In this study a recent dam type, concrete face rockfill dam (CFRD), its design and behaviour is overviewed. The design features of G&ouml / k&ccedil / eler Dam are introduced as a case study. Selection of concrete face rockfill type for G&ouml / k&ccedil / eler Dam Project is discussed together with the other two alternatives, namely earth core rockfill (ECRD) and roller compacted concrete (RCC) dam. G&ouml / k&ccedil / eler Dam type selection as concrete face rockfill dam is also verified by an economic analysis conducted calculating internal rate of return for all alternative types. In cost analysis a currency independent defined unit cost (DUC) is specified to verify the time independent validity of the economic analysis.

[pt] A construção de Barragens de Enrocamento no Brasil tem se desenvolvido nas últimas décadas, por ser uma solução adequada para regiões onde há falta de solos finos e grande volume de escavações obrigatórias em rocha. Este desenvolvimento está relacionado tanto à quantidade de barragens construídas quanto ao incremento da altura das mesmas. A construção de protótipos de instrumentos para medição de deslocamentos neste tipo de barragem é de fundamental importância. Com a simulação das leituras em laboratório, torna-se possível implementar modificações no projeto, na construção, na instalação e na operação destes instrumentos, disponibilizando-se leituras mais acuradas e precisas, obtendo-se maior confiabilidade nos dados e, assim, informações mais consistentes sobre o comportamento das barragens. Além da elaboração de uma abrangente revisão bibliográfica sobre instrumentação geotécnica, foram estudados dois protótipos de instrumentos de medidas de deslocamento, Medidor Hidrostático de Recalques e Extensômetro Horizontal de Hastes Múltiplas. Ambos desenvolvidos no Laboratório de Engenharia Civil de Furnas, em Aparecida de Goiânia, estado de Goiás. Os resultados obtidos permitirão modificações na construção e instalação destes instrumentos. / [en] The number and height of rockfill dams in Brazil has been steadily growing, because rockfills constitute an adequate solution when the project requires a large volume of rock excavation and there is a lack of fine grained soils in the region. The development of new equipment for measuring displacements in these dams is of fundamental importance. Testing prototypes in the laboratory, under simulated field conditions, allows the researcher to implement modifications in the design characteristics and installation procedures for the instrument. As a result, measurements with higher accuracy and reliability are obtained and, consequently, higher safety for the dams. A comprehensive review of the literature on geotechnical instrumentation is presented. Two prototypes of displacement measuring devices have been studied and tested: a hydrostatic displacement cell and a multiple rods horizontal extensometer. Both were constructed and tested in the Civil Engineering Laboratory of Furnas, in Goiás, Brazil. The results and conclusions obtained will result in important modifications in the design and installation details of these instruments.

Une modélisation numérique des grands barrages en enrochement à masque amont (CFRD) a été entreprise pour mieux comprendre les pathologies observées sur ces ouvrages récemment construits, principalement des fissures horizontales et verticales sur le masque amont en béton en phase de construction et de mise en eau. Le but de cette modélisation est ensuite de confirmer, préciser ou compléter les solutions proposées par les experts pour éviter ces désordres.D‟abord, une loi de comportement développée au sein d‟EDF-CIH appelée L&K-Enroch a été présentée. Il s'agit d'un modèle élastoplastique qui prend en compte les déformations irréversibles de l‟enrochement sous sollicitation déviatorique et isotrope dans les grands CFRD. Cette thèse propose aussi une méthode de calage des paramètres de ce modèle.Deux modélisations des barrages sont également présentées dans cette thèse afin de vérifier la fiabilité de la loi de comportement L&K-Enroch et de mieux comprendre les pathologies sur le masque amont en béton du CFRD. La modélisation en déformation plane (2D) est d‟abord entreprise et a comme support le barrage d‟Aguamilpa (180,5 m), au Mexique. Une modélisation plus poussée en 3D prenant en compte de l'effet de la vallée est ensuite entreprise. Elle a comme support le barrage de Mohale (145 m) au Lesotho.L'effet d‟échelle de l'enrochement est également étudié en comparant les résultats de simulation pour les matériaux de différentes tailles. L'impact de l‟effet d‟échelle sur le comportement du barrage est aussi analysé.Les simulations présentées en 2D et 3D sont une contribution à l'analyse du comportement mécanique des grands CFRD. Les résultats de la modélisation 2D montrent généralement une bonne correspondance avec les mesures in-situ. La modélisation 3D explique, d'une manière plus convaincante, l‟apparition des fissures sur le masque amont en béton des CFRD. Certaines mesures constructives sont finalement proposées afin de limiter ou d'éviter ces désordres dans le masque. / A numerical modeling of high concrete face rockfill dam (CFRD) has been considered in order to better understand the pathology of cracks observed in the recently constructed high CFRD, especially the horizontal and vertical cracks detected on the concrete face slab during the construction and the impoundment. The purpose of this modeling is then to confirm, clarify or complete the solutions proposed by the experts to avoid these disorders.This PhD thesis presents a constitutive model developed by EDF-CIH known as L&K-Enroch. It is an elastoplastic model that takes into account the irreversible deformations of rockfill under deviatoric and isotropic loading in high CFRD. A first attempt of proposing a parameter calibration approach has been made as well.Two dam modellings are also presented in this thesis in order to verify the reliability of the constitutive model and to better understand the pathology of cracks observed on the concrete face slab of CFRD. A 2D modeling is compared to the behaviour of the 180.5 m Aguamilpa Dam, Mexico; a 3D modeling taking into account the valley effect is compared to the behaviour of the 145 m Mohale Dam, Lesotho.This thesis also studies the scale effect of rockfill through a comparison of the simulation results of materials of different sizes. The impact of the scale effect on the dam behavior is analyzed as well.The presented 2D and 3D simulations are a contribution to the analysis of the mechanical behaviour of high CFRD. The results of the 2D modeling show a relatively good agreement with the monitored data. The 3D modeling explains, in a rather convincing way, the pathology of cracks on the slab face of CFRD. Some measures are proposed to limit or avoid these different kinds of cracks.

Numerical analyses are presented in this thesis to address potential stability problems that may occur during gradual raisings and under seismic loading conditions of Aitik tailings dam in northern Sweden. The dam is mainly raised using upstream construction method. It is planned to raise the dam gradually in several stages. Two dam parts were studied. The first dam part is a straight dam portion, and the second dam part is a corner. The main concerns associated with future raisings of the straight dam part were: (i) the stability of the dam could be affected by an increase in excess pore pressures during sequential raisings, (ii) how to gradually strengthen the dam by using rockfill berms as supports in such a way that required slope stability can be achieved with a minimum volume of rockfill berms, and (iii) if the dam is subjected to seismic loading, whether or not an increase in excess pore pressures could lead to extensive liquefaction which may cause a failure. The problems related to the dam corner were that tension zones and/or low compression zones could develop because of the horizontal pressure of the stored tailings on the inside of the curvature of the dam corner.Numerical analyses were conducted on both the dam parts using finite element method. Two dimensional (2D) plane strain finite element model was utilized to analyse the straight dam. The dam corner was analysed with both the three dimensional (3D) finite element model, and the 2D axisymmetric finite element model. Coupled deformation and consolidation analyses, and slope stability analyses were performed on both the dam parts to simulate gradual raisings, and to compute safety factors. In addition to this, dynamic analyses were carried out on the straight dam part to evaluate the potential for liquefaction, and seismic stability of the dam. The seismic behaviour of the dam was analysed for two cases: (i) a normal case (earthquake of 3.6 Swedish local magnitude), and (ii) an extreme case (earthquake of 5.8 moment magnitude).The results of the straight dam part, with only previously existing rockfill berms, indicate that stability of the dam was reduced due to an increase in excess pore pressures during raisings. Rockfill berms were utilized as supports to raise the dam with enough safety. An optimization technique was utilized to minimize the volume of rockfill berms. This technique could result in significant saving of cost of rockfill berms.The results of the dam corner show that tension zones and/or low compression zones were located on the surface of the dam corner, mainly above the phreatic level. It is interpreted that there is no risk of internal erosion through the embankments because no seepage path occurs above the phreatic level, and a filter zone exists along the slope of the dam. It is suggested to gradually strengthen the dam corner with rockfill berms. The results of the 2D axisymmetric analyses of the dam corner were in a fairly good agreement with those of the 3D analyses. This implies that the 2D axisymmetric analyses are valid for this dam corner. This is an important finding as 2D axisymmetric analyses require much less computational time compared to 3D analyses.The results of the dynamic analyses performed on the straight dam (including additional rockfill berms) suggest that, for the extreme case, liquefaction could occur in a limited zone that is located below the surface near the embankments. For both the normal and the extreme case, (i) seismically induced displacements seem to be tolerable, and (ii) the post seismic stability of the dam is considered to be sufficient.The findings of this study have been practically applied to the Aitik tailings dam. In general, the modelling procedure and the optimization technique to minimize volume of rockfill berms, presented in this study, could be applied to other tailings dams. / Godkänd; 2013; 20130513 (muhauc); Tillkännagivande disputation 2013-05-20 Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Muhammad Auchar Zardari Ämne: Geoteknik/Soil Mechanics and Foundation Engineering Avhandling: Numerical Analyses of Stability of a Gradually Raised Tailings Dam Opponent: Professor Daichao Sheng, School of Engineering, The University of Newcastle, New South Wales, Australia Ordförande: Professor Sven Knutsson, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Torsdag den 13 juni 2013, kl 10.00 Plats: F1031, Luleå tekniska universitet

In this study, two major internal erosion initiation processes, suffusion and concentrated leak mechanisms, which lead to both defect formation in a dam’s body and its foundation and high throughflow in dams subjected to internal erosion were studied. This understanding has the potential to facilitate numerical modelling and expedite dam safety assessment studies.  The throughflow properties of coarse rockfill material were studied by; analysing filed pump test data, performing extensive laboratory experiments with a large-scale apparatus and numerically simulating the three-dimensional flow through coarse rock materials, replicating the material used in the laboratory experiments. Results from the tests demonstrate that the parameters of the nonlinear momentum equation of the flow depend on the Reynolds number for pore Reynolds numbers lower than 60000.  Numerical studies were also carried out to conduct numerical experiments. By applying a Lagrangian particle tracking method, a model for estimating the lengths of the flow channels in the porous media was developed.  The shear forces exerted on the coarse particles in the porous media were found to be significantly dependent on the inertial forces of the flow. Suffusion and concentrated leak mechanisms were also studied by means of laboratory experiments to develop a theoretical framework for continuum-based numerical modelling. An erosion apparatus was designed and constructed with the capability of applying hydraulic and mechanical loading. Results were then used to develop constitutive laws of the soil erosion as a function of the applied hydromechanical load for both suffusion and concentrated leak mechanisms. Both the initiation and mass removal rate of were found to be dependent on the soil in-situ stresses. A three-dimensional electrical-resistivity-based tomography method was also adopted for the internal erosion apparatus and was found to be successful in visualising the porosity evolution due to suffusion. / <p>QC 20161006</p>

Les structures en enrochements sont parmi les ouvrages les plus usuels de génie civil (barrages, murs de soutènement,. . . ). Des tassements importants peuvent apparaître tout au long de leur durée de vie et sont principalement dus à la rupture des blocs rocheux. Cette thèse propose un modèle numérique permettant de simuler le comportement de matériaux granulaires présentant des ruptures de grains. Afin de prendre en compte la nature discontinue de ces milieux, la méthode des éléments discrets est utilisée. La modélisation adoptée est de type "Non-Smooth Contact Dynamics", où les grains et particules sont supposés rigides. Afin de générer des blocs ayant des formes complexes, un modèle de grain 3D est proposé. Ce modèle de grain est ensuite discrétisé en sous-éléments de forme tétraédrique liés par des liaisons cohésives afin de pouvoir représenter la rupture. Un critère de rupture de Mohr-Coulomb est utilisé. Le modèle est implémenté sur la plateforme logicielle LMGC90. Le modèle est d’abord éprouvé lors de simulations d’écrasement de blocs cassables entre deux plaques. Plusieurs paramètres contrôlant la résistance du grain sont étudiés : cohésion intergranulaire, taille, discrétisation, forme et orientation du grain. L’effet d’échelle observé sur ce type de matériau est vérifié. Le modèle est ensuite testé lors de simulations numériques de compression œdométrique d’enrochements. L’effet des paramètres du modèle et de l’assemblage du milieu granulaire est également étudié. Les simulations œdométriques sont confrontées à des résultats expérimentaux et présentent une bonne concordance. Enfin, des expérimentations numériques sont menées afin d’étudier les énergies mises en jeu dans ces essais. L’énergie de création de surface est estimée pour ce type de matériau. Les résultats sont proches des données de la littérature. / Rockfill structures are very popular among civil engineering structures (dams, retaining walls, . . . ). Important settlements can take place during the lifetime of these structures, settlements mainly caused by the breakage of rockfill grains. This thesis proposes a numerical model that allows the simulation of the behavior of granular materials exhibiting grain breakage. To take into account the discrete nature of these media, the discrete element method is chosen. The adopted strategy is the Non-Smooth Contact Dynamics method, where grains are considered to be rigid. To generate blocks having complex shapes, a 3D grain model is suggested. This grain model is then discretized into tetrahedral subgrains, joined together using cohesive bonds so that breakage can be simulated. A Mohr-Coulomb failure criterion is used for the cohesive bonds. The model is implemented into the LMGC90 software platform. At first, the model is tested in single grain crushing simulations between two plates. Multiple parameters controling the strength of the grain are studied : the intra-granular cohesion, the size, the discretization and the orientation of the grain. The scale effect that characterizes this type of material is verified. Then the model is tested in numerical simulations of œdometric compression of rockfill. The influence of the parameters of the model and of those of the granular medium are studied. The results of œdometric simulations are compared to experimental results, and present a good agreement. Lastly, numerical experimentations are conducted in order to study the energies that are brought into play in the simulations. The surface creation energy is estimated for this type of material. Results are close to the data provided in the literature.