Exploring the gravity-driven failure of a cohesive granular column.

Discrete two-dimensional simulations of cohesive granular collapse are carried out with a focus on the failure process. The existence of a reliable criterion to characterize the failure orientation is discussed. A criterion based on the distribution of the grains' cumulative displacement over the duration of the failure is selected. Questioning its reliability, it appears that a criterion based on grain displacement is fragile in the face of variations of system geometry and stability. Nevertheless, the measure of failure plane orientation appears fairly robust against moderate variations of the displacement criterion and against fluctuations of cohesive states close to the stability limit. This suggests that the measure of the failure orientation at the stability limit is reliable information. However, this work stresses the elusive nature of cohesive granular failure and the important role of fluctuations in granular matter in general.