State of the Art on Rock Avalanche Dynamics from Granular Flow Mechanics

Abstract

Granular flow is a main stage in the propagation of rock avalanches, which is of significant importance for revealing the hypermobility of rock avalanches. The main methods and theoretical achievements of granular flow can provide important technical means and theoretical basis for the study of rock avalanche dynamics. Focusing on the research of granular flows, its current research progress is reviewed firstly from the perspectives of its concept, flow regimes and corresponding constitutive models, and size-segregation mechanisms. Then, the granular flow theories and methods involved in rock avalanche research are systematically reviewed from the aspects of theoretical analysis, experiments and numerical modeling. On these bases, the key issues involved in the research of rock avalanche dynamics are proposed from the viewpoint of granular flow, i.e., what physical processes is related to the hypermobility of rock avalanche? How to quantify and model its polydispersity and fragmentation? How to quantitatively describe the temporal and spatial evolution of its grain size distribution and related coupling processes? How to retrieve its propagated mechanisms from the deposit? Facing these problems, future works that should be focused are proposed, including research on the physical processes of granular flow from sedimentology, on granular flow dynamics with scale effect considered, on the dynamic mechanisms and their constitutive models of rock avalanche based on the physical processes, and on the application of new technologies and methods.