Analysis of the active stress field in hoppers

Abstract Slice element methods are widely used for calculation of stresses in silos. However, more accurate means are available, since large computer capacities facilitate numerical calculation procedures. The active state of stress in plane-strain silos prevailing after initial filling of a silo is investigated by the method of characteristics with special emphasis on the stress pattern in the hopper section. Considering boundary conditions derived from the Mohr stress circle limits the solution of the active state of failure, i.e. plastic equilibrium, to certain combinations of the parameters internal friction, wall friction and hopper wall inclination. Other combinations of these parameters will only permit an elastic solution of the active stress field. If, however, the active state of stress does exist, then the vertical stresses prevailing in the hopper are very high and have to be considered for design of feeders and internals.