Análise de estabilidade de uma barragem de terra: abordagens determinística e probabilística

Abstract

Concern about the safety of dams has gained space in the technical environment, especially with the repercussion of recent accidents. Earth dams characterize the oldest documented construction method, being the most frequent type in cases of multi-purpose water reservoir. The variability inherent in the building materials used, that is, the different types of soils and rocks, is reflected in the safety issue of these structures in Brazil, as they recorded the largest number of accidents and incidents in 2017, according to the Annual Dam Safety Report. Therefore, this work aims to analyze the stability of an earth dam according to criteria established by the Dam Safety and Inspection Manual, based on the Limit Balance methods and from a deterministic and probabilistic approach using the Monte Carlo method. The methodology consists of computational modeling using the GeoStudio software, where the percolation analysis was performed to define the water table and the stability analysis for the end of construction, steady state operation and fast lowering, obtaining the coefficients of safety of upstream and downstream slopes, both deterministic and probabilistic. The results of the investigations showed that the calculated safety factors are in accordance with those established in the current manuals. In addition, they highlighted the importance of obtaining a rupture probability and a reliability index as a result of dam stability and safety analyzes by comparing deterministic and probabilistic results. It is concluded that the use of probabilistic methods brings significant advances in the safety diagnosis of a dam, since it allows considering the variability of material characteristics and provides results associated with a level of reliability.