Student Number : 0112584H - MSc research project - School of Mining Engineering - Faculty of Engineering and the Built Environment / With the acquisition by AngloGold Ashanti Ltd of open pit mines in East and West Africa with possible addition of Greenfield and Brownfield operations, the emphasis of this research document was to improve the current open pit mines in this region. By identifying Mineral Resource Management (MRM) as a way to improve and manage operating practices, additional value and the accompanied risks have been identified. It was also realised that the current traditional, predominantly financial indicators are becoming increasingly inadequate, thus looking at alternative operating principles. Subsequent to this, proposals have been made to acquire the necessary production and cost change by integrating structure, strategy, systems, style, skills, staff and the defined goals as proposed in this document. Using a “process-based” approach integrating (best) operating practices, concepts such as: living out the company’s strategic values; a learning organisation; better informed decision-making; people management; self-directed teams; continuous improvement; asset and capital management; integrated information systems; and an improved internal and external customer relationship be obtained.

Projetos de estabilidade de escavações mineiras por meio de estudos de caracterização do maciço rochoso com o uso da mecânica de rochas são indispensáveis para otimizar o aproveitamento das jazidas, garantir segurança nas operações de lavra e minimizar os impactos ambientais decorrentes da instabilidade dos taludes da cava. Nesta dissertação utilizou-se de critérios recentes de ruptura em rocha, para obtenção de dados de entrada em métodos já clássicos de análise da estabilidade de taludes em maciços rochosos para a cava de dolomito lavrada a céu aberto. Os critérios utilizados serão avaliados com relação à compatibilidade dos resultados obtidos com sua aplicação e a coerência com a situação atual observada na lavra em desenvolvimento. Análises sobre a paralisação da lavra em decorrência dos problemas de instabilidade também serão avaliadas e discutidas. Para ilustrar esta dissertação foi eleita a jazida de dolomito localizada no Sinclinal do Gandarela em virtude dos problemas de instabilidade encontrados na cava. As conclusões finais são apresentadas nos últimos itens deste trabalho. / The design of stable excavations using rock masses characterization with the tools provided by rock mechanics, are indispensable for optimizing the economic exploitation of ore deposits, to ensure the safety in the mining works and to minimize the environmental impacts deriving of the open pit slopes instability. In this Dissertation, for obtain the input data for classic methods of rocky slopes stability analyses, it is used the most recent criteria of rock mass failure applied for an open pit mine of dolomite. The utilized criteria compatibility will be evaluated by the results obtained with their utilization and the coherence with the real situation verified at the developing mine. Will be evaluated and discussed the analyses about the stoppage of the mine works due to the slope instability problems. To illustrate this Dissertation are elected a dolomite ore deposit situated at the Gandarela Synclinal on account of the instability problems that occurred in the mine pit. The final conclusions are listed in the items presented at the end of this work.

Projetos de estabilidade de escavações mineiras por meio de estudos de caracterização do maciço rochoso com o uso da mecânica de rochas são indispensáveis para otimizar o aproveitamento das jazidas, garantir segurança nas operações de lavra e minimizar os impactos ambientais decorrentes da instabilidade dos taludes da cava. Nesta dissertação utilizou-se de critérios recentes de ruptura em rocha, para obtenção de dados de entrada em métodos já clássicos de análise da estabilidade de taludes em maciços rochosos para a cava de dolomito lavrada a céu aberto. Os critérios utilizados serão avaliados com relação à compatibilidade dos resultados obtidos com sua aplicação e a coerência com a situação atual observada na lavra em desenvolvimento. Análises sobre a paralisação da lavra em decorrência dos problemas de instabilidade também serão avaliadas e discutidas. Para ilustrar esta dissertação foi eleita a jazida de dolomito localizada no Sinclinal do Gandarela em virtude dos problemas de instabilidade encontrados na cava. As conclusões finais são apresentadas nos últimos itens deste trabalho. / The design of stable excavations using rock masses characterization with the tools provided by rock mechanics, are indispensable for optimizing the economic exploitation of ore deposits, to ensure the safety in the mining works and to minimize the environmental impacts deriving of the open pit slopes instability. In this Dissertation, for obtain the input data for classic methods of rocky slopes stability analyses, it is used the most recent criteria of rock mass failure applied for an open pit mine of dolomite. The utilized criteria compatibility will be evaluated by the results obtained with their utilization and the coherence with the real situation verified at the developing mine. Will be evaluated and discussed the analyses about the stoppage of the mine works due to the slope instability problems. To illustrate this Dissertation are elected a dolomite ore deposit situated at the Gandarela Synclinal on account of the instability problems that occurred in the mine pit. The final conclusions are listed in the items presented at the end of this work.

Braunkohle ist aktuell immer noch ein wichtiger Rohstoff für die Energieversorgung in Deutschland. Ein großes Abbaugebiet befindet sich in Nordrhein-Westfalen. Im sogenannten rheinischen Braunkohlenrevier liegen mächtige Braunkohleflöze, welche seit einigen Jahrzehnten im Tagebaubetrieb abgebaut werden. Allerdings fallen auch große Mengen an Abraum (die Deckschichten über der Braunkohle) an, welche meist auf der, dem Abbauort, gegenüberliegenden Seite, wieder verkippt werden. Dort bilden die verkippten Massen eine Böschung, die im Fall des Tagebaus Hambach ein Böschungssystem mit über 400m Höhe erreicht hat. Diese sich ständig verändernden Böschungen müssen, wie alle hohen Böschungen, durch Fachpersonal auf ihre Standsicherheit überprüft werden. Für diese Standsicherheitsberechnungen bedarf es Kennwerte, u. a. die undrainierte Scherfestigkeit für die Nachweise der kurzfristigen Standsicherheit, für die vorliegenden verkippten Böden. Diese liegen nach der Verkippung meist heterogen vor und verändern durch eine fortschreitende Konsolidation ihren Zustand. Diese Arbeit beschäftigt sich mit der Bestimmung des Kennwertes der undrainierten Scherfestigkeit in fein- und gemischtkörnigen Böden. Dazu werden zunächst die Klassifikations- und Zustandseigenschaften während der Verkippung der Böden für die in den Tagebauen Inden und Hambach verwendeten Materialklassen vorgestellt. Dabei wird auch auf die Besonderheiten der Böden im Tagebau, wie z.B. die Zustandsänderung während des Transportes oder die vorliegende Heterogenität, eingegangen. Es werden analytische und numerische Prognosemodelle zur Bestimmung der undrainierten Scherfestigkeit vorgestellt. Die Grundlage dieser Modelle bilden die Konsolidationstheorien, mit welchen sich die Zustandsvariablen, wie die Porenzahl oder die effektive Spannungen, berechnen lassen. Über verfügbare Stoffmodelle, wie z.B. das hypoplastische Modell nach Mašín können anhand der Zustandsvariablen die undrainierten Scherfestigkeiten abgeleitet werden. Mit den in dieser Arbeit verwendeten Modellen lassen sich undrainierte Scherfestigkeitskennwerte zu verschiedenen Zeitpunkten prognostizieren, mit denen wiederum z.B. Standsicherheitsberechnungen von Böschungen durchgeführt werden können. Die statistischen Auswertungen der Klassifikationseigenschaften und Zustände erlauben eine Beurteilung von im Tagebaubetrieb häufig verwendeten Kennwerten (z.B. Fließgrenze oder Wassergehalt) und deren Streubreiten innerhalb der Materialklassen. / Lignite was and still is an essential source for producing energy in Germany. One huge extraction site is located in North-Rhine-Westphalia (in between Mönchengladbach, Cologne and Aachen). The so called Rhenish lignite district contains very thick lignite deposits, which are mined in open pit mines since a few decades. There are huge overburdens (on top on the lignite) which are transported and dumped on the opposite to the excavation side. The dumped soil masses create slope systems, that can amount to 400m of height (in open pit mine Hambach). These large slopes undergo permanent changes and have to be assessed considering their safety and stability by specialists. Characteristic properties regarding shear strength of the heterogeneous fine- and mixed grained soils are required for such calculations. The main challenge is the description of the state of the soil, as it is permanently changing due to consolidation. One essential characteristic is the undrained shear strength. The main focus of this thesis is the determination of the undrained shear strength. Therefore, the soil properties are determined with classification tests and the state of the soils at the time of dumping is assessed. The results are categorised using the material classes of the open pit mines Inden and Hambach. The particularities of dumped soils in open pit mines are shown, for instance the change of state during transport or the heterogeneity. Moreover, analytical and numerical models are employed to predict the undrained shear strength. The basis of all these models are consolidation theories, which are applied to determine the state variables such as void ratio and effective stresses. The undrained shear strength can then be predicted by using constitutive models such as the hypoplastic model for clays according Mašín. Using the approach presented in this thesis the undrained shear strength can be predicted and employed for example for slope stability analyses. The statistic evaluation of the soil properties allows a review of the soil characteristics that are typically employed in open pit mining. Furthermore, the scattering of properties of the material classes in the open pit mines can be assessed.

The purpose of the present study was to determine the concurrent validity of learning potential and psychomotor ability measures for the prediction of haul truck operator (N=128) performance in an open-pit mine. Specific aims were to determine the nature of the relationship between learning potential and psychomotor ability; whether there are higher order cognitive or psychomotor factors present in the combined use of the TRAM 1 and Vienna Test System measures; and the relative contribution of learning potential and psychomotor ability in the prediction of haul truck operator performance. The validity of learning potential and psychomotor ability measures was partially supported. A positive correlation between general (cognitive) ability (g) and psychomotor ability was reported. Factor analysis provided relatively consistent evidence for a general (cognitive) ability factor (g) underlying performance on all measures. The relative contribution of learning potential and psychomotor ability in the prediction of performance could not be established. / Industrial and Organisational Psychology / M. Com. (Industrial and Organisational Psychology)

The purpose of the present study was to determine the concurrent validity of learning potential and psychomotor ability measures for the prediction of haul truck operator (N=128) performance in an open-pit mine. Specific aims were to determine the nature of the relationship between learning potential and psychomotor ability; whether there are higher order cognitive or psychomotor factors present in the combined use of the TRAM 1 and Vienna Test System measures; and the relative contribution of learning potential and psychomotor ability in the prediction of haul truck operator performance. The validity of learning potential and psychomotor ability measures was partially supported. A positive correlation between general (cognitive) ability (g) and psychomotor ability was reported. Factor analysis provided relatively consistent evidence for a general (cognitive) ability factor (g) underlying performance on all measures. The relative contribution of learning potential and psychomotor ability in the prediction of performance could not be established. / Industrial and Organisational Psychology / M. Com. (Industrial and Organisational Psychology)

La stabilité des exploitations à ciel ouvert (mines ou carrières) excavées dans des massifs rocheux dépend de leur géométrie, des caractéristiques géométriques de la fracturation (orientation et espacement) du massif et des caractéristiques mécaniques du massif et des discontinuités. L'évaluation du risque d'instabilité rocheuse dépend de la quantité et la qualité des informations disponibles sur le massif rocheux et des méthodes d'analyse mises en œuvre pour évaluer le comportement mécanique de l'assemblage de blocs rocheux. Différents sites de talus naturels, d'excavation routière et de carrières et mines à ciel ouvert présentés dans le mémoire montrent que les informations connues peuvent beaucoup varier d'un site à l'autre. Les étapes de collecte et de synthèse des données, puis de modélisation afin d'analyser la stabilité d'une pente rocheuse conduisent à des incertitudes. Le mémoire traite plus particulièrement de l'influence des incertitudes géométriques et différentes méthodes de regroupement des fractures en familles sont explorées. La combinaison du travail proposé par différents auteurs conduit à une nouvelle méthode nommée PSMY. Cette méthode ainsi que la méthode spectrale ont été programmées sous l'environnement Mathematica et les résultats sont comparés à des regroupements "manuels" réalisé avec le logiciel DIPS. Les méthodes de regroupement sont présentées selon le pourcentage d'orientations classé par la méthode. L’orientation et l’espacement des familles de fractures sont ajustées à des lois statistiques. Les paramètres statistiques sont comparés en fonction de la méthode regroupement. Ces paramètres influencent la construction d'un modèle géométrique du massif rocheux appelé DFN (Discrete Fracture Network). L'influence des regroupements sur l'analyse de stabilité est étudiée à partir de modélisation stochastiques à l'équilibre limite utilisant les logiciels SWEDGE et RESOBLOK. Ces logiciels ne prennent pas en compte les mêmes incertitudes et en sortie ils fournissent des indicateurs de stabilité différents. Une analyse de sensibilité des indicateurs (nombre de blocs instables, volume moyen du bloc instable, volume total instable) aux méthodes de regroupement et aux orientations de talus est réalisée. Une analyse de variance permet de préciser l'influence de ces deux facteurs. Une évaluation de l’état de stabilité global du massif, en fonction de la cohésion et de l'angle de frottement est proposée. L'influence de la méthode de modélisation est évoquée en comparant des calculs tridimensionnels à l'équilibre limite et des modélisations bidimensionnel et tridimensionnels en éléments discrets rigides ou déformables. Un couplage entre le logiciel RESOBLOK (équilibre limite) et LMGC90 (éléments discrets) permet de comparer les analyses pour une même géométrie. Pour le cas de la déviation d'Ax-les-Thermes et certaines configurations géométriques instables l’influence des paramètres de modèles sur stabilité du talus est testée. Plusieurs variantes sont comparées. La simulation d’une excavation en 3D multi phases est réalisée et l’indice de mobilisation est étudié pour comparer les divers types de contacts dans LMGC90 par rapport à l’éventuel glissement des blocs dans les étapes successives / The stability of open-cast operations (mines or quarries), excavated in rock mass depends on their geometry, the geometrical characteristics of the rock mass fractures (orientation and spacing) and the mechanical characteristics of the rock mass and the discontinuities. The assessment of the rock instability risk depends on the quantity and quality of the available information on the rock mass and the analysis methods used for the evaluation of the mechanical behavior of the rock block collection. Different sites of natural rock slopes, of road cuts, and of open-cast mines and quarries, described in the present document, show that the known information can vary a lot from one site to the other. The steps of data gathering and analysis, then the modelling step used to analyze the stability of the rock slope, lead to uncertainties. The present work deals in particular with the influence of the geometrical uncertainties, and the different clustering methods, to define families of fractures, are examined. The combination of works suggested by several authors leads to a new method called PSMY. This method, together with the spectral method, was coded in the Mathematica platform, and the obtained results are compared with "hand-made" clusters, done with the DIPS software. The clustering methods are presented according to the ratio of classified orientations. The orientation and spacing of fracture families are fitted by statistical law. The statistical parameters are compared according to the clustering method used. These parameters have an influence on the construction of the rock mass geometrical model, called DFN (Discrete Fracture Network). The influence of the clusters on the stability analysis is studied from the stochastic models based on the limit equilibrium analysis, in the SWEDGE and RESOBLOK software. These programs do not take into account the same uncertainties, and as a result, they give different stability indicators. A sensitivity analysis of these indicators (number of unstable blocks, average volume of unstable blocks, and total volume of unstable blocks) versus the clustering methods used, and the orientation of the slopes, is carried out. A variance analysis allows an evaluation of the influence of these factors. The assessment of the global stability condition of the rock mass, depending on the cohesion and the friction angle, is proposed. The influence of the modeling method is analyzed by comparing 3D calculations using the limit equilibrium calculations, and 2D and 3D models using discrete rigid and deformable blocks. A coupling between RESOBLOK (limit equilibrium) and LMGC90 (discrete elements) allows the comparison of results on the same original geometry. For the case of Ax-les-Thermes road-cut, and for various unstable geometries, the influence of the model parameters is tested. Several cases are compared. The 3D simulation of an excavation, at different steps, is performed, and the mobilization index is studied, in order to compare several types of contacts, within the LMGC model, in relation to the possible sliding of blocks, at those different steps