Publications

This paper presents the analysis of the probability of occurrence of wave overtopping events as well as its consequences at the Port of Las Nieves in Agaete, Gran Canaria Island, with the evaluation of the resulting level of flood risk. The study has been conducted using a third-generation spectral wave model to reproduce wave propagation from deep to shallow water depths considering the associated mean sea level, and a neural network-based model, for estimating mean wave overtopping discharges. Results reveal that overtopping in the initial sections of the port, located in the port access area, is substantially higher than that associated with the cross-sections of the main body of the breakwater, so that control actions to reduce overtopping are required due to the important socioeconomic implications regarding the infrastructure inoperability.

Neste trabalho, descreve-se a aplicação ao porto e baía da Praia da Vitória, na ilha Terceira, Açores, Portugal, da metodologia de avaliação do risco de galgamentos em estruturas marítimas em desenvolvimento no LNEC, considerando duas ferramentas neuronais para cálculo dos galgamentos baseadas em resultados da aplicação de redes neuronais artificiais, nomeadamente a ferramenta NN_Overtopping2 e a Overtopping Predictor v1.1. Em particular, avalia-se comparativamente quais as implicações que a utilização de cada uma destas ferramentas tem em termos de número de eventos de galgamento e magnitude dos caudais médios galgados, bem como consequente grau de risco, para as 9 secções-tipo de estruturas marítimas estudadas no porto e baía da Praia da Vitória. O período de estudo é de 5 anos (2008 a 2012).

O galgamento de estruturas portuárias consiste na passagem de água sobre o coroamento da estrutura pela ação da agitação marítima e é um dos fenómenos com maior impacto na integridade da estrutura e na segurança da zona por ela protegida. O principal objetivo deste trabalho é estudar o galgamento num quebra-mar de taludes, com um importante muro cortina, protegido por um quebra-mar submerso. Em particular, pretende-se otimizar a geometria do quebra-mar submerso situado a barlamar do quebra-mar de taludes, no qual se pretende diminuir o galgamento.A estrutura marítima em estudo é o molhe norte do Porto de Leixões, em frente ao qual já existe um quebra-mar submerso na zona da cabeça. Pretende-se estender a zona do molhe protegida pelo quebra-mar submerso e, para tal, é necessário estudar qual a melhor geometria e posição a adotar para este quebra-mar.Para estudar a influência da geometria e da posição do quebra-mar submerso no galgamento do molhe norte, utilizou-se o modelo numérico IH2VOF. Simularam-se três condições de agitação regular, que diferem somente na altura de onda, e sete geometrias do quebra-mar submerso, que diferem da configuração original (a existente atualmente) em três características: a distância entre o quebra-mar submerso e o molhe, a cota de coroamento do quebra-mar submerso e a sua largura de coroamento.Com a realização deste estudo, para as condições de agitação consideradas, verificou-se que as características com maior impacto na redução do galgamento no molhe norte do Porto de Leixões são: o aumento da distância entre o quebra-mar submerso e o molhe e o aumento da cota de coroamento do quebra-mar submerso. O caudal médio de galgamento para as condições de agitação em estudo reduziu-se de um valor máximo de 0,71 l/s/m para a configuração original para 0,02 l/s/m em duas das novas configurações analisadas, ou seja, uma redução de 97% face à configuração original.

The susceptibility of bridge decks to vortex induced oscillations can b eaddressed through wind-tunnel testing. This paper considers the case of the Vila-Real Bridge, in the north of Portugal, which has the highest deck above ground (230m), among concrete-deck bridges cable-stayed in the central plane. It has a single-cell rectangular box girder with a wide top flange supported by regularly spaced inclined struts. Aeroelastic studies of this precise type of deck seem nonexistent in the literature.Results of sectional model tests are presented for a selection of three distinct angles of attack and three deck configurations, including a solution, alternative to the usual mitigation measures, that solved the susceptibility to vortex induced vibration of the deck and that has no relevant additional design or building costs.With the proposed approach, bridge designers may be able to relegate the use of sections with high aerodynamic performance

Wave-induced flow velocity and turbulence may cause scouring in the seabed around coastal structures depending on the wave climate and tidal water depth. A 3-D physical modelling study was conducted to investigate the possible causes of the sinking of two submerged coastal structures on the Santa Maria del Mar (SMM) beach, Spain. The experimental investigation was conducted by employing a Froude similarity law with a geometric scale of 1:20, and the submerged modular structure was subjected to different wave climates and tidal water levels. The combinations of the significant wave height and peak period were chosen from in-situ real wave conditions thatwere monitored during the sinking of the prototype structures. Linking and unlinking conditions for the modules in the structure were investigated in this study. The results show that the modules sank to approximately 48% of their height at the end of the tests with storm waves and semi-linking conditions of low water depth. Most of the experimental results were compatible with the prototype monitoring results. Tests with proper linking among themodules and testswith an appropriate gravel foundation resulted in a sustainable solution because they presented much less or almost no scouring and sinking.

Despite the simplicity of the geometry of the circular cylinders, the uniform flow around them is complex,since it may induce unsteady forces on structures associated with vortex shedding. This paper describes the study of two circular cylinders (the downstream one is elastically mounted in transversal direction) in tandem arrangement subject to bi-dimensional uniform laminar flows at low Reynolds numbers. The academic numerical model Ifeinco, which is based on the finite element method and uses a partitioned scheme that considers two-way interaction of fluid flow and structure, has been employed to the analysis.Firstly, both stationary cylinders in tandem arrangement for Re = 100 are analysed for center to center distance between the cylinders, L/D, from 1.5 to 6.0. Results of lift and drag coefficients and Strouhal number are compared with other numerical results and good agreement is found. Secondly, numerical results for L/D = 5.25, considering downstream elastically mounted cylinder, are analysed for Reynolds numbers ranging from 100 to 140. It shows that the resonance occurs for Reynolds numbers between 115 and 120 and the maximum dimensionless amplitude of oscillation is 0.721 for Re = 118.

Techniques based on artificial neural networks (ANNs) have been increasingly applied to predict emergency situations, such as extreme wave conditions, wave overtopping or flooding, and damage to maritime structures, in coastal and port areas. In this work, a fuzzy adaptive resonance theory with mapping (FAM) ANN was trained to predict the wave regime both inside and at the entrance to the Port of Sines, one of the major trade and economic gateways of the Iberian Peninsula, located on the Portuguese west coast. In situ measurements using pressure sensors, wave buoy data, and results from two numerical wave propagation models

The main goal of this paper is to develop a photogrammetric method in order to obtain arobust tool for damage assessment and quantification of rubble-mound armour layers during physicalscale model tests. With the present work, an innovative approach based on a reduced number ofdigital photos is proposed to support the identification of affected areas. This work considers twosimple digital photographs recording the instants before and after the completion of the physicaltest. Mathematical techniques were considered in the development of the procedures, enabling thetracking of image differences between photos. The procedures were developed using an open-sourceapplication, Scilab, nevertheless they are not platform dependent. The procedures developed enablethe location and identity of eroded areas in the breakwater armour layer, as well as the possibilityof quantifying them. This ability is confirmed through the calculation of correlation coefficients ineach step of the search for the more damaged area. It is also possible to make an assessment of themovement of armour layer units.

Nesta comunicação, descrevem-se os mais recentes desenvolvimentos no LNEC em termos de instalações experimentais, técnicas de construção, equipamentos e metodologias utilizadas nos ensaios em modelo físico, com a apresentação de casos de estudos realizados para as zonas portuárias de Peniche Ponta Delgada, Leixões

Within the BlueSafePort project, an early warning system (EWS) for moored ships in the port of Sines as developed. In order to improve the reliability and accuracy of the system, two neural networks (NN) were trained,using wave buoys measured datasets. Numerical models results for the wave propagation are djusted and forecasts are improved.The trained neural networks were able to produce more accurate stimates for the significant wave height and mean wave period, at the buoy location, deployed in front of the ines Port. The use of the new NN led to an overall reduction of the root mean square error of around 80% compared with SWAN numerical model simulations, thus reducing potential errors in subsequential alculations and alert levels issued by the system for the moored ships.

Within the LIFE Garachico project, an HIDRALERTA EWS is being extended to include methodologies for creating an effective flexible adaptation strategic framework for coastal area of Praia da Vitória. This strategic framework is based on the definition of acceptable risk levels and specific interventions at the local level, allowing to increase the resilience of coastal urban areas against extreme coastal events (both present and future) consequences of climate change.

Esta comunicação descreve os ensaios de pressões efetuados para a caraterização das pressões máximas exercidas nos pilares de secção circular da ponte que liga o porto de Dakhla à costa bem como dos perfis verticais de pressões associadas.

Nesta comunicação são descritos os desenvolvimentos iniciais dos sub-casos do projeto C2IMPRESS referentes aos portos de Aveiro e da Figueira da Foz. A fase inicial envolveu a estimativa preliminar do galgamento induzido pelas ondas em alguns perfis das estruturas dos dois portos, assim como um primeiro inquérito sobre risco aos utilizadores desses dois portos.

Esta comunicação descreve os estudos em modelo reduzido tridimensional de estabilidade hidráulica e de galgamentos para o prolongamento do molhe leste correspondente à 3ª Fase de Expansão do Terminal XXI, do Porto de Sines.

Neste trabalho apresenta-se uma metodologia para determinar as condições de segurança e acessibilidade de navios ao longo do trajeto de acesso ao porto, ilustrando-se a sua aplicação nos casos de estudo dos portos de Sines. este trabalho insere-se no âmbito do desenvolvimento de novos sistemas de previsão e alerta para a navegação nos portos de Sines e Aveiro.

O litoral português apresenta um valor natural, económico e cultural único e de importância amplamente reconhecida. O dinamismo costeiro pode levar à ocorrência de galgamentos de estruturas de proteção costeira em situações de temporal, que podem causar inúmeros danos, podendo mesmo resultar na perda de vidas humanas ou na destruição de estruturas próximas da linha de costa. Deste modo, a gestão das zonas costeiras próximas de aglomerados populacionais deve considerar a implementação de medidas sustentáveis que mitiguem os fenómenos que afetam o litoral de forma mais gravosa, de que são exemplo a implementação de estruturas de proteção costeira.

No âmbito do projeto BlueSafePort está a ser desenvolvido um sistema para prever e alertar situações de emergência causadas pela agitação marítima, relacionadas com a navegação em portos, bem como constrangimentos operacionais. A paralisação dos terminais portuários leva a grandes perdas económicas e afeta em grande parte a competitividade geral do porto. Assim, o objetivo deste sistema é reduzir a vulnerabilidade do porto aumentando a sua capacidade de planeamento e resposta e

Physical modelling is one of the tools to help characterize wave runup and overtopping in maritime structures. Usually, the determination of wave runup is made by using resistive wave gauges along the breakwater slope while the evaluation of overtopping volumes (individual or total) is made by weighing the water overtopped with a scale that is collected in a reservoir installed on this scale.Nowadays, non-intrusive methodologies for the assessment of those parameters are being used, due to their simplicity and low cost. Video cameras, constitute a good alternative to old methods; however, their performance depends essentially on the post-processing methodologies used.The present paper presents the application of the Timestack methodology done so far, in the evaluation of: wave runup in 2D and 3D physical tests. The video-derived statistical parameters of wave runup (Rumax, Rumin, Rumed e Ru2%) are compared with the corresponded ones obtained with resistive wave gauges. The total water volume and the average overtopping flow rate from video data is compared with the one collected by a reservoir. Those cases will illustrate the advantages and drawbacks associated with Timestack methodology.

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