Author(s): Nobuyoshi Suganuma; Youichi Yasuda; Keito Masui
Linked Author(s): Youichi Yasuda
Keywords: Energy dissipator; Concrete blocks; Surface jet flow; Drop structure; Mainstream position
Abstract: Recently, the experimental investigation on sloping energy dissipator with stacked boulders revealed that a surface jet flow with three dimensional might be effective for both energy dissipator and prevention of river bed. The formation of surface jet flow is characterized by a lift of the main flow to center part of water surface from the bottom, and a high velocity flow might be dissipated by the formation of the main flow with a strong turbulence. From the point of environmental problems, the reuse of installed concrete blocks below apron must be considered. This study presents the possibility of sloping energy dissipator with concrete projective blocks by using a scale model. The experiments yielded that the formation of surface jet flow was confirmed by installing the blocks in 1/15 slope, even if the tailwater level was same level as in the case of the limited jump below abrupt drop structure. Furthermore, the hydraulic condition required to form the surface jet flow was discussed. The velocity decay and the location of the main flow, and vertical distributions of turbulent intensity revealed that the formation of the surface jet flow might be effective for both protection of river bed and energy dissipator. The sloping energy dissipator with concrete projective blocks was compared with that with stacked boulders, and the application might be decided from gravel and rock sizes in the sediment transport.
Year: 2020