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The Global Industry Standard on Tailings Management (GISTM) promotes performance-based approaches in geotechnical assessments. Hence, characterizing the spatial variability of deposited tailings is expected to be a key input for some tailings storage facilities (TSFs); however, it has seldom been investigated. In this study, we assess the spatial variability of thickened and conventional tailings that have been deposited into the same TSF, providing a unique opportunity to investigate two tailings technologies. A dense array of 15 cone penetration tests (CPTus) has been conducted to collect data. The results were processed using traditional and machine learning-based methods for data detrending when deriving random fields. In terms of correlation lengths, we find similar ranges for the thickened and conventional tailings and similar distributions, likely influenced by the depositional processes. In contrast, the variance in the conventional tailings is higher, which we attribute to its segregating nature. 

The Global Industry Standard on Tailings Management (GISTM) promotes performance-based approaches in geotechnical assessments. Hence, characterizing the spatial variability of deposited tailings is expected to be a key input for some tailings storage facilities(TSFs); however, it has seldom been investigated. In this study, we assess the spatial variability of thickened and conventional tailings, which have been deposited into the same TSF, providing a unique opportunity to investigate two tailings technologies. A dense array of 15 cone penetration tests (CPTus) with an average offset of 1.5 m has been conducted to collect data. In addition to evaluating the spatial variability, the collected information is also used to assess the potential of machine learning (ML) for detrending when deriving random fields. Using a new proposed stationarity score, we find that an ML-based detrending outperforms traditional procedures for most scenarios. In terms of correlation lengths, we find similar ranges for thickened and conventional tailings (vertical: δwv ¼ 0.2–0.6 m, horizontal δwh ¼ 1.5–4.5 m)and similar distributions, likely influenced by the depositional processes. In contrast, the variance in the conventional tailings is higher, which we attribute to its segregating nature. Finally, by inspecting previous studies on natural soils, we find that the variability of mine tailings(δwh=δwv ¼ 2–21) resembles that observed in alluvial deposits, which we attribute to the parallels in the depositional process 

This study assesses the robustness of a framework based on critical state soil mechanics (CSSM) principles in evaluating earthquake-induced liquefaction manifestation. The assessment is motivated by the contrasting procedures in evaluating static and cyclic liquefaction, where mechanical properties commonly inform the former, whereas the latter often relies on semiempirical-based methods. The framework discussed in this study considers as ingredients (1) laboratory-based mechanical properties that are an average representation of soil’s microstructure, (2) state inversion, (3) the link of state with cyclic resistance ratio (CRR), and (4) the seismic demand, represented by the cyclic stress ratio (CSR). The framework is assessed using ~5000 cone penetration tests (CPTus) conducted after the Canterbury earthquake sequence, where each CPTu is associated with liquefaction manifestation levels. The discussed framework is used to estimate safety factors, which are then combined with several liquefaction severity indexes (LSIs) to evaluate liquefaction manifestation in the context of a classification problem (i.e., “Yes” and “No”). The framework’s performance is assessed using machine learning by estimating receiver operating characteristic curves (ROC). Different state inversion procedures are also considered, and recommendations based on their performance are provided. In particular, a calibrated cavity expansion-based inversion for New Zealand is proposed. We find that the discussed framework offers comparable performance to state-of-practice procedures, even when general considerations for mechanical properties based on CSSM are made, which is encouraging. Moreover, by including mechanical properties, it can better inform extrapolations for regions without significant data and non-typical soils as long as adequate properties are considered. In this context, it shares conceptual similarities with non-ergodic approaches in earthquake engineering. 

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 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