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The current document compiles some of the most relevant information concerning the symptoms and respective causes of common anomalies observed in concrete dam bodies. These include physical degradation phenomena, like abrasion, cavitation and freeze-thaw cycles, and chemical reactions, such as expansive reactions and leaching. The methodologies available to detect, assess and monitor these are addressed as well, with a special focus on cracking.
Local scouring around bridge foundations is a major reason for bridge collapse worldwide. It occurs due to the formation of vortices around bridge foundations as a result of changing the unidirectional approach flow into the three-dimensional field in an erodible channel bed, leading to the development of a scour hole in its vicinity. In the present work, two different techniques were applied for a full characterization of the scour hole geometry developed in a sand bed flume experiment...
The flow originated by a dam failure is a complex 3D two-phase flow thus the breaching process details can only be addressed with comprehensive and controlled laboratorial work. This study represents a contribution to achieve this goal and is based on laboratory tests on failure by overtopping of cohesive homogenous earthfill dams. These were performed in a medium-scale facility at the Portuguese National Laboratory for Civil Engineering under hydraulic and geotechnical controlled conditions....
This paper aims to present a Wireless Sensor Network using a Libelium Smart Water kit to allow remote water quality monitoring communication in real time. Equipped with multiple sensors that measure the most relevant water quality parameters, the Smart Water kit can be connected to the internet (using a mobile broadband connection) for real-time water quality control. The water quality parameters measured include pH, oxidation-reduction potential (ORP), electrical conductivity (EC) and temper...
As alterações climáticas causam impactos no ciclo hidrológico e nas disponibilidades hídricas, criando desafios adicionais à gestão integrada e sustentada dos recursos hídricos, nas suas componentes de qualidade, quantidade e suporte dos ecossistemas. As águas subterrâneas não estão imunes aos impactos das alterações climáticas, que se conjugam ainda com os devidos às alterações demográficas, sociais e de uso e ocupação do solo. Os estudos de alterações ...
No contexto das elevadas concentrações em cloreto, sódio e fluoreto encontradas nas águas subterrâneas de algumas captações destinadas ao consumo humano em diversas ilhas dos Açores, a Entidade Reguladora dos Serviços de Águas e Resíduos dos Açores (ERSARA) solicitou ao LNEC a "Análise das origens de água para abastecimento público em diversas ilhas dos Açores visando otimizar a qualidade da água destinada ao consumo humano". O LNEC desenvolveu este trabalho em colaboração com a Universidade ...
A cal aérea é um ligante com grande durabilidade, como atestam inúmeros vestígios arqueológicos da época romana e não só. Quando é referido que uma determinada argamassa ou pintura mural foi executada com cal aérea, poucas vezes é descrito que ela é do tipo dolomítico. A escassez de referências a este tipo de ligante pode ser atribuída à menor disponibilidade de calcários dolomíticos. Porém, existem vários casos em Portugal, e em outros Países, da sua utilização que não parecem estar só assoc...
O objetivo deste artigo é apresentar e discutir os contextos de algumas “falas” de quem faz a cal, destacando a importância destas “falas” como património intangível. Para efeito, recorre-se a estudos realizados com mestres caleiros no âmbito de projetos de investigação desenvolvidos em Beja (Alentejo/Portugal); explorando ainda alguma da literatura produzida nesta área temática, todavia, privilegiando-se aquela assente em estudos empíricos realizados em Portugal, nomeadamente onde a “voz” do...
This report was developed as part of the LIS-Water (Lisbon International Centre for Water) project, which has received funding from the European Union’s Horizon 2020 research and innovation programme under the Grant Agreement Number 763562. The centre will focus on public policies, regulation and management on water services and related water resources and will be located in Lisbon, Portugal. The goal of this work package (WP6) is to create the LIS-Water operational plan that is the legal for...
A Operação, também designada projeto, GO-LNEC - Capacitação para a Melhoria da Qualidade na Gestão Operacional do LNEC, visa capacitar o Laboratório com modelos organizativos e de gestão do negócio, racionalizados, ágeis, automatizados, flexíveis, uniformes, transparentes e eficientes. O projeto divide-se em dois subprojetos: ● Subprojeto A – Implementação do Modelo de Autoavaliação CAF (Common Assessment Framework) na Administração Pública; ● Subprojeto B – Capacitação para a Melhoria Oper...
Detailed models of concrete mesostructure can be used to understand the interactions between its components and predict complex deterioration scenarios. The discrete or distinct element method (DEM) is currently being used for modeling the fracture process of quasibrittle materials, such as rock and concrete. An explicit formulation of a DEM contact model that includes aging viscoelastic behavior based on the solidification theory is proposed, allowing the DEM particle model to be applied to ...
The Ribeiradio-Ermida multipurpose hydro scheme, built between July 2010 and the end of 2015, is the first major project in the Vouga River basin and is located in the centre of Portugal. Its main purposes are power generation, water supply and flood control. The Ribeiradio dam is a 83 m high concrete gravity dam, with a controlled gated spillway over the dam structure. This project encompasses a second lower dam, Ermida, located 5 km downstream, to regulate Ribeiradio flows. Both schemes are...
The Foz Tua Project is the latest accomplished hydroelectric investment of EDP - Energias de Portugal, located in a tributary of Douro River, close to its mouth, in the northeast of Portugal, which includes a concrete double curvature arch dam 108 m high with a total crest length of 275 m, closing a narrow granitic valley. After a brief presentation of the project, the monitoring system is introduced, reporting namely the automatically controlled remote observations. The overall characteriz...
The present study aims at understanding the changes in the channel conveyance and in the turbulent flow structure due to the presence of both submerged vegetation in the floodplains and riparian vegetation. An experimental campaign was carried out comprising uniform compound channels flows (i) without any kind of vegetation, (ii) with synthetic grass in the floodplains, (iii) with synthetic grass in the floodplains and rods in the interface between main channel and the floodplain and (i...
Evolution of Nazaré beach after the construction of the fishing harbour • The evolution of Nazaré beach from the establishment of the fishing harbour in the early 1980s to the present is examined based on aerial images and topo-bathymetric data. After the construction of the harbour, a trend of shoreline advance is observed. On average, the rate of change is estimated at 2.5 m/year. The result seems consistent with the increase of the crosssectional area at the north jetty (estimated at a...
Concentration polarization is intrinsically associated with the selective character of membranes and often means flux decline and which causes a subsequent decrease of ultrafiltration and nanofiltration performance. More important is the fact that it acts as a precursor of membrane fouling and creates severe fouling problems in the longer times range. The quantification of its dependence on the operating parameters of cross-flow velocities and transmembrane pressures makes recourse to th...
The Óbidos lagoon (central west coast of Portugal) is a small coastal system exposed to intense wave action. Because its inlet is highly dynamic and closes occasionally, frequent interventions have been carried out by local and national authorities. However, their results have been ephemeral, and the interventions’ efficiency needs to be assessed. A monitoring program was applied to understand the morphodynamics of the lagoon during the implementation of a dredging plan in its downstream ...
A sensitivity analysis was performed on the mean infragravity wave period by varying five input parameters associated to short-waves. The mean infragravity wave period was estimated from the short-wave directional spectrum using a second-order wave theory. The analysis was based on a sensitivity index and showed that the mean infragravity wave period is more sensitive to both the significant short wave height and the mean short wave period than to the water depth, the directional spreadi...
This study aims to investigate the changes in the infragravity wave energy under partial short-wave breaking conditions induced by a longshore bar. Field observations of near-bottom pressure records on a cross-shore array were analysed for such purpose. The bispectrum was employed to detect the phase-coupling between short and infragravity wave frequencies. This allowed to separate the infragravity wave energy in bound and free energy components. The bar crest induced a decrease on the s...
Usually, physical model tests support the design of breakwaters considering different incident wave conditions, including extreme events. This paper describes two-dimensional physical model tests of a rock armour breakwater, performed at LNEC´s experimental facilities, under the framework of the HYDRALAB+ project. The goal of the present work is to evaluate damage evolution under wave conditions resulting from future climate change scenarios. Test results are presented in terms of the non-dim...
LNEC's Scientific Repository
The LNEC Scientific Repository has the purpose of publicizing and allowing free access to the scientific production of its research community in the fields of civil engineering and related areas, promoting the sharing and visibility of scientific information and assuring the preservation of the institution's intellectual memory.
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