5-. 6 426
STUDY ON ENERGY DISSIPATION OF FLOW OVER A MULTI-STEP TYPE OF DROP STRUCTURE
1 2 3
Kiyoshi WADA, Yuichiro FUJITA and Motohiro OTSUBO
1 3501-0495 2236-2
2 3501-1193 1-1
3
Various types of drop structure are constructed to stabilize riverbeds by reducing enormous energy of flood flows and imbalance of transported sediment. Energy dissipating effect was estimated for multi- drop structures of rock-connecting type introduced in Northern anastomotic branch in the Kiso river by using a vertically averaged two-dimensional numerical model implemented in iRIC. The most suitable geometrical condition are studied to install this multi-drop structures to reduce flow energy more effectively by changing discharge and by arranging shapes of drop structure on the basis of 3D-Laser scanning data. The numerical analysis results clarified that changes in water surface profiles, Froude numbers and energy loss quantity depend on locations of hydraulic jump forced by the structures and that flood flows over the structures maintain super-critical conditions when flow discharge exceeds 110m3/s.
Also, it is pointed out that multi-drop structures can cause higher energy reduction effect by raising the top heights of each drop structure.
Key Words : Multi-step type of drop structure, hydraulic jump, energy dissipation, Froude number, iRIC, 3D-Laser scanning
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論文
河川技術論文集，第23巻，2017年6月- 141 - - 139 -
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2)
152p. , 2000.
3)
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pp.214-217, 1992.
5)
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