Dam Failure Research Articles

Safety assessment in dams due to downstream slope anomalies

Recent cases of tailings dam failure in Brazil have demonstrated in the current methods of safety assessment of these structures. One of the most employed methods is the evaluation through routine inspections and audits, but this method is considered non-deterministic and affected by the expertise of the evaluator. This paper presents the results of numerical simulations of anomalies commonly found in safety inspections to measure the impact of these anomalies on the dam safety factor. The study was limited to numerical simulations of five types of dams (three downstream and two upstream dams), with varying embankment and tailings strength parameters, simulating different magnitudes of downstream slope anomalies (cracks, scour, and resurgence), totaling a sample space of 270 analyses. The results show that there were average reductions in safety ranging from 4% to 10% for scour simulations, 8% to 25% for resurgence, and 9% to 24% for cracking. The sample standard deviation of the analyses ranged from 8 to 12%. It was also observed that the combined effect of the anomalies showed proportional overlapping effects in reducing the range of safety. It was concluded that the simulated failures are important variables to be evaluated in inspections, not only for demonstrate deviations in the operation and maintenance of structures, but also to predict the magnitude of these failures in dam designs.

Mudanças intensas na morfologia da confluência impulsionadas por um pulso hidrológico extremo: impactos na restauração do Rio Doce

ABSTRACT On January 2022, the Carmo River (a tributary of the Doce River) was affected by an extreme hydrological event, with 50-yr return interval. This event was 50% higher than that associated to one of the largest tailing dam failures ever reported that took place in the Gualaxo do Norte River. This delivered to Doce River, through the Carmo River, in a Y-shaped confluence, the contaminated tailing slurry. In order to understand the role of tributaries in the recovery of the Doce River, 2D hydrodynamic and 2D sediment transport models were applied at the confluence of the Carmo River with the Piranga River. Our results, based on hydraulic modeling, remote sensing, and in-situ measurements, indicated that significant amounts of sediments were trapped on the riverbanks and stone banks, making this confluence an important site for the retention of contaminated sediments, influencing sediment budgets and downstream water quality. Therefore, this confluence deserves special attention from water engineering in order to prevent the sediments retained in this area from being transported downstream during extreme events in the coming years. These results can contribute to decision-making, to identify reaches with greater susceptibility to erosion and sediment deposition and to plan the restoration of these rivers.

A Framework for Monitoring Stability of Tailings Dams in Realtime Using Digital Twin Simulation and Machine Learning

Tailings dam failures cause catastrophic impact on the environment and surrounding communities. Incidences of failure in the recent past have caused industrialists and researchers to seek innovative ways for proactively managing their safety and disaster mitigation. Given Industry 4.0 technologies now available, researchers are looking to develop digital tools for cost-effective, realtime monitoring of tailings dams. However, published literature indicates that a reliable framework is still lacking. This paper proposes a framework for developing a data-driven system for monitoring tailings dam stability and early warning detection. The framework relies upon digital twin simulation and machine-learning (ML) techniques, and comprises four main components: realtime data collection, digital twin modelling, ML-based early detection and prediction, and intelligence-driven decision-support. Sensors gather real-time geophysical data from monitored structure, and the digital twin uses this data to simulate dam behaviour. ML algorithms analyse the data and simulations to enable early detection of instability and failure prediction. Literature suggests that digital twin and ML-based approaches may have advantages over traditional monitoring techniques and other AI-based methods. The paper concludes with a discussion of the framework's limitations, opportunities for improvement, and potential for application in mining and geotechnical engineering. The paper serves as a basis for model development and future research.

Numerical Modeling of Downstream Morphological Evolution during Mount Polley Tailings Dam Failure

Numerical Modeling of Downstream Morphological Evolution during Mount Polley Tailings Dam Failure

A Review on Significance and Failure Causes of Small-Scale Irrigation Dams in Arid and Semi-arid Lands (ASAL)

Water scarcity is increasingly becoming a significant challenge in arid and semi-arid lands. In these areas, small dams and reservoirs are important in providing water resources, supporting agricultural activities, and contributing to sustainable and resilient rural communities as they require an affordable investment. However, their frequent failures pose significant challenges to sustainable water management and agricultural development in these regions. This review study was developed based on the review of many international standards and guidelines from published studies in scientific journals in addition to information from practitioners. We examined the significance and causes of the failure of small dams and reservoirs; and discussed design criteria and considerations involved in their construction. The outcomes of this study offer valuable insights into the significance of small-scale irrigation dams and shed light on the multifaceted causes of their failure. A holistic approach to address the challenges identified are approach is required. Integrating engineering solutions such as improving design, and regular maintenance, with sustainable land management are crucial for optimising the small dams and ensuring that they adequately serve the needs of the community. The causes of failure were found to be multifaceted encompassing factors such as poor construction and maintenance practices and inadequate design considerations. Finally, this review highlighted the key elements in assessing structural conditions critical to the functionality and sustainability of small dams and reservoirs.

Analysis of Gongseng Dam Break-Induced Flood in East Java, Indonesia Through 2D Iber Software

The dam is a crucial river-crossing structure that ensures a sustainable water supply and offers numerous benefits. However, the potential hazard of dam failure is an imminent threat that could materialize unexpectedly. To comprehend the potential impact of dam break flood and identify vulnerable areas, it is essential to conduct rigorous analysis and simulate various dam failure scenarios. This comprehensive assessment is invaluable for informed land use planning and the development of effective emergency response plans. Therefore, this study aimed to analyze flood inundation resulting from the hypothetical failure of Gongseng dam, using Iber model. The modeling approach relied on a two-dimensional finite volume shallow water model, guided by specialized software. The scenarios for Gongseng dam break showed inundation areas of 12.57 km² and 7.55 km² for overtopping and piping failure, respectively. Overtopping failure resulted in the highest discharge, with Von Thun method causing severe damage due to wide break dimensions, and eventually leading to catastrophic consequences. However, this study showed that Froehlich method provided the most rational prediction for break parameters. In contrast to the other methods focusing solely on water height behind dam, Froehlich equation considered both the volume and height at the time of failure. Implementing dam break analysis held the potential to benefit downstream communities by providing inundation maps, thereby aiding in the mitigation of flood risks. Particularly, in situations with limited data and resources, as shown in this study, the cost-effective modeling method proposed could be an attractive option for simulating extreme flood induced by dam break.

Experimental study on overtopping dam-break of a tailing reservoir under extreme conditions.

There is a high risk of dam breakage in tailing reservoirs under extreme conditions. Once a dam breaks, it causes serious pollution to the surrounding ecological environment. To explore the effects of a tailings dam break under extreme conditions (flood conditions, drainage failure, flood discharge failure, and dam saturation), the mechanism underlying an overtopping dam break must be accurately understood. In this study, fine-grained tailings and perlite were selected to create composite model sand, and a prototype tailing reservoir was restored at a scale of 1:200. Furthermore, the dam-break process and results were analyzed and summarized by performing an overtopping dam-break test on the tailing reservoir under extreme conditions. The results show that the tailing discharge process has a high sand content, strong sand-carrying capacity, and high speed. The amount of model sand discharge accounted for 15.13% of the total storage capacity, and the amount of tailings deposition in the downstream area accounted for 95.21% of the discharge, which were both greater than the results of similar physical model tests and actual tailings dam failure accidents. An overtopping dam break in a tailing pond is a progressively destructive process. The dam break mechanism can be divided into two stages: prior breach penetration and subsequent breach horizontal expansion. In the process of a tailings dam break, the motion state of the tailings particles is transformed between the bed-load and suspended-load movement states. These results can provide important reference for the reinforcement of mine management and the formulation of preventive measures, which are essential to improving the safety of tailings reservoirs and protecting the ecological environment.

General Properties of Commingled Materials for Mix Designs

Tailings volumes continue to collectively increase worldwide, leading to larger dams and tailings management facilities. With numerous high-profile dam failures in the past decade, the risks of these management practices are also growing. A potential shift to waste management practices at mineral mines is to commingle waste rock and dewatered tailings. This blended material should have superior physical strength properties provided by the waste rock together with improved chemical stability characteristics associated with the low permeability of the tailings. Ideally, commingled tailings and waste rock can be used to construct various mined earth landforms that are both physically and chemically stable, which will enhance operational performance and ultimately provide for the sustainable decommissioning and closure of the mining facility. To study these materials, the University of Alberta Geotechnical Centre is working with global industry partners to test commingled materials from several mine sites with varying ore and host rock types and climate regimes. The first stage of this study is described here and is focused on the optimum density, saturated hydraulic conductivity, and soil–water characteristic curves of various blend ratios, performed at laboratory scale.

Study on the Disaster Mechanism Analysis and Enlightenment of Dam Failure

With the continuous advancement of infrastructure construction, dam, as an important water conservancy project, plays the role of water storage, flood regulation and power generation. However, due to the influence of extreme weather and other reasons, there may be the possibility of dam failure accidents when the dams are put into operation. The dam break accident may bring great losses to the downstream dam section. The theme of this paper is the disaster mechanism analysis and enlightenment of dam failure. By combining the statistics of dam break data with the analysis of potential causes, the disaster mechanism of dam break is obtained. According to the disaster mechanism, the corresponding treatment plan and future development trend are discussed, with the aim of monitoring the design, construction and operation stages of the dam. Suggestions for improvements include improving the dam's ability to withstand extreme weather, carrying out precise construction according to specific steps, and improving the professionalism of managers. These suggestions can reduce the probability of dam break accidents and reduce the casualties and economic losses caused by dam break accidents.

Study on the impact of debris flow from tailings dam failure on shale gas well station

The shale gas well station plays a critical role in the extraction of shale gas, and its safety status exerts significant influence not only on shale gas production but also on the ecological balance of the surrounding environment. To investigate the response characteristics of the shale gas well station under the impact of tailings dam failure debris flow, a comprehensive analysis was conducted using a combination of physical modeling and numerical simulation. The analysis focused on the dynamic inundation process and the impact siltation law caused by the downstream flow of tailings dam failure debris at the shale gas well station. The depth of inundation and the extent of siltation damage were employed as key parameters for characterization. Experimental findings revealed that the downstream mudflow inundation process could be divided into three distinct stages: rapid increase (0–60 s), steady increase (60–106 s), and slow advance (106–250 s). The pattern of mudflow siltation height variation at the well station exhibited an initial rise, followed by a subsequent decline and eventual stabilization. The highest siltation volumes recorded at measurement points A to D were 4.4, 4, 5.2, and 6 m, respectively. Additionally, by employing computational fluid dynamics, numerical calculations were performed under unprotected conditions, with the error between the calculated conclusions and the test results not exceeding 15%. Furthermore, the blocking effect of 8 and 16 m debris flow blocking dam on the debris flow was thoroughly investigated. The study demonstrated that the check dam with a height of 16 m yielded the most effective blockage, resulting in the highest sediment siltation height of 0.4 m. The research results provide some reference for the prevention and control of debris flow disasters.

Study of a Tailings Dam Failure Pattern and Post-Failure Effects under Flooding Conditions

Tailings dams are structures that store both tailings and water, so almost all tailings dam accidents are water related. This paper investigates a tailings dam’s failure pattern and damage development under flood conditions by conducting a 1:100 large-scale tailings dam failure model test. It also simulates the tailings dam breach discharge process based on the breach mode using FLOW-3D software, and the extent of the impact of the dam failure debris flow downstream was derived. Dam failure tests show that the form of dam failure under flood conditions is seepage failure. The damage manifests itself in the form of flowing soil, which is broadly divided into two processes: the seepage stabilization phase and the flowing soil development damage phase. The dam failure test shows that the rate of rise in the height of the dam saturation line is faster and then slower. The order of the saturation line at the dam face is second-level sub-dam, third-level sub-dam, first-level sub-dam, and fourth-level sub-dam. The final failure of the tailings dam is the production of a breach at the top of the dam due to the development of the dam’s fluid damage zone to the dam top. The simulated dam breach release results show that by the time the dam breach fluid is released at 300 s, the area of over mud has reached 95,250 square meters. Local farmland and roads were submerged, and other facilities and buildings would be damaged to varying degrees. Based on the data from these studies, targeted measures for rectifying hidden dangers and preventing dam breaks from both technical and management aspects can be proposed for tailings dams.

Dynamic planning method of evacuation route in dam-break flood scenario based on the ACO-GA hybrid algorithm

As the major water storage infrastructure, the failure of a reservoir dam will cause significant losses to people's lives and property. A scientific and reasonable evacuation route is one of the essential measures to reduce casualties. Thus, it is of great significance to realize the dynamic planning of evacuation routes in dam-break flood scenarios to reduce the risk of dam failure. This study employed a physically based mathematical model (Breach model) and a two-dimensional hydrodynamic model to simulate dam-break flood routing. Further, a road network construction method was proposed based on the graph theory and flood routing information. The ant colony optimization algorithm (ACO) was improved by the backtracking, the improved heuristic function, and the elite ants, and the genetic algorithm (GA) was optimized according to the characteristics of flood avoidance route planning. Accordingly, an improved ant colony-genetic optimization hybrid algorithm (ACO-GA) was proposed. Compared with the basic ACO algorithm, the correct rate of simulation results of the ACO-GA hybrid algorithm was improved by 34 %, the average number of iterations was reduced by 18.3 times, and the optimization ability was markedly enhanced. Based on the constructed dam-break flood scenario and the ACO-GA hybrid algorithm, the novel dynamic planning method for evacuation routes in the dam-break flood scenario was proposed. Moreover, this method was applied to a typical water conservancy engineering project, and the planned optimal evacuation routes accurately avoided the flood influence, and the calculation results were reasonable and accurate. The real-time dynamic planning of flood avoidance routes based on flood routing information was realized. This study provides effective guarantee for the emergency transfer of downstream people, which has valuable implications for the theoretical research and engineering practice of reservoir dam safety and management.

ASSESSING THE IMPORTANCE OF ENVIRONMENTAL AND SOCIAL STANDARDS FOR THE ARTIK RESERVOIR RECONSTRUCTION PROJECT IN THE SHIRAK REGION OF ARMENIA

The Artik Reservoir, located in Shirak region within the Karangu River basin, is poised for reconstruction beginning in 2023. This initiative is spearheaded by a consortium consisting of the Institute of Water Problems and HydroEngineering after Academician I.V. Yeghiazarov CJSC and the Shushi Technological University Foundation, commissioned by the Water Committee of RA MAIE. The reservoir, essential for irrigating agricultural lands in five villages, namely Nor Kyank, Panik, Vardakar, Anushavan and Meghrashen, faces reconstruction due to a dam failure during floods in 1994. The affected communities, integral to the Artik expanded community, are primarily engaged in agriculture, facing income constraints & labor migration due to water scarcity. Despite this, the region boasts historical and cultural monuments, presenting an opportunity for diverse forms of tourism. The region is also diverse in flora & fauna representatives with a significant number red listed since 2010. The article emphasizes the importance of adhering to environmental and social standards within the framework of the project, as well as seeks to contribute valuable insights to the ongoing discourse surrounding the project, highlighting the critical role of sustained environmental and social studies throughout its development. The primary objective is to assess the expected benefits and risks associated with the Artik Reservoir Reconstruction Project, with a particular focus on its environmental and social aspects, ultimately striving for a balanced and sustainable outcome.

Deformation Field Analysis of Small-Scale Model Experiment on Overtopping Failure of Embankment Dams

There are a large number of reservoir dams in China, of which embankment dams account for more than 90%, and public safety will be seriously endangered in case of dam failure. Overtopping is the leading cause of dam failure, and the existing research mainly focuses on the study of the failure process, with less research on the change in the deformation field during the failure process. In this study, the measured deformation field data of a modeled embankment dam during the whole process of impoundment, operation, and failure were obtained by carrying out indoor small-scale model experiments of overtopping failure, embedding inclinometers inside the dam body, and setting vertical displacement measurement markers on the surface. A refined analysis of the measured deformation data shows that the dam body displaces vertically downward during the impoundment stage and the vertical displacement at the dam crest has the largest amplitude; the internal horizontal displacement changes to the left bank and downstream side, and the amplitude of the internal horizontal displacement (upstream and downstream direction and dam axis direction) on the right dam sections is more significant than that in the middle of the dam; during the breaching stage, the time sequence of the sudden change in each internal horizontal displacement measuring point is from the downstream side to the upstream side and from the higher elevation to the lower elevation, which is basically consistent with the process of overtopping of embankment dams; and the overall sudden change in left and right bank horizontal displacements within the downstream side of the dam crest and the downstream side of the dam body gauges is significant, and the sudden change in upstream and downstream horizontal displacement (U&D HD) within the downstream side of the dam crest gauges is significant. The experimental analysis results can support the disaster mechanism of embankment dam failure and the theory of early warning of failure.

The Effect of Deformation Parameters of Clay-Core on Arching Behaviour of Rockfill Dam

In zoned embankment dams, horizontal and vertical cracks developing in the upstream-downstream direction for various reasons cause internal erosion, resulting in serious consequences such as dam failure. Hydraulic fracturing is one of the mechanisms that cause these cracks to develop in the upstream-downstream direction. Hydraulic fracturing occurs when the stresses at the upstream face of the core are less than or equal to the hydrostatic stresses originating from the reservoir. The arching phenomenon creates the stress environment in which hydraulic fracturing can develop. In transverse arching, one of the arching types, stress transfer occurs from the core to the transition and shell zones. As a result of this stress transfer, the vertical stresses on the upstream surface of the clay core decrease. This study examines the effect on zoned dam transverse arching behavior in combinations where the geomechanical characteristics of the clay core (Elasticity modulus and Poisson ratio) change, provided that the material characteristics in the transition and shell zones are constant. Numerical analyses were carried out using the finite element method using the maximum cross-section of Çınarcık Dam. As a result of numerical analysis, it was seen that the increase in the elasticity modulus and Poisson ratio values, which are the deformation parameters of the clay core, was effective in reducing the transverse arching potential.

Deformation Pattern and Failure Mechanism of Railway Embankment Caused by Lake Water Fluctuation Using Earth Observation and On-Site Monitoring Techniques

The prediction of railway embankment failure is still a global challenge for the railway industry due to the complexity of embankment failure mechanisms. In this work, the pre-failure deformation and the settlement from abnormal deformation to the final failure were investigated based on earth observation and on-site monitoring with a focus on the deformation stage and failure mechanism of railway embankments. Some new viewpoints are suggested: (1) the differential settlement of ~19 mm revealed via InSAR at the failure region of the embankment may have been caused by internal erosion after rapid drawdown. The cumulative settlement was found to increase with the decline of the lake water level. (2) The railway embankment experienced three phases of primary, secondary, and accelerated creep phases, similar to the evolution of most landslide or dam failures. However, the train loading and seepage force may have aggravated the secondary consolidation, promoting the embankment to enter the accelerated creep phase quickly. The deformation pattern was presented as an exponential curve trend. (3) The formation mechanism of embankment collapse can be summarized as “seepage failure-creep-shear slip-collapse” failure under repeated train loading and rapid drawdown. This work provides some clues for early warnings and for the development of maintenance plans.

A Modeling of Human Reliability Analysis on Dam Failure Caused by Extreme Weather

Human factors are introduced into the dam risk analysis method to improve the existing dam risk management theory. This study constructs the path of human factor failure in dam collapse, explores the failure pattern of each node, and obtains the performance shaping factors (PSFs) therein. The resulting model was combined with a Bayesian network, and sensitivity analysis was performed using entropy reduction. The study obtained a human factor failure pathway consisting of four components: monitoring and awareness, state diagnosis, plan formulation and operation execution. Additionally, a PSFs set contains five factors: operator, technology, organization, environment, and task. Operator factors in a BN (Bayesian network) are the most sensitive, while the deeper causes are failures in organizational and managerial factors. The results show that the model can depict the relationship between the factors, explicitly measure the failure probability quantitatively, and identify the causes of high impact for risk control. Governments should improve the significance of the human factor in the dam project, constantly strengthen the safety culture of the organization’s communications, and enhance the psychological quality and professional skills of management personnel through training. This study provides valuable guidelines for the human reliability analysis on dam failure, which has implications for the theoretical research and engineering practice of reservoir dam safety and management.

Two-Dimensional Simulation of Dam Break with Partial Damage Condition using Ansys Software

The issue of dam failure has been a key contributor to massive catastrophes, as well as economic and physical destruction. Nevertheless, the effectiveness and accuracy of the simulation of a dam break model are still under debate. In this study, a simulation of a 2D model of the dam breaking half-filled water tank was carried out using Ansys software to evaluate the deformation and water pressure of dam break flow. Four sensors were installed to examine the changes in pressure of the water deformation. Deformation of water at a certain time of the dam break simulation and the pressure of water inside were analyzed and compared with the experimental result, which has been reported by Lobovský. Validation and verification of hydrostatic tests have been found to be in agreement with the current model simulation. An extensive set of data for the simulation is given access as supplementary materials for the direct result of the recent initiative. The results show that by excluding minor differences in wave shape and duration of water movement, the deformation of water exemplifies the same behavior as the experimental results. For experimental data, the non-dimensional time of the dam break event is ranged within 0 to 7.14828 ms while the pressure of water flow is within 0 to 3.0441 Pa. As for simulation results, the non-dimensional time of the dam break event is ranged within 0 to 202 ms whereas the pressure of water flow is within 0 to 0.54124 Pa. Thus, to strengthen the quality numerical model, future work should emphasize the initiative to incorporate the Smooth Particle Hydrodynamics (SPH) method with the goal of improving computational validity and efficiency.

Probabilistic mapping of life loss due to dam-break flooding

AbstractAssessment of flood damage caused by dam failures is typically performed deterministically on the basis of a single preselected scenario, neglecting uncertainties in dam-break parameters, exposure information, and vulnerability model. This paper proposes a probabilistic flood damage model for the estimation of life loss due to dam-break flooding with the aim of overcoming this limitation and performing a more comprehensive and informative evaluation of flood risk. The significant novelty lies in the fact that the model combines uncertainties associated with all three components of risk: hazard, exposure, and vulnerability. Uncertainty in flood hazard is introduced by considering a set of dam-break scenarios, each characterized by different breach widths and reservoir levels. Each scenario is linked to a probability, which is assumed conditional on the dam-break event. Uncertainty in exposure is accounted for using dasymetric maps of the population at risk for two socio-economic states (representing business and non-business hours of a typical week), along with associated likelihood. Vulnerability to flooding is described through a well-established empirical hazard-loss function relating the fatality rate of the population at risk to the flood hazard, the flood severity understanding, and the warning time; a confidence band provides quantitative information about the associated uncertainty. The probabilistic damage model was applied to the case study of the hypothetical collapse of Mignano concrete gravity dam (northern Italy). The main outcome is represented by probabilistic flood damage maps, which show the spatial distribution of selected percentiles of a loss-of-life risk index coupled with the corresponding uncertainty bounds.

Two-phase modelling of erosion and deposition process during overtopping failure of landslide dams using GPU-accelerated ED-SPH

Erosion and deposition induced by overtopping flow strongly impacts the breaching evolution of landslide dams. However, these two processes are not yet sufficiently captured in current dam breaching models. In this paper, we simulate the Erosion and Deposition process during overtopping dam breaching using a novel Smooth Particle Hydrodynamics (ED-SPH) method. A new multi-function boundary is proposed to prevent the penetration of water and soil particles and ensure steady inflows. Dam break and movable erosion scenarios are simulated as a means to validate the model. Dam breach simulations using the ED-SPH method reveal that the proposed model can capture the complex dam soil erosion, entrainment, and depositions behaviors. The soil deposition hinders the eroded particle movement and reduces the water velocity at the water-soil interface. If soil deposition is not considered, as in many existing models, the breaching time decreases and the outburst flood discharge is magnified. We further investigate the re-erosion of deposited soils by varying the re-erosion coefficient. With decreasing the re-erosion coefficient, the peak discharge increases whereas the residual dam height decreases due to the blockage by the deposited soils.