HYDRAULIC MODEL EXPERIMENTAL STUDY ON BARK STRIPPING PROCESS USING DRIFTWOOD MODEL

Abstract

Due to heavy rain such as typhoons, landslides and slope failures are caused, and driftwood occurs along with debris flows. Since the bark of driftwood peels off during flow, elucidating the bark peeling process will lead to the estimation of the source of driftwood. It is also considered to be useful for river management. There is a study of the past that examined the situation of the detachment using the branch. However, the scale of the driftwood model had a problem. It had a small real model for a scale. In this study, a driftwood model was created using the bark of grown cedar (Cryptomeria japonica) and fixed in a waterway for peeling experiments. As a result, when fresh water and earth and sand were circulated, the bark peeling rate increased in the order of upstream side, side surface, and downstream side due to the collision of earth and sand. Furthermore, the separation rate on the riverbed side was higher than that on the water's surface side. In the case that only freshwater circulated, it was revealed that the fluid power did not influence the bark exfoliation. Observation of the progress of the exfoliation confirmed two cases, exfoliation produced by the friction with sand and lump of the bark exfoliates.