captures correctly the increase of the localization potential resulting from a coarser gradation or a narrow grain size distribution.