Mechanical coupling between two innovative theories on erosion, transportation and phase-separation: Solving some long-standing problems in mass flows

München

2017

Sonderdruck

202745

Debris flows are gravity driven mixture flows of soil, sand, rock and water. The solid particles and viscous fluid
governs the rheological properties, and their coupling significantly influences the dynamics. For example, debris
flows can dramatically increase their volume and destructive potential, and become exceptionally mobile by entraining bed material. The mixture composition can evolve to strikingly change the spatial distribution of particles
and fluid, and thus frictional and viscous resistance. So, erosion-deposition and phase-separation between solid
and fluid, which strongly depend on material composition, play a critical role in debris flow dynamics. Proper
understanding of these complex physical processes is very important in accurate description of impact forces, inundation areas, landscape evolution and developing reliable mitigation plans. Predicting the underlying processes
of erosion, phase-separation and deposition in debris flow are long-standing challenges. However, due to lack of
data and suitable models, there exists no runout prediction method that includes observed processes of erosion of
dry and saturated beds, entrainment and diffusion of eroded material, grain sorting, phase-separation, levee/lobe
formation and evolution of deposition patterns.