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Static liquefaction has been associated with numerous recent failures of tailings storage facilities (TSFs) around the world (e.g., the 2019 Brumadinho failure). These failures lead to devastating consequences for the environment and civil infrastructure as well as the loss of human lives. In this study, we present trends for the mechanical response of mine tailings considering (i) triaxial tests, (ii) bender element tests, and (iii) consolidation tests on 53 mine tailings materials (including recent case histories). These materials have a broad range of states, particle size distributions, and compressibility. The trends are evaluated in the context of static liquefaction using critical state soil mechanics concepts, focusing on the variation of the shear strength (residual and peak), state and brittleness soil indexes, excess pore pressure indexes, instability stress ratios, and dilatancy. In particular, we highlight that mine tailings’ mechanical properties reflect both the properties of the particles themselves and the relative proportions of different particle sizes. For instance, the observed trends suggest that particle gradation influences the small strain stiffness and dilatancy; the proportion of voids to the size of fine particles influences strength, and particle shape affects dilatancy. Finally, we propose static liquefaction screening indexes based on the observed trends.
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Trends for the Monotonic Response of Mine Tailings Under Critical State Soil Mechanics
Static liquefaction has been associated with several failures of tailings storage facilities (TSFs) around the world. The failures result in devastating consequences for the environment and for civil infrastructure, as well as losses of human life. In this study, we present trends for the response of mine tailings to monotonic loading considering a) triaxial tests, b) bender element tests, and c) consolidation tests performed on mine tailings. These materials have a broad range of states, particle size distributions, and compressibility. The trends are evaluated in the context of static liquefaction using the critical state soil mechanics framework. In particular, we present trends for shear strength (residual and peak), state and brittleness soil indexes, instability stress ratios, and dilatancy. Besides, we highlight that mine tailings' mechanical properties reflect both the properties of the particles themselves and the relative proportions of different particle sizes. For instance, the observed trends suggest that particle gradation influences the small strain stiffness and dilatancy; the proportion of voids to the size of fine particles influences strength, and particle shape affects dilatancy. Finally, static liquefaction screening indexes are proposed based on the observed trends
more »
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- Award ID(s):
- 2013947
- PAR ID:
- 10405914
- Date Published:
- Journal Name:
- Tailings 2021 conference on tailings management
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Static liquefaction has been associated with numerous recent failures of tailings storage facilities (TSFs) around the world (e.g., the 2019 Brumadhino failure in Brazil). These failures lead to devastating consequences for the environment and civil infrastructure and lead to loss of human lives. Static liquefaction is just another facet of soil behavior under monotonic loadings, and hence it should be explained under a mechanistic framework. In this study, we present trends for the response of mine tailings to monotonic loading considering a) triaxial tests, b) bender element tests, and c) consolidation tests performed on 53 mine tailings materials (including recent case histories). These materials have a broad range of states, a range of particle size distributions (from silty sand to almost pure silt mine tailings), and a broad range of compressibility. The trends are evaluated in the context of static liquefaction using critical state soil mechanics concepts and considering different state definitions. In particular, we present trends for shear strength (residual and peak), state and brittleness soil indexes, excess pore pressure indexes, and dilatancy. Finally, static liquefaction screening indexes are proposed based on the observed trends.more » « less
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Static liquefaction has been associated with the failure of several tailing storage facilities (e.g., the Brumadinho failure in 2019) and has been a persistent topic of discussion in the mining and tailings communities. Experimental studies have suggested that the onset of static liquefaction is dependent on the initial state (void ratio and confinement) and fabric anisotropy. In this context, traditional constitutive models developed under the critical state theory (CST) have been used to investigate the onset of static liquefaction for several complex loading paths. However, these models do not capture the effect of soil fabric anisotropy (inherent and induced) that are relevant in field conditions. In this study, the Anisotropic Critical State Theory (ACST) framework is used to assess the onset of static liquefaction in particulate materials, incorporating the effects of inherent and induced fabric. Our assessments derive an analytical criterion to assess static liquefaction that can be applied to screening assessments. The derived analytical criterion is a function of material properties, state, and fabric anisotropy, which couple the effects of fabric and loading direction. The use of the derived criteria in particulate materials is illustrated, and the implications of assessing the static liquefaction of mine tailings under generalized loading is also discussed.more » « less
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