Transmission of stresses in static and sheared granular beds: The influence of particle size, shearing rate, layer thickness and sensor size

The spatial non-uniformities and temporal fluctuations in the normal stress transmitted across a sheared granular layer have been studied through a combination of experiments in a Jenike shear cell equipped with normal force (stress) transducers imbedded on the bottom shearing surface and discrete element method (DEM) simulations. Experiments were carried out with particles of different sizes and layers of different thicknesses; the normal stress was measured at several different shearing rates and at several positions on the bottom surface. The DEM simulations revealed a direct link between the spatial inhomogeneities and temporal fluctuations in the stress recorded in our measurements. We found that the dependence of the average normal stress on the bottom surface as a function of height mirrored that in Janssen's analysis of stresses in wall-bounded static assemblies.