移動床における掃流砂れきの不規則運動性状について

Abstract

Bed load transport process is characterized by irregular motion of individual sediment parti-cles, and such a property causes a various kind of alluvial phenomena. Hence, the statisticalcharacteristics of bed load movement based on the mechanism of motion of individual particlesare important to be clarified. In this study, the behaviors of individual bed load particles bothon a fixed bed and on an alluvial bed are observed and their characteristic quantities such asdistributions of particles velocities are measured elaborately, by making use of a movie cameraand a film motion analyzer. As the result of such measurements the bed load transport processcan be divided into following subprocesses. One is collision process with protrusions distributedon a rough bed and it gives the phenomena rapid variations. This process can be analyzed by aphysical model for collision, a statistical model for bed surface irregularity and some stochastictechniques. The other one is moving process of a sand particle without collisions. This can bedescribed by equation of sliding motion based on some experimental investigations and consider-ing some probabilistic characteristics.Such a study suggests that no methods but the combined type of deterministic approach andstochastic one can describe the bed load transport process and some trials were shown here.