Granular materials can behave as harmless sand dunes or as devastating landslides. A granular avalanche marks the transition between these distinct solid-like and fluid-like states. The solid-like state is typically described using plasticity models from critical state theory. In the fluid regime, granular flow is commonly captured using a visco-plastic model. However, due to our limited understanding of the mechanism governing the solid–fluid-like transition, characterizing the material behavior throughout the life cycle of an avalanche remains an open challenge. Here, we employ laboratory experiments of transient avalanches spontaneously generated by a rotating drum. We report measurements of dilatancy and grain kinematics before, during, and after each avalanche. Those measurements are directly incorporated into a rate-dependent plasticity model that quantitatively predicts the granular flow measured in experiments. Furthermore, we find that dilatancy in the solid-like state controls the triggering of granular avalanches and therefore plays a key role in the solid–fluid-like transition. With the proposed approach, we demonstrate that the life cycle of a laboratory avalanche, from triggering to run out, can be fully explained. Our results represent an important step toward a unified understanding of the physical phenomena associated with transitional behavior in granular media.
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The author would like to thank Ryan Hurley for his fruitful comments. This work has been partially funded by Keck Institute for Space Studies (KISS) and the California Institute of Technology; this support is gratefully acknowledged.
George DL, Iverson RM (2014) A depth-averaged debris-flow model that includes the effects of evolving dilatancy II Numerical predictions and experimental tests. Proc R Soc A 470:20130820MathSciNetCrossRefzbMATHGoogle Scholar
Pailha M, Nicolas M, Pouliquen O (2008) Initiation of underwater granular avalanches: influence of the initial volume fraction. Phys Fluids 20:11701CrossRefzbMATHGoogle Scholar
Pan B, Qian K, Xie H, Asundi A (2009) Two-dimensional digital image correlation for in-plane displacement and strain measurement: a review. Meas Sci Technol 20:062001CrossRefGoogle Scholar
Peng C, Guo X, Wu W, Wang Y (2016) Unified modelling of granular media with smoothed particle hydrodynamics. Acta Geotech 11:1231CrossRefGoogle Scholar
Pouliquen O, Renaut N (1996) Onset of granular flows on an inclined rough surface: dilatancy effects. J Phys II Fr 6:923–935Google Scholar
Prime N, Dufour F, Darve F (2014) Solid-fluid transition modelling in geomaterials and application to a mudflow interacting with an obstacle. Int J Numer Anal Methods Geomech 38:1341–1361CrossRefGoogle Scholar
Rajchenbach J (1990) Flow in powders: from discrete avalanches to continuous regime. Phys Rev Lett 65:2221–2224CrossRefGoogle Scholar