Effects of flow volume and grain size on mobility of granular flows of angular rock fragments

Laboratory experiments have shown that the finer the grain size of granular flows of angular rock fragments (all the other features the same), the more mobile their centre of mass. This is due to the fact that the finer the grain size, the larger the number of particles in the flow so that their agitation due to the interaction with the subsurface asperities has a smaller penetration within the flow. The smaller the agitation of the particles per unit of flow mass, the smaller the energy dissipated per unit of travel distance. Also, the larger the flow volume, the smaller the mobility of its centre of mass. This is due to the fact that a deposit accretes backward during its deposition on a slope change. However, the frontal end of a larger-volume deposit is more distal than that of a smaller-volume deposit because the larger the volume, the larger its longitudinal spreading. .