Modelling of Short-Term Interactions Between Concrete Support and the Excavated Damage Zone Around Galleries Drilled in Callovo–Oxfordian Claystone

peer reviewedProduction of energy from nuclear power plants generates high-level radioactive nuclear waste, harmful during dozens of thousand years. Deep geological disposal of nuclear waste represents the most reliable solutions for its safe isolation. Confinement of radioactive wastes relies on the multi-barrier concept in which isolation is provided by a series of engineered (canister, backfill) and natural (host rock) barriers. Few underground research laboratories have been built all over the world to test and validate storage solutions. The underground drilling process of disposal drifts may generate cracks, fractures/strain localisation in shear bands within the rock surrounding the gallery especially in argillaceous rocks. These degradations affect the hydro-mechanical properties of the material, such as permeability, e.g. creating a preferential flow path for radionuclide migration. Hydraulic conductivity increase within this zone must remain limited to preserve the natural barrier. In addition galleries are currently reinforced by different types of concrete supports such as shotcrete and/or prefab elements. Their purpose is twofold: avoiding partial collapse of the tunnel during drilling operations and limiting convergence of the surrounding rock. Properties of both concrete and rock mass are time dependent, due to shotcrete hydration and hydromechanical couplings within the host rock. By the use of a hydro-mechanical coupled Finite Element Code with a Second Gradient regularization, this paper aims at investigating and predicting support and rock interactions (convergence, stress field). The effect of shotcrete hydration evolution, spraying time and use of compressible wedges is studied in order to determine their relative influence

Excavation damaged zone modelling in claystone with coupled second gradient model

peer reviewedGalleries excavation leads to damage and significant properties changes of the host rock. The fracture structure of the excavation damaged zone created around the galleries remains nowadays a major issue especially in the context of underground storage. In order to correctly model the strain localisation, the second gradient local model (regularization method) is used within a hydro-mechanical modelling of a gallery excavation. The numerical results provide information about the strain localisation bands pattern

Effect of chronic alcohol feeding on physiological and molecular parameters of renal thiamin transport

The renal thiamin reabsorption process plays an important role in regulating thiamin body homeostasis and involves both thiamin transporters-1 and -2 (THTR1 and THTR2). Chronic alcohol use is associated with thiamin deficiency. Although a variety of factors contribute to the development of this deficiency, effects of chronic alcohol use on renal thiamin transport have not been thoroughly examined. We addressed this issue by examining the effect of chronic alcohol feeding of rats with liquid diet on physiological and molecular parameters of renal thiamin transport. Chronic alcohol feeding caused a significant inhibition in carrier-mediated thiamin transport across the renal brush-border membrane and was evident as early as 2 wk after initiation of alcohol feeding. Similarly, thiamin transport across the renal basolateral membrane was significantly inhibited by chronic alcohol feeding. The inhibition in renal thiamin transport was associated with a marked decrease in the level of expression of THTR1 and -2 proteins, mRNAs, and heterogeneous nuclear RNAs. Chronic alcohol feeding also caused a significant reduction in the level of expression of thiamin pyrophosphokinase but not that of the mitochondrial thiamin pyrophosphate transporter. These studies show that chronic alcohol feeding inhibits the entry and exit of thiamin in the polarized renal epithelial cells and that the effect is, at least in part, mediated at the transcriptional level. These findings also suggest that chronic alcohol feeding interferes with the normal homeostasis of thiamin in renal epithelial cells

Indicateurs pour le stress en eau. Rapport final - Projet AquaStress D2.1.3

This report provides a detailed overview of the development of an integrated tool for evaluation conditions of water stress, to be referred to as the Aquastress Water Stress Matrix (AWSM). This tool combines a selection of information relevant for water management decision making, and has at its core, a composite index of water stress, here referred to as the Aquastress Water Stress Index (AWSI). In addition to this composite index, the details of this index are presented in ways that can be visualised, as a means of overcoming the problem of providing complex water stress information as a single number. The framework allows including further information for decision makers within this matrix, like mapped and photographic evidence relating to the specific site under examination, as well as guidance, using a traffic light approach, on the urgency of the situation

Aquastress D2.1.3 - Rapport sur les indicateurs de caractérisation du stress en eau

This report provides a detailed overview of the development of an integrated tool for evaluation conditions of water stress, to be referred to as the Aquastress Water Stress Matrix (AWSM). This tool combines a selection of information relevant for water management decision making, and has at its core, a composite index of water stress, here referred to as the Aquastress Water Stress Index (AWSI). In addition to this composite index, the details of this index are presented in ways that can be visualised, as a means of overcoming the problem of providing complex water stress information as a single number. The framework allows including further information for decision makers within this matrix, like mapped and photographic evidence relating to the specific site under examination, as well as guidance, using a traffic light approach, on the urgency of the situation

Hollow Cylinder Tests on Boom Clay: Modelling of Strain Localization in the Anisotropic Excavation Damaged Zone

peer reviewe