SPILLWAY IN CASE OF EXCEPTIONAL FLOODS FOR DAMS COMPRISING AT LEAST TWO SLUICES

摘要

An exceptional spillway for dams and similar structures of the type comprising two spillway devices; one of the two devices is constituted by an overflow threshold whose crest is located at a first predetermined level lower than a second predetermined level corresponding to a maximum level or highest water level for which the dam is designed. The difference of the first and second levels corresponds to a predetermined maximum flow of an exceptional flood. A movable riser closing the threshold comprises at least one rigid and massive elevation element, which is placed on the crest of the overhanging threshold and is held in place thereon by gravity; the riser has a predetermined height at least equal to the difference of the first and second predetermined levels and is dimensioned in size and weight so that the moment of the forces applied by water to the riser reaches the moment of gravity forces which tend to keep the rising element in place on the overflow threshold and that consequently the rising element is unbalanced, when the water reaches a third predetermined level at most equal to the second predetermined level.