Initiation and Laws of Motion of Debris Flow

by Zhaoyin Wang, Inst of Water Conservancy and, Hydroelectric Power Research IWHR, Beijing, China,
Xinyu Zhang, Inst of Water Conservancy and, Hydroelectric Power Research IWHR, Beijing, China,



Document Type: Proceeding Paper

Part of: Hydraulics/Hydrology of Arid Lands (H²AL)

Abstract: The mechanism of initiation and laws of motion of debris flow are studied experimentally, by allowing water or clay muds, with different clay concentrations and at different flow rates, to flow over a flume bed piled with gravels (d=4-25 mm), and observing and measuring movement of gravels, flow of muds and interaction of the two phases. As the flow rate is high enough gravels on the bed are scoured and then move in saltation or roll on the bed. A large amount of gravels concentrates in the front of the flow wave and forms a high head of debris flow like a bulldozer. Initiation of debris flow depends mainly on the energy of liquid phase supplying to gravels. The concentration of gravels in the head is much higher than that in trunk zone while speed of the head is much smaller than velocity of liquid or gravels in trunk zone. Large gravels are acted by a large tractive force from the liquid phase and a small resistance force from collisions with other particles, therefore, they move faster than small ones and concentrate in the head consequently.

Subject Headings: Solids flow | Water flow | Gravels | Debris | Flow measurement | Flow rates | Fluid flow | Equations of motion

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