EXPERIMENTAL RESEARCH IN FORMATION BY WAVES OF STABLE PROFILES OF UPSTREAM FACES OF EARTH DAMS AND RESERVOIR SHORES

Within the last few years the Soviet hydraulic engineers have been making continuous efforts to avoid use of concrete slabs and blocks and stone riprap as protective cover of upstream slopes of earth dams and reservoir shores against the disrupting effects of waves generated by the action of wind upon the water surface. Their efforts have been aimed at finding the cheaper procedure. Of all the possible ways of slope and shore protection, an engineering measure, the idea of which consists in distributing the wave energy dissipation over a considerably large portion of a sufficiently gentle slope, should be given a special attention. This measure makes it possible to substantially relieve the protective cover and in some cases to leave the slope uncovered. The possibility of unlined slopes, stable enough agains wave action is proved out by the experience of reservoir operation. Shores and underwater slopes of artificial lakes composed of non-cohesive soils are usually subject to considerable disintegration due to wave action. The process of disintegration which goes on rather fast at the initial stage of lake existence, slowff down with the formation of a flat lake-side shallow, whereon dissipation of wave energy takes place. At a certain stage of development the underwater slope assumes such dimensions and outlines which enable it to dissipate the whole of the wave energy and practically to protect shores from further destruction. The profile of the slope at which it will permanently stand underwater is referred to as the "profile of equilibrium" or "dynamically stable profile". The term "equilibrium" in this case doesn't imply absolute immovability of the material acted on by waves, but stands for such a movable state at which particles of the soil are making oscillatory movements round some middle position without the resultant movement neither towards nor off shore.