Grainsize dependence of clastic yielding in unsaturated granular soils

Abstract

We use a recent reformulation of the Breakage Mechanics theory explaining comminution in wet granular assemblies. By using a dataset for sands, we quantify the relationbetweenageometricdescriptoroftheassembly(i.e., the mean grainsize) and the model constants that control the suction air-entry value and the stress threshold at the onset of crushing. Such relations are used to define two contrast- ing scenarios for the coupling between degree of saturation and yielding. In the first scenario, the suction air-entry value scales inversely with the mean grainsize, while the energy input for comminution is assumed to be independent of the size of the particles. The outcome of this assumption is that changes in degree of saturation are predicted to play a more intense role in finer gradings. Conversely, if we assume that alsotheenergy input forgrainbreakage scalesinversely with the size of the particles, the effect of the degree of saturation is predicted to be stronger in coarser assemblies. In other words, the deterioration of the yielding stress due to grain-