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Abstract(s)
O Programa Nacional de Barragens de Elevado Potencial Hidroeléctrico apresenta-se como uma
das repostas do governo português perante as exigências da União Europeia (EU) quanto à
diminuição da emissão de gases nocivos. Associada a esta iniciativa, foram refeitos, com base em
dados mais actualizados, estudos de cheias nas barragens existentes que originaram a
necessidade de construção de novos órgãos hidráulicos para dar vazão aos caudais de projeto,
nomeadamente, a construção de descarregadores complementares de cheia (DCC). O recurso a
explosivos para o desmonte do maciço rochoso é uma das formas mais rápidas e eficientes ao
nível económico para a construção dos DCC.
As vibrações induzidas no solo são um dos impactos resultantes da utilização de explosivos
em escavações, podendo entre outros, provocar danos nos maciços remanescentes e nas
estruturas circundantes, sendo desta forma necessário promover a sua monitorização e controlo.
A Norma Portuguesa (NP) 2074:1983, em vigor até 2015, para o controlo e monitorização
deste tipo de efeitos em estruturas, encontra-se orientada na sua maioria para edifícios e não para
estruturas especiais como as barragens. No entanto, a sua orientação é que este controlo seja
realizado no decorrer das operações de desmonte, comparando os valores observados com os
limites estabelecidos pela mesma.
Este trabalho foi motivado pelo apoio do Laboratório Nacional de Engenharia Civil (LNEC)
à empresa Energias de Portugal (EDP) numa das suas recentes obras efetuadas na Barragem de
Salamonde, nomeadamente, a construção de um novo DCC e uma nova central. Neste âmbito,
desenvolve-se um modelo numérico dinâmico tridimensional híbrido descontínuo de Elementos
Discretos e Elementos Finitos. Este modelo simula a barragem, o maciço de fundação, a
construção do DCC, e o fenómeno de geração, propagação e impacto das vibrações devidas aos
desmontes de rocha. Esta metodologia pode oferecer uma solução anterior à realização das
operações, possibilitando uma análise dos efeitos originados pelas vibrações resultantes do
desmonte do maciço rochoso com recurso a explosivos.
O modelo desenvolvido permitiu reproduzir as vibrações tanto na fundação como no corpo
da barragem, obtendo-se resultados quantitativos da mesma ordem de grandeza dos medidos
durante a obra. Em relação aos métodos clássicos de definição de leis de propagação, a
metodologia desenvolvida permite simular obras semelhantes com um bom grau de confiança.
The National Program for Dams of High Hydroelectric Potential is one of the answers of the Portuguese government to the requirements of the European Union regarding the reduction of the emission of noxious gases. Associated with this initiative, studies of floods in the existing dams have been redone, based on more updated data, which led to the need for the construction of new hydraulic bodies to give vent to the project flows, namely the construction of complementary dump fillers (DCC). The use of explosives to dismantle the rocky massif is one of the fastest and most cost-effective ways to build DCCs. The vibrations induced in the soil are one of the impacts resulting from the use of explosives in excavations, which can, among others, cause damage to the remaining massifs and to the surrounding structures, and it is therefore necessary to promote their monitoring and control. The Portuguese Standard 2074: 1983, in force until 2015, for the control and monitoring of this type of effects in structures, is mostly oriented to buildings and not to special structures such as dams. However, its orientation is that this control be performed during the dismantling operations, comparing the observed values with the limits established by the standard. This work was motivated by the support of the National Civil Engineering Laboratory to the company Energias de Portugal in one of his recent works at the Salamonde Dam, namely the construction of a new DCC and a new powerplant. In this context, a discontinuous hybrid threedimensional dynamic numerical model of Discrete Elements and Finite Elements is developed. This model simulates the dam, the foundation mass, the construction of the DCC, and the phenomenon of generation, propagation and impact of the vibrations due to the dismantling of rock. This methodology can provide a solution prior to the realization of the operations, allowing an analysis of the effects caused by the vibrations resulting from the rock mass removal using explosives. The developed model allowed to reproduce the vibrations in both the foundation and the body of the dam, obtaining quantitative results of the same order of magnitude of those measured during the work. In relation to the classical methods of definition of propagation laws, the developed methodology allows to simulate similar works with a good degree of confidence.
The National Program for Dams of High Hydroelectric Potential is one of the answers of the Portuguese government to the requirements of the European Union regarding the reduction of the emission of noxious gases. Associated with this initiative, studies of floods in the existing dams have been redone, based on more updated data, which led to the need for the construction of new hydraulic bodies to give vent to the project flows, namely the construction of complementary dump fillers (DCC). The use of explosives to dismantle the rocky massif is one of the fastest and most cost-effective ways to build DCCs. The vibrations induced in the soil are one of the impacts resulting from the use of explosives in excavations, which can, among others, cause damage to the remaining massifs and to the surrounding structures, and it is therefore necessary to promote their monitoring and control. The Portuguese Standard 2074: 1983, in force until 2015, for the control and monitoring of this type of effects in structures, is mostly oriented to buildings and not to special structures such as dams. However, its orientation is that this control be performed during the dismantling operations, comparing the observed values with the limits established by the standard. This work was motivated by the support of the National Civil Engineering Laboratory to the company Energias de Portugal in one of his recent works at the Salamonde Dam, namely the construction of a new DCC and a new powerplant. In this context, a discontinuous hybrid threedimensional dynamic numerical model of Discrete Elements and Finite Elements is developed. This model simulates the dam, the foundation mass, the construction of the DCC, and the phenomenon of generation, propagation and impact of the vibrations due to the dismantling of rock. This methodology can provide a solution prior to the realization of the operations, allowing an analysis of the effects caused by the vibrations resulting from the rock mass removal using explosives. The developed model allowed to reproduce the vibrations in both the foundation and the body of the dam, obtaining quantitative results of the same order of magnitude of those measured during the work. In relation to the classical methods of definition of propagation laws, the developed methodology allows to simulate similar works with a good degree of confidence.
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 Dams Vibrações Vibrations Explosivos Explosives Análise dinâmica Dynamic analysis Modelação numérica Numerical modelling Método elementos discretos Distinct element method
Citation
FONSECA, Ricardo Duarte Arsénio da - Estudo do comportamento de barragens de betão sujeitas a vibrações provocadas por desmonte do maciço rochoso com recurso a explosivo. Lisboa: Instituto Superior de Engenharia de Lisboa, 2018. Dissertação de mestrado.
Publisher
Instituto Superior de Engenharia de Lisboa