Artigos de Revista

À realização de obras subterrâneas está associada a descompressão do meio escavado, que,invariavelmente, conduz ao desenvolvimento de uma bacia de subsidência à superfície do terreno. Assim,designadamente em meio urbano, põe-se o problema de avaliar as consequências dos movimentos de superfície sobre o património edificado aí existente. No artigo apresenta-se o método de Avaliação de Risco de Dano em Edifícios desenvolvido por Burland e ilustra-se a sua utilidade. Inicialmente trata-se O problema da estimativa dos movimentos superficiais induzidos por escavações (2), e consequentes efeitos sobre estruturas existentes (3). De seguida, apresenta-se a metodologia de avaliação de risco (4), cuja utilidade é finalmente ponderada e ilustrada à custa de alguns exemplos (5).

This paper presents the technical decisions taken during the designand development of GESTBARRAGENS, which is an Information System thatmanages data concerning dam safety. We focus the discussion around its dataanalysis features, namely: (1) the generation of dynamic forms in ASP.NET; (2)the reporting mechanism implemented with MS Reporting Services; and (3) thespatial analysis based on a GIS infrastructure using the ESRI arcIMS tools.

Results of an experimental research into the physical, chemical, mechanical, and aesthetical changes suffered by pultruded glass-fiber-reinforced polyester profiles during their testing for accelerated aging under the action of moisture, temperature, and ultra violet (UV) radiation are presented. The profiles were submitted to the influence of four different exposure environments: (i) in an immersion chamber, (ii) in a condensation chamber, (iii) in a QUV accelerated weathering apparatus, and (iv) in a xenon-arc accelerated weathering apparatus. The results obtained were analyzed regarding the changes in their weight, sorption ability, tensile and flexural strength characteristics, color, and gloss; the chemical changes were investigated by means of Fourier-transform infrared spectroscopy. Considerable chromatic changes were observed, especially owing to the UV radiation. Although some reduction in the mechanical properties was observed, particularly in the immersion and condensation chambers, the durability tests proved a generally good behavior of this material under the aggressive conditions considered.

This paper investigates the effect of natural and artificial morphological changes in a tidal inlet on the tidal propagation and on the water exchanges with the sea, through data analysis and numerical modeling. Bathymetric and tidal data reveal a strong seasonal signal, as a result of the changes in the relative importance of tidal and wave action: during the maritime winter the M2 tidal amplitude decreases by 50% and flood dominance increases. This trend is reverted during maritime summer, and tidal amplitudes can be further enhanced by dredging of the inlet.Hydrodynamic and residence time (RT) simulations were set up for three different bathymetric configurations of the lower lagoon, representative of distinct situations. Hydrodynamic results confirmed that tidal propagation depends strongly on the bathymetric configuration. At the transitions between channels, tidal energy losses occur and flooddominance increases. Dredging the channels and repositioning the inlet throat improve tidal propagation and promote sediment flushing to the sea.The spatial variability of RTs was evaluated through the integration of individual particle results in morphologically relevant units, while time variability was examined within the tidal and neap/spring cycles. Residence times depend heavily on the morphological changes associated with both dredging operations and inlet migration, and on the particle releasetime, both within the tidal cycle and within neap/spring cycles. The relative importance of each of these factors depends on the particle location within the lagoon. The upstream regions of the lagoon have very large RTs (years), as a result of the small tidal amplitudes and velocities. In some of these regions, RTs vary by a factor of 4 depending on the bathymetry ofthe inlet. In the lower lagoon, tidal amplitude also has a significant effect on RTs. Dredging the channels and repositioning the inlet throat from the southern margin to a central position improves the flushing of both southern and northernchannels.

This paper presents equations for the evaluation of advective flow rates though composite liners involving GCLs. Advective flow is due to the existence of defects in the geomembrane, and depends on the contact condition between the geomembrane and the GCL. In this paper the geomembrane-geosynthetic clay liner contact condition is quantitatively defined, based on expermental data. Accordingly, empirical equations are presented for circular defects having diameters im two different ranges: 2 to 20mm and 100 to 600 mm, The validity of the empirical equation obtained for the smallest range of diameters is compared with experimentalresults and with an existing empirical equation. The empirical equations developed in this paper are then combined in a simple analytical solution, leading to semi-empirical equations that aliow one to predict flow rates for narrow and wide defects, taking account of the flow that takes place at both ends of these defects of finite length. A parametric study shows, through a correlation factor, the importance of the flow at both ends of defecis of finte length, mainly for narrow defects.

O presente trabalho corresponde à primeira fase do projecto POCI/ECM/57909/2004 (2005-2008) - Avaliação de desempenho de Estações de Tratamento de Água e de Estações de Trata-mento de Águas Residuais, cujo objectivo é o estabelecimento de metodologias de avaliação de desempenho de sistemas de saneamento básico, nas suas vertentes de tratamento de água e de tratamento de águas residuais.Neste artigo apresenta-se a caracterização da situação na-cional em termos de estações de tratamento de água e de águas residuais relativamente a localização geográf ca, a ca-pacidade de tratamento, a tipos de tratamento mais comuns e a monitorização. Esta caracterização reveste-se de importância para o projecto atrás referido uma vez que irá permitir o estabelecimento dos cenários sobre os quais serão delineadas as metodologias de avaliação de desempenho.

The hydrodynamic pressures due to jets impinging on plunge pools must be taken into account in the stability design of pool floor concrete slabs. The contraction joints between slabs are normally sealed with waterstops, which prevent the transmission to the foundation of the pressures applied on the upper faces of the slabs. However, a waterstop failure will allow pressure transmission to the foundation, inducing uplift forces on the slabs. The use of open joints might also become a feasible solution for the lining of plunge pool floors if the pressure field that develops around each slab could be adequately evaluated. This paper presents an analytical model and experimental research developed to assess the forces on plunge pool slabs, considering either open or closed. The influence of the relative width of the contraction joints and the joint between the slabs and the foundation is analyzed. The mean value and standard deviation of the hydrodynamic vertical force are determined based on point pressure measurements, and their relative importance is discussed.

Este artigo apresenta uma possibilidade de melhorar o desempenho de argamassas cimentícias através da incorporação de agregados muito finos (reduzidos a pó) de cerâmica de barro vermelho no seu fabrico.Deste modo, elaborou-se um estudo experimental da incorporação de resíduos de barro vermelho em argamassas cimentícias, tendo como objectivo principal o melhoramento da performance das argamassas a vários níveis: resistência, absorção de água, retracção, permeabilidade à água, durabilidade, entre outros.Os resultados obtidos apresentam-se bastante promissores, pelo que é uma matéria cuja investigação deverá ser mais desenvolvida futuramente.

Composite liners comprising a geomembrane (GM) with a circular hole, a geosynthetic clay liner (GCL) and a compacted clay liner were studied in tests conducted at three scales to measure the flow rates at the interface between the GM and the GCL and in the composite liners. The tests conducted aimed at studying the influence of the prehydration of the GCLs, the influence of the confining stress, and the influence of the hydraulic head on flow rates through composite liners due to defects mn the GM. Another goal of thesetests was to check the feasibility of an extrapolation of results obtained from small-scale tests to field conditions. The results indicate that the prehydration affected flow rate in a different way according to the confining stress applied and the GCL used. These also indicate that the flow rate decreases with the increase mn confining stress and that this effect 1s higher for prehydrated GCLs than for non-prehydrated GCLs. These results show as well that the flow rate increases when the hydraulic head increases. Finally, small-scale tests overestimate the flow as compared to intermediate and large-scale tests and thus flow obtained in small-scale tests represent an upper bound of flow that would be obtained in field conditions.

A recarga é um processo importante a considerar na definição da sustentabilidade da exploração das águas subterrâneas. Contudo, a recarga não pode ser medida directamente, pelo que a sua quantificação constitui um processo estimativo que recorre a equações de balanço de massa. Estas equações traduzem o modelo conceptual de funcionamento hídrico de uma área de estudo, possibilitando a estimativa da recarga. O modelo conceptual depende da definição espaço-temporal das áreas de recarga, das áreas de descarga, das áreas onde pode ocorrer evapotranspiração a partir da zona saturada, dos limites do corpo hídrico subterrâneo, dos volumes de entrada de água no sistema em estudo, incluindo a precipitação, e das extracções e utilizações de água superficial e subterrânea e respectivas localizações. Nesta comunicação começa-se por se apresentar um modelo conceptual global e a respectiva equação de balanço hídrico, particularizando-se posteriormente para diversas situações que introduzem simplificações nas equações de balanço hídrico. Para os processos dessas equações que não são medidos directamente referem-se métodos de cálculo.