DBB http://repositorio.lnec.pt:8080/jspui/handle/123456789/40 2026-05-11T18:53:31Z 2026-05-11T18:53:31Z Braga Farinha, M. L. Azevedo, N. Oliveira, S. http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019805 2026-05-05T16:38:16Z 2026-01-01T00:00:00Z

Title: Effects of geometry, joint properties, and deterioration scenarios on the hydromechanical response of gravity dams Authors: Braga Farinha, M. L.; Azevedo, N.; Oliveira, S. Abstract: An explicit coupled two-dimensional (2D) hydromechanical model (HMM) that can simulate discontinuous features in the foundation, as well as the effects of grout curtains and drainage systems, is employed to evaluate the influence of key parameters such as dam height, foundation behaviour, joint patterns, joint stiffness and strength, hydraulic apertures, and grout curtain permeability. A parametric sensitive study using four gravity dams, and a real case study of an operating dam are presented. The results presented show that dam height influences the relationship between water level in the reservoir and drain discharges, with higher dams showing more pronounced curved nonlinearity. The strength properties of the concrete–rock interface are also shown to have a meaningful influence on the HM response, especially for an elastic foundation and for higher dams, showing the need to properly characterize this interface through in situ testing. The joint aperture at nominal zero stress is shown to be the parameter with the most significant effect on the HM response. The results also show that a progressive degradation scenario of the concrete–rock interface or of the grout curtain permeability is easier to identify through the hydraulic measurements than in the mechanical displacement field.

2026-01-01T00:00:00Z Gomes, J. P. Lamas, L. Carvalho, E. http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019703 2026-05-05T16:37:36Z 2025-08-01T00:00:00Z

Title: MEDIÇÃO IN SITU DE TENSÕES NO BETÃO E NAS ARMADURAS DAS ESTRUTURAS SALIENTES DO DESCARREGADOR DE MEIO FUNDO DA BARRAGEM DE CAHORA BASSA Authors: Gomes, J. P.; Lamas, L.; Carvalho, E. Abstract: A barragem de Cahora Bassa, localizada no rio Zambeze, em Moçambique, é uma abóbada de dupla curvatura com uma altura máxima de 166 m. O fenómeno expansivo, devido a reações álcali-agregado, tem vindo a ser acompanhado desde que foi detetado há cerca de 40 anos. As estruturas salientes dos descarregadores de meio fundo são elementos em consola, em betão armado pré-esforçado, que servem de suporte às comportas. Qualquer alteração das suas dimensões (por exemplo devido às reações expansivas do betão) são muito importantes porque podem originar a inoperacionalidade das comportas, colocando em risco a segu- rança operacional da barragem. Foi desenvolvido um programa de ensaios para determinar as tensões instaladas no betão do corpo da barragem e nas armaduras dos descarregadores de meio fundo, para comparação dos valores determinados pelos ensaios com os obtidos pelos modelos numéricos desenvolvidos e sua calibração. Na medição de tensões no betão do corpo da barragem foi utilizado o método de sobrecarotagem, com equipamento originalmente desenvolvido pelo U.S. Bureau of Mines. Este método foi desenvolvido para a medição de tensões em maciços rochosos, onde é utilizado de forma rotineira, mas a sua aplicação em betão de barragens não é habitual. Este é um aspeto inovador do trabalho efetuado. O artigo apresenta o programa de trabalho de campo, pormenores sobre os ensaios de determinação de tensões, os valores obtidos e sua comparação com os do modelo numérico, e algumas considerações sobre os resultados.

2025-08-01T00:00:00Z Pereira, R. Bogusz, W. Lamas, L. http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019212 2026-05-05T15:11:15Z 2025-07-02T00:00:00Z

Title: Design of Spread Foundations on Rock Mass in the Second Generation of Eurocode 7 Authors: Pereira, R.; Bogusz, W.; Lamas, L. Abstract: This paper outlines the key developments in the second generation of the Eurocodes, with a focus on the integration of rock engineering into the updated Eurocode 7—Geotechnical Design (EN 1997). It introduces the various methodologies used for safety verification of geotechnical structures and provides a brief overview of limit state design, including the semi-probabilistic approach and other reliability-based methods. The paper details the introduction of specific partial factors for intact rock, rock mass, and discontinuities and discusses specific aspects of the design of spread foundations on rock using calculations. This includes the shift from traditional global safety factor methods to the partial factor format prescribed by Eurocode 7, as well as the use of fully probabilistic analyses. To assess the practical implications of these updates, a case study on the design of a spread foundation is presented. The study compares three design approaches: the global safety factor method (based on mean values of actions and strength properties), the Eurocode 7 partial factor method (using characteristic values), and a probabilistic method (based on statistical distributions). Additionally, the paper examines the application of two failure criteria—Mohr–Coulomb and Hoek–Brown—in the calculation process.

2025-07-02T00:00:00Z Spross, J. Ashcroft, B. Pereira, R. Stille, H. http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019211 2026-05-05T15:29:56Z 2025-08-01T00:00:00Z

Title: On the limit state design of bolted rock slopes: Challenges and a way forward Authors: Spross, J.; Ashcroft, B.; Pereira, R.; Stille, H. Abstract: Design of support for rock slopes has traditionally used deterministic safety factors for verification of the structural safety. Following the introduction of limit state design concepts to modern design codes like the Eurocodes, there is a strong trend to implement limit state design also to rock engineering structures. A recent example is the second generation of Eurocode 7, which suggests that limit states be set up for bolted rock slopes and verified using partial factors. There is, however, a lack of research regarding the applicability of limit state design principles in general – and the partial factor method in particular – to bolted rock slopes. In this short paper, we investigate the appropriateness of applying limit state design principles to bolted rock slopes. We aim to establish a way forward toward a consistent and rational design approach for rock slopes that satisfies societal safety requirements without being overly conservative, while still being user-friendly to practicing rock engineers.

2025-08-01T00:00:00Z