多自然型護岸の水理機能に関する一実験

Abstract

About 1000 rich-in-nature river works are being carried out by central and local governments as pilot projects in the beginning of 1992.As revetment works occupy the main portion in river improvement works, various types of rich-in-nature revetments are being applied in many rivers.Their hydraulic functions, especially their strength against flood and bank protection capabilily, have risen as one of important subjects of river management in Japan.Some aspects common to rich-in-nature revetments were discussed, showing several examples and a typical but conceptual type of them was focused.A five-step type of revetments with mean slope of 1 5 was chosen to be studied by hydraulic experiment.Four runs were carried out to examine its hydraulic performance by using two models and measuring velocity fields.Secondary flows and their influence on shear distribution were detected from velocity distributions.Riprap of toe protection proved to reduce flow velocity largely but to produce a certain range of velocity fluctuations, sand bed around individual stones being scoured.