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Propostas de modelos para dimensionamento de dispositivos de controle de percolação interna - abraços - em barragens de terra por meio de técnicas de apredizado de máquina

Wed, 01 Jan 2025 00:00:00 GMT

Título: Propostas de modelos para dimensionamento de dispositivos de controle de percolação interna - abraços - em barragens de terra por meio de técnicas de apredizado de máquina Autor(es): Sousa, Ana Cinthya Mariano de Abstract: This research develops predictive models aimed at the optimized design of internal seepage control devices in earth dams, commonly referred to as wraparound, which play a key role in mitigating erosion processes along the soil–structure interface. To achieve this, an integrated approach was adopted, combining three-dimensional computational simulations based on the Finite Element Method (FEM) with machine learning techniques, enabling an in-depth analysis of hydraulic flow behavior across a wide range of geotechnical, hydraulic, and geometric conditions. The numerical modeling accounted for a series of parametric variations, including different values of hydraulic conductivity, degrees of saturation, foundation characteristics, and diverse geometries of the control devices. As a result, a robust and representative dataset was generated and used to train various machine learning algorithms, notably Artificial Neural Networks, Decision Trees, Random Forests, and the XGBoost model. Among the models evaluated, XGBoost exhibited the most satisfactory performance, achieving a coefficient of determination (R2) of 96.58% for the training dataset and 90.58% for the test dataset, along with low error metrics (Mean Absolute Error – MAE = 7.03; Root Mean Square Error – RMSE = 16.38; Mean Absolute Percentage Error – MAPE = 13.7%), demonstrating the model’s strong predictive capability in estimating the optimal device length. The use of these models enabled the identification of the most effective “abraço” configurations, leading to a reduction in critical hydraulic gradients and, consequently, the prevention of internal erosion mechanisms. Therefore, the findings provide valuable technical insights for improving earth dam design, particularly in contexts with limited experimental data, establishing a reliable, efficient, and cost-effective solution within geotechnical engineering applied to the safety of hydraulic structures. Tipo: Dissertação

Modelagem hidrodinâmica e da dispersão de óleo na zona costeira de Fortaleza-Ce: uma ferramenta de suporte à gestão ambiental e a planos emergenciais.

Wed, 01 Jan 2025 00:00:00 GMT

Título: Modelagem hidrodinâmica e da dispersão de óleo na zona costeira de Fortaleza-Ce: uma ferramenta de suporte à gestão ambiental e a planos emergenciais. Autor(es): Silva, Luiz Felipe Cavalcante da Abstract: Oil spill incidents pose a serious threat to coastal socio-ecological systems, potentially causing persistent environmental and socio-economic impacts and biodiversity loss. This dissertation evaluates the applicability of computational modeling as a support tool for port and environmental management, with emphasis on the development of emergency action plans for oil spill events in the coastal zone of Fortaleza (CE), Northeastern Brazil. To this end, the SisBaHiA® hydrodynamic model and the ADIOS2 oil weathering/decay model were implemented to perform hydrodynamic simulations and to simulate oil release, transport and weathering in the coastal domain of Fortaleza. The principal objectives were to implement, calibrate and validate a hydrodynamic model for the Fortaleza coastal domain using field observational data, and to simulate the formation and dispersion of oil slicks under three hypothetical spill volumes (8 m³, 200 m³ and 1000 m³) at the Mucuripe Port terminal, accounting for seasonal extremes of wind forcing and mapping areas of potential contamination. Hydrodynamic results were evaluated against observational time series from a tide gauge station and an ADCP. The comparison showed strong agreement for surface elevations (coefficient of determination R² > 0.90; PBIAS < ±1%; RMSE ≈ 5–14 cm; model–observation agreement index CIM > 90%), whereas current velocity predictions exhibited moderate performance (R² ≈ 0.40–0.50; PBIAS ≈ -3%; RMSE ≈ 0.08 m/s; CIM > 80%), reflecting the greater physical complexity involved in the spatiotemporal representation of coastal currents. Oil-spill simulations produced maps that combine probabilistic representations of areas potentially affected by hydrocarbons with deterministic trajectories for the events deemed critical. It is concluded that SisBaHiA® can provide useful inputs for local-scale risk assessment and response planning, although further adjustments and refinements, as well as continuity of this research, are recommended to optimize the model’s predictive capability for oil behaviour in the marine environment. Tipo: Dissertação

Proposição de curvas de distribuição temporal da precipitação de projeto para a região da bacia do Rio Maranguapinho em Fortaleza-Ce

Wed, 01 Jan 2025 00:00:00 GMT

Título: Proposição de curvas de distribuição temporal da precipitação de projeto para a região da bacia do Rio Maranguapinho em Fortaleza-Ce Autor(es): Pinto, Paulo Guilherme de Sousa Abstract: This study created temporal distribution curves for design rainfall in Fortaleza, Brazil. Using data from the local pluviograph, intense rainfall events were selected based on duration and precipitation amount criteria. The adopted methodology was based on the Huff method. A total of 36 temporal distribution curves for design rainfall were obtained for different quartiles of exceedance probabilities, which were compared to the curves from the Huff and Alternating Blocks methods. Simulations in the Maranguapinho basin allowed for the comparison of the resulting hydrographs from each distribution. It was concluded that the application of the Alternating Blocks method is not recommended for design rainfall in the city of Fortaleza, with the curves for the 2nd quartile from Fortaleza and Huff showing better results. Tipo: Dissertação

Estudo do comportamento mecânico de solos arenosos reforçados com microgrelhas por meio de ensaios de placa

Wed, 01 Jan 2025 00:00:00 GMT

Título: Estudo do comportamento mecânico de solos arenosos reforçados com microgrelhas por meio de ensaios de placa Autor(es): Sernache, Neyla Lima Carneiro Abstract: The pursuit of improvements in soil strength and stiffness is a significant topic in geotechnical engineering. The use of geosynthetic reinforcements has proven to be an effective solution, enhancing the stability of structures and the bearing capacity of soils. These materials are applied in projects requiring greater stiffness, shear strength, and tensile resistance, such as foundations and retaining structures. Among these, microgrids perform functions of separation and reinforcement. However, as a relatively recent geosynthetic on the market, its properties as a soil reinforcement material are still underexplored in the literature, highlighting the need for further research on the subject. This research aimed to evaluate the improvement in the mechanical behavior of a foundation on natural soil by comparing it with the performance of compacted sandy soils and compacted soils reinforced with three layers of microgrids. To achieve this, three field load tests were conducted at the same location: one on natural soil, another on compacted soil, and a third on compacted soil with the inclusion of microgrids. Due to the absence of distinct physical failure in the load tests, the stiffness extrapolation method proposed by Décourt (1996; 2008) was applied to estimate the failure stress. The analyses were based on pressure versus settlement curves and parameters obtained from plate load tests, allowing a comparison of soil behavior under different conditions. The results showed an increase in bearing capacity, stiffness, vertical reaction coefficient, and elastic modulus, as well as a reduction in settlements with the use of improvement techniques. These improvements were more significant in compacted soil with microgrids. The results were also compared to failure stresses calculated using parameters from laboratory tests in previous studies with samples from the same location. The failure stresses were estimated using Terzaghi's method (1943) for saturated soils in natural, compacted, and compacted-with-microgrid conditions, and Vanapalli and Mohamed's method (2007) for unsaturated natural soil. The theoretical methods were more conservative for natural and compacted soils; however, for compacted soil with microgrids, Terzaghi's method was less conservative than the field results. This highlights the need for adjustments to better represent the conditions of tests conducted with microgrid inclusion. Furthermore, the analyses from the stiffness method in this research indicated the absence of physical failure in the respective direct load tests, a fact already supported by Décourt (2008). Tipo: Dissertação