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In this study, a robust non-Newtonian numerical model that can simulate coupled mudflow and sediment transport processes is used to model downstream geomorphic changes during a tailings dam failure. The catastrophic breach of the Mount Polley tailings dam is studied to assess the model performance. Spatial and temporal variation of flow properties like density, viscosity, yield stress, sediment size fractions, and friction are considered in the model. A flexible triangular mesh is adopted, and this helps reduce the computational time significantly compared with structured grid with the same average resolution. High resolution multitemporal digital elevation models (DEMs) are used for the detection of geomorphic changes and estimation of erosion and deposition volumes. The results indicate that the final distribution of tailings deposits obtained from the model results is in good agreement with that obtained from topographic analysis. The model predicted the total volume of erosion and deposition with almost 93% accuracy. The tailings characteristics followed the full Bingham model during the propagation. Different runout scenarios obtained from the mudflow-morphodynamic model and a mudflow fixed-bed model are analyzed, and it was concluded that maximum mudflow depth of the flood wave is higher when bed entrainment is considered. Sediment concentration is higher in the wavefront and middle regions and lower in the tail zone. The mudflow fixed-bed model could underestimate the downstream flood arrival time. The results also confirm that the adopted approach can efficiently model the sediment budget in the study site and the volume of tailings and bed materials released to the downstream lake. Tailings dams are used to store waste solids and water generated during mining operations. Failure of such dams can cause serious damage to human settlements and the downstream environment. For public safety, it is necessary to conduct proper risk assessment, and numerical modeling is crucial for estimating flood magnitude, flood path, and flood arrival time. Tailings water is high in sediment concentration and is viscous; thus, its flow characteristics are different from that of pure water. During the collapse of tailings dam, erosion of the downstream terrain occurs, and changes in the downstream channel morphology can be potentially significant. There can also be a change in the total sediment load when additional solids get eroded from the bed layer. The modeling approach used in this study helps to model erosion and deposition patterns and estimate the downstream flood arrival time when transport of sediment in the downstream channel is considered along with the viscous nature of tailings. When conducting risk assessment of tailings dam failures and when planning for evacuation, this mobile-bed modeling approach can be implemented by design engineers and emergency planners. [ABSTRACT FROM AUTHOR]

There is a critical need for a global monitoring capability for Tailings Storage Facilities (TSFs), to help protect the surrounding communities and the environment. Satellite Synthetic Aperture Radar Interferometry (InSAR) shows much promise towards this ambition. However, extracting meaningful information and interpreting the deformation patterns from InSAR data can be a challenging task. One approach to address this challenge is through the use of data science techniques. In this study, the representation of InSAR metadata as Entity Embeddings within a Deep Learning framework (EE-DL) is investigated for modelling the spatio-temporal deformation response. Entity embeddings are commonly used in natural-language-processing tasks. They represent discrete objects, such as words, as continuous, low-dimensional vectors that can be manipulated mathematically. We demonstrate that EE-DL can be used to predict anomalous patterns in the InSAR time series. To evaluate the performance of the EE-DL approach in SAR interferometry, we conducted experiments over a mining test site (Cadia, Australia), which has been subject to a TSF failure. This study demonstrated that EE-DL can detect and predict the fine spatial movement patterns that eventually resulted in the failure. We also compared the results with deformation predictions from common baseline models, the Random Forest model and Gaussian Process Regression (GPR). Both EE-DL and GPR greatly outperform Random Forest. While GPR is also able to predict displacement patterns with millimetric accuracy, it detects a significantly lower number of anomalies compared to EE-DL. Overall, our study showed that EE-DL is a promising approach for building early-warning systems for critical infrastructures that use InSAR to predict ground deformations. [ABSTRACT FROM AUTHOR]

This paper analyses the feasibility of estimating the fundamental frequency of an 85 m high cycloned-sand tailings dam located in the Central-North area of Chile using the single-station H/V Spectral Ratio Method (HVSR), calculated from seismic ambient noise and earthquakes recorded by a temporal seismic array deployed along the embankment crest, the downstream slope, and the dam toe, directly over the foundation soil. The fundamental vibration frequencies obtained from the HVSRs show consistency with results from the Standard Spectral Ratio method (SSR) calculated between the crest and the toe using the available earthquake records, particularly in the dam central part. [ABSTRACT FROM AUTHOR]

The article analyses the power of mining corporations in areas at risk of tailings dams failures in Minas Gerais, emphasising the Central Region in the context of the disasters in the Doce and Paraopeba river basins. Since these disasters, and due to changes in the federal and state regulations of tailings dams, mining companies began to exercise their territorial power incisively, defining, without prior notice, the need for the compulsory displacement of hundreds of families in communities and cities downstream of dams. Furthermore, corporate control over information and the political definition of the use of the territory substantially altered the localities' social, economic and cultural life. These dynamics aggravated the unequal power relation guided by economic dependence and the constant fear of new failures. At the same time, the mines continued operating to serve the reproduction of capital and the production/appropriation of value. The research was developed based on secondary data and analysis of media material. [ABSTRACT FROM AUTHOR]

Modified Newmark method is proposed including the equivalent seismic loading and critical acceleration dependant on the dynamically exerted plastic yielding and tension cutoff effects along the base of the sliding mass. The fully nonlinear FE analysis is based on elasto-plastic Mohr-Coulomb material model. The proposed algorithm was validated in an example of 72 m high tailings dam. The Newmark permanent displacements were compared with the average plastic deformations resulting from the nonlinear Mohr-Coulomb model. The comparison shows satisfactory agreement for low to moderate nonlinear slope behavior. For deep nonlinearity, the modified Newmark method can be used as a decision-making tool only. [ABSTRACT FROM AUTHOR]

To better understand the seepage field in tailings dam with a drainage structure that combines drainage mat, drainage tube, and geotextile, an equivalent seepage analysis method for the drainage structure is presented. In the method, an equivalent drainage structure is suggested to replace the original drainage. It has enough size to be easily presented in the three-dimensional (3d) model of a tailings dam. According to a back analysis procedure using the quasi-3d models of a tailings dam with original and equivalent drainage structures, the material properties of the equivalent drainage structure can be obtained under the principle of drainage capacity equivalence. It is demonstrated that the suggested method is accurate enough to capture the seepage field in a tailings dam based on comparing the calculated and measured phreatic lines in a tailings dam for verification. Then, the method is employed to investigate the seepage field in a tailings dam in China for a case study. The rise of water level, damage of drainage structure, or increase of tailings discharge speed and time will lift up phreatic line. After terminating tailings discharge, phreatic line will first rise and then fall. The effect of tailings discharge on phreatic line will almost disappear after terminating tailings discharge for 24 h. [ABSTRACT FROM AUTHOR]

Recent disastrous tailings dam failures have heightened public concerns about the safety of these structures. Typically, tailings are disposed of as a slurry in a loosely saturated state, making them susceptible to static liquefaction. The widely used limit equilibrium method for analysing tailings dams may overlook potential failures and is incapable of simulating static-liquefaction-type dam failures. This paper presents simulations of the initiation of progressive failure within a finite element framework, using a well-described tailings dam in Brazil as a basis. Three different constitutive models (Hardening Soil, SANISAND2004, and NorSand) were employed to demonstrate a numerical modelling procedure for simulating tailings dam static liquefaction and a practical approach to numerically account for the effects of fines content in slime layers. Models that incorporate the state parameter (ψ) as an integral part can realistically depict the loss of strength in loose granular materials during a liquefaction process. Stress–strain paths of representative points in critical zones of the studied tailings dam indicate localized shear deformations that lead to progressive failure due to static liquefaction. [ABSTRACT FROM AUTHOR]

A tailings dam failure can be catastrophic. One constantly dumps or removes ore-related materials behind or within a dam before its closure, creating substantial surface change or deformation. The deformation can be assessed with multiple temporal synthetic aperture radar (SAR) observations and interferometric SAR (InSAR) techniques. The surface deformation is one prerequisite causing the failure. The water content increase is another primary factor that can reduce the surface friction among piled materials and induce further surface deformation. Intuitively, large deformation and high water content behind the tailings dam are concerns of a possible dam failure. Thus, we propose a new joint analysis of the InSAR-derived surface deformation and SAR-derived moisture content to achieve the objectives, delineating the stable/unstable status of a tailings dam and capturing a possible pre-failure signal of the dam. We study three types of tailing dams to verify the proposed analysis. The first is the Majiatian tailings dam in China, closed safely at the end of 2020. Our analysis determines that the dam status is stable. The second is the collapsed Córrego de Feijão Tailings Dam I in Brazil. The analysis identified a turning point from stable to unstable near December 2018, and the dam failure occurred in January 2019. In case three, an unstable status first at the Maanshan tailings dam was delineated. The findings were conveyed to parties interested in dam safety, and they carried out mitigation activities afterward. The analysis continued until February 2023, indicating a stable status of the tailings dam. The analysis is also robust to slight variations of moving window size around the proposed value. Thus, a valid joint analysis has been studied and is transferable to locations since the analysis and multitemporal SAR observations are available. • The failure of a tailings dam has catastrophic social and economic consequences. • The surface deformation or water content alone cannot identify the dam's status. • A method to delineate the stable/unstable status of a tailings dam is validated. • The method is robust to slight deviations in moving window size and transferable. [ABSTRACT FROM AUTHOR]

The basic principle of the three-dimensional stress state test is deduced based on the relationship between the normal stress and the conventional stress state, and the relationship between the total stress state and the effective stress state is given based on Terzaghi's effective stress principle. On this basis, we made a three-dimensional earth pressure device by using a pedestal obtained by 3D printing technology, 6 micro earth pressure cells, a pore pressure cell and an attitude sensor. Considering the effect on the tested values of the dynamic change in the normal stress direction, the conversion relationship between the absolute test direction and the relative test direction of the test device is deduced, which can be used to dynamically test the three-dimensional total stress state and three-dimensional effective stress state. In addition, a method to calculate the K0 value is proposed based on the earth pressure device comparing with the direct test result by the K0 oedometer and indirect test results by direct shear test and triaxial test in laboratory. Two three-dimensional earth pressure devices are used in a simulation experiment of tailings dam construction, and the results show that with the increase in pore pressure, the calculated errors of the three-dimensional stress state caused by rotation angles will be more noticeable. This study has engineering value for in situ geotechnical testing and soil strength prediction. [ABSTRACT FROM AUTHOR]

Modeling safety scenarios for dams strengthens effectiveness of disaster risk management plans in this kind of work by reducing risk of failures that can cause considerable damage. The aim of the present paper was a proposal of a modeling methodology for safety scenarios in tailing dams from the Cuban nickel industry, to determine indicators and failure mechanisms, in order to achieve early detection risks and their reduction, as well as to minimize the negative impacts on the economy, the population, and the environment through a risk and disaster management plan. [ABSTRACT FROM AUTHOR]

Modeling safety scenarios for dams strengthens effectiveness of disaster risk management plans in this kind of work by reducing risk of failures that can cause considerable damage. The aim of the present paper was a proposal of a modeling methodology for safety scenarios in tailing dams from the Cuban nickel industry, to determine indicators and failure mechanisms, in order to achieve early detection risks and their reduction, as well as to minimize the negative impacts on the economy, the population, and the environment through a risk and disaster management plan. [ABSTRACT FROM AUTHOR]

With ongoing catastrophic mine tailings dam failures, the hindsight revelation of poor safety records, and an increasing prevalence of public scrutiny and attention of mining operations, there is an immediate call for enhanced safety of tailings dams. Today, challenges arise in identifying and utilising the ability of monitoring systems to understand the complex performance and behaviours of these dams, reflecting on the system's ability to predict deterioration before failure occurs. New literature, mining regulators, insurance firms, and mining practitioners are calling for increased diligence in the form of real-time monitoring: but what can the industry offer in response? This research establishes a centralisation of real-time monitoring instruments suitable for tailings dams, discussing the specifications, advantages, and disadvantages of each. An understanding of traditional instrumentation, online monitoring systems, and the value of centralised monitoring was detailed. Collaboration with suppliers discovered innovative systems which enable monitoring of different failure modes and mechanisms. [ABSTRACT FROM AUTHOR]

Irreversible losses of natural areas and damage to ecosystem services are caused by large-scale mining. These effects are prominent in Minas Gerais, which is home to a mining industry with hundreds of tailings dams concentrated in global hotspots: the Cerrado and the Atlantic Forest. We present an overview of the spatial overlap between protected areas (PAs), priority conservation areas (PCAs), tailings dams, and their influence areas. A total of 218 dams accumulated environmental costs and liability that are represented by 2.24 thousand million m3 of tailings and industrial waste. Most dams (≈ 70%) are located in PCAs, 45 dams in conservation units, 58 in their respective buffer zones, and 51 in special protection areas. We have identified an urgent need to implement adequate public policies to establish management and monitoring mechanisms in PAs and PCAs and to address a scenario of high potential for socioenvironmental damage associated with tailings dams. [ABSTRACT FROM AUTHOR]

The Aznalcóllar tailings dam failure moved the Spanish authorities to pay attention to tailings deposits. The Almagrera tailings dam holds one of the largest mining waste deposits in Andalucía. The dry closure of this dam has been detailed in this manuscript. Some serious difficulties had to be solved. Firstly, the dam had undergone up to five raisings before the closure operations started, and this process had not been properly documented. Secondly, the reservoir water was contaminated by the toxic tailings placed several metres below and, due to the high acidity of this water, the geotechnical characterization of the tailings deposit has been really challenging. Thirdly, the definition of the model itself has been a complex task due to the consideration of many phases and different hypotheses. In the finite element calculation, a constitutive model of perfect non-associated plasticity has been used for the dam and a soft soil creep model for the tailings. Next, it has been decided to decontaminate a closed mine by placing its abandoned material—Las Viñas fill—on top of the tailings deposit inside the reservoir. This operation generated important settlements on the tailings deposit. These settlements had to be accelerated by placing drainage wells to avoid the cracking of the final cap. The safety factor during the dry closure operations under dynamic loading was insufficient and a compacted rockfill reinforcement had to be laid on the downstream slope of the dam. Very few papers describe a successful dry closure of a tailings dam as is done here. [ABSTRACT FROM AUTHOR]

Not long ago, certain iron ore processing plants in Brazil were unable to efficiently recover iron ore fines and, as a result, operated only with high grade iron ore. For this reason, material stored in some iron ore tailings dams have considerable amounts of iron content with a potential to produce pellet feed fines through a concentration process. This study presents the results of magnetic concentration tests carried out on samples from four iron ore tailings dams located in Minas Gerais, named as A, B, C and D. The average iron content is 54% for A dam, 36% for B dam, 49% for C dam, and 58% for D dam. This material had a significant amount of ultra-fine particles, with more than 50% below 0.045mm for all dams, particularly the A and D dams, which present more than 80% of the below 0.045mm on average. Magnetic concentration tests were conducted on bench and pilot scales. The resulting concentrates showed the following average iron content: 66% for dam A, 63% for dam B, and 67% for dams C and D, with a mass recovery of 42% for dam A, 38% for dam B, 75% for dam C, and 63% for dam D. These results confirm the potential for pellet feed production from tailings dams through magnetic concentration. [ABSTRACT FROM AUTHOR]

Many embankments have been constructed in Japan, but most have lacked seismic design, except for important embankments, such as earth dams. However, because embankments are often damaged by large earthquakes, seismic inspections have recently been carried out on existing embankments, and countermeasures have been taken to deal with unstable embankments. This paper describes the seismic inspection methods and countermeasures currently implemented in Japan for river dikes, tailings dams, and embanked residential lands. River dikes are dangerous when they subside and their crests become lower than the river water levels. Therefore, seismic inspections are being carried out using a simple static method to analyze the amount of subsidence against level 2 seismic motion. Countermeasures are being taken, such as compacting the ground under the vicinity of the toe of a dike. For tailings dams, dynamic analysis is performed for level 2 seismic motion, and seismic inspection is performed based on the amount of slip displacement. As countermeasures, solidification etc. have been implemented. There are 51,306 large residential areas embanked in hilly valleys in Japan. Soil investigations and stability analyses will be conducted in these areas as secondary screenings, and these areas are currently being prioritized for such screenings. It will likely be many years before the screenings and countermeasures are completed. • Most of the embankments are not seismically designed and are damaged during earthquakes. • Seismic inspection of embankments is necessary to prevent damage during earthquakes. • In Japan, inspections are being conducted on river dikes, tailings dams, residential areas. • Countermeasures are being taken at river dikes where settlement causes flooding. • Since there are 51,306 embanked residential areas, screening priorities are being determined. [ABSTRACT FROM AUTHOR]

Abstract Cleaner production is the continuous application of an integrated preventive environmental strategy which stressed the importance of environment and human beings. Although the application of cleaner production is becoming more and more mature in different industries, since the complexity of the mining operation itself and its extensive and complex impacts on the ecological environment, the application of cleaner production in the mining industry encounters great challenges. For this purpose, the paper presents some developments and new insights of environmental problems and deep mining strategy for cleaner production in mines. Firstly, the general impacts on the ecological environment of mining industry and the current corresponding solutions as well as future prospects are presented. Secondly, the ecological environment pollution induced by tailings dam and its elimination approaches are reviewed. For the accelerating volume of tailings dam waiting to be processed, the exploration and research of the comprehensive utilization and treatment of tailings is expected to be more effective with larger consumption and wider range of application. The development direction is the establishment of mine without tailings. With the development of modern technology, some intelligent monitoring and warning technologies have helped the mining engineers to keep a vigilant eye on tailings dam continually. Finally, to convert the "harm" of four highs and one disturbance induced by the complex mechanical environment in deep mines into "benefit", various specific measures with relatively high novelty and sustainability are recommended. Moreover, the conception map of safer and more efficient exploitation of resources in deep mines is depicted for industrial best practice and future research directions to enhance cleaner production work in mining. [ABSTRACT FROM AUTHOR]

Tailings dams are traditionally monitored by routine visual inspections combined with the use of instruments such as piezometers, topographical landmarks, and water level indicators. As they are structures that have high potential damage associated, the use of robust investigation methods is essential to ensure the operational safety of these dams. Geoelectrical methods have been successful in mapping humid zones inside the tailings dam structures, using the proper acquisition parameters and data sampling that these methods allow. This is a promising approach to investigating a tailings dam with a heterogeneous embankment made of limestone tailings, that has been in operation for 50 years in São Paulo state, Brazil. Considering its structural complexity, electrical resistivity sections were acquired with a tight profile spacing – of 10 to 15 m, processed, and modeled by applying a specific workflow. The Electrical Resistivity Tomography (ERT) operational workflow applied to the dataset obtained from two field campaigns, conducted in the embankment and the right abutment of the dam, performed well in mapping possible high water content zones inside the structure, defining a relevant element for the risk assessment. For this purpose, compartmentalization of the resistivity ranges, and three-dimensional modeling techniques were used, both constrained by the geotechnical instruments of the structure. The embankment campaign mapped zones of attention in the right abutment driving the decision to perform a follow-up survey dedicated to this region. The right abutment campaign mapped zones of high resistivity, associated with the natural terrain, composed of sandy soils, saprolite, and rock, as well as zones of low resistivity related to high moisture content regions. The geometry of these conductive zones made it possible to infer the depth of the water table in the region between the direct measurements from the instrumentation and to model zones with low resistivity values. The 3D modeling revealed that part of the conductive zones, present in the right abutment and extending to the embankment indicate a possible contribution of moisture from the natural terrain towards the embankment of the dam. Thus, the achieved results demonstrated that 3D modeling applied to the combination of the geotechnical and geophysical datasets contributes to expanding the knowledge of the internal structure of the dam and consequently the safety of the operations, especially where there is no instrumentation, improving the tailings dam risk management. • Three-dimensional model, correlating geoelectric and geotechnical information • Numerical model for modeling high moisture zones • Volumetric investigation in correlation with located geotechnical data [ABSTRACT FROM AUTHOR]

Using a 400 g-ton geotechnical centrifuge, a centrifugal model test system was developed to investigate the overtopping-induced breach process of tailings dams. According to abrupt changes in the erosional characteristics and breach morphological evolution, the breach processes of tailings dams could be divided into three stages, namely, the initial, acceleration, and stable stages. The breach mechanisms mainly consisted of backward erosion during the initial stage, followed by rapid downcutting and widening accompanied by intermittent lateral expansion caused by the collapse of breach-side slopes until the rebalancing of the breach channel occurred. Furthermore, a detailed physical hydrodynamic model was used to simulate dam breaching. The Reynolds-averaged Navier–Stokes (RANS) equations combined with the renormalization group (RNG) k - ε turbulence model were adopted to calculate the complex hydrodynamic conditions. In addition, the model considered the sediment transport equations for bedload and suspended load, as well as the breach-side slope sliding. The governing equations of the model were computed using the finite volume method on a rectangular grid. The calculated breach hydrograph and dynamic breach evolution were consistent with the observations made using the centrifugal tests. This study can provide a scientific reference to estimate the failure process of tailings dams. [ABSTRACT FROM AUTHOR]

Thanks to advances in geoelectrical resistivity method over the past two decades, researchers can now gather massive geophysical data sets encompassing long distances and depths, at reasonable cost. The enhanced resolution and spatial coverage of these techniques make them, now, very attractive for use in geological engineering applications, an area for which they were previously charged to be unsuitable. The study shows the capability of electrical resistivity imaging (ERI) to identify key subsoil features that might affect a future tailings dam slated for construction at the Zaruma-Portovelo Mining District, Ecuador. The ERI profiles were gathered and processed with the aim of obtaining resistivity images of a sufficiently resolution for geotechnical use. A geophysical model was created based on these images. The resistivity images were calibrated according to geomorphological, hydrogeological and geotechnical data in order to translate geophysical information into rational geological information. The ERI results, supported by the geomorphological and geotechnical work, suggested that the rock massif is composed of weathering horizons of different rock qualities, slopes are affected by sliding surfaces and these features exert a control on the groundwater flow. These results indicated that the original site selected to construct the dam dike was susceptible to land sliding and an alternative construction site was suggested. Based on the same results, a geomorphological–hydrogeological conceptual model for layered weathered granitic massif in mountainous areas was also proposed. [ABSTRACT FROM AUTHOR]

It is very important for mine production safety to ensure the stability of the tailings dam. Taking a flatland tailings pond as the background, a threedimensional computational model was built based on a tailings dam under mullock heap preloading condition. Considering the current operating water level conditions, a liquid-solid coupling analysis of the model was conducted. The deformation characteristics of the tailings dam were revealed during successive preloading at the front of the dam. The safety factor and the potential slide face of the tailings dam were calculated under different conditions using the strength reduction method. The results show that the tailings dam in its current condition is basically stable, but if the mullock heap continues to be heightened, the tailings dam will become unstable. Therefore, in order to limit the height of the mullock heap, establishing a monitor and early warning mechanism are put forward to ensure mine production safety. [ABSTRACT FROM AUTHOR]

The authors have developed the FEM geomechanical model to describe evolution of temperature and hydrodynamic fields at the tailings dam of the Kumtor Gold Mine, Kyrgyzstan, in the permafrost region. The influence exerted by the temperature variation in the liquid waste accumulated in tailings pond and by the changes of size of impervious screen on the volume of filtrate material through the dam is evaluated in numerical experiments. It is shown that the pressure variation rate in the observation hole can be the indicator of the impervious screen rupture. [ABSTRACT FROM AUTHOR]

The eastern region of the northern part of Japanese mainland has been known historically as an area of mines producing gold and silver. When the extraordinarily strong earthquake rocked the eastern part of the Japanese mainland on March 11, 2011, there were more than 20 old and new dams retaining tailings from many mines. Out of these, three dams suffered breach due to liquefaction of tailings materials and released a large amount of slime, bringing about damage to farmlands and houses downstream. Of particular interest was Kayakari dam at Ohya mine that failed and Takasega-mori dam in its vicinity that did not, although they were equally subjected to strong shaking. In this paper features of these two dams in the design and construction, and damage or non-damage during the earthquake will be described, together with the geotechnical investigations and some analyses that were conducted after the earthquake. [ABSTRACT FROM AUTHOR]

The use of Internet of Things (IoT) technologies is becoming a preferred solution for the assessment of tailings dams safety. Real-time sensor monitoring proves to be a key tool for reducing the risk related to these ever-evolving earth-fill structures, that exhibit a high rate of sudden and hazardous failures. In order to optimally exploit real-time embankment monitoring, one major hindrance has to be overcome: the creation of a supporting numerical model for stability analysis, with rapid-enough response to perform data assimilation in real time. A model should be built, such that its response can be obtained faster than the physical evolution of the analyzed phenomenon. In this work, Reduced Order Modeling (ROM) is used to boost computational efficiency in solving the coupled hydro-mechanical system of equations governing the problem. The Reduced Basis method is applied to the coupled hydro-mechanical equations that govern the groundwater flow, that are made non-linear as a result of considering an unsaturated soil. The resulting model's performance is assessed by solving a 2D and a 3D problem relevant to tailings dams safety. The ROM technique achieves a speedup of 3 to 15 times with respect to the full-order model (FOM) while maintaining high levels of accuracy. • The Reduced Basis Method is applied to hydro-mechanical problems of groundwater flow. • The Reduced Basis Method is successfully applied to non-linear coupled problems. • A Reduced Order Model is used to solve 2D and 3D problems in earthfill dams. • The order of magnitude of the error introduced by the Reduced Order model is 1 0 − 3 . • Hydro-mechanical problems are solved 3 to 15 times faster with Reduced Order Models. [ABSTRACT FROM AUTHOR]

An alternative method for quality control of earthworks in mining tailing dams is described in this article. It is composed by a penetrometer, known by the acronym DCP (Dynamic Cone Penetrometer), and is used primarily in road construction (quality assessment of pavement layers). With this apparatus, strength measurement of superficial layers of natural and compacted soils can be performed, including mine sand tailings, in a fast and efficient manner. The instrument was successfully used in the construction control of an iron ore mining tailings staged dam in the Quadrilatero Ferrifero, in Minas Gerais State, and the results showed distinctly effective densification of the embankment compacted layers, but with a sort of irregularity in their spatial distribution. In addition, field control using the traditional core-cutter method was also performed for comparison between both techniques. [ABSTRACT FROM AUTHOR]

Although numerous studies focus on the mechanical behaviour and instability of tailings dam materials, a framework that adequately describes all the processes involved in their failure and fluidization is still needed. Therefore, we used a series of instrumented flume tests, with pore pressure transducers, micro-seismic accelerometers, internal displacement transducers and laser scanning, to investigate the mechanisms of tailings-dam failure and fluidization. The artificial rainfall induced water infiltration was adopted to induce the failure. The test results showed that continuous rainfall expanded macro-voids and led to particle rearrangement and local collapse, producing a gradual buildup of pore pressure. Furthermore, the increasing porosity enhanced seepage forces and thus reduced the shear strength of the tailing's materials so that the dam models were close to liquefaction. However, a dam model with a higher hydraulic conductivity would not be totally damaged, even if failure and fluidization occurred. The amount of antecedent rainfall likely significantly contributed to dam failure because it raised the moisture content of the tailing's materials, which promoted internal erosion; thus, the rainfall might have been sufficient to generate local fluidization. Rainfall decreased the peak pore pressures required to initiate failure and shortened the time to failure but hardly influenced the fluidization movement distance. • We use a series of instrumented flume tests to investigate the mechanisms of tailings-dam failure and fluidization. • We find that the relative density of tailing material can largely influence the failure pattern of the tailing slope. [ABSTRACT FROM AUTHOR]

Abstract: Tailings disposal is a significant consideration for the mining industry, with the majority of the ore processed in most mining operations ending up as tailings. Several tailings dam failure accidents have occurred during the past few years and mine tailings dam failures, which are disastrous with the serious damage and the loss of lives, are occurring at relatively high rates. To improve the tailings dam safety, a tailings dam monitoring and pre-alarm system (TDMPAS) based on the internet of things (IOT) and cloud computing (CC) is accomplished with the abilities of real-time monitoring of the saturated line, impounded water level and the dam deformation. TDMPAS has helped the mine engineers monitor the dam safety 24/7 and acquire pre-alarm information automatically and remotely in any kind of weather conditions. TDMPAS has been applied in several mines and has demonstrated the feasibility of monitoring the tailings dam physical condition. [Copyright &y& Elsevier]

Abstract: We developed a new algorithm, the Adaptive Stormwater Infrastructure (ASI) algorithm, to incorporate ancillary data sets related to stormwater infrastructure into the grid-based hydrologic analysis. The algorithm simultaneously considers the effects of the surface stormwater collector network (e.g., diversions, roadside ditches, and canals) and underground stormwater conveyance systems (e.g., waterway tunnels, collector pipes, and culverts). The surface drainage flows controlled by the surface runoff collector network are superimposed onto the flow directions derived from a DEM. After examining the connections between inlets and outfalls in the underground stormwater conveyance system, the flow accumulation and delineation of watersheds are calculated based on recursive computations. Application of the algorithm to the Sangdong tailings dam in Korea revealed superior performance to that of a conventional D8 single-flow algorithm in terms of providing reasonable hydrologic information on watersheds with stormwater infrastructure. [Copyright &y& Elsevier]

Damage caused by accidents at hydraulic structures, due to natural hazards or human causes (e.g. terrorist sabotage) can be comparable to those caused by natural disasters. The paper identifies the major advantages of a common methodology for risk identification and quantification regarding the potential impact of accidents at tailings dams on the environment. Relevant Romanian and EU legislation and regulations enacted following the “Baia Mare” accident in 2000 are reviewed, along with a common risk evaluation methodology that can be applied by the mining sector to tailings dams. [ABSTRACT FROM AUTHOR]

This work analyzed the effectiveness of two electrical geophysical methods in characte-rizing tailings dams. A large flotation cell used for sludge thickening in the concentration plant of the Federico Mine (closed in 1985) within the old mining district of La Carolina (southeastern Spain) was selected for this research. In addition to the direct information provided by the geology of the study area and the surface exposure of the waste deposits, information regarding the construction of this mining structure was available, which helped in the interpretations of the geophysical survey data. In this study, two geophysical surveying methods were used simultaneously: Electrical resistivity tomography (ERT) and induced polarization (IP). Six profiles were acquired, processed, and interpreted. The length of the profiles allowed the obtaining of data reaching maximum investigation depths ranging between 7 and 65 m. These profiles provided information for a detailed analysis of the internal characteristics of the deposited materials. The lateral and vertical observed variations are linked to different degrees of moisture content. The study also defines the geometry of the top of the bedrock and the tectonics that affect the pouring/dumping hole. Old flotation sludge has resistivity values that range between 1 and 100 Ωm (i.e., wet waste 1–30 Ωm, dry waste 30–100 Ωm), while phyllites in the rocky substrate have resistivities larger than 200 Ωm and can even reach va-lues greater than 1000 Ωm. Between the waste and unaltered phyllites, there is a supergene alteration zone (weathering) with resistivity values between 100 and 200 Ωm. The IP method was used to detect the presence of metals in the accumulated waste in the pond by analyzing the presence of large chargeability anomalies. Anomalies were detected in four of the profiles, which ranged from low (i.e., between 0 and 8 mV/V) to medium (i.e., between 8 and 18 mV/V) and high values (i.e., 18 and >30 mV/V). [ABSTRACT FROM AUTHOR]

We present a series of flume tests to observe the process of tailings slope failure when subjected to a concentrated water flow. Progressive flow slides were observed in a range of tailing deposits with varying relative densities, in which hydraulic conductivity reduced with increasing relative density. Slope densification by compaction of very loose or loose tailings deposits can lead to a lower permeability, generating excess pore pressure, and subsequently reducing slope stability. This is evident from the great number of acoustic emission signals before sudden failure, and from a sharp increase in the surface displacement and internal displacement observed after excess pore pressure generation. The variation of fluid-pressure distribution results in successive sliding, onset at the toe and progressing from the toe to the rear of the slope. Excess pore pressure generation is found to occur after, rather than prior to sliding, and it only occurs along the slip surface. An optimal relative density of 0.35 was identified, in which the slope failure changes from a sudden collapse to a progressive failure. However, the optimal relative density may vary with the height of the slope. This research extends existing knowledge about behavior of tailings materials, while the observed discrepancy between the failure mechanisms of slopes made of loose and dense deposits could provide insights for preventing failures of tailings dams. • Excess pore pressure generation caused the decrease of shear resistance, resulting in sudden rupture. • The progressive failure is evident in dense deposits. • Monitoring the siignals of densification may be an effective method for pre-warning. [ABSTRACT FROM AUTHOR]

Differential Interferometric SAR (DInSAR) has been used to monitor surface deformations in open pit mines and tailings dams. In this paper, ground deformations have been detected on the area of tailings Dam-I at the Córrego do Feijão Mine (Brumadinho, Brazil) before its catastrophic failure occurred on 25 January 2019. Two techniques optimized for different scattering models, SBAS (Small BAseline Subset) and PSI (Persistent Scatterer Interferometry), were used to perform the analysis based on 26 Sentinel-1B images in Interferometric Wide Swath (IW) mode, which were acquired on descending orbits from 03 March 2018 to 22 January 2019. A WorldDEM Digital Surface Model (DSM) product was used to remove the topographic phase component. The results provided by both techniques showed a synoptic and informative view of the deformation process affecting the study area, with the detection of persistent trends of deformation on the crest, middle, and bottom sectors of the dam face until its collapse, as well as the settlements on the tailings. It is worth noting the detection of an acceleration in the displacement time-series for a short period near the failure. The maximum accumulated displacements detected along the downstream slope face were −39 mm (SBAS) and −48 mm (PSI). It is reasonable to consider that Sentinel-1 would provide decision makers with complementary motion information to the in situ monitoring system for risk assessment and for a better understanding of the ongoing instability phenomena affecting the tailings dam. [ABSTRACT FROM AUTHOR]

Tailings dam is an indispensable part of mining safety production and environmental sustainability. The stability, monitoring, pre-alarming, and sustainability of tailings dam are crucial for mining disaster control, environment, and human beings. The paper introduces the damage of tailings dam failure by 44 typical accidents (2138 deaths in total), and then presents some developments and new insights for environmental sustainability and disaster control of tailings dam. Firstly, three kinds of methods for stability analysis of tailings dam were summarized and compared. Limit equilibrium methods (LEMs) were focused on Sweden methods, Janbu method, Bishop method, and Morgenstern-Price method. Numerical simulation methods were discussed about finite element method (FED), discrete element method (DEM), boundary element method (BEM), and finite difference method (FDM). Uncertainty methods were compared, including gray system evaluation method, reliability method, and fuzzy evaluation method. Secondly, the research progress in the field of safety monitoring and pre-alarming of tailings dam was reviewed, covering the aspects of traditional monitoring methods and coupled monitoring systems. Finally, the conception map of disaster prevention, disaster control, and environmental sustainability for safety management and environment to enhance cleaner production work in tailings dam was presented. The map for safety work and environmental sustainability achieves the goals from "lagging" to "real time", from "point" to "solid", from "surface" to "internal", and from "passive" to "coupled passive and active". • Comprehensive stability analysis with multiple methods improves dam reliability. • Pre-alarming systems using displacements and seismic monitoring are recommended. • The concept map for safety management and environment of tailings dam is proposed. • The monitoring methods from "surface" to "internal" are achieved. [ABSTRACT FROM AUTHOR]

The timely and accurate mapping and monitoring of mine tailings dams is crucial to the improvement of management practices by decision makers and to the prevention of disasters caused by failures of these dams. Due to the complex topography, varying geomorphological characteristics, and the diversity of ore types and mining activities, as well as the range of scales and production processes involved, as they appear in remote sensing imagery, tailings dams vary in terms of their scale, color, shape, and surrounding background. The application of high-resolution satellite imagery for automatic detection of tailings dams at large spatial scales has been barely reported. In this study, a target detection method based on deep learning was developed for identifying the locations of tailings ponds and obtaining their geographical distribution from high-resolution satellite imagery automatically. Training samples were produced based on the characteristics of tailings ponds in satellite images. According to the sample characteristics, the Single Shot Multibox Detector (SSD) model was fine-tuned during model training. The results showed that a detection accuracy of 90.2% and a recall rate of 88.7% could be obtained. Based on the optimized SSD model, 2221 tailing ponds were extracted from Gaofen-1 high resolution imagery in the Jing–Jin–Ji region in northern China. In this region, the majority of tailings ponds are located at high altitudes in remote mountainous areas. At the city level, the tailings ponds were found to be located mainly in Chengde, Tangshan, and Zhangjiakou. The results prove that the deep learning method is very effective at detecting complex land-cover features from remote sensing images. [ABSTRACT FROM AUTHOR]

• The presence of Al affected negatively the growth of R. natans. • The increase of R. natans biomass was mainly affected in the highest concentration of Mn. • The growth coefficient (μ) and the doubling time (td) were altered indicating damages in macrophyte growth metabolism. • The temperature of 27 °C was the one that most affected the growth of Ricciocarpos natans. One of the consequences of global mining is the exposure of metals into the environment, caused by the rupture of tailings dams. Excess of metals, such as aluminum (Al) and manganese (Mn) can cause serious damage to fauna and flora. The presence of these metals, associated with the temperature increase that occurs nowadays can potentially increase biochemical and metabolic rates in plant tissues and may affect growth. Therefore, the objective of this work was to evaluate the toxicity of the metals Al and Mn into the biomass' growth of the macrophyte Ricciocarpos natans, under two temperatures (25 and 27 °C). R. natans individuals (n = 10 ± 0.5 cm wide) were exposed during 30 days to Al (1.5; 2.5 and 5.0 mg L−1) and Mn (0.7; 1.5 and 3.0 mg L−1) at temperatures and photoperiod-controlled germination chambers. Fresh macrophyte masses were determined gravimetrically to determine the kinetic growth using a logistic model. With that, it was noticed that the presence of Al interfered negatively in the increase of the R. natans biomass, mainly in the highest concentrations and at 27 °C. Mn, on the other hand, affected the increase in biomass, mainly in the highest concentration. As a result, the growth coefficients (μ) changed, being up to 4 times lower in the Al bioassays and up to 2 times higher than the control in the Mn bioassays. However, the dry R. natans biomass individuals that were exposed to the treatments was reduced when compared to the control, except for the lower concentration of Mn. These results contribute to the understanding of the environmental changes that can occur due to metals contained in mining tailings in aquatic ecosystems and the influence of global warming on the metabolic processes of the growth of aquatic macrophytes. [ABSTRACT FROM AUTHOR]

The clogging of drainage facilities, which reduces the permeability coefficient, raises the phreatic line, and increases the possibility of seepage damage, seriously impacts the safety of tailings dams. The core cause of clogging is the oxidation of active minerals or ions and the formation of gelatinous materials. These materials, the most typical of which are active iron minerals (such as pyrite or ferrous ions), are adsorbed in the percolation passage to block the flow of liquid. This paper aims to study the effect of ferrous ions on the hydraulic conductivity of fine tailings. First, we introduce a new apparatus based on the column experiment to examine the permeation characteristics of fine tailings. Second, a systematic experimental study was conducted to obtain the effect of ferrous ion content, nonwoven geotextile layer number, and specimen height (reflecting the length of the seepage path) on the tailings permeability ratio using this apparatus. Third, scanning electron microscopy (SEM) was performed on selected geotextile samples that underwent filtration to assess the clogging mechanism. The results show that the ferrous ions were oxidized to form the low solubility iron(III) oxide-hydroxide (Fe(OH) 3), which was deposited or adsorbed in the percolation channel and caused chemical clogging. Meanwhile, in the case of more geotextile layers or slower seepage rates, the blockage of the fine tailings formed faster in the penetration experiment. According to the results of the SEM, there were glue coverings on the fiber surface, and ultrafine tailings particles (−10 μm) were adsorbed, adhered and deposited on it and formed a chemical-physical clogging. • Clogging formation is more sensitive to ferrous ions content in the tailings sample. • Geotextile thickness (or number of layers) has a significant impact on the formation of clogging. • The ultrafine particles (−10 μm) are more easily adsorbed, banded, and even encapsulated by colloidal compounds. • Clogging formation seems to be dependent on the hydraulic environment. [ABSTRACT FROM AUTHOR]

This article shows the interesting results of a pioneer effort by IAG/USP researchers to use ground-penetrating radar (GPR) for humanitarian purposes, guiding the rescue of victims in the tragedy of Brumadinho. The tailings Dam I at the Córrego do Feijão iron ore mine, located in the Brumadinho complex, Minas Gerais State, Brazil, collapsed on 25 January 2019. About 11.7 million m3 of mining mud was spilled from the dam, burying bodies, equipment, structural buildings, buses, and cars along a length of 8.5 km up to the Paraopeba River. Additionally, the contaminated mud traveled more than 300 km along the bed of the Paraopeba River toward the São Francisco River. This work shows the results of a geophysical investigation using the GPR method 17 days after the event. To carry out the geophysical survey, an excavator was used for soil compaction. The data acquisition was performed on the tracks left by the excavator chain using SIR-4000 equipment and antennas of 200 and 270 MHz (GSSI). The GPR studies aimed to map bodies, structural buildings, and equipment buried in the mud. The location of the profiles followed preferably the edge of the slope due to the higher probability of finding buried bodies and objects. The GPR results allowed the detection of subsoil structures, such as concentrations of iron ore and accumulations of sand from the dam filter. The GPR was effective because the iron ore sludge in the mixing process became porous and the pores were filled with air, which provided penetration and reflection of the GPR electromagnetic waves up to a depth of 3.5 m. The results were surprising. Although no bodies or underground equipment were found, the results of this research served to eliminate the studied areas from future excavations, thus redirecting the rescue teams and optimizing the search process. These important results can serve as an additional motivation for the use of GPR in future humanitarian work in areas of tragedies. [ABSTRACT FROM AUTHOR]