流砂運動の素過程と流砂量に及ぼす粒子形状・粒度分布の影響

抄録

Gravel-bed rivers are composed of a large variety of particle sizes and shapes.Large particles on the bed resist against flows, but they are picked up and move intermittently. Particle motions are different from those in sandy rivers where most of particles move continually. To estimate sediment transport rate in gravel-bed rivers, fundamental movement processes of particles with different sizes and shapes have to be examined. In this paper, three-dimensional numerical movable-bed simulations were conducted, and sediment transport rate and fundamental movement processes of particles were measured under three conditions of spheres, gravel particles and mixed particles. We found that particle shapes affected significantly pick-up processes and this resulted in great differences of sediment transport rate among particles with different shapes.