Imaging-based evaluation of material heterogeneity and its impact on strain localization in sand

The effects of spatial material density variation on pre-peak strain non-uniformity and shear band formation in a sand undergoing plane strain compression are investigated. X-Ray Computed Tomography (CT) is used to spatially quantify the extent of an imposed density variation in the form of a loose sand layer embedded in an otherwise dense sand specimen. Digital Image Correlation (DIC) is used to quantify in-plane, local specimen displacements, to grain-scale intensity, throughout plane strain compression. The loose layer is found to attract concentrated straining in the pre-peak regime, and is seen to highly influence the location of the eventual shear band. The results emphasize how clearly the imaging techniques utilized capture these highly localized displacement processes. Such techniques hold extreme promise for advancing understanding of mutli-scale soil behavioral processes.