Análise do potencial de liquefação estática do rejeito de uma barragem do Quadrilátero Ferrífero

Abstract

The liquefaction phenomenon can act both as a primary cause of rupture, by abruptly reducing the strength of the material, and because of other modes of failure, when significant deformations or stress redistributions promote conditions favorable to the structural collapse of the dam, inducing triggers for the occurrence of this phenomenon. When triggered, this condition can lead to progressive destabilization of the mass and overall failure of the structure. Given this, it is essential to understand the liquefaction potential of the tailings based on an understanding of their characteristics. The phenomenon of liquefaction can occur either due to vibrations induced by earthquakes or detonations, characterizing dynamic liquefaction, or by the application of static loads, characterizing static liquefaction. This study will evaluate the susceptibility of granular tailings to static liquefaction. To investigate the static liquefaction potential of iron ore tailings, field tests (SPT and CPTu) and laboratory tests were performed on reconstituted and undeformed tailings samples. Thus, it was possible to evaluate the static liquefaction potential of iron ore tailings from the dam studied, located in the Iron Quadrangle, using methodologies based on field and laboratory tests. The results showed that, in the context of the tailings studied, methodologies based on field tests that explicitly incorporate the drainage conditions of the test itself are fundamental for assessing susceptibility to liquefaction, providing greater reliability in the interpretation of the phenomenon. The importance of integrating field and laboratory approaches for a more robust interpretation of the material's behavior was also highlighted, since laboratory tests allowed us to observe that, although the material exhibits a contractile response at certain stress levels, no signs of softening typical of metastable materials, usually associated with the phenomenon of liquefaction, were observed.