Abstract: To explore the hydraulic characteristics of stepped spillway at high altitude, we conducted model test on the stepped spillway of a dam with slope θ=32°and dam crest at elevation 2586.0 m. By changing the incoming flow rate, we compared the hydraulic characteristics (time-averaged pressure in vertical and horizontal planes, water surface profile, flow velocity, and fluctuation pressure) in different conditions. Results prove that in all the three conditions, the stepped spillway has high energy dissipation efficiency and no cavitation. Pressure on step vertical plane and horizontal plane distributes in a bouncing manner along the spillway, and the height of water surface and the flow velocity will keep stable after reaching a certain value.

Key words: stepped spillway, hydraulic characteristics, cavitation, high altitude, energy dissipation rate