Ensaios triaxiais de extensão em um rejeito de minério de ferro

Abstract

In this study, iron tailings from the Fundão Dam were studied by means of drained triaxial extension tests. Several authors concluded that triaxial extension in soils is more likely to exhibit strain localization (ROSCOE et al., 1963; YAMAMURO and LADE, 1995; LADE et al., 1996; WU and KOLYMBAS, 1991), which amplifies the radial strains in the sample, resulting in incorrect calculation of the stress level. In order to overcome this problem, YAMAMURO and LADE (1995) proposed an apparatus that enforces uniform strains in the sample, while WU and KOLYMBAS (1991) used strain collars to measure the change in the sample radius. The solution adopted in this research was to use digital photographs and CAD software to measure the actual diameter during the shear stage. This actual diameter was used to determine the cross-sectional area and the vertical stress. The effects of edge distortion on photographs and parallax were considered, as well as corrections for the phenomenon of optical refraction. This method is an accessible alternative to be applied in extension tests carried out in conventional equipment. The shear strength and the critical state line determinations were satisfactory and compared well to other results of the same material.