Artigos de Revista

As técnicas mais frequentemente utilizadas para a conservação e reabilitação de pavimentos flexíveis, que representam mais de 90% da extensão da rede rodoviária nacional, compreendem a remoção de camadas betuminosas degradadas e sua substituição por novos materiais. O reaproveitamento destes materiais, designados por

Para reducir la agitación en el interior del puerto de Vila do Porto, Azores, se ha proyectado una modificación del muelle interior de atraque de los ferries, con el objetivo de aminorar la reflexión y disminuir el rebase, sin que con eso se reduzca demasiado el área útil de la dársena portuaria. La solución propuesta es una plataforma de forma triangular en planta apoyada en pilares rectangulares, bajo la cual se ha colocado un talud de escollera para disminuir la reflexión. Se presentan los resultados de ensayos en modelo físico 3D y los obtenidos con dos modelos numéricos RANS en lo que se refiere a presiones en la plataforma y reducción de la reflexión (el modelo IH-2VOF y el FLUENT).

O consórcio LNEC/Geoplano testou uma metodologia emergente de remediação in situ de solos e águas subterrâneas fazendo a aplicação de nanopartículas de ferro zero valente numa parcela de terreno de um parque empresarial no Barreiro. O teste piloto foi efetuado numa área onde predomina a contaminação por metais pesados, sulfatos e nitratos. A execução da remediação in situ foi precedida pela caracterização físico-química dos solos, das águas subterrâneas e dos lixiviados produzidos pelos solos contaminados. Em laboratório testou-se o efeito da utilização de diferentes dosagens de nano partículas de ferro zero valente na diminuição da concentração dos elementos contaminantes na água. No terreno efetuou-se a injeção de soluções com três concentrações distintas de nano partículas.Após a injeção das nanopartículas implementou-se um programa de monitorização para aferir a variação das concentrações dos elementos contaminantes nas águas subterrâneas e nos lixiviados dos solos. Neste artigo descrevem-se os procedimentos de execução, apresentam-se e discutem-se os resultados obtidos

Red mud (RM) is a solid waste derived from processing bauxite ore to produce alumina and is considered a hazardous waste due to its high pH. This paper describes the use of untreated mud and after calcination at distinct temperatures (450, 650, and 1000 °C) to attempt to improve its reactivity in cement mortars. In the formulations, portland cement was replaced with up to 30 wt% red mud, and the addition of the red mud changed the hydration process, setting time, and workability. The temperature of hydration increased as more RM was added, particularly when calcined in the interval of 450–650 °C. In these conditions, the hydration process was accelerated, and the workability decreased. These findings indicate that the presence of red mud significantly altered important properties of portland cement.

Submarine outfalls need to be evaluated as part of an integrated environmental protection system forcoastal areas. Although outfalls are tight with the diversity of economic activities along a denselypopulated coastline being effluent treatment and effluent reuse a sign of economic prosperity, precautionsmust be taken in the construction of these structures. They must be designed so as to have the leastpossible impact on the environment and at the same time be economically viable. This paper outlines theinitial phases of a risk assessment procedure for submarine outfall projects. This approach includesa cost-benefit analysis in which risks are systematically minimized or eliminated. The methods used inthis study also allow for randomness and uncertainty. The input for the analysis is a wide range ofinformation and data concerning the failure probability of outfalls and the consequences of an operationalstoppage or failure.As part of this risk assessment, target design levels of reliability, functionality, and operationality weredefined for the outfalls. These levels were based on an inventory of risks associated with suchconstruction projects, and thus afforded the possibility of identifying possible failure modes. Thisassessment procedure was then applied to four case studies in Portugal. The results obtained were thevalues concerning the useful life of the outfalls at the four sites and their joint probability of failureagainst the principal failure modes assigned to ultimate and serviceability limit states. Also defined werethe minimum operationality of these outfalls, the average number of admissible technical breakdowns,and the maximum allowed duration of a stoppage mode. It was found that these values were inconsonance with the nature of the effluent (tourist-related, industrial, or mixed) as well as its importancefor the local economy. Even more important, this risk assessment procedure was able to measure theimpact of the outfalls on human health and the environment.

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The beach profile morphodynamic processes can be relatively well reproduced in large scale physical models. However,the cost associated to their use makes this methodology not always practicable. As alternative, it is desirable to exploreand apply smaller scales laboratory infrastructures with confidence, despite the different scaling laws, that is, theimpossibility to simulate all relevant variables in correct relationship to each other. The combination of physical andnumerical modelling can be a methodology to improve the required confidence (HYDRALAB III European Programme). Scale effects in a numerical process-based beach profile model, applied to simulate beach profileevolution under erosive wave conditions, were investigated in the present study. The numerical model was applied at laboratory and prototype scales, first with the default settings and then calibrated. Its performance was evaluated using the Brier Skill Score. The numerical results of the profile evolution in both scales were compared after reducing the results from the prototype scale to the laboratory scale. The profile erosion prediction was overestimated in the laboratory scale and underestimated in the prototype scale. Despite the calibration parameter that causes the largestmodifications of the beach profile being the same in both scales, the Gamma2 wave parameter, the most efficientparameter was different. For most of the calibration parameters, the value for the best case was not coincident in bothscales. It was concluded that there are scale effects using the Litprof model.

During seismic action, energy dissipation in structures occurs in structural and non-structural components, as well as in the substructure. Several of these dissipative mechanisms are modelled explicitly in nonlinear dynamic analyses, notably through relatively sophisticated hysteretic finite elements. Nevertheless, in most practical applications, it is not possible to simulate all the physical contributions to energy dissipation.Structural engineers are thus constrained to overcome this limitation by a mathematical artifice, in the form of equivalent linear viscous damping, which accounts for the remaining

Shrinkage-compensating concrete is usually used to minimize cracking caused by shrinkage. This type of concrete is recommended in structural and non-structural repairs, when there are internal or external restraints for the concrete elements. Commercial products which include concrete based on expansive cements or made with shrinkage reducing admixtures are available. This study evaluates the behavior of two commercial products, both at early age and also after some 2 years. The results indicate an appropriate behavior between demolding and the first weeks, both in sealed and submerged environments, but, after that, a consistent and relevant increase of shrinkage was observed.

Neste artigo descreve-se a ferramenta numérica SWAMS que se baseia nos modelosnuméricos DREAMS, BOUSS-WMH e MOORNAV para caracterizar a resposta dum navioamarrado no interior dum porto sujeito à acção da agitação marítima. Os dois primeirosmodelos simulam a propagação de ondas lineares e não lineares em zonas abrigadas deprofundidade variável, tendo em conta os fenómenos da refracção, difracção, reflexãoparcial, dissipação de energia devida ao atrito de fundo e rebentação das ondas. Enquantoo modelo DREAMS é um modelo linear baseado na equação de declive suave, o modelonão linear BOUSS-WMH é baseado nas equações de Boussinesq. O comportamento donavio amarrado é simulado com o pacote numérico MOORNAV que engloba um modelonumérico para resolver, no domínio da frequência, os problemas de radiação e de difraçãoda interacção de corpos flutuantes com ondas e um modelo que converte os resultadosdaqueles problemas do domínio do tempo para o domínio da frequência e que monta eresolve as equações do movimento do navio amarrado, BAS.Apresentam-se asmodificações introduzidas no modelo WAMIT para calcular as forças de difracção com basenas relações apresentadas em Haskind. Tais relações, porque utilizam o potencial develocidades obtido com o modelo DREAMS ou com o modelo BOUSS-WMH, permitemlevar em conta a refracção, difracção ou reflexão que podem ocorrer na propagação dasondas para o interior de uma bacia abrigada. Para além da descrição dos modelosnuméricos na ferramenta SWAMS, apresenta-se a forma como os resultados sãotransferidos entre eles bem como aplicações da mesma para ilustrar as suas capacidades.