Dissipated energies and friction coefficients in granular flow by flume tests

Laboratory flume tests on granular flow were conducted in order to investigate the influences of water content, grain size distribution, grain shape, fines content and flume angle on dissipated energy in the granular flow. Energy dissipated during the flow is evaluated from initial/residual potential energies and kinetic energy at the outlet of the flume. Though all parameters addressed here have measurable impact on the energy dissipation and the corresponding equivalent friction coefficient μ, it should be noted that the increase in fines content Fc up to a certain threshold tends to increase the equivalent friction coefficient μ. Beyond that threshold, the μ-value suddenly decreases due to a change in soil fabrics, transforming slow-speed granular flow to a high-speed mud flow. The evaluated μ-values for all tested cases have been found to be dependent on slope gradient.