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Previous issue date: 2017-08-08 / Os riscos associados ? ruptura de barragens s?o elevados. Problemas de instabilidade envolvendo estas estruturas trazem consequ?ncias catastr?ficas ? sociedade. A barragem do A?u, ? uma obra geot?cnica de significativa notoriedade e import?ncia no Nordeste, principalmente no estado do Rio Grande do Norte. ? a maior barragem do estado e ganhou destaque na literatura nacional e internacional com o rompimento do talude de montante no final do per?odo construtivo. Em casos de ruptura, a retroan?lise ? uma t?cnica confi?vel para determina??o dos par?metros de resist?ncia ao cisalhamento dos solos de forma a contribuir para que se evite casos semelhantes. A partir da avalia??o de dados de resist?ncia dispon?veis no meio acad?mico, este trabalho teve como objetivo retroanalisar a ruptura ocorrida para obter os par?metros m?dios de resist?ncia ao cisalhamento do material argiloso preto que constitu?a o n?cleo da barragem do A?u antes do acidente ocorrido. Na primeira etapa do trabalho foram realizadas an?lises de estabilidade do talude de montante da barragem e na segunda etapa a retroan?lise determin?stica e probabil?stica. Essas an?lises foram realizadas no software Slide 7.0 pertencente ? plataforma RocScience. Os resultados mostraram que o talude romperia com os par?metros de resist?ncia da argila siltosa preta na condi??o saturada, com valores de probabilidade de ruptura variando de 60 a 97% entre os m?todos de equil?brio limite utilizados nas an?lises. Tamb?m foi poss?vel definir os poss?veis par?metros m?dios de resist?ncia ao cisalhamento da argila siltosa preta e estabelecer as causas de ruptura da barragem. Os valores da coes?o e do ?ngulo de atrito, no instante de ruptura, obtidos na retroan?lise determin?stica para a argila siltosa preta foram cu=47,1 kPa e ?u=0?. Na retroan?lise probabil?stica os valores da coes?o e do ?ngulo de atrito obtidos foram cu=33,8 kPa e ?u=3,1?, com uma probabilidade de ruptura de 52,7%. Com isso, conclui-se que a ruptura do talude de montante da barragem do A?u ocorreu por causa de erros na fase de projeto e de constru??o da barragem acompanhado pela perda de resist?ncia do solo devido aos excessos de poropress?es gerados durante a constru??o. / Risks associated to dam failure are very high. Problems of instability involving these structures bring catastrophic consequences to the social comunity. The A?u dam is a geotechnical work with significant importance in the Northeast, mainly in Rio Grande do Norte state. It is the largest dam of the state and has gained prominence in national and international literature with the slice of the upstream slope at the end of its construction period. In cases of failure, back analysis is a reliable technique used to calculate the shear strength parameters of the soil in order to avoid similar cases to happen. Considering the evaluation of strength data available in the academic environment, this work had as purpose to analyze the failure occurred in order to obtain the average shear strength parameters of the black clayey material that constituted the A?u dam core before the accident. In the first stage of this work the slope stability of the dam was analyzed and in the second stage the deterministic and probabilistic back analysis was performed. These analyzes were performed in Slide 7.0 from Rocscience platform. The results showed that the slope would fail with strength parameters of the black silty clay in the saturated condition, with values of probability of failure ranging from 60 to 97% between the equilibrium limit methods used in the analyzes. It was also possible to define the possible average shear strength values of black silty clay and to establish the causes of the dam failure. The cohesion and the friction angle values obtained at the instant of failure in the deterministic back analysis for black silty clay were cu=47.1 kPa and ?u=0?. For the probabilistic back analysis the cohesion and the friction angle values obtained were cu=33,8 kPa and ?u=3,1?, with a probability of failure of 52,7%. Therefore, it is concluded that the A?u dam upstream slope failure occurred because of errors in the design and construction phase of the dam accompanied by the loss of soil strength due to the excess of poropressures generated during the construction.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/24603 |
| Date | 08 August 2017 |
| Creators | Vilhete, Didoney Fernandes |
| Contributors | 35816384449, Silva Filho, Francisco Chagas da, 22872426353, Bezerra, Raimundo Leidimar, 07850654404, Freitas Neto, Osvaldo de, Santos J?nior, Olavo Francisco dos |
| Publisher | PROGRAMA DE P?S-GRADUA??O EM ENGENHARIA CIVIL, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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