http://repositorio.lnec.pt:8080/jspui/handle/123456789/47 Thu, 21 May 2026 08:25:53 GMT 2026-05-21T08:25:53Z http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019443 Title: Self-organizing maps for water quality assessment in reservoirs and lakes: A systematic literature review Authors: Almegdadi, O.; Marcelino, J.; Fakhreddine, S.; Manso, J.; Marques, N. Abstract: Sustainable water quality underpins ecological balance and water security. Assessing and managing lakes and reservoirs is difficult due to data sparsity, heterogeneity, and nonlinear relationships among parameters. This review examines how Self-Organizing Map (SOM), the unsupervised AI technique, is applied to water quality assessment. It synthesizes research on parameter selection, spatial and temporal sampling strategies, and clustering approaches. Emphasis is placed on how SOM handles multidimensional data and uncovers hidden patterns to support effective water management. The growing availability of environmental data— from in-situ sensors, remote sensing imagery, IoT technologies, and historical records—has significantly expanded analytical opportunities in environmental monitoring. SOM has proven effective in analysing complex datasets, particularly when labelled data are limited or unavailable. It enables high-dimensional data visualization, facilitates the detection of hidden ecological patterns, and identifies critical correlations among diverse water quality indicators. This review highlights SOM’s versatility in ecological assessments, trophic state classification, algal bloom monitoring, and catchment area impact evaluations. The findings offer comprehensive insights into existing methodologies, supporting future research and practical applications aimed at improving the monitoring and sustainable management of lake and reservoir ecosystems. Fri, 28 Nov 2025 00:00:00 GMT http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019443 2025-11-28T00:00:00Z http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019419 Title: Structural health monitoring and inspection of dams based on unmanned aerial vehicles photogrammetry with 3D model reconstruction Authors: Leite, D.; Marcelino, J.; Guerra, N.; Manso, J.; Marques, N. Abstract: Ensuring dam safety requires continuous monitoring to detect structural anomalies such as cracks, displacements, and seepage. This study explores aerial surveys using Unmanned Aerial Vehicles combined with open-source software to enhance dam monitoring capabilities. The methodology enables efficient inspections in difficult-access areas and supports early identification of potential failure indicators. High-resolution aerial imagery was processed to generate detailed three-dimensional representations including point clouds, orthophotos, and textured models. A novel Ground Control Points Finder tool was developed to automate identification and georeferencing, significantly improving spatial accuracy and survey efficiency. The study systematically presents fourteen failure modes detectable through aerial mapping, including piping, hydraulic fracturing, foundation instability, and freeboard loss, with their characteristic surface manifestations. The approach was validated using Lapa Dam as a case study through two aerial surveys conducted ten months apart. Analysis using open-source software successfully identified surface deformations, settlements, and vegetation changes, demonstrating the methodology’s effectiveness in detecting structural anomalies associated with potential failure modes. The results confirm that integrating aerial surveys with open-source processing tools offers a low-cost solution to complement dam safety assessments. The approach improves early detection of various failure modes, reduces inspector exposure to hazardous conditions, and supports informed decisions in monitoring embankment dams through accessible technology. Wed, 06 Aug 2025 00:00:00 GMT http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019419 2025-08-06T00:00:00Z http://repositorio.lnec.pt:8080/jspui/handle/123456789/1018736 Title: Yielding of Rockfill under Relative Humidity Control Authors: Manso, J.; Marcelino, J.; Caldeira, L. Abstract: This paper presents a fundamental study on the evolution of particle breakage during triaxial compression tests, focusing on the effect of total suction. This analysis was based on triaxial compression tests, performed with RH control. The tested material comes from the sta- bilizing shoulders of Montesinho CFRD and three RHs were stud- ied: 50%, 75%, and 100%. Experimental procedures are presented, with details of the prep- aration of specimens, and stress–suction paths are given. Special at- tention is given to the compaction and the application of different suctions. First, the influence of confining stress is analyzed. Results show that the confining stress led to a contractive behavior, de- creasing dilatancy. For a confining stress of 0.75 MPa, the dilatancy almost disappears. Considering the analyzed values of total suction, the maximum difference of deviatoric stress between specimens with different values of total suction was obtained when the mate- rial reached the peak condition, and was attenuated for larger values of axial strain. By determining the volumetric and axial strains, as well as the shear strains, it is possible to plot the stress paths and the plastic strain increment vectors. It is also possible to separate the elastic and plastic components. This allows for confirmation that speci- mens compress volumetrically during the initial part of the loading curve, up to a certain level of stress. Near the peak deviatoric stress, the material exhibits dilatancy, probably because of particles fitting together intricately, as a result of particle breakage and rearrangement. Another aspect analyzed was particle breakage; this tends to in- crease with the confining stress and the decrease in total suction. To assess the amount of breakage during triaxial loading, the Einav breakage factor was determined. The results corroborate the con- clusion that the values of the breakage factor increase with confin- ing stress and with the decrease of total suction. A 10% increase was observed in the breakage factor when the total suction was de- creased from 93.86 to 0 MPa. Dilatancy is described in terms of stress ratio, particle breakage, and average confining stress, and the experimental results show thatthe major effect of the decrease of total suction is contraction of the peak failure envelopes in the p–q plane by about 5.5% (for mean stresses up to 2.5 MPa). At the end of the tests, dilatancy was prac- tically independent of suction, decreasing only with confining stress to 1/3 (for the studied confining stresses: 0.20, 0.40, and 0.75 MPa). The research findings indicate that suction has a limited effect on the measurement of dilatancy. In any case, its effects, al- though noticeable and broadly consistent with observations in other tests with controlled suction on weak soils and gravels, are substan- tially smaller than the rest of the variables mentioned. Sat, 01 Feb 2025 00:00:00 GMT http://repositorio.lnec.pt:8080/jspui/handle/123456789/1018736 2025-02-01T00:00:00Z http://repositorio.lnec.pt:8080/jspui/handle/123456789/1018548 Title: Southern Expansion of the Cerro do Lobo Waste Facility. Mechanical Characterization of Soil-rockfill Mixtures Authors: Brito, A.; Manso, J.; Marcelino, J.; Galrão, R.; Oliveira, M. Editors: Carlos Pina, Eliane Portela e Laura Caldeira Abstract: The Southern Expansion of the Cerro do Lobo Waste Facility, inserted in the Neves-Corvo Copper and Zinc Mining Concession, is located in Baixo Alentejo, district of Beja, covering the municipalities of Castro Verde and Almodôvar, Portugal. During the operational phase, the mining waste will be deposited vertically, in stages. At the same time, the deposition area will expand approximately 10%. This enlargement includes the southern expansion of the tailings dam. This dam will contain waste up to level 8 (at elevation 272 m), has a maximum height of 17 m, and its walls have slopes of 1(V):2.5(H) upstream, to allow the application of geosynthetics, and 1(V):2(H) downstream. The body of the dam consists of materials resulting from excavation inside the reservoir (rockfill and soil-rockfill mixtures) and a transition layer (0.30 m thick) to support the materials that constitute the waterproofing system. Soil-rockfill mixtures (SRM) represent an environmentally friendly material that capitalises on the reuse of the material excavated. Recently, it has been giving particular attention to SRM by the fact that many embankments, constructed with such materials, have presented a poor performance and required, in many cases, the implementation of corrective measures. To improve the knowledge about the mechanical behaviour of soil-rockfill mixtures applied in tailings dams and also to prevent the use of a less capable material behaviour, LNEC, in cooperation with the Dam Owner, carried out an experimental study. This paper presents the results of the performed experimental program, which involved undrained triaxial tests among others. Tue, 01 Apr 2025 00:00:00 GMT http://repositorio.lnec.pt:8080/jspui/handle/123456789/1018548 2025-04-01T00:00:00Z