Un esperimento in mare sulla riflessione delle onde e la stabilità delle difese a muro

On may, 1991 a small breakwater with a wall of 12x12 m, and water depth of 1.5 m was built in front of the Reggio Calabria beach. Thirthy transducers were functioning along the wall and in front of it. Since the first measurements, the confirmation was got the deep differences between reflection of the sea waves and classic reflection of the regular waves, as predicted by Boccotti's theory (1988). In particular, starting on one wave length from the wall, nodes and antinodes tend to disappear just as it was predicted by the theory. The small breakwater of Reggio Calabria can be thought of as a small scale model. In a scale of 1:30, the prototype should weight 570 tons/m in water like the caisson breakwater of Genova-Cornigliano, but it should be remarkably more hazardous. The model withstood orthogonally incident waves with significant height of 0.42 m and peak period of 2.56 s, which, for the prototype, correspond to a strong hurricane. The breakwater stood thanks to 3 design modifications with respect to the common breakwaters, and thanks to a phenomenon of pressure-fall under the wave-crest, being apparent in all the highest waves.