Influence of erodible layer on granular column collapse using discrete element analysis

Landslides, debris flows and avalanches are geophysical hazards, which require sophisticated multi-scale analysis to understand the nature of the flow behaviour. This article discusses numerical investigation of the behaviour of granular flows through granular column collapse model. The column is allowed to collapse on an erodible bed of granular particles to understand the mechanism of entrainment. Discrete Element Method (DEM) is used to model the column collapse to investigate the run-out length and velocity of flow. Simulations were performed at the particulate level in this method. Particle-particle interaction in DEM helps in better understanding of the entrainment phenomenon. Run-out lengths increase with the increase in the initial column aspect ratio of the granular column with rigid bed. In this study, substantial variations were observed in the final run-out lengths in the presence of erodible bed in the model. The force of impact induces frontal ploughing giving rise to the entrainment of particles into the flowing mass and increased mean flow velocity. Column collapse over erodible bed resulted in thicker final deposits, which is evident from the increased coordination number.