ABSTRACT
Granular materials are in abundance in nature and are also estimated to constitute over 75% of all raw material feedstock to industry (Nedderman 1992). They have been extensively studied by both the scientific and engineering communities, and yet they sometimes display behaviour that is counter-intuitive and a full understanding remains elusive. One classic granular mechanics problem is that of a humble ‘sandpile’ in which a significant dip in the vertical pressure on the base is observed underneath the apex of a poured pile, at the location where a simple interpretation might expect the maximum pressure. This ‘sandpile’ phenomenon is relevant to the bulk handling of industrial solids because many different bulk solids are commonly stored in open stockpiles, particularly in the mining industry (Fig. 1). The design of a gravity reclaim system for a stockpile requires knowledge of the base pressure distribution underneath the stockpile. The same phenomenon must also occur in silos that are filled from a ‘point source’ which might be expected to result in increasing the silo wall pressures near the highest wall contact. But this phenomenon is not recognised at all in the silos experimental literature.
