Some Mechanisms of a Granular Mass in a Silo — Model Tests and a Numerical Cosserat Approach

After opening a silo bottom outlet some characteristic phenomena can be observed: The lateral pressure on the silo wall increases immediately after the beginning of emptying and can be a multiple of the one during filling.Shear zones come into being along the silo wall and, for a dense fill, also inside the flowing granular material. The dilatancy constraint in the shear zones (caused by the stiffness of neighbouring material) results in a scale effect in model silos, i.e. an additional increase of dimensionless wall stresses.Stress fluctuations are registered during the whole emptying process in big and in model silos as well.