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Limit state design approach for the safety evaluation of the foundations of concrete gravity dams
No full textThe application of the limit state design (LSD) in the geotechnical area has increased over the last two decades, but this approach is not yet widely used in dam safety evaluation. This study aims to widen the use of the LSD application for large dams, in particular concrete gravity dam foundations. This paper starts with a brief reference to the LSD approach in recently published guidelines for dam design, followed by a detailed description of the LSD formulation when applied to the foundation of concrete dams. The relevance of the joint application of the concepts of ultimate limit states and of numerical methods is highlighted. Comments are made regarding the criteria adopted in order to determine the characteristic values of the material mechanical properties, with an emphasis on discontinuities, taking into account the spatial variability. The sliding safety assessment of the foundation of a concrete gravity dam using the LSD and a discrete element model, both in persistent and in an accidental design situation, is presented. Results led to the conclusion that the LSD methodology may be followed for dam foundation design with the partial factor values prescribed in Eurocode 7.1306-1322ppVol. 11, Nº 10DBB/NOStructure and Infrastructure Engineering: Maintenance, Management, Life-Cycle Design and Performanc
Avaliação ambiental do plano estratégico dos transportes e infraestruturas - Relatório das consultas
No full textEste registo pertence ao Repositório Científico do LNECPor solicitação da Secretaria de Estado das Infraestruturas, Transportes e Comunicações, do
Ministério da Economia do Governo de Portugal, entidade responsável pelo “Plano Estratégico dos
Transportes e Infraestruturas” (PETI3+), o Laboratório Nacional de Engenharia Civil, I. P. (LNEC) foi
incumbido de proceder à elaboração do relatório ambiental deste plano para efeitos do respetivo
processo de avaliação ambiental, nos termos do disposto no Decreto-Lei n.º 232/2007 de 15 de
junho.
O presente documento apresenta os resultados das consultas promovidas no âmbito do processo de
avaliação ambiental do PETI3+.Secretaria de Estado das Infraestruturas, Transportes e Comunicações, Ministério da Economia do Governo
de Portugal / NÃO CONFIDENCIALCD/C
Full-size experiments of air curtains for smoke control in case of fire
No full textThis paper analyses the possibility of use of air curtains to prevent the smoke flow to outside of
fire compartments. These air curtains are installed in an approximately vertical position through
vertical permanent slots (doors). Full size experiments have been developed and several
conditions relevant to smoke-tightness have been adopted. It was concluded that it is possible
to obtain smoke-tightness, provided that the adequate parameters of the plane jet are adjusted
in association with smoke exhaust from the compartment.12pDED/NAIC
Dam regional safety warning using time-series InSAR techniques
No full textAccurate and frequent monitoring of dams and its surroundings is an extremely important task to ensure the safety of settlements located downstream. Time-series InSAR techniques are a cost-effective way for measuring millimeter-level displacements on the Earth surface, at a regional scale, and can be used as an early warning system for the safety of structures and their surroundings. This study presents the application of one of these techniques to the earth dams Álamos I and Álamos II, in Portugal. The results obtained for Álamos I were compared to geodetic measurements and it was verified that the maximum difference of the average displacement rate between the two techniques is 3.2 mm/yr. Preliminary processing was performed for the concrete dam Alqueva.10pDBB/NG
Point clouds and orthomosaics from photographs their use in a Civil Engineering Laboratory
No full textGenerating point clouds or orthomosaics from photographs can be a very affordable and easy
way of access to valuable information of an object or a surface. Close range photographs,
good acquisition geometry, allows that one can achieve high quality point clouds and
othomosaics, sometimes reaching sub-millimetre accuracy. The authors of this paper, the
three working in the National Laboratory for Civil Engineering of Portugal, are identifying
within the Laboratory, applications where point clouds and orthomosaics can be useful to
studies performed by their colleagues, being that this paper presents the first results.
The “objects” that were under study, and here presented, are: a sample of a rock joint, where
the point clouds will help to characterize the surface roughness and the orthomosaic will
support the studies or the variation of the colour of the surface of the specimen during shear
tests; a scaled model of a breakwater, where point clouds will be used to support the
evaluation of the stability of the structure to the impact of waves; walls of concrete dams, as a
support to visual inspections; a timber beam under stress, where photos can be used to
measure the displacements.17pCD/CDProceedings of FIG Working Week 201
Implementing water-energy loss management in water supply systems through a collaborative project: the Portuguese national initiative
No full textThe aim of this paper is to present the collaborative project iPERDAS, on water losses and energy efficiency management, and provide examples of the main results achieved by the participants during 2014. iPERDAS, led by LNEC (National Civil Engineering Laboratory, Portugal), was a project through which 17 water utilities developed their own water-energy losses programmes, following a joint training and capacitation approach (www.iPERDAS.org). The group of participating water utilities was distributed across the country and supplies water to nearly 16% of the Portuguese population along 11633 km of pipes. The group was quite heterogeneous in terms of dimension, corporate structure and level of maturity in water losses management which enabled rich discussions and sharing of best practices. Utilities have received collective as well as one-on-one support, specific training, and benefited from networking with each other in a common and simultaneous process, with similar difficulties and challenges, leading to an effective sharing of solutions. The most significant results of this project include the utilities’ Water and Energy Losses Management Plans, the establishment of solid procedures to carry out water and energy audits, the improvement of inter-departmental communication and the development of an integrated and sound organisational process for water-energy management.8 pComunicação apresentada no IWA World Water Development Congress and Exhibition, Jordânia, Outubro de 2015DHA/NE
Assessment of subterranean termite symbiotic fauna under different diets
No full textSubterranean termites are known as serious pests of wood, having highly efficient lignocellulose degradation ability which largely relies on flagellate protist symbionts present in the hindgut. It is clear that the symbiotic association between lower termites and their hindgut symbionts have advantages for both, since the termites are able to receive an extra energy supply resulting from lignocellulose degradation, while hindgut symbionts have shelter, protection and food, supplied by the termite host. Termite gut microbiota and respective cellulosic activity may be a strategic target for designing molecular-based bio-pesticides for termite control. For such an innovative strategy, the characterization of the flagellate protist symbiotic fauna should be pursued.
The effect of different diets on termite flagellate protists community of the lower termite Reticulitermes grassei (Clément), the principal subterranean termite species in Portugal, was investigated. The main objectives of this STSM were to obtain high quality microscopy images of flagellate protists and to assess the correct methodology to perform a transcryptomic analysis of flagellate protists.
Termites were collected in Portugal and offered six different diets (natural diet (pieces of the wood from where they were collected), pine wood (Pinus pinaster Aiton), European beech (Fagus sylvatica L.), thermally modified beech (submitted to 180ºC during 4 hours), cellulose (cellulose powder mixed with deionized water) and starving (no source of cellulose offered to the termites) for 14 days. After this trial, termites were evaluated in terms of flagellate protists diversity and abundance and prepared for microscopical and molecular analysis.
The results obtained showed clearly that termite flagellate protist communities living inside their hindgut change according with the type of diet. The RNA and DNA extraction techniques experimented, although not as successfully as expected, were a step forward towards the optimization of the methodology to be applied to achieve good quality samples for further analysis. The use of Transmission Electron Microscopy enabled the first visualization of flagellate protists from R. grassei hindgut, allowing the further analysis of their internal physiology, important for their correct identification.
The search for new wood treatments and biobased materials must take into consideration their resistance to biological degradation agents, as subterranean termites. On the other hand, further knowledge of the effect of the different products on the symbiotic interactions on the termite gut might lead to interesting developments in future termite control.11p.This work supported by a STSM Grant (COST-STSM-FP1303-20909) from COST Action FP1303DE/NC
Daivões dam spillway: a novel solution for the stilling basin
No full textThe Upper Tâmega Hydroelectric Project is located in the Tâmega River, a tributary of Douro River, and includes, among other elements, the construction of three dams: Alto Tâmega, Daivões and Gouvães. Daivões Dam is a concrete arch gravity structure, 77 m high above foundation, with a gated controlled spillway, located in the center of the dam, and followed by stilling basin controlled by a tall end weir to force the hydraulic jump in a shorter distance. The hydraulic performance of the proposed spillway stilling basin was tested and optimized on a physical model at 1:50 scale. The paper presents the results of the physical models study and the final unconventional solution adopted for the spillway stilling basin.01-10ppDHA/NR
Utilização de RCD em estruturas de drenagem de obras geotécnicas
No full textO aumento da utilização das matérias-primas secundárias no setor da construção é fortemente incentivado e apoiado pela Comissão Europeia no âmbito de iniciativas como o Horizonte 2020. Este trabalho apresenta o estudo da durabilidade e do comportamento hidráulico de um agregado de betão britado, proveniente de resíduos de construção e demolição. O mesmo estudo foi efetuado com agregados naturais de basalto e de calcário, com o objetivo de servir de referência aos resultados obtidos com o agregado reciclado. Todos os materiais foram ensaiados com água da rede de abastecimento público e com um lixiviado recolhido num aterro de resíduos sólidos urbanos. A viabilidade técnica de aplicar agregado reciclado de resíduos de construção e demolição em estruturas de drenagem de obras geotécnicas e de infraestruturas de transporte, é avaliada.79-90ppDG/NGE
Effects of relative column width and pile-cap elevation on local scour depth around complex piers
No full textAn experimental campaign of 25 long-duration (13–47 days) laboratory tests was carried out with three complex pier models under steady clear-water flow conditions. Each model, characterized by a different relation between the column and the pile-cap widths, Dc=Dpc, was tested for a variety of pile-cap positions relatively to the initial bed, Hc. The experimental data were used to describe the temporal evolution of the scour depth as a function of Hc=h (h = approach flow depth). The common criterion to stop experimental tests
on complex piers was analyzed, and a new criterion was introduced. The equilibrium scour depth, dse, was calculated by extrapolation of data series. The results are used to evaluate the effect of Dc=Dpc and Hc=h on dse when the pile cap is above the bed (Situation 1), partially buried in the bed (Situation 2), and completely buried in the bed (Situation 3). The analysis includes the definition of Hc at which the maximum dse occurs through an equation that takes into account the Dc=Dpc ratio, the relative pile-cap thickness, T=h, and the column and pile-cap shapes.09pDHA/NREJournal of Hydraulic Engineerin