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Several case history failures of slope systems have highlighted that the instability onset in loose materials can be triggered under prevailed drained conditions and stress paths that can be represented by constant shear drained (CSD) loading. This study uses the anisotropic critical state theory (ACST) to assess the effect of fabric anisotropy and loading characteristics (e.g., Lode angle and principal stress direction) on the instability onset under CSD stress paths, comparing our numerical-based observations with available experimental information. Towards this end, the ACST-based SANISAND-F model’s performance under CSD stress paths is also assessed. In addition, multiaxial conditions are incorporated through the estimation of instability surfaces. The numerical simulations are useful in explaining that the instability onset under CSD loading is dictated by a trade-off of volumetric strain components. Moreover, the results show an important effect of fabric anisotropy on the instability stress ratio (𝜂𝑓 ). For conditions representative of common experimental setups, 𝜂𝑓 decreases with the increase of the Lode angle and the major principal stress inclination, and 𝜂𝑓 increases with the increase of initial fabric intensity, consistent with available experimental evidence. However, these trends can change based on the interaction between the Lode angle and loading/fabric directions; hence, departing from typical experimental observations. Finally, we discuss the potential of a simplified approach to estimate 𝜂𝑓 analytically, including fabric effects. 

The onset of static liquefaction in anisotropically consolidated soils is of relevance in assessing the performance of geotechnical systems. Previous studies have also highlighted the role of inherent soil fabric. This study derives an analytical instability criterion for granular materials under undrained loading by using the relatively new anisotropic critical state theory (ACST). The criterion is established using the SANISAND-F model, and it is amenable to incorporating consolidation anisotropy and fabric effects. We assess different numerical strategies for simulating the instability onset on materials sheared from initially anisotropic conditions. Our assessments indicate that simulations that consider consolidation followed by shear better represent the response observed in laboratory tests. It is observed that the degree of anisotropic consolidation has no significant effect on the instability stress ratio, but a very high degree of anisotropic consolidation results in a spontaneous collapse. It is also observed that the anisotropic consolidated specimens have a higher instability stress ratio in triaxial compression than in triaxial extension, highlighting the effect of loading direction relative to the existing fabric. 

Arguably, critical state soil mechanics (CSSM) is now the preeminent methodology for understanding static liquefaction of mine tailings, having been used in the mining industry by the expert panels retained to investigate recent TSF failures. One of the key ingredients of the CSSM framework is the assessment of a critical state line, which separates contractive from dilative states. A critical state line is often defined by a linear relationship and two parameters, namely the altitude of the critical state line at 1 kPa (􀟁) and its slope (􀟣). In this study, we use the TAILENG mine tailings database to investigate potential relationships between the particle features and the particle size distribution, and the critical state properties. Towards this end, the critical state line is evaluated for a range of mine tailings with broad gradations and compressibility, defining 􀟁and 􀟣, with known particle size distributions. This information is subsequently used to investigate potential correlations. Insights from the observations are shared, and potential fundamental mechanisms in explaining correlations between the critical state properties and particle features are discussed. 

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. 

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. 

Static liquefaction has been associated with numerous recent failures of tailings storage facilities (TSFs) around the world. These failures lead to devastating consequences for the environment and civil infrastructure and lead to the loss of human lives. In this study, we present trends for the response of mine tailings to monotonic loading considering (1) triaxial tests, (2) bender element tests, and (3) consolidation tests performed on mine tailings. These materials have a broad range of states (i.e., from very loose to dense states), a range of particle size distributions (i.e., 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 considering different state definitions. In particular, we present trends for shear strength (residual and peak), state and brittleness soil indexes, and excess pore pressure indexes. Finally, static liquefaction screening indexes are proposed based on the observed trends, highlighting that static liquefaction is just another facet of soil behavior under monotonic loadings, and hence it should be explained under a mechanistic framework. 

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. 

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