Dynamic pressures and forces on smooth and rough inclined walls under irregulare waves: an experimental investigation

The present paper deals with an experimental investigation carried out to examine the pressure distribution and the relevant crest and trough forces acting on smooth and artificially rough inclined walls under irregular waves. In a previous paper (Gentile e Rebaudengo Landò, 2007) starting from experimental results obtained with slope 1:2 the distribution of the averaged dimensionless crest and trough pressures have been described from a statistical point of view. In the present paper, further experimental results with a different slope (1:1) are shown and discussed and comparisons are made between the results obtained in the two configurations. When the slope is lower the run-up extension is more important, giving rise to overtopping conditions, mainly on smooth walls, but the run-down extension is less important. The slope being the same, the roughness limits the run-up and gives rise to a more compact collapsing zone. From the time histories of the pressures those of the forces are deduced and the characteristic crest and trough forces are obtained, which substantially correspond to the run-up and run-down conditions. The roughness feebly reduces the crest and trough forces but the rough wall is more interestig from a technical point of view due to the reduced overtopping. The characteristic significant crest and trough forces are also examined in terms of horizontal and vertical components, showing that the wall slope affects more the horizontal trough component than the horizontal crest one. The results suggest the possibility of adopting trapezoidal caisson breakwaters with an inclined rough wall as the vertical component of the wave forces may be able to counteract the up-lift force more than it happens vith the well-known sloping top caissons.