Avaliação da estabilidade de uma barragem de rejeitos de mineração de ferro

Evaluation of the stability of an iron mining tailings dam

Abstract

In engineering practice, the evaluation of dam stability is commonly done in a deterministic way, using Limit Equilibrium Methods. However, probabilistic methods have been increasingly accepted as a complementary analysis tool to represent the real condition of soil variability in the field. Thus, the article presents an evaluation of the stability of an upstream tailings dam, in the iron mining region of Minas Gerais, Brazil. In the research, the commercial program Slide 2D from the company Rocscience®️ was used. The stability studies adopted in the present work were based on the Limit Equilibrium Method proposed by Morgenstern-Price (1965). Probabilistic analyzes were carried out, using the classic methods of Monte Carlo (MC) and FOSM (First Order Second Moment), obtaining a deterministic factor of safety (FS) in the order of 1.06, for the condition of the previous dam rupture. The value of probability of rupture (Pr) by the FOSM Method was 27.0% (or 1:3.7), with a reliability index (β) equal to 0.621. Using the MC Method, Pr = 25.6% (or 1:3.9) and β = 0.705 were obtained. It appears, therefore, that both methods indicated a precarious condition of the stability of the dam, which broke in 2019.