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Advisor(s)
Abstract(s)
O controlo da segurança de barragens baseia-se na monitorização da resposta das obras ao longo
do tempo e na comparação entre resultados observados e resultados previstos através de modelos
numéricos. Em geral os resultados observados analisam-se com base em modelos de separação de
efeitos (MSE), o que facilita a comparação com resultados de modelos de elementos finitos (MEF).
Com esta dissertação pretende-se contribuir para o desenvolvimento das metodologias de análise
do comportamento de barragens de betão em fase de exploração normal, em particular de barragens
com problemas de expansões. Nomeadamente é objetivo deste trabalho contribuir para melhorar o
programa DamSafe3.0 para apoio à análise dos dados da observação de barragens recorrendo à
utilização integrada de MEF e de MSE. O programa DamSafe3.0, desenvolvido em MATLAB, inclui
um módulo de análise estrutural com elementos finitos (MEF) e um módulo para análise dos
resultados observados por separação de efeitos (MSE). O programa está estruturado para facilitar a
comparação gráfica entre resultados de MEF e de MSE.
Como exemplo de aplicação considera-se o caso da barragem da Aguieira, uma barragem de três
abóbadas, com cerca de 90 m de altura que entrou em serviço no início da década de 80.
Analisa-se o comportamento estrutural da barragem ao longo do tempo na perspetiva de caracterizar
o efeito estrutural da expansão do betão, que foi identificada na última década.
Os deslocamentos observados com fios de prumo e por métodos geodésicos (planimetria e
nivelamento), nas três abóbadas e nos contrafortes, são analisados com base em MSE desenvolvidos
especificamente no âmbito desta dissertação e incluídos no módulo MSE do programa DamSafe3.0.
Estes MSE estão preparados para recorrer a informação proveniente de MEF e permitem separar os
efeitos do tempo em várias parcelas, nomeadamente, em duas parcelas de fluência (o programa
permite considerar diferentes coeficientes de fluência na lei de Bazant e Panula, adaptados a betões
com ou sem dano), uma associada à pressão hidrostática e outra ao peso próprio, e numa parcela
associada a expansões. Utilizam-se funções exponenciais para simular o efeito elástico do nível da
água e funções do tipo sigmoide para simular a evolução das expansões ao longo do tempo. O efeito
da temperatura é simulado com base em temperaturas observadas. Os diferentes efeitos obtidos nos
vários pontos observados com o MSE, são comparados com os correspondentes efeitos determinados
numericamente com o MEF, em termos de linhas de influência e de deformadas globais, com especial
ênfase na parcela correspondente ao efeito das expansões em termos de deslocamentos verticais e
horizontais.
The safety control of dams is based on the structural response monitoring across time and on the comparison between observed and predicted results, with the latter ones obtained by numerical models. The observed results are mostly analyzed through effect separation models (ESM), to compare the referred results with those from the finite elements numerical models (FEM). This thesis contribution is centered in the development of methodologies to analyze the concrete dams’ behavior at an operational phase, particularly when concerning dams with swelling problems. This thesis contributes for the upgrade of DamSafe3.0, which is a program to support the dams’ observation data analysis resorting to the integrated use of FEM and ESM. DamSafe3.0 was developed in MATLAB and is composed by a FE module for the structural analysis and a ES module for the analysis of the observed results. The program structure enables an easier graphical comparison between the FEM and ESM results. Aguieira dam was considered as the case study. This dam is a multiple arch dam of 90 m high with three arches and two counterforts. Aguieira dam first filling was in the early 80’s. The structural dam behavior is analyzed across time because the concrete swelling behavior needs to be characterized since it was identified in the last decade. The observed displacements measured with plumb lines and geodetic methods (leveling and planimetric), at the three arches and at the counterforts, are analyzed with ESM developed specifically within this thesis scoop and included in DamSafe3.0 ESM module. This ESM module is prepared to retrieve information from FEM and is able to separate the time effects into individual parts, namely: into two creep components (the program can consider different creep laws from Bazant and Panula, adapted to concretes with and without damage), one related to the hydrostatic pressure and the other one to the self-weight; and into a third component related to the swelling reaction. Additionally, exponential functions are used to simulate the water level elastic effect and sigmoid functions are used to simulate the swelling evolution across time. The temperature component is simulated based on observed temperatures. The different components obtained by the ESM, at various observation points, are compared with the corresponding components determined by the FEM, in terms of influence lines and global deformed shape, with special emphasis on the swelling component effect on the vertical and horizontal displacements.
The safety control of dams is based on the structural response monitoring across time and on the comparison between observed and predicted results, with the latter ones obtained by numerical models. The observed results are mostly analyzed through effect separation models (ESM), to compare the referred results with those from the finite elements numerical models (FEM). This thesis contribution is centered in the development of methodologies to analyze the concrete dams’ behavior at an operational phase, particularly when concerning dams with swelling problems. This thesis contributes for the upgrade of DamSafe3.0, which is a program to support the dams’ observation data analysis resorting to the integrated use of FEM and ESM. DamSafe3.0 was developed in MATLAB and is composed by a FE module for the structural analysis and a ES module for the analysis of the observed results. The program structure enables an easier graphical comparison between the FEM and ESM results. Aguieira dam was considered as the case study. This dam is a multiple arch dam of 90 m high with three arches and two counterforts. Aguieira dam first filling was in the early 80’s. The structural dam behavior is analyzed across time because the concrete swelling behavior needs to be characterized since it was identified in the last decade. The observed displacements measured with plumb lines and geodetic methods (leveling and planimetric), at the three arches and at the counterforts, are analyzed with ESM developed specifically within this thesis scoop and included in DamSafe3.0 ESM module. This ESM module is prepared to retrieve information from FEM and is able to separate the time effects into individual parts, namely: into two creep components (the program can consider different creep laws from Bazant and Panula, adapted to concretes with and without damage), one related to the hydrostatic pressure and the other one to the self-weight; and into a third component related to the swelling reaction. Additionally, exponential functions are used to simulate the water level elastic effect and sigmoid functions are used to simulate the swelling evolution across time. The temperature component is simulated based on observed temperatures. The different components obtained by the ESM, at various observation points, are compared with the corresponding components determined by the FEM, in terms of influence lines and global deformed shape, with special emphasis on the swelling component effect on the vertical and horizontal displacements.
Description
Trabalho final de mestrado elaborado no Laboratório Nacional de Engenharia Civil (LNEC) para a obtenção do grau de mestre em Engenharia Civil pelo Instituto Superior de Engenharia de Lisboa no âmbito do protocolo de cooperação entre o ISEL e o LNEC
Keywords
Barragens de betão Concrete dams Modelos de separação de efeitos Effects separation models Modelos numéricos de elementos finitos Numerical finite element models Comportamento observado ao longo do tempo Observed behavior over time Expansão do betão Concrete swelling
Citation
SIMARRO, Mariana Salles da Silva - Observação e análise do comportamento de barragens de betão ao longo do tempo tendo em conta o efeito de ações expansivas : utilização integrada de modelos de elementos finitos e de modelos de separação de efeitos. Lisboa: Instituto Superior de Engenharia de Lisboa, 2017. Dissertação de mestrado.
Publisher
Instituto Superior de Engenharia de Lisboa