Granular packings with moving side walls

The effects of side wall movement on granular packings were investigated. The studies showed that the resultant structure of the pack did not depend strongly on the magnitude of the wall movement, as long as the packing was moved for an equivalent distance. The main effect of wall movement was to drive the particle-wall and particle-particle contacts to the Coulomb criterion. This forced the packing in the high wall velocity case to obey the Janssen form, which took the Coulomb criterion as one of its main assumptions.