L'Agence nationale pour la gestion des déchets radioactifs (Andra) a commencé en 2000 la construction du Laboratoire Souterrain de Meuse / Haute-Marne (LS-M/HM) avec l'objectif principal de démontrer la faisabilité d’un stockage géologique dans l’argilite du Callovo-Oxfordien. Un réseau de galeries expérimentales a été excavé, principalement en suivant les directions des contraintes horizontales (majeure et mineure), avec des variations sur : la méthode d'excavation, la géométrie de la structure et le soutènement. Chaque galerie a été instrumentée en différentes sections pour suivre le comportement hydromécanique de la roche face à l’excavation. Le suivi de la zone autour des galeries excavées au niveau principal (-490 m) a révélé le développement d'une zone fracturée (fractures en extension et en cisaillement) induite par l'excavation. La distribution de la zone fracturée dépend à la fois de l'orientation de la galerie et du champ de contraintes in-situ et a une influence importante sur la déformation des galeries. En effet, les mesures de convergence ont montré une fermeture anisotrope de la section de la galerie. De plus, il a été observé un champ de distribution anisotrope de la pression de pores ainsi que des surpressions autour des galeries.Afin d’analyser la réponse anisotrope du massif pendant l’excavation et après celle-ci, les travaux effectués dans le cadre de la thèse sont axés principalement sur une étude directe des mesures de convergence in-situ. Cette analyse s’effectue à l’aide de la loi semi-empirique proposée par Sulem et al. (1987) [Int J Rock Mech Min Sci Geomech Abstr 24: 145–154]. A cet égard, différentes galeries excavées dans le LS-M/HM ont été étudiées. Ces galeries présentent certaines différences dans leurs orientations et l’état initial des contraintes, dans la méthode et la vitesse d’excavation ainsi que dans les diamètres de la section et les types de soutènements installées. Cette analyse permet d’obtenir des prédictions fiables de la convergence à long-terme, ce qui peut servir pour le dimensionnement et la prévision de la performance du soutènement à long-terme.En outre, nous avons étudié la réponse anisotrope du champ de pression interstitielle observée in-situ. Cette analyse est basée sur une approche poroélastique anisotrope. L’objectif principal est de reproduire qualitativement l’évolution de la pression des pores autour des galeries avec une approche simple qui prend en compte l’anisotropie intrinsèque du matériau. Enfin, une analyse de l’apparition de la rupture montre le rôle clé que joue le couplage hydromécanique dans l’extension de la zone fracturée / The French National Radioactive Waste Management Agency (Andra) began in 2000 the construction of an Underground Research Laboratory (URL) with the main goal of demonstrating the feasibility of a geological repository in Callovo-Oxfordian claystone. Several research programs have taken place to improve the knowledge of the rock properties and its response to the excavation progress. A network of experimental drifts has been constructed with variations on: excavation method, structure geometry, supports system and orientations with respect to principal stresses’ directions. In each drift different sections have been instrumented to monitor the hydro-mechanical behavior of the rock mass formation. Continuous monitoring of the excavated zone around the drifts in the main level (-490 m) revealed the development of a fractured zone (extensional and shear fractures) induced by the excavation. The extent of this fractured zone depends on the drift orientation regarding the in-situ stress field. Accordingly, the convergence measurements showed an anisotropic closure which depends also on the drifts’ orientations. Moreover, marked overpressures and an anisotropic pore pressure field around the drifts have been also observed.The approach proposed in this work is mainly based on a direct analysis of the convergence measurements, for studying the anisotropic response of the rock formation during and after excavation. The convergence evolution is analyzed on the basis of the semi-empirical law proposed by Sulem et al. (1987) [Int J Rock Mech Min Sci Geomech Abstr 24: 145–154]. The monitoring and analysis of convergence data can provide a reliable approach of the interaction between rock mass and support. Therefore, the anisotropy and the variability of the closure are analyzed taking into account different field cases: drifts excavated in two different orientations (i.e. influence of the initial stress state), different methods, sizes and rates of excavation and different supports systems with different conditions of installation. This broad range of cases permits to refine the analysis for reliable predictions of the convergence evolution in the long term. This approach can thus be used for the design of various types of support and the evaluation of its performance in the long term.On the other hand, the pore pressure evolution induced by excavation of drifts as recorded in situ has been analyzed. The anisotropic response observed in-situ suggests that the intrinsic anisotropy of the material plays a key role in the response of the rock formation. To understand these phenomena, an anisotropic poroelastic analysis of the pore pressure evolution induced by the drift excavation is performed. The main goal is to simulate the main trends of the pore pressure evolution with a simple model taking into account the inherent anisotropy of the material. Finally, an analysis of the onset of failure shows the key role of the hydro-mechanical coupling on the extension of the failed zone around the drifts

Pesquisas e projetos envolvendo a complexa interação de maciços rochosos com estruturas de suporte de túneis evoluem constantemente. A adoção de modelos numéricos sofisticados aliada ao desenvolvimento de computadores com capacidade de processamento crescente possibilitam representações mecânicas de processos complexos. Para análises geotécnicas, considerações de resistência, deformabilidade e condutividade hidráulica do maciço são encontradas em códigos computacionais com representações próximas das encontradas nas pesquisas experimentais de vanguarda da área. Por outro lado, estes mesmos códigos atribuem com frequência ao comportamento do concreto reforçado representações simplistas, muitas vezes com base na teoria da elasticidade. Implicações econômicas e de incerteza na avaliação da segurança decorrem desta forma de representação. Esta pesquisa visa a contribuir para análises da interação entre maciço e suporte de uma escavação subterrânea. Para tanto foram elaboradas simulações numéricas considerando técnicas consagradas de avaliação mecânica de uma escavação, aliadas a uma representação do concreto reforçado considerando o marcante efeito de fissuração. Com foco no comportamento do concreto foram desenvolvidas simulações numéricas de distintas estruturas de concreto reforçado selecionadas na literatura e que contam com boa instrumentação e caracterização mecânica adequada de seus materiais. Os resultados obtidos indicam a possibilidade da avaliação concomitante das complexas características do maciço assim como do concreto reforçado. Este fato contribui para a avaliação da segurança de uma escavação subterrânea com possíveis repercussões no custo das obras. / Research and projects involving the intricate interaction between rock mass and tunnel support structures constantly evolve. The adoption of sophisticated numerical models allied to the development of computers with an increasing processing capacity allows mechanical representations of complex processes. For geotechnical analysis, considerations on rock mass strength, deformability and hydraulic conductivity are found in computational codes with representations close to those found in vanguard experimental research of this subject. However, these same codes often attribute simplistic representations to reinforced concrete behavior, frequently based on elasticity theory. Economic and uncertainty implications in safety evaluation result from this sort of representation. This research aims to contribute to analysis of interaction between rock mass and support of an underground excavation. Thus, numerical simulations were elaborated considering established techniques of mechanical evaluation of excavations, allied to a reinforced concrete representation taking into account the prominent effect of cracking. Focused on the concrete behavior, there were developed numerical simulations of distinct reinforced concrete structures selected in literature and that rely on fair instrumentation and adequate mechanical characterization of the involved materials. The results indicate the possibility of concomitant evaluation of the rock mass complex character and the reinforced concrete. This fact contributes to safety evaluation of an underground excavation with potential repercussions on project cost.

A ocupação do espaço subterrâneo tem assumido importância crescente na sociedade atual; destaca-se no Sul do Brasil o uso de escavações subterrâneas em empreendimentos hidrelétricos, executadas nas rochas efusivas da Formação Serra Geral (FSG). Algumas destas obras registraram tensões elevadas nos maciços rochosos, as quais ocasionaram grandes prejuízos por não terem sido previstas em projetos e não terem solução adequada quando são utilizadas correlações empíricas. Tendo em vista estas dificuldades no desenvolvimento dos projetos, esta tese teve o objetivo de estudar o comportamento das rochas efusivas da FSG e utilizar os dados na simulação numérica de túneis. Foi feito o acompanhamento da execução de cerca de 650m do túnel de adução da UHE Castro Alves, tendo sido coletados os dados de geologia, resultados da instrumentação da obra e coletadas amostras das rochas encontradas no túnel. Foram realizados ensaios de laboratório em corpos de prova para determinar o comportamento tensão versus deformação destes materiais e suas envoltórias de ruptura. Foram obtidas correlações entre alguns dos parâmetros. Os parâmetros determinados nos ensaios (rocha intacta) foram extrapolados para o maciço rochoso. Diversos dados da obra, bem como o cruzamento entre eles e os parâmetros geomecânicos obtidos foram colocados em uma plataforma SIG, a qual se mostrou uma ferramenta bastante útil e de grande potencialidade para uso nestes projetos. Com os parâmetros geomecânicos determinados para o maciço foi realizada uma análise numérica 3D do túnel escavado, a partir da qual foi feita uma retro-análise dos deslocamentos medidos em campo, sendo possível estimar o valor de K0 de campo de cerca de 1,3. Foram também realizadas análises paramétricas para estudar a importância da correta estratigrafia dos derrames basálticos (especialmente a presença das brechas) e a simulação de tensões horizontais elevadas, tendo se demonstrado a necessidade de análises deste tipo para verificação de soluções adequadas em túneis em maciços com estas condicionantes. / In the present society the underground occupation has become increasingly relevant. In Southern Brazil it is possible to observe the use of underground excavation applied to tunneling for hydro electric power plants, as carried out in the Serra Geral Formation (FSG) effusive rocks. Some of these tunnels showed high stresses in the rock mass, which resulted in time and money wasted as it was not expected in the project development and also because there was not a suitable solution found when empirical correlations were applied. Considering these difficulties during the project development, this thesis studies the FSG effusive rocks behavior and the utilization of tunnel data for numerical simulations. About 650m of tunnel excavation has been monitored at the UHE Castro Alves. Geology data, instrumentation results and rock samples have been obtained. To determine the shear stress versus strain behavior, laboratory tests were carried out. The correlation between some parameters was obtained and test parameters of the intact rock were extrapolated to the rock mass. A SIG platform has been used with the field data and the geomechanical parameters; it appears to be a useful tool with great potential for this kind of work. Since the geomechanical parameters have been determined, a FEM 3D analysis was carried out; field displacements back-analysis from the 3D analysis made possible the estimation of a K0 value approximately equal to 1,3. Parametrical analyses were also carried out to study the relevance of considering the correct rock strata and the effects of high horizontal stresses on the numerical simulation results, which showed the need for this kind of analysis in tunnels excavated under these conditions.

Made available in DSpace on 2014-07-29T15:18:25Z (GMT). No. of bitstreams: 1 DM LUCAS.pdf: 3465036 bytes, checksum: 8f3ffb1c56acebb8a4d9a43cdb6113d2 (MD5) Previous issue date: 2009-06-09 / Currently, the increasing demand for great workmanships in Brazil, had become an impediment for the development of Brazil. The Geotechnical Engineering is considered an essential tool, in great workmanships (hydroelectric power plants, subways, tunnels, etc.) supplying technical support for design and construction. In this context, the underground excavations in rock have increased too much. This work presents a study of the behavior of the closer of an underground excavation in rock, where it was considered as case study, Simplício hydroelectric power plant, located in the Paranaíba do Sul river, in frontiers of the States of Rio de Janeiro and Minas Gerais. By means of laboratory tests with samples of intact rock and survey mapping of discontinuities, was characterizes the rock mass. Establishing the principal geomechanic parameters and estimating the in-situ stress state of the rock mass, then was chose the geomechanical model and made a numerical simulation of the excavation process tunnel help downstream of tunnel 3. For the tunnel study was conducted a numerical axial analysis symmetry of the relaxation of the excavated mass on the distance from the face of excavation, to determine the moment of installation and simulate a support of the tunnel closer. For the carried out simulation, the rock mass behaved only in the elastic range, finding closer the results of the simulation, the results on the field by monitoring the tunnel. It was observed that for the degree of alteration of the studied mass, the rupture could occur for the rock as well for the discontinuities, depending on the wedges formed for the discontinuities families and the support type applied in the rock mass / Atualmente, a crescente demanda por grandes obras no Brasil, tem se tornado um gargalo para o desenvolvimento. A Geotecnia se coloca como uma ferramenta essencial, em obras de infra-estrutura (usinas hidrelétricas, metrôs, túneis etc.); fornecendo suporte técnico para projetos e execução de obras. Neste contexto, as escavações subterrâneas em rocha têm aumentado muito na última década. Esta dissertação apresenta um estudo do comportamento da convergência de uma escavação subterrânea em rocha, onde foi considerado como estudo de caso, a Usina Hidroelétrica (UHE) de Simplício/Anta, localizada no Rio Paraíba do Sul, na divisa entre os Estados do Rio de Janeiro e Minas Gerais. Por meio de ensaios em laboratório com amostras de rocha intacta, levantamento estrutural da rocha, e resultado de ensaios em campo foi caracterizado o maciço rochoso. Determinados os principais parâmetros geomecânicos e estimado o estado das tensões originais da rocha, foi então escolhido o modelo geomecânico e realizado a simulação numérica do processo de escavação do túnel auxiliar de jusante do túnel 3 (TAJ TN3). Para o túnel estudado foi realizado uma analise numérica axissimetrica da relaxação do maciço escavado em relação a distância da face de escavação, para determinação do momento da instalação do suporte e simulação bidimensional da convergência do túnel. Para a simulação realizada o maciço comportou-se apenas na faixa elástica, aproximando os resultados obtidos pela simulação, dos resultados em campo através do monitoramento da convergência. Foi observado que para o grau de alteração do maciço estudado, os modos de ruptura, podem ser tanto pela rocha quanto pelas descontinuidades, dependendo das cunhas formadas pelas famílias de descontinuidades e pelo tipo de suporte aplicado no maciço rochoso

Study of Production Drifts Stability and Assessment of Reinforcement Requirements at LKAB Konsuln Test-Mine Levels 436 and 486 Using Geologic Structures Data, and Modelling Software - Dips and Unwedge:  a Part of dp1 Project (Mine Layout and Technology) of the Sustainable Underground Mining (Sum) Project Oludare Joseph Olufe Global population has been on exponential increase over the past half century. The population explosion is driving massive urbanization and infrastructure developments across the globe, which result in huge demand for metals, especially steel. The trend is forecasted to continue to rise steeply in for the next two decades. This is putting enormous strain on metals mining, especially because new surface economic deposits are rare to come by. Therefore, mining is steadily going deeper in many of the mining destinations across the world.     Mining at great depths present unique challenges, particularly regarding stability of excavations at depths. Rock falls, rock burst, excavation collapse are common occurrences associated with deep mining. In regions with high seismicity potentials the frequency and consequences could be very high. Over the past decade ground instability has become a significant challenge confronting mining at LKAB deep mines. There had been incidents that resulted in long term closure of sections of the mines, with resultant adverse economic impacts. More undesirable is loss of live of personnel.     The study was conducted at the Konsuln test mine levels 436 and 486, aimed to investigate the impacts of geologic structures on excavations instability at depths, at the Kiruna iron ore mines, on one hand.  And on the other hand, evaluate the influence of geologic structures on ground reinforcements at the mine. Structural data were collected and analysed using Dips program to define orientation of major structures. The results were used for wedge analysis and excavations stability modelling using Unwedge program. Important rock mechanical parameters were defined based on data provided, and others based on literatures. A design factor of safety of 1.5 was used.     Results from the study established that structures have significant impact on excavations instability at the Konsuln mine. 100% of the production drifts studied has minimum of four wedges formed in its perimeters. Out of this approximately 37% has factor of safety lower than 1.5. Evaluation of reinforcements (shotcrete and rock bolts) implemented in the mine found that approximately 15% of the total wedges formed in the production drifts has factor of safety less that 1.5 after both shotcrete and rock bolt reinforcements had been implement. Also, approximately 5% of the total wedges has apex height longer the rock bolt length.     It was therefore concluded that structurally induced instability is a major contributor to excavations instability at the Kiruna mine. The study approach presented a new methodology to understand and provide robust solution to ground instability problem at the mine.

Le comportement à long terme des excavations souterraines est un enjeu social et économique majeur, en particulier dans le contexte du stockage en formation géologique profonde de déchets nucléaires à Haute Activité et Vie Longue (HAVL). Plusieurs galeries expérimentales ont été creusées dans le laboratoire de recherche souterrain de Meuse/Haute-Marne situé près de Bure en France, où des études sont menées pour comprendre le comportement global de la roche constitutive : l’argilite du Callovo-Oxfordien (COx).L’objectif de cette thèse est d’effectuer une modélisation avec Code_Aster d’ouvrages souterrains, et en particulier d’une des galeries du laboratoire de Meuse/Haute-Marne, en prenant en compte une approche non locale, l’effet du fluage et le couplage hydromécanique dans le cadre de la mécanique des milieux poreux, et de comparer les résultats numériques avec les données expérimentales disponibles.Le modèle élastoviscoplastique spécifiquement utilisé pour cette étude est le modèle L&K : il offre d’une part un couplage entre le comportement instantané et différé, et prend en compte d’autre part la dilatance, paramètre qui gouverne les déformations volumiques du matériau lors d’une sollicitation, et ses fortes variations, caractéristique essentielle des géomatériaux et en particulier du COx. La présence d’un fluide s’écoulant à travers le matériau va ajouter une composante hydraulique à la modélisation, dont le couplage avec la mécanique est assuré par les équations de Biot. Une autre nouveauté de ce travail concerne le couplage entre ce comportement rhéologique complexe et une approche non locale dans un cadre industriel. Parmi les méthodes de régularisation disponibles dans Code_Aster, la méthode second gradient de dilatation a été choisie parce que bien adaptée aux géomatériaux. Son but est de corriger la dépendance au maillage et les solutions numériques localisées.Une fois les outils numériques opérationnels et les paramètres du modèle L&K calés sur des essais effectués en laboratoire sur des échantillons, un bon accord général a été trouvé entre les résultats numériques et les mesures in situ, sans aucun recalage des paramètres. Les effets du temps observés expérimentalement sur l’évolution des déplacements et des pressions d’eau sont retrouvés au sein d’une même modélisation, validant ainsi la démarche prédictive suivie / The long term behaviour of underground excavations is a social and economic stake, in particular in the context of storage in deep geological formation of high activity and long life nuclear waste. Several experimental galleries have been dug in the underground research laboratory (URL) of Meuse/Haute-Marne located close to Bure in France, where studies are leaded in order to understand the global behaviour of the constitutive rock which is the Callovo-Oxfordian (COx) argillite.The purpose of this PhD Thesis is to establish a modelling with Code_Aster of underground excavations, and especially of a Meuse/Haute-Marne laboratory gallery, taking into account non local approach, creep effect and hydromechanical coupling in the framework of the mechanics of porous media, and then to compare numerical results with available experimental data.The specific elastoviscoplastic model used in this study is the L&K model: it offers a coupling between instantaneous and delayed behaviour, and it takes into account the dilation, parameter which governs the volume strains of the material during a solicitation, and its strong variation, a specificity of geomaterials and so of COx argillite. The fluid flowing through the material adds a hydraulic component to the modelling, which is coupled to mechanic component thanks to Biot’s equations.Another novelty of this work concerns the coupling between such complex rheological behaviour and a non local approach in an industrial way. Among methods of regularization available in Code_Aster, the second gradient of dilation is well fitted to geomaterials. Its aim is to correct mesh dependency and numerical localized solutions.After describing numeric tools and setting parameters of the L&K model on laboratory tests, a good general agreement was found between numeric results and in situ measures, without resetting parameters. Time effects experimentally measured on displacement and pore pressure evolution are observed in the same modelling, validating the followed predictive approach