Author(s): Youichi Yasuda; Nozomi Fuchino; Wang Jiayu

Linked Author(s): Youichi Yasuda

Keywords: Slit type Sabo dam; Assembled boulders; Subterranean stream; Riverbed protection; Flow velocity fields

Abstract: The installation of consecutively assembled boulders on steep slope might be effective for the migration route of multi-aquatic animals during normal stages, stability of structure, and flood control against local scouring and erosion. Regarding the velocity field inside the assembled boulders, there is no information. It is necessary for hydraulic design of assembled boulders to clarify flow characteristics around the consecutively assembled boulders. This paper presents the results of an experimental investigation of the velocity field around the consecutively assembled boulders, including inside the assembled boulder, at a downstream 1/10 slope of a slit-type check dam. The installation of assembled boulders in the supercritical flow region and in the transition from supercritical to subcritical flows allows control of the main velocity and position of the mainstream, and the installation is effective as an energy dissipater. The distributions of mean velocity and standard deviation at the assembled boulders have been shown by using electromagnetic velocity meter with I-type probe. Furthermore, spectral analysis shows differences from the inside of the assembled boulders to the surface around the assembled boulders, and the structure of the flow velocity inside the assembled boulders has been characterized. The formation of subterranean stream inside the assembled boulders can create a situation where the bed velocity near the consecutively assembled boulders can be reduced. Note that the velocity near the bottom when the gaps between the assembled boulders are filled is more than twice as fast as the velocity when the gaps between the assembled boulders are maintained.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p0050-cd

Year: 2023