Session K.pdf - Clarkson University

According to monitoring in spring 2002 and 2003, floods on the Nerl River started atpositive average daily temperatures. Then an interlayer of water appeared between theFusegate walls and the ice. But inside the Fusegates, ice did not float up and it meltsfew days after crest overflowing has started.Small ice drifting could be observed a few days before the maximum flood. Ice blocksmeasuring up to 1 m 2 broke off the floe and fell over the labyrinth. The main ice massdid not pass over spillways and it melted in the headwater.CONCLUSIONWith its innovative design, Khorobrovskaya spillway combines the advantages ofungated spillways to the performance of gated spillways. It is particularly suitable forice-affected projects located in remote areas. After three years of records, the Fusegateshave shown their capacity to operate under harsh winter conditions. They enhance damsafety during flood periods, increase HPPs reservoir storage capacity and improve thedischarge capacity when required.Monitoring has shown that Hydroplus Fusegates are stable in various temperatures, includingice conditions, when Fusegates’ crest constant overflow can be prevented.Roof-like ice builds forms over the Fusegate labyrinth during hard frost. They are heldby surface ice along the sill edge and in the centre. If there are wells, this “roof” will befrozen on the well and will create the Fusegate overturning moment. In such conditions,it is therefore recommended to use another type of Hydroplus Fusegates.Concrete labyrinth spillway can be used in severe climate regions. It does not causeany complications both with and without crest overflow when temperatures are notbelow – 30 o C.Ice loads do not affect Hydroplus Fusegates as long as these loads are shifted to thedownstream direction in relation to the pier heads, since the ice breaks off along the lineof the pier heads during water level fluctuation. The relationship between the span widthand the portion of the pier length projected towards headwater will be the subject of furtherstudies.Testing of the Fusegates will continue at Khorobrovskaya HPP and specifically the t-esting of recoverable Hydroplus Fusegates.REFERENCESAït Alla A. The Role of Fusegates in Dam Safety. Hydropower & Dams, Volume Three, Issue Six, 1996.Aït Alla A., Jones S.J., Lounatsi M.E., Rodionov V.B. and Spencer D. The Reliability of Fusible Gates inIce-Affected Environments. Hydropower & Dams, Volume Three, Issue Three, 1996.Al Nashir J., Leseberg G. and Slopek R. Power to the People, International Water Power & Dam Construction,December 1996.Kocahan H., Rodionov V.B. The Behaviour of Fusegates in Ice Affected Environments. Association ofSafety of Dams Engineers (ASDSO), Las Vegas, USA, October 2003.Tuthill A.M. Operating Hydro Projects to Control River Ice. Hydro Review, November 2000.358