軽量・重量骨材を用いた河床変動の実験手法

抄録

Hydraulic model tests and flume experiments for mountainous torrents and rivers have been conducted to clarify flow characteristics for many kinds of sediment movement modes such as mud flow, debris flow and so on. Especially, in case of mud flows and sediment laden flows with wide sediment grain size distribution, there are problems to be solved for not only similarity in experimental approach, but also flow model and constitutive relationship in numerical simulation.
In flume tests, coarse sediment particles can reproduce sediment erosion/deposition in those flow regimes, focusing on that locally spatial and time averaged bed variation is formed mainly by bedloads. However, it can be quite difficult to reproduce turbulent flow with fine sediment particles in model flume. In case of mud flows, modeling and treatments for muddy flow body which is liquid-phase are still now difficult and coarse sediment particles can be regarded as particles with small specific weight in comparison to sand. Additionally, in case of sediment laden flows with nonuniform sediment, it can be important to consider how to reproduce wide grain size distribution of sediment particles in model. It can be better that artificial material is used in place of sand particles based on Froude and dimensionless bed shear stress similarity to reproduce several sediment transport modes. In present study, the applicability of light and heavy artificial material for hydraulic experimental teats is examined using experimental data such as sediment flux concentration and flow resistance in flows over erodible bed.