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This paper re-evaluates the Edenville earth dam that failed in 2020 after a rapid rise in reservoir level caused by prolonged significant rainfall. The dam instability and possibility of static liquefaction–induced flow failure are assessed in the framework of critical state soil mechanics (CSSM). Both undrained loading and drained unloading stress paths are considered for flow liquefaction assessment. Using documented triaxial compression tests, the Norsand constitutive model is calibrated for finite-element numerical models. This study supplements the analyses conducted by an independent forensic team (IFT) in charge of failure investigation. The advances achieved by tailings dam practitioners are leveraged here to study flow liquefaction as recommended by the IFT. Multiple ways are employed to generate reasonable initial field stresses. Simulation of dam construction coupled with steady-state seepage analysis creates an appropriate starting condition for further flow liquefaction assessment. The numerical outputs confirm the result of the IFT's limit equilibrium analyses for an undrained boundary condition. Stress analyses with a drained boundary condition show that a major stress change with a constant-shear-drained (CSD) stress path develops below the dam crest due to a rising reservoir level. The results of our models with a CSD stress path and drained-to-undrained transition better explain the evolution of the Edenville dam failure. The current study provides a practical approach to earth dam design and evaluation. [ABSTRACT FROM AUTHOR]

In view of many past failures of tailings storage facilities, practising engineers have been analysing current design guidelines for different elements of these facilities, including for tailings dams. In this paper, an attempt is made to investigate how varying tailings slurry solids concentration (${c_s}$ c s ) affects the stability of tailings dam embankment slope. To achieve this, elaborate two-dimensional limit equilibrium and finite element simulations were conducted and a steady-state seepage analysis was performed so as to obtain accurate free surface water flux through the slope. Initially, numerical analyses were performed for the downstream embankment slope when no material is retained upstream. Subsequently, with all parameters kept constant, the same slope was then checked when water is retained upstream, and finally for varying slurry solids concentration. Special attention was paid to the boundary between sedimentation and consolidation, defined as the solids concentration limit beyond which effective stresses start to develop. From the stability analyses performed, it is found that the factor of safety of embankment slope varies nonlinearly with total unit weight of the slurry. For coal tailings slurry, factor of safety reduced from 1.24 when water is retained to 1.15 when tailings slurry with ${c_w}$ c w = 60% is retained, representing a drop by 7.3%. [ABSTRACT FROM AUTHOR]

To investigate the influence of a geogrid-reinforced tailings dam on the seepage stability of the dam body, this paper was based on the field test of a reinforced tailings accumulation dam. The study utilized the finite element strength reduction method to simulate the stability of the main dam of the Fengshuigou tailings reservoir under different seepage conditions using ABAQUS software. Additionally, the paper discussed the impact of conventional heightening, dry beach length, and geogrid reinforcement on the position and safety factor of the saturation line of the dam body. The results showed that when the dam body was raised, the saturation line rose by 2.8–5.3 m, resulting in a decrease in the safety factor. The geogrid effectively reduced the height of the saturation line in the tailings dam. In comparison to the unreinforced condition (dam heightening), the saturation line of the tailings dam decreased by 0.9–2.8 m under the local reinforcement condition and by 3.2–12.5 m under the overall reinforcement condition. The geogrid significantly improved the stability of the tailings dam. Furthermore, under the local reinforcement condition, the safety factor of the dam increased by 3.8–5.5%, and under the overall reinforcement condition, it increased by 35.9–42.9%, when compared to the unreinforced condition. Increasing the dry beach length improved the stability of the tailings dam, and under normal working conditions, the safety of the tailings dam was much higher than under the minimum dry beach condition. These results served as a reference for the design of the dam and the new tailings reservoir, laying a foundation for the sustainable development and environmental protection of the tailings pond. [ABSTRACT FROM AUTHOR]

Breaches of tailings dams have had catastrophic consequences in the mining industry worldwide. Therefore, the characteristics of tailings and their effects on the stability of tailings dams need to be investigated. In this paper, the mechanical properties of uniform tailings and smaller sedimentary tailings are analyzed in laboratory testing. The critical hydraulic gradient of tailings is explored and a tailings dam model is constructed. The results of testing indicate that the strength of tailings gradually decreases with an increase in the content of fine particles smaller than 0.075 mm. The critical content of fine particles is 35% fine particles smaller than 0.075 mm. The strength, cohesion, and internal friction angle of uniform tailings are greater than those of smaller sedimentary tailings. The critical hydraulic gradient decreases with an increase in the content of fine particles smaller than 0.075 mm, and the critical content of fine particles is again approximately 35%. However, the critical hydraulic gradient of smaller sedimentary tailings is higher than that of uniform tailings. An equation is presented to calculate the critical hydraulic gradient of tailings. The seepage failure of the tailings dam can be divided into four parts. An equation is presented to calculate the critical hydraulic gradient of a tailings dam. [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]

Tailings pond builded by central line method usually has the advantages of large storage capacity and high slope stability. However, due to the strict requirements for the balance of sand volume inside and outside the reservoir, this method has relatively few engineering applications in China. Taking a central line tailing pond of coarse sand deficiency type as an example, combined with the classification test results of hydro cyclones, the contradiction between the overall abundance of damming sand and the deficiency of damming sand by stages is analyzed. The centerline embankment method is successfully implemented by adopting such technological measures as deflecting the dam axis position, filling the downstream dam slope with waste rock, and optimizing the external slope ratio of the dam. On this basis, the spatial seepage field law and dam stability of the tailings pond are comprehensively analyzed. The research conclusion shows that the saturation line of the tailings dam is relatively deep under all working conditions, and the tailings pond has a high level of intrinsic safety. [ABSTRACT FROM AUTHOR]

In Chile, the limit equilibrium analysis under pseudostatic conditions is compulsory according to the Supreme Decree 248 (DS248, 2007), which establishes a minimum factor of safety (FoS) of 1.2 for stability analysis. In Chilean geotechnical practice, it is usually considered just the horizontal seismic coefficient (kh) for the analyses. However, there is a constant discussion about the necessity of applying both horizontal and vertical seismic coefficient (kv) into the analyses. In addition, there is uncertainty about what kv/kh should be considered and the effect that the sense of application (upward or downward) could have on the FoS. This paper presents an analysis of the effect of considering different |kv|/kh from 0 to 1 on both analysis directions for generic downstream tailings sand dam. Based on this, different dam heights, beach lengths and seepage conditions are also analysed. The obtained results show that when both kh and kv are applied, the FoS increase if kv acts downward and decrease when it acts upward. In addition, the effect for |kv|/kh ≤ 0.5 is almost neglectable, especially for kh ≤ 0.15. Furthermore, although a short beach length significantly impacts the FoS, the influence of applying both kh and kv seems to be independent of the beach length. [ABSTRACT FROM AUTHOR]

Catastrophic breaches of water and mine waste retaining impoundments in recent history have emphasized the severity and consequences to the downstream environment. In this study, the applicability and suitability of the XBeach numerical model for modelling earth dam failures driven by overtopping with water is explored by detailed comparison with controlled experimental data. The XBeach model is applied to simulate laboratory-scale breaches caused by overtopping failure of dams constructed with uniform sand at the Queen's University Landslide Flume by Walsh et al. (2021a). The model sensitivity to boundary conditions for different virtual flume sizes, different sediment transport equations that influence erosion rates, and the process of avalanching are investigated. The model results are in best agreement with laboratory measurements when the Soulsby-van Rijn sediment transport formulation is used, which depends on grain size, and the avalanching module is activated, indicating the importance of these processes. The model is also run for different dam geometries to investigate the influence of upstream slope angle, which is relevant for tailings dam breach analyses. The results indicate that for flatter slopes the model is in closer agreement with observations of the peak discharge, while for steeper slopes the model results are better for breach duration time. Overall, XBeach provides promising results for the prediction of the dam breach outflow hydrograph at the laboratory scale and has potential to improve understanding of earth dam failure outcomes with further investigation. • XBeach is applied to simulate the failure and morphological evolution of earth dams. • Results are compared to laboratory measurements for a range of upstream slopes. • XBeach is a promising tool for predicting the breach outflow hydrograph response. [ABSTRACT FROM AUTHOR]

Static liquefaction has been identified as the cause of several recent tailings storage facility (TSF) failures. Partially based on the investigations carried out, significant advances on the analysis of static liquefaction triggering (SLT) have been made. These include applications of critical-state-based models in a stress–deformation framework to identify if in situ conditions are approaching a level where SLT could occur. However, several important uncertainties remain. In this work, three of these uncertainties (geostatic stress ratio K0, intermediate principal stress ratio and principal stress angle from vertical) were investigated, along with their effects (both independently and in conjunction) on the identification of SLT and slope failure. These uncertainties were examined through a series of numerical analyses of an idealised TSF. Various values of K0 were used to examine their effect on SLT, while different approaches were taken to assess the potential effects of the intermediate principal stress ratio and the principal stress angle from vertical on instability. This work revealed that the current state of knowledge in these areas is such that significant uncertainty seems unavoidable in attempting to identify exactly when a particular slope may undergo SLT. Experimental and in situ test programmes that may be useful in reducing this uncertainty are outlined. [ABSTRACT FROM AUTHOR]

Liquefaction assessments for tailings facilities have significant uncertainty, yet their results are typically presented as single-value deterministic factors of safety (FoSs) to compare against standard practice guidance. Some of the uncertainty is due to inherent material variability or measurement error associated with in situ testing techniques. There is also a considerable – and often ignored – contribution from the transformation models used to convert in situ measurements to design parameters. For seismic liquefaction assessments, the key sources of transformation model uncertainty are from the empirical relationships relating standard penetration testing or cone penetration testing (CPT) results to cyclic resistance and residual undrained strength. While the uncertainties associated with the material variability and measurement error will vary by site and can usually be reduced through additional investigation, the model uncertainties are constant and irreducible without further work. This paper shows how the transformation model uncertainties associated with CPT-based liquefaction assessments can be incorporated into design practice to estimate probabilities of failure and lead to very different outcomes than simply considering FoS alone. [ABSTRACT FROM AUTHOR]

One of the Letšeng Diamond Mine's two tailings storage facilities has high volumes of toe seepage, which could be caused by internal erosion within the embankment, a major reason for many dam failures. A resistivity survey delineated two prominent anomalies associated with saturated spots within this embankment, which might have been due to free water in the tailings supernatant pond, water from the spigotting operation moving through the dam fill as wetting fronts, or embankment ponding due to rainfall. However, standpipe piezometers indicated that these anomalies were not associated with a phreatic surface in the embankment. Constructed entirely from coarse tailings with a saturated hydraulic conductivity of 2 × 10–05 m/s, the embankment is pervious, which inhibits development of a phreatic surface. Apart from toe seepage, there was no evidence of leaks at the embankment's downstream face. Steady state seepage was conservatively calculated as 15 L/s, which is periodically exceeded by almost threefold. A review of toe seepage vs. rainfall and groundwater levels suggests that these seepage fluctuations were due to increased precipitation-induced groundwater recharge and runoff. [ABSTRACT FROM AUTHOR]

The past decade has witnessed the failure of numerous tailing storage facilities and earthen dams. The most common factors causing failure include seepage and slope instability, apart from seismic activities. In the present study, a series of centrifuge model tests have been conducted to study the performance of water retention type (WRT) tailings dams impounded with fine tailings material (and water) on the upstream side. A custom-designed test setup to simulate upstream reservoir filling and inertial loading is employed in a 4.5 m radius large beam geotechnical centrifuge facility available at the Indian Institute of Technology Bombay, India. The centrifuge models were instrumented with pore pressure and displacement transducers to record porewater pressure (PWP) and surface settlement, respectively, and to ensure long-term safety and integrity of tailings dam. Additionally, an onboard digital camera was used to capture the front elevations of the centrifuge models to perform digital image analysis (DIA) for deducing slope face movements, surface settlements, and failure patterns. The results effectively demonstrate the performance of the WRT dam, delineate the slip surface and failure pattern, and quantify the critical design parameter related to inertial loading, which is the horizontal seismic coefficient (i.e. K Hyield and K Hmax). Based on these physically observed results, the analytical equations were also deduced for the WRT dams to quantify the stability (in terms of factor of safety, FS) and deformation response. The analytically obtained results agree reasonably well with the performance of WRT tailings dam models in the geotechnical centrifuge. • Use of centrifuge technique and tilt table-based custom-developed experimental test setup for tailings dams. • Performance of water retention type tailings dam subjected to seepage and inertial loading conditions. • Use of digital image analysis. • Formulation of analytical equations for factor of safety and seismic displacement. [ABSTRACT FROM AUTHOR]

Piping has been a documented cause of collapse of multiple tailings dams, hydraulic structures and natural slopes. Important limitation of the existing piping criteria for a sloped ground is that they are treating soils as hydraulically isotropic, which is rarely the case in real life problems. Another obstacle for wider application of these criteria in engineering practice is that they have not been translated into an adequate definition of the safety factor against piping. This paper provides rigorous yet simple piping criteria and safety factors for slopes built of hydraulically stable anisotropic materials, as well as the safety factor against instability of an infinite anisotropic slope with a slope-parallel flow. It has been demonstrated why it is important to account for anisotropy, and how the proposed analytical expressions can be applied to practical problems with calculated flow nets and piezometric field measurements. [ABSTRACT FROM AUTHOR]

The existing methods of dam deformation detection of tailings reservoir have the problems of poor accuracy and slow speed. Therefore, a fault diagnosis algorithm based on tailing dam deformation detection method is proposed. The grey theory is used to accumulate the original feature sequence, and the first cumulative sequence is obtained. Based on this, the grey detection model is constructed, and then the concrete deformation of tailings dam body is accurately detected by precision test. Experimental results show that the method has high accuracy, high speed and practicability. [ABSTRACT FROM AUTHOR]

Focusing on the tailings containing high sodium silicate (water glass), this study conducted laboratory experiments and semi-industrial tests of flocculation and sedimentation for rapid tailings dewatering. Various reagent combinations, lime and anionic flocculant (APAM) (L&A), sulfuric acid and APAM (S&A), and calcium chloride and APAM (C&A), were tested. The results show that (i) all the three combinations presented a good effect in the laboratory experiments, and the relatively optimum dosages were L&A of 2 kg/t & 30 g/t, S&A of 2.6 kg/t & 20 g/t, and C&A of 3 kg/t & 30 g/t. (ii) The overflow water of the L&A group became turbid after 10 hours, and the pH increased to 14. While, for the S&A and C&A groups, the solid content in overflow wastewater (SCOW) fluctuated over time but could be mostly controlled in 300 ppm. The pH declined from 7 to 4 with time in the S&A group, and it was 7-8 in the C&A group. (iv) Thus, a backfill system with dewatering technology based on the C&A combination was designed. In the field application, the overflow water was recycled with the SCOW of less than 250 ppm and the pH of 7.5, while the underflow concentration was greater than 70 wt.%. The achievement provides a way to utilize the tailings containing sodium silicate effectively and environmentally, which will reduce the tailings dam on the Earth. [ABSTRACT FROM AUTHOR]

The intent of this paper is to establish the foundation for improvement of monitoring strategies for the safe and controlled management of the geotechnical stability of a tailings storage facility. This paper establishes what currently defines best practice in an effort to realign global practices and in turn encourage greater collaboration in safety. Best practice is established through a critical review of guidelines, acts, and regulations, a survey and analysis of 25 global tailings dam practitioners, and recommendations are made for the development of a global industry best practice, comprehensive monitoring strategy for tailings dams. [ABSTRACT FROM AUTHOR]

Dams are structures that barrier rivers and streams for a variety of purposes. The constant maintenance of these structures is essential, since a possible accident can lead to damage of catastrophic proportions. In November 2015 in the city of Mariana, Minas Gerais (MG), Brazil, a tailings dam burst and spilled 56 million cubic meters of tailings. In addition to victimize 19 people, the event caused material, economic and environmental damage—it is considered the largest environmental disaster of Brazil. This research presents a cheap and quickly applied alternative for investigation of seepage of water in earth dams, built with distinct embankment materials—one dam composed of predominantly silt and clay soil and the other predominantly composed of sandy soil. The research methods used were: geotechnical tests as gradation test, permeability test with the Guelph permeameter method and the application of the (DC) resistivity geophysical method from the electrical resistivity tomography (ERT) technique in Wenner array. Three ERT lines were positioned parallel to the longitudinal axis at each dam. The data are presented in 2D and 3D geophysical images with electrical resistivity values modeled. Based on the physical principle of electrolytic conduction, i.e., decrease in electrical resistance in materials or siliceous minerals in moisture conditions compared to the material in the dry state, the results revealed low-resistivity zones restricted to some points, associated with water infiltration in the transverse direction. The results indicate saturation restricted to some points and low permeability, at the present time, an installation of piping processes. [ABSTRACT FROM AUTHOR]

The BP neural network algorithm is used to construct a stable slope angle prediction model for open-pit mines, which can successfully predict the ultimate slope angle of the mine. At the same time, a multi-tool combination of Surpac, Madis, and Flac3D is used to create a numerical model for stable slope angle in mines. The model is used to test the final slope angle prediction structure for stable mines. Through a comprehensive analysis of the ore deposit model technology constructed by the series of realms, the economic parameters involved in the generation of realm boundaries are known, and specific primaries are pointed out with the error requirements of each parameter analyzed in the realm of series. A concrete solution is put forward to the issue of realm gap. From the point of view of the power and responsibility parameters, the series of realm production methods are analyzed, and the rapid generation methods of the realm of open-pit mine series are pointed out. [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]

The execution of permeability tests using a triaxial cell makes it possible to eliminate the uncertainties that characterize tests performed using conventional equipment. This paper contains the results of 48 tests carried out on three materials recovered from tailings of Riotinto mines (Spain). The equipment involved a modified triaxial system to facilitate the execution of permeability tests under constant head. The tests were performed on samples consolidated to 50, 100, 200, and 300 kPa for four different hydraulic gradients established by applying a backpressure difference (ΔBp). The magnitude of the backpressure difference was applied as a percentage of the initial effective consolidation pressure, expressed as ΔBp/ --> σ c ′ --> ; namely, values of 10%, 15%, 20%, and 25%, which resulted in hydraulic gradients between 5 and 80. The backpressure (Bp) was constant (400 kPa) in all cases, allowing a degree of saturation close to 100% to be achieved. This was verified by calculating Skempton's B parameter, which was very close to unity in all cases. The results indicate that it is feasible to define an empirical function including the coefficient of permeability (k) and the effective consolidation pressure (--> σ c ′ -->), the mean effective confining pressure (--> σ cav ′ -->), and the backpressure differential (ΔBp). [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]

The stability of tailings dams has become a critical concern for mining industry due to the recent tailings dam failures. The authors have presented a good paper to investigate the failure of tailings dam due to static liquefaction using the commercial FE code Plaix2D. Three procedures that can trigger static liquefaction were investigated in the paper, including surface load, toe deformation, and rise in phreatic surface. However, this discussion presents several simple observations regarding the simulation of the static liquefaction and additional analysis on the Fundão tailings dam. [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]

The consolidation process could be slow in an upstream tailings dam; therefore, the stability can reduce due to an increase in excess pore pressures when the dam is raised. The safety of the dam can be enhanced by constructing rockfill berms on the downstream side. This paper presents a case study on the strengthening of an upstream tailings dam with rockfill berms. The finite element analyses were performed for modelling the staged construction of the dam and for optimizing the volume of the rockfill berms. The dam was raised in 11 stages; each stage consisting of a raising phase and a consolidation phase. The study shows that the slope stability of the dam reduced due to an increase of excess pore pressures during the raising phase. The stability of the dam was successfully improved by utilizing rockfill berms as supports on the downstream side. A technique has been presented to minimize the volume of the rockfill berms so that the required stability can be achieved at minimum cost. This paper shows that the finite element method can be a useful tool for modelling the consolidation behaviour of an upstream tailings dam and minimizing the volume of the rockfill berms that may be needed to maintain the stability of the dam during staged construction. [ABSTRACT FROM AUTHOR]

Abstract: This case study describes the design, and construction of an earth dam built on recently sedimented tailings consisting of low strength, low plasticity silt/clay, and variably silty sand. The tailings were encountered within the construction limits of Cell 7 at the 4km2 Loxahatchee (L-8) Reservoir in western Palm Beach County, Florida. Fully coupled steady state and transient seepage models with slope stability analyses were performed for operational and rapid drawdown conditions, respectively, using both limit equilibrium methods (LEM) and finite element stress-based modeling (FESBM) techniques. In addition, stability calculations utilizing fully coupled stress/pore pressure analysis were performed to analyze rapid drawdown stability during drawdown. [Copyright &y& Elsevier]

Flow liquefaction is a major design issue for large soil structures such as mine tailings impoundments and earth dams. If a soil is strain softening in undrained shear and, hence, susceptible to flow liquefaction, an estimate of the resulting liquefied shear strength is required for stability analyses. Many procedures have been published for estimating the residual or liquefied shear strength of cohesionless soils. This paper presents cone penetration test-based relationships to evaluate the susceptibility to strength loss and liquefied shear strength for a wide range of soils. Case-history analyses by a number of investigators are reviewed and used with some additional case histories. Extrapolations beyond the case-history data are guided by laboratory studies and theory. [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 self-potential (SP) method is easy to apply, efficient and low cost in cases of detecting anomalous water flows in earth dams. This type of dam is quite common for water storage and mining tailing disposal. SP causes are exposed in here, both in its original use – prospecting for massive sulfides –, and in studies of groundwater flows, such as it is done in this article. The flow study in dams shows they have their directions defined as being from a lower to a higher potential. These potentials come from the ion movement in solution transported by undersurface waters. These two cases in which the method was successfully used are reported, an older one (1996), and other recent one (2019). Obtained results showed quite clearly the presence of features correlated to anomalous flows inside dam massifs evidenced by iso value maps of SP measurements. • Accidents with mining tailings dams in Brazil. • Identifying anomalous water flows inside earth dams. • SP origin is caused by the flow potentials and are due to the movement of fluids through the pores of earth dams. • Safety of dams with SP use. • Show simple and low cost methodology on dam safety. [ABSTRACT FROM AUTHOR]

Since it has a territory of continental proportions and notable geological diversity, Brazil has always had mining activities as one of the pillars of its economy. On a daily basis, great amounts of byproducts are produced, being necessary to build adequate storage locations, such as tailings dams. After the breakage of the tailing dam of Fundão in the city of Mariana/MG, an adequate allocation of byproducts became a big concern, being its main goal the protection of the environment. This paper sought to validate the utilization of SIAQUA-IPH, a quality water model for analyzing the dispersion of sediments resulted from the breakage of tailing dams. The case studied concerns the breakage of the tailing dam of Fundão (MG) itself, and the results obtained were compared to the data published by the Brazilian Company of Research and Mineral Resources ("CPRM").The results presented satisfactory values to the relation between the period of passing of the flood waves calculated and observed. However, the calculated values for the concentration were higher than those provided by CPRM, being necessary the realization of more studies to understand this issue. [ABSTRACT FROM AUTHOR]

Tailings dams are earth embankments used to store toxic mine waste and effluent, often constructed with steep slopes and using the tailings to save on costs. Their failure, estimated to be more than two orders of magnitude than for water dams, can cause loss of life, irreversible damage to ecosystems and large economic damages. In countries with limited resources, it is challenging for the authorities to be able to effectively monitor this type of infrastructure, especially when located in remote areas.We are developing a system for a sustainable and cost effective way of remotely monitoring tailings dams. We are measuring the displacement of the structures using earth observation technologies such as Interferometric Synthetic Aperture Radar (InSAR) and Global Navigation Satellite System (GNSS) technologies, combined with real-time in-situ devices. Data analysis, weather forecasting tools and assessment of consequences support the monitoring, allowing the issue of alerts for unusual behaviour or weather conditions that could lead to failure. We are working with mining companies, local governments and private stakeholders in Peru to test our approach on a number of sites. The project focuses in the mining region of Cajamarca, where in 2015 there were at least 9,000 inactive mining facilities registered. The system contributes to a sustainable management of tailings storage facilities, reducing the risk and the consequent damage to population and ecosystem services downstream, upon which many vulnerable communities rely for both their source of water and livelihoods. [ABSTRACT FROM AUTHOR]