A lot of mine waste rock and tailings arise from all mining processes and have to be stored in an appropriate way. Tailings are deposited in impoundments retained by tailings dams. The objective of tailings dams is to retain the slurry from the mining process and in that way prevent spill into the surroundings that might be harmful for the environment. Tailings dams are often constructed as staged embankments so that construction costs and demand of materials are spread more evenly over the period of deposition. The objective of this thesis has been to compile information about and evaluate events at Swedish tailings dams and also to develop a collective database for all Swedish mining companies for all tailings dams and all events that occur at tailings dams. Information about 60 events at Swedish tailings dams has been gathered and evaluated. The evaluation has been performed by comparison between and analysis of individual parameters and also by use of a multivariate statistical method called PLS. The statistical analysis shows a decrease in the numbers of events during the last five years, which indicates improved dam safety within the mining industry. The analysis also shows that severe events and the human factor might be related when it comes to the initiating cause of the event. Further relations between the parameters and the severity of the events can be seen from the PLS-analysis, for example that low and short tailings dams to a greater extent are subjected to severe events. To be able to draw more reliable conclusions further studies with a more complete basic data are needed. This work has shown a need of a collective database within the Swedish mining industry for tailings dams and occurring events at tailings dams so that more complete basic data could be obtained for future studies. A structure for such a database has been developed in Microsoft Access 2000. The aim of the database is to facilitate feedback within the mining industry and to gather comprehensive data for future statistical evaluations. / Vid alla gruvprocesser skapas stora mängder restprodukter i form av gråberg och anrikningssand som måste tas om hand på lämpligt sätt. Anrikningssanden deponeras tillsammans med vatten från gruvprocessen i magasin omgärdade av dammvallar, s.k. gruvdammar. Gruvdammar har som syfte att hålla kvar anrikningssand och vatten och måste vara stabila så att de skyddar omgivningen från utsläpp av anrikningssand som skulle kunna vara skadligt för miljön. En gruvdamm byggs ofta upp i etapper eftersom byggkostnaderna och behovet av dammfyllnadsmaterial då sprids över tiden. Syftet med arbetet har varit att sammanställa och utvärdera händelser vid svenska gruvdammar samt att utforma ett för gruvindustrin gemensamt dammregister och felrapporteringssystem. 60 händelser vid svenska gruvdammar har sammanställts och utvärderats. Utvärderingen har genomförts dels genom att enskilda parametrar jämförts och analyserats och dels med hjälp av den multivariata analysmetoden PLS. Den statistiska analysen visar på en minskning i antal händelser under de senaste fem åren, vilket tyder på ett förbättrat dammsäkerhetsarbete inom gruvindustrin. Analysen har kunnat uppvisa ett samband mellan allvarliga händelser och den mänskliga faktorn när det gäller vad det är som initierat händelserna. Genom PLS-analysen har ytterligare samband mellan de undersökta parametrarna och allvarlighetsgraden av händelserna kunnat utläsas, bl.a. visar analysen att låga och korta dammar i större utsträckning drabbas av allvarliga händelser jämfört med höga och långa dammar. För att säkra slutsatser ska kunna dras krävs dock vidare studier med ett mer komplett statistiskt underlag. Examensarbetet har påvisat ett behov av ett branchgemensamt damm- och felrapporteringsregister för att ett mer komplett underlag ska kunna erhållas i framtiden. En färdig databasstruktur för ett sådant dammregister och felrapporteringsregister för svenska gruvdammar har utformats. Databasen är uppbyggd i Microsoft Access 2000 och är tänkt att underlätta erfarenhetsåterföring inom branschen samt att ge ett underlag för framtida statistiska undersökningar.

In this study, the first hardfill dam in Turkey, Cindere Dam, is evaluated regarding current and alternative measurement systems in detail. Cindere Dam is a notable project, especially with its height as an example of hardfill dam, not only in Turkey but also in the world. First, the current instrumentation system of Cindere Dam is evaluated as a whole with reference to the parameters measured, instruments and data acquisition system. Second, an alternative instrumentation system is developed by using additional parameter and instruments to the current instrumentation system. Furthermore, each instrumentation system equipped with manual and automatic data acquisition systems is considered. The comparison between the current and the alternative instrumentation systems are also carried out in terms of technical and economical feasibility aspects. Although, the current instrumentation system is found to be satisfactory, it is observed that the alternative system promotes the current system in various aspects without increasing the cost significantly.

Dams are important large structures providing vital benefits to human life. These strategic structures are necessary in order to supply water and energy and to control floods. Moreover, dams have important roles in regional development and national economy. Thus, the design of dams deserves rigorous studies. Deterministic approach may be acceptable for design of dams and may satisfy safety requirements if large safety factors are used. However, such an approach will not be cost-effective in economic terms. High safety factors utilized in deterministic approaches necessitates large dimensions. One remedy for this overestimation is integrating statistical information and techniques, such as Monte-Carlo simulations into the analysis and design of dams. Probabilistic approaches may result in more economical and reasonable designs. CADAM is a software program which allows the user to analyze dams using Monte-Carlo simulation technique. Uncertainties associated with tensile strength, peak cohesion, peak friction coefficient, normal upstream reservoir elevation, drain efficiency and horizontal peak ground acceleration are incorporated into stability and stress analysis using Monte-Carlo simulations. In this thesis, utilization of CADAM software is demonstrated on a case study. Cindere dam is evaluated in terms of structural safety

Successful dam design endeavor involves generating technical solutions that can meet intended functional objectives and choosing the best one among the alternative technical solutions. The process of choosing the best among the alternative technical solutions depends on evaluation of design conformance with technical specifications and reliability standards (such as capacity, environmental, safety, social, political etc pecifications). The process also involves evaluation on whether an optimal balance is set between safety and economy. The process of evaluating alternative design solutions requires generating a quantitative expression for lifetime performance and safety. An objective and numerical evaluation of lifetime performance and safety of dams is an essential but complex undertaking. Its domain involves much uncertainty (uncertainty in loads, hazards, strength parameters, boundary conditions, models and dam failure consequences) all of which should be characterized. Arguably uncertainty models and risk analysis provide the most complete characterization of dam performance and safety issues. Risk is a combined measure of the probability and severity of an adverse effect (functional and/or structural failure), and is often estimated by the product of the probability of the adverse event occurring and the expected consequences. Thus, risk analysis requires (1) determination of failure probabilities. (2) probabilistic estimation of consequences. Nonetheless, there is no adequately demonstrated, satisfactorily comprehensive and precise method for explicit treatment and integration of all uncertainties in variables of dam design and risk analysis. Therefore, there is a need for evaluating existing uncertainty models for their applicability, to see knowledge and realization gaps, to drive or adopt new approaches and tools and to adequately demonstrate their practicability by using real life case studies. This is required not only for hopefully improving the performance and safety evaluation process accuracy but also for getting better acceptance of the probabilistic approaches by those who took deterministic design based research and engineering practices as their life time career. These problems have motivated the initiation of this research. In this research the following have been accomplished: (1) Identified various ways of analyzing and representing uncertainty in dam design parameters pertinent to three dominant dam failure causes (sliding, overtopping and seepage), and tested a suite of stochastic models capable of capturing design parameters uncertainty to better facilitate evaluation of failure probabilities; (2) Studied three classical stochastic models: Monte Carlo Simulation Method (MCSM), First Order Second Moment (FOSM) and Second Order Second Moment (SOSM), and applied them for modeling dam performance and for evaluating failure probabilities in line with the above mentioned dominant dam failure causes; (3) Presented an exact new for the purpose analytical method of transforming design parameters distributions to a distribution representing dam performance (Analytical Solution for finding Derived Distributions (ASDD) method). Laid out proves of its basic principles, prepared a generic implementation architecture and demonstrated its applicability for the three failure modes using a real life case study data; (4) Presented a multitude of tailor-made reliability equations and solution procedures that will enable the implementations of the above stochastic and analytical methods for failure probability evaluation; (5) Implemented the stochastic and analytical methods using real life data pertinent to the three failure mechanisms from Tendaho Dam, Ethiopia. Compared the performance of the various stochastic and analytical methods with each other and with the classical deterministic design approach; and (6) Provided solution procedures, implementation architectures, and Mathematica 5.2, Crystal Ball 7 and spreadsheet based tools for doing the above mentioned analysis. The results indicate that: (1) The proposed approaches provide a valid set of procedures, internally consistent logic and produce more realistic solutions. Using the approaches engineers could design dams to meet a quantified level of performance (volume of failure) and could set a balance between safety and economy; (2) The research is assumed to bridge the gap between the available probability theories in one hand and the suffering distribution problems in dam safety evaluation on the other; (3) Out of the suite of stochastic approaches studied the ASDD method out perform the classical methods (MCSM, FOSM and SOSM methods) by its theoretical foundation, accuracy and reproducibility. However, when compared with deterministic approach, each of the stochastic approaches provides valid set of procedures, consistent logic and they gave more realistic solution. Nonetheless, it is good practice to compare results from the proposed probabilistic approaches; (4) The different tailor-made reliability equations and solution approaches followed are proved to work for stochastic safety evaluation of dams; and (5) The research drawn from some important conclusions and lessons, in relation to stochastic safety analysis of dams against the three dominant failure mechanisms, are. The end result of the study should provide dam engineers and decision makers with perspectives, methodologies, techniques and tools that help them better understand dam safety related issues and enable them to conduct quantitative safety analysis and thus make intelligent dam design, upgrading and rehabilitation decisions.

In 1990 Flödeskommittén released new guidelines which redefined the method used to determine design flows. The method, combined with more complete measurements of flow variations, has resulted in higher design flows which in turn call for increases in the discharge capacity of hydropower plants. This work is still in progress. Since many Swedish hydropower stations were constructed in the 1950's and 60's they require modernization. Today Statkraft owns and operates 55 hydropower stations in Sweden several of which have a discharge capacity below the design flow. For this reason, the dam safety of these hydropower stations is reduced. According to current guidelines the turbine flow is not added to the discharge capacity since the availability of the electrical grid is not guaranteed during extreme flows. When the electric grid is unavailable the generator has no load and cannot produce an electric torque. Without the electric torque the turbine accelerates which may result in equipment failure. This thesis considers the introduction of an alternative local load where the generator power can be dumped as heat, hence termed dump load. The dump load has the potential to increase the discharge capacity by adding the turbine flow. However, operation of the dump load requires the availability of the generator and turbine, making the discharge capacity dependent on the status of the plant. In turn, achieving a sufficient discharge capacity is of primary concern to dam operators since it determines dam safety. Consequently, this thesis evaluates the effects on dam safety when utilizing a local load to increase the discharge capacity. Three different designs were evaluated; a medium to high voltage electrode water boiler, electrodes submerged in the river and a low voltage electric water boiler. The evaluation shows that all three designs are feasible and can be used to increase the discharge capacity provided the generator and turbine have high availability. The complexity and number of components constituting the dump load should be minimized to reduce the risk of malfunctions and redundancy should be introduced for key components when feasible. The dump load power should be controlled using voltage regulation but further work is required to determine the specifics of this governor. The results also show that the cost of the dump load is a fraction of the cost of a new spillway. However, the topic is controversial and the dump load requires practical testing in order to evaluate operational reliability.

Reservoirs and dams are often situated in the mountains upstream of cities and towns. This implies a theoretical but difficult to evaluate hazard potential for downstream communities. This paper reflects experiences of the related safety analysis practice including the steps from the breach estimation towards the drawing of special hazard maps.

This master thesis was made to investigate the possibilities of using the Matlab-basedsoftware Basegrain to determine grain size distributions of erosion protections onhydropower dams. Basegrain is a photogrammetric tool developed to generate grainsize distributions and other information about coarse flood sediments by analyzing adigital photo of the stone bed. The investigation was made by validating the ability forBasegrain to assess grain size distributions of various materials smaller than the blocksused in an erosion protection by comparing sieving results or manual measurementswith the results obtained by the program. A statistical comparison was then made bycomparing the results from sieving and the program. The possibilities of using thesame method on existing hydropower dams were then investigated by determiningwhether the method was practically viable or not.The results showed that Basegrain generated grain size distributions for coarse gravelthat were very close to the sieving results. It also provided grain size distributions forlarger fractions of stones quite close to the results made by measuring the diameterof the stones by hand. The results also showed it was possible to use the samemethod on existing erosion protections on hydropower dams and obtain grain sizedistributions.

Thesis (M. Eng.(Structural Engineering))--University of Pretoria, 2008. / Includes bibliographical references.

Thesis (M.S.)--Mississippi State University. Department of Geosciences. / Title from title screen. Includes bibliographical references.

Made available in DSpace on 2014-12-02T11:16:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-09-25Bitstream added on 2014-12-02T11:20:49Z : No. of bitstreams: 1 000797929.pdf: 12522148 bytes, checksum: 64739180db3a3786cbd7a4443a47299e (MD5) / No Brasil existe um número significativo de pessoas que residem em regiões situadas a jusante de barragens. A Lei 12.334/2010 determina aos proprietários de barragens a elaboração de um Plano de Segurança e um Plano de Ação Emergencial para barragens classificadas como passíveis de provocar Dano Potencial Alto. O presente trabalho busca avaliar o comportamento das ondas de cheia geradas por vazões induzidas e vazão de ruptura hipotética da barragem da usina hidrelétrica de Três Irmãos, da CESP - Companhia Energética de São Paulo, para elaboração de um Plano de Ação Emergencial. Foram avaliados os tempos de chegada da onda, as cotas e vazões máximas alcançadas em diferentes pontos do curso d’água, para diferentes cenários. São apresentados mapas de inundação indicando a área atingida pela onda de ruptura que serviram de base para definição de plano de evacuação da população impactada. Foi usado o modelo hidrodinâmico unidimensional HEC-RAS, calibrado a partir da reprodução de níveis d’água históricos. Os hidrogramas de ruptura gerados a partir de diferentes equações resultaram em vazões máximas entre 20.915 e 40.507 m3/s, com tempos de abertura de brecha entre 1,0 e 14,0 h. A onda de cheia foi propagada em uma extensão de 32 km desde a usina até a confluência com o rio Paraná. Os resultados mostraram pouca variação tanto na extensão quanto no tempo de submersão das áreas atingidas pela inundação, com diferença sensível apenas no tempo de chegada do pico. Além disso, as simulações em regime permanente e variável não apresentaram grandes variações nas cotas máximas observadas a jusante, o que mostra que a cheia gerada pela ruptura tem características de onda cinemática, devido ao longo tempo de esvaziamento do reservatório. Tendo em vista que a barragem de Jupiá, localizada a jusante, opera a fio d’água e pode controlar vazões até cerca de 50.000 m3/s, não se ... / In Brazil there is a significant number of people living in regions located downstream of Dams. The law 12.334/2010 determines that the dam’s owners have to elaborate a Security Plan and an Emergency Action Plan for dams classified as likely to cause High Potential Damage. The present study attempts o evaluate the behavior of waves generated by full flow and flow induced by hypothetical dam rupture of the Três Irmãos hydroelectric, of CESP, Energetic Company of São Paulo, for preparation of an Emergency Action Plan. We evaluated the arrival times of the wave, quotas and peak flows achieved at different points of the watercourse, for different scenarios. Flood maps are presented indicating the area affected by the flood wave that served as the basis for defining evacuation plan of the affected population. It was used the one-dimensional hydrodynamic model HEC-HAS, calibrated from the reproduction of historical water levels. The outflow hydrographs generated from different available equations resulted in peak flows between 20.915 and 40.507 m³/s, with peak times between 1 and 14 h. The dam breach flood wave was propagated along a 32 km reach, from the plant to the confluence with the Paraná River. The results showed little variation in both the extent and the time of submersion of areas affected by flooding, with only appreciable difference in arrival time of the peak. Furthermore, the simulations in steady and unsteady flow regimes showed no large variations of the downstream maximum water depth, suggesting that the resulted flood wave propagates with characteristics of a kinematic wave, due to the long depletion time of the reservoir. The risk of cascade rupture was not identified, considering that at the downstream, the Jupiá dam operates at constant level and can control flow rates up to 50.000 m³/s. From the results and the methodology was elaborated an PAE - Emergency Action Plan for the Três Irmãos ...