Integration of 3D geological and numerical models based on tetrahedral meshes for hydrogeological simulations in fractured porous media

Une nouvelle approche de modélisation des milieux géologiques fracturés représentés par un modèle conceptuel de fractures discrètes et déterministes est présentée dans cette thèse. L'objectif principal de l'étude est de reproduire l'hétérogénéité et la complexité des milieux poreux fracturés dans un modèle géométrique tridimensionnel afin d'effectuer des simulations numériques dans le but d'améliorer les capacités de modélisation en hydrogéologie. Ceci est réalisé à travers le couplage entre une plateforme de modélisation géologique (GOCAD) et un code numérique (HydroGeoSphere). Les principaux défis à relever sont: la représentation géométrique du réseau de fractures, la sélection d'un maillage approprié pour la discrétisation spatiale du domaine de simulation et l'adaptation du code numérique à ce maillage. La nouvelle approche est basée sur une première phase de modélisation géologique 3D, suivie par la génération d'un maillage tétraédrique 3D et par la simulation numérique de l'écoulement souterrain en conditions saturées et du transport de solutés. En général, le maillage tétraédrique s'avère plus adéquat que les maillages de blocs ou de prismes pour discrétiser les geometries complexes telles que les milieux fracturés. De plus, une définition alternative du maillage "dual", qui est essentiel pour appliquer la méthode numérique élément finis - volume de contrôle utilisée par HydroGeoSphere, est analysée et intégrée dans le code numérique. Le code numérique proposé est d'abord vérifié par l'intermédiaire de simples scénarios de simulation dont les solutions, analytiques et numériques, sont déjà connues. La complexité des simulations est augmentée de façon graduelle. L'approche de modélisation est finalement appliquée au site Olkiluoto (Finlande) où un laboratoire de recherche souterrain est en construction afin d'évaluer la faisabilité du stockage géologique profond de déchets nucléaires à haute activité. Les techniques de modélisation géologique mises au point permettent de modéliser facilement la géométrie des fractures identifiées à travers la caractérisation géologique in situ. De plus, le modèle numérique s'avère adéquat pour la simulation de l'écoulement et du transport de solutés dans ce site complexe. Ce travail de recherche présente une contribution au développement des techniques de modélisation hydrogéologique des milieux fracturés

Anchorage of Large High-Strength Reinforcing Bars with Standard Hooks and Heads: Initial Tests

The reaction frame to be used to test No. 14 and No. 18 bar beam-column joint specimens, the modified reaction frame used to test initial No. 11 beam-column joint specimens, and the design of beam-column joint specimens are described. Concrete strengths of 5,000 psi to 15,000 psi will be used with bar sizes of No. 11, No. 14, and No. 18 with bar stresses at anchorage failure in excess of 100 ksi in future work. Thus far, the testing apparatus has been designed, test procedures have been established, and initial specimens have been tested. The initial test results show that the descriptive equation used to calculate the anchorage strength of headed bars presented by Shao et al. (2016) is accurate for No. 11 bars. Testing will continue using the apparatus and procedures described in this report, and the results will be added to the database developed at The University of Kansas to better understand how large high-strength headed and hooked bars behave in beam-column joints

Numerical evaluation of grouting scenarios for reducing water inflows in underground excavations – Goldcorp’s Éléonore mine study case

Water inflows through fracture networks are one of the many challenges that the Éléonore mine has to face. Although pregrouting of pilot holes during mine development has been proven to efficiently reduce water inflows into mine excavations, the actual design methods are empirical and can be optimized to increase grouting efficiency and decrease the associated costs. Optimization of the amount of cement needed for pre-grouting is achieved by designing the grouting approach based on the location of major faults around the excavations. Here, a base case finite-element numerical model and associated sensitivity analyses are used to simulate groundwater inflows into a stope, based on the Éléonore mining site characteristics. Simulations are conducted for testing various grout injection scenarios for various major fault locations around the stope. Sensitivity analyses have shown that for a fault located above the stope, the inflow reduction is greater when the zone between the fault and the stope is grouted instead of directly grouting the fault itself. Also, in the case of a fault intersecting a stope, the results have demonstrated that the fault itself should be grouted as widely as possible, instead of sealing only the immediate surroundings of the stope

Early venous congestion after diep flap breast reconstruction: case report of a successful management

BACKGROUND AND AIM: More than 250 000 women estimated to be diagnosed with breast cancer in the USA every year. Mastectomy is primary treatment for more than a third of those with early-stage disease. Most of the patients undergoing mastectomy receive breast reconstruction. A number of. Surgical techniques have been described to reconstruct the breast. With autologous tissue breast reconstruction, the plastic surgeon uses patient's own tissues, taken from a different part of the body where there is an excess of fat and skin. Deep inferior epigastric perforator (DIEP) flap is the autologous breast reconstruction technique of choice in our department due to long lasting results, low donor site morbidity and positive patient reported outcomes have been described.   Case Report: We present the case of a 42-year-old woman who underwent neoadjuvant chemotherapy followed by left breast simple mastectomy, axillary lymph-nodes dissection and later adjuvant radiation therapy (RT). After conclusion of RT a DIEP flap breast reconstruction was performed. Nine-hours after the operation, signs of acute venous congestion were noted. The venous congestion was treated by a combined surgical and medical approach based on pedicle discharge and ICU resuscitation protocol. After take back surgery, the patient was tightly monitored in the intensive care unit where intravenous heparin infusion and leech therapy were performed for 2 days. Flap congestion resolved completely, and the patient was discharged.   Conclusions: Venous congestion is very difficult to treat due to its potential multifactorial nature. The most important step is to recognize this kind of emergency because irreversible microvascular damages will develop in 6-8 hours. Because of multiple causes of venous congestion a timely multidisciplinary approach is mandatory, to maximize flap salvage and success rates

Analyzing variation of the water table level with three-dimensional numerical simulations to assess reclamation techniques for an acidic tailings impoundment

RÉSUMÉ: Tailings with sulphide minerals exposed to oxygen and water can oxidize and produce acid mine drainage (AMD). This study evaluated the impact of natural conditions and of a thin cover deposition on the water table level, with respect to selecting the reclamation technique to control AMD on the elevated portion of an abandoned tailings impoundment. The reactive tailings were partly covered with alkaline tailings transported as a pulp from a nearby mine. A three-dimensional numerical variably saturated groundwater flow model of the tailings impoundment and its surrounding area was built. The simulation results reproduced well the field observations before, during, and after the deposition of a thin layer of tailings. The calibrated model was then used to forecast the evolution of the water table position for the next 100 years under various site conditions, including a period of 5 years with dry summers. The results show that the water table levels are on average several metres below the interface between the reactive tailings and the cover, thus failing to meet the target criterion to control the production of AMD determined from previous column tests. The results are analyzed and discussed in terms of the site configuration and atmospheric recharge. ABSTRACT: Les résidus miniers sulfureux exposés à l'oxygène et à l'eau peuvent engendrer la production de drainage minier acide (DMA). Cette étude évalue l'impact de la déposition d'une couverture sur l'établissement d'une nappe phréatique surélevée (NPS) comme méthode de contrôle du DMA sur un parc à résidus miniers abandonné. Les résidus réactifs ont été recouverts partiellement par des résidus alcalins sous forme de pulpe provenant d'une mine voisine. Un modèle numérique tridimensionnel d'écoulement souterrain à saturation variable du parc à résidus et ses environs a été construit. Les résultats de ces simulations reproduisent bien les niveaux phréatiques observés avant, durant et après la déposition des résidus. Le modèle calibré a ensuite été utilisé pour prédire l'évolution du niveau phréatique pour les 100 prochaines années et dans le cas de périodes estivales plus sèches. Les résultats ont montré que la nappe phréatique serait en moyenne plusieurs mètres sous l'interface entre les résidus réactifs et le recouvrement, soit nettement sous la cible permettant de contrôler la production de DMA selon des essais antérieurs. Les résultats sont analysés et discutés selon la configuration du site et la recharge atmosphérique

Review of Recent Drilling Projects in Unconventional Geothermal Resources at Campi Flegrei Caldera, Cornubian Batholith, and Williston Sedimentary Basin

Unconventional geothermal resource development can contribute to increase power generation from renewable energy sources in countries without conventional hydrothermal reservoirs, which are usually associated with magmatic activity and extensional faulting, as well as to expand the generation in those regions where conventional resources are already used. Three recent drilling experiences focused on the characterization of unconventional resources are described and compared: the Campi Flegrei Deep Drilling Project (CFDDP) in Italy, the United Downs Deep Geothermal Power (UDDGP) project in the United Kingdom, and the DEEP Earth Energy Production in Canada. The main aspects of each project are described (geology, drilling, data collection, communication strategies) and compared to discuss challenges encountered at the tree sites considered, including a scientific drilling project (CFDDP) and two industrial ones (UDDGP and DEEP). The first project, at the first stage of pilot hole, although not reaching deep supercritical targets, showed extremely high, very rare thermal gradients even at shallow depths. Although each project has its own history, as well as social and economic context, the lessons learned at each drilling site can be used to further facilitate geothermal energy development.This research was co-funded by ICDP consortium and INGV for the CFDDP. Grant number CFDDP 05-2008.Peer reviewe

Stochastic fractured rock facies for groundwater flow modeling [Representación estocástica de facies de rocas fracturadas para la modelación del flujo de aguas subterráneas]

This paper presents simulation results of groundwater flow in fractured rocks. A stochastic approach is employed to build the conceptual model, a stochastic Equivalent Porous Medium fractured rock facies model, for the low-permeability bedrock found at Olkiluoto (Finland), which is the site chosen for the case-study. The volume of rock investigated is located around a cluster of boreholes and it covers an area of 160000 square meters. Field measurements during hydraulic interference tests are used to calibrate the groundwater flow model. Multiple stochastic facies realizations are considered to evaluate the impact of distribution and number of facies on simulated hydraulic heads and flow rates. This study quantifies the variability of numerical results, which is important for uncertainty analysis of hydrogeologic systems. Moreover, it shows that the stochastic facies conceptual model is a suitable alternative to discrete fracture network conceptual models