Stability of dams for water accumulation in Brazil subjected to seismic loads: case study of Armando Ribeiro Gonçalves dam
Earth dam; Earthquakes in Dams; Armando Ribeiro Gonçalves dam
Dams are extremely important, and it is necessary to guarantee their integrity and stability in adverse conditions, exemplified by earthquakes. The seismic evaluation can be carried out by several methods, highlighting the pseudo-static methodology. The applicability of this method depends on the ability to define representative horizontal and vertical reference levels. In Brazil, the ANA allows the application of fixed coefficients, defined disregarding seismic regionality. The northeast region of Brazil presents a relevant seismic risk, having the Açu dam as one of its most important dams. Pseudo-statics were analyzed with the Açu dam, adopting determination decisions in different ways. When inclined to those suggested by ANA, the dam showed stability, with FS close to 1.4. However, when applied the methodology proposed by Cruz et al. (2021), the dam has evaluable stability considering return times of 475 and 975 years, and evaluable instability considering return times of 2,475 and 10,000 years. It was noticed that verification by the ANA is capable of representing smaller scale events, which may not guarantee an adequate level of safety depending on the location in Brazil, suggesting the use of other methodologies to define these homologation coefficients in dams.