The new solution of a large barrage For impounding tidal estuaries in dry season

Abstract

     This paper presents the new solution of a large caisson barrage for impounding a tidal estuary in dry season. The bed structure of a barrage is a caisson. The gate valve is also a float valve type. The bed structure and the float valve is lifted semiautomatically by hydraulic forces; So the high capacity lifting machine is advoidable; therefore the gate of barrage can be also much more large than usual. Based on the study results, we firstly propose two types of the float valves so that impounding tidal estuaries in dry season. The first type of float valve is to have two plates. It's operation looks like opening and closing a door. The first valve can float up 45 cm in vertical direction, can revolve to the closing site with the small machine assistance during the small difference between the upstream and downstream water levels. The second type is to have two float valve. It's operation is very simple. Each valve can move in vertically parallel direction only in the slit area, float up and down to the bed structure of the berrage. In order to lift up the float valve the water inside is pumped out. If we want the float valve submerging down to the barrage bed the valves attached on the wall are opened to pour water into the float valve body. Both two types of these float valves are hightly feasible in use, especially for the second type. The float large barrage proposed by us is prospectively for impounding tidal estuaries in dry season of Vietnam.