The impact of particle form on the packing and shear behaviour of some granular materials: an experimental study.

This paper reports the results of experiments carried out to explore the effects of particle form, sometimes referred to as sphericity, on the depositional density and subsequent shear behaviour of granular material. Previous experimental studies have generally neglected this important control, considering only rotund or bulky particles. However, the results of a few numerical studies have suggested its importance. Pluviated granular materials were tested in triaxial compression under free-end conditions, achieved using enlarged lubricated platens, which allowed specimens to be taken to high axial strain levels without strain localisation. Strains were measured locally. The results show that the limiting void ratios, $$e_{max}$$ and $$e_{min}$$ , the void ratio range ( $$e_{max}- e_{min})$$ and the depositional anisotropy increase as particles become platy. Almost all aspects of behaviour during shear are significantly affected by particle form, including mobilised friction at the onset of dilation, peak state and ultimate (or critical) state, dilation and particle breakage. For extremely platy material it appears that dilatancy may be completely suppressed, even for dense packings of particles. [ABSTRACT FROM AUTHOR]