Admissible stress fields and arching in piles of sand

Stress distributions under conical and prismatic heaps of sand can exhibit a local minimum at the centre of the base. Occurrence of the ‘dip’ in the stress distribution is affected by the sand deposition history and the deflection of the base. The dip is due to arching of sand over the centre core of the heap. Radial stress fields in prismatic piles of sand are constructed, and distributions with a dip indicative of arching are found. Arching is promoted in stress fields where the sections adjacent to the sloping surfaces are in the yielding state whereas the inner core of the heap is in the elastic state. The static approach of limit analysis is used to find that the tendency to arching increases with an increase in the horizontal component of the reaction under half of the mound.