Jamming and fragility in granular columns.

Jamming is a complex behavior in large multi-particle macroscopic systems whose details often depend upon microscopic interactions of particle-particle contacts as well as fluids, gases and even organic materials that occupy interstitial space within the granular media. However, even these microscopic factors lack components that present the full picture of the micro-to-macro behavior. The understanding of jammed behavior must include specifics of how the material is mechanically forced toward the jammed state, the changes in the energy domain, and any inherent anisotropy resulting from those processes. Prior work has investigated how the quantities of strength and stability can be distinguished in jammed granular columns and described by a low-dimensional thermostatistical model based on the granular temperature. As a consequence of how these granular columns are constructed, anisotropy exists between the jammed dimension and the lateral dimensions of the structure. In the lateral dimensions, the granular column is in a dense but fragile state. To investigate and describe this anisotropy, we construct cubic blocks in the same manner as the previously described larger jammed granular columns. The strength and stability of these cubes are investigated in 3D for completely dry and variable fluid saturations to better understand the mechanics of the larger granular columns.