Resumo

BAIRRAO, Miguel; NEVES, Maria da Graça; REIS, Maria Teresa  e  PINTO, Francisco Taveira. Overtopping of a harbour structure protected by a submerged breakwater: Leixões Harbour, Portugal. RGCI [online]. 2016, vol.16, n.2, pp.121-131. ISSN 1646-8872.  https://doi.org/10.5894/rgci568.

Overtopping of a harbour structure protected by a submerged breakwater: Leixões Harbour, Portugal Overtopping of port structures, which is the passage of water over the structure crest due to wave action, is one of the phenomena that has the greatest impact on the structure integrity and on the safety of the protected area. The main goal of this research is to study the wave overtopping of a rubble-mound breakwater, with an important wave return wall, protected by a submerged breakwater. In particular, the study aims to optimize the geometry of the submerged breakwater located in front of the rubble-mound breakwater, in order to reduce its overtopping. The studied structure is the northern breakwater of the Port of Leixões, Portugal, which is already protected by a submerged breakwater near the port entrance. The study proposes to extend the protected zone of the northern breakwater. In order to do so, it is necessary to analyse the best geometry for this submerged breakwater and its distance to the protected structure. To study the influence of the submerged breakwater geometry and location on the overtopping of the rubble-mound breakwater the IH2VOF model was used. Three regular wave conditions were studied, with different wave heights only. Seven geometries for the submerged breakwater were considered, which differed from the original configuration (the geometry which already exists) in three characteristics: the distance between the submerged and the main breakwaters and the submerged breakwater crest level and width. For the wave conditions considered, the characteristics that had the greatest impact on reducing the overtopping of the main breakwater of the Port of Leixões were: the increase of the distance between the submerged and the main breakwaters and the increase of the crest level of the submerged breakwater. The mean overtopping discharge for the studied wave conditions was reduced from a maximum value of 0.71 l/s/m for the original configuration to 0.02 l/s/m in two of the analysed new configurations, which corresponds to a 97% overtopping reduction compared to the original configuration.

Palavras-chave : Numerical modelling; IH2VOF; physical modelling.

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