Étude des efforts hydrodynamiques sur un fond mobile en aval d'un dissipateur d'énergie de type auge

Abstract

The continuous scour of an erodible bed downstream a roller bucket energy dissipater makes it difficult to quantify the efforts applied on the bed. An astute technique allows the measurement of these efforts for various stages of scour and facilitates a better comprehension of the interaction between these efforts and the scour downstream. This technique consists in measuring the bed profile (downstream the dissipater) as a function of time and reproducing scoured profiles using a solid model (concrete) that allows the setting of the measuring devices. The analysis of the efforts has shown that as soon as the scour starts, a small bed deformation induces important changes in the pressure and in the pressure fluctuation distributions in the vicinity of the structure. As erosion goes on, the efforts vary slightly and the distributions remain unchanged. The behaviour of the efforts regarding the erosive process could be interpreted by the nature of scour phenomenon, which develops strongly during the initial phase, and by the specific behaviour of the zone in the vicinity of the bucket, which evolves rapidly and stabilizes quickly.Key words: hydrodynamic efforts, pressure, pressure fluctuation, energy dissipater, roller bucket, movable bed.