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Numerical investigation of the development of the excavation damaged zone around a deep polymetallic ore mine
No full textInternational audienceThis paper deals with the development of a non-linear constitutive model of a rock mass and its application to predict the extension of the excavation damaged zone (EDZ) around openings. A comparison of the model results with the simulations of triaxial compression tests shows a good agreement between predictions and theoretical values of peak and residual strengths as well as a good reproduction of the transition between brittle failure and ductile response. The relevance of the proposed model to evaluate the potential failure around stopes of the Garpenberg mine was examined. The comparison of the results proved satisfactory and highlighted the interest of considering a more realistic mechanical behavior of hard rock masses in rock engineering compared with the elastic perfectly plastic models generally used in numerical modeling of underground deep mines. Finally, a 3D simulation of the complete mine geometry was carried out in order to model the first phases of stope mining operations. The predicted stresses were compared with the continuous measurements of induced in situ stresses recorded by stress cells at different points around the stope. The predictions of the proposed constitutive model provided a much better agreement with stress measurements than those obtained with elastic perfectly plastic models
Développement d'un modèle toxicocinétique à base physiologique décrivant la bioaccumulation par voie alimentaire d'un acide perfluoroalkyl sulfonique chez la truite (oncorhynchus mykiss)
No full textInternational audienceLes composés perfluorés (PFAS) possèdent des propriétés physicochimiques uniques, telles qu'une excellente stabilité thermique et chimique et une bonne résistance à la dégradation biologique, expliquant leur ubiquité dans l'environnement. Les milieux aquatiques sont particulièrement exposés et de nombreuses études ont démontré la bioaccumulation de certains de ces composés par les vertébrés aquatiques. Pourtant, les données liées aux mécanismes d'absorption, de distribution, de métabolisation et d'élimination des PFAS demeurent limitées. Il est donc primordial de mieux comprendre ces processus ainsi que leurs déterminants, d'autant plus que la production et l'utilisation industrielles des PFAS évoluent rapidement. Dans ce contexte, une approche par la modélisation parait pertinente puisqu'elle permet d'intégrer l'ensemble des processus dynamiques influençant la toxicocinétique des composés d'intérêt. Les modèles toxicocinétiques à base physiologique (PBTK) se révèlent être des outils puissants pour comprendre et expliquer le comportement d'une substance et prédire leur devenir au sein d'un organisme. Cependant, les applications des modèles PBTK aux PFAS sont encore inexistantes pour les vertébrés aquatiques. Nous avons donc développé un premier modèle PBTK, basé sur la physiologie de la truite arc-en-ciel (Oncorhynchus mykiss), décrivant le comportement du perfluorooctane sulfonate (PFOS), composé de référence, majoritaire dans les matrices environnementales malgré l'arrêt de sa production depuis quelques années. Celui-ci, inspiré principalement de deux modèles mécanistiques (Ng et Hungerbühler 2013 ; Nichols et al., 2004), a été calibré à partir d'un jeu de données obtenu grâce à une exposition par voie alimentaire chez la truite arc-en-ciel adulte. Des simulations de la cinétique du PFOS ont été réalisées pour les phases d'absorption et de dépuration, tout en prenant en compte la croissance des organismes. Ainsi, nous avons pu étudier la contribution de chaque organe concernant la distribution du PFOS et celle des différentes voies d'élimination (urine, bile, fèces, branchies), encore controversées dans la littérature. Par ailleurs, plusieurs perspectives d'extension du modèle sont envisagées : effets de la température de l'eau sur les processus d'absorption et d'élimination et application à d'autres PFAS, tels que le perfluorohexane sulfonate, alternative industrielle au PFOS
Fire safety engineering method evaluation based on a real tunnel fire case
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SWOT analysis of the MERLIN-Expo tool and its relevance in legislative frameworks
No full textInternational audienceThe MERLIN-Expo tool was evaluated using a SWOT analysis, which was based on expert judgement and literature review. A list of criteria was set up containing the major model characteristics, which were divided in general model criteria and relevance model criteria. Relevance model criteria were defined as criteria, which are highly depending on the regulatory framework the model is used in. From the analysis presented above, it appeared that certain regulatory chemical frameworks (e.g. REACH, biocides) are stricter towards their requirements compared to others (e.g. site-specific/local regulatory frameworks). Based on expert judgement, the MERLIN-Expo tool was evaluated using the general and relevance criteria. MERLIN-Expo has many advanced functionalities (such as uncertainty analysis, modular approach, dynamic model, combines environmental fate with pharmacokinetics) and models (many fate processes and environmental compartments, different human populations). At the same time, the threat is that current (regulatory) applicability frameworks do not always require these advanced assessment functionalities. The MERLIN-Expo tool appeared to be most suitable for the site-specific assessment as this is the most flexible framework. Based on this analysis, weaknesses of the MERLIN-Expo tool for its use in a certain regulatory framework could also be identified. These weaknesses are at the same time further development opportunities for MERLIN-Expo. On general model characteristics, MERLIN-Expo was identified as a highly documented (both for novice and expert level), transparent, user-friendly tool with regular trainings. Its main treat now is to ensure continuing support and mechanisms for future developmental work and updates
Impact of multiple stressors on biomarker responses in sympatric dreissenid populations
No full textInternational audienceDreissenid mussels, well-known invaders of the northern hemisphere, also constitute good biomonitors for freshwater quality assessment. Whereas the oldest, Dreissena polymorpha, is relatively well-known, the new invasive, Dreissena rostriformis bugensis, has been very little characterized. The aim of this study was to compare subcellular biomarker responses within these species, by taking into account inter- and intra-specific variability in biomarker responses during a multi-stress assessment. Indeed, due to local environmental conditions and genetic background, biomarker responses can be different between populations of a given species, not only between species. To evaluate these differential responses, we sampled mussels on two sites where they are both present in sympatry (plus another D. r. bugensis population), and we exposed these populations in laboratory to different stressors: thermal stress (12 or 17 °C), dietary stress (fed or unfed), contamination (nickel at 0, 20 and 500 μg L−1) and exposure duration (0, 4 or 8 days). Results mainly evidenced strong inter-species and inter-population differences, underlining the need to discriminate correctly between the two species and to know well the populations used in biomonitoring. Results also evidenced thermal and food stress-related effects. The numerous data obtained during this multi-stress experiment also highlight the complexity of working on several stressors and analysing the associated results
Is learning a normative more than a descriptive notion?
No full textOther activity during the congress : S. Tillement, F. Garcias & G. Minguet(IMT Atlantique Nantes, Université de Lille)Designing innovative nuclear reactor: a study of technological innovation in contested industries through learning and unlearning processesDiscussion: M. Dupré & J.-C. Le CozeInternational audienceIn this communication, we start with an overview of the field of learning from incident and accident (LFIA). First, there are classic analyses of disasters (Turner, Vaughan, Hopkins) which have been turned by some of these authors into studies of failure to learn. Second, there are reviews of LFIA with synthetic ambitions and third, empirical studies of how LFIA happens in practice. The increase of research on LFIA in recent years is commented, and some reasons hypothesised. The presence of a normative approach is emphasised, discussed and questioned. We follow this overview of the literature with a research strategy that complement LFIA studies by further contextualising and embedding empirical research of LFIA during daily operations. The purpose is to explain why in our view LFIA is an ideal that in practice remains imperfect because of the operational realities of high-risk systems. The characterisation and acceptable extent of such imperfection remain a thorny issue for safety research
A multi-biomarker assessment of chronic effects of an insecticide Acer 35 EC on Nile Tilapia Oreochromis niloticus under laboratory conditions
No full textInternational audienceAcer 35EC is an insecticide (20 g/L lambda-cyhalothrin + 15 g/L acetamipride) widely used in pest control in many West African countries, and particularly in cotton culture in north Benin. This study aimed to investigate under laboratory conditions the chronic effects of Acer 35EC on Nile tilapia Oreochromis niloticus using a multi-biomarker approach. For this purpose, juveniles of Nile tilapia were exposed to sublethal concentrations of Acer 35 EC (0, 1 and 10% of LC50- 96 h value) in glass aquariums during 56 days. After 0, 28 and 56 days of exposure, several biomarkers including enzymatic activities (indicators of detoxification and oxidative stress, neurotoxicity and immune responses) sex steroid hormones (Testosterone, Estradiol-17β and 11-Keto-testosterone) and histological alterations of liver, kidney and gonads were measured in males and females. A biomarker index (BI) was calculated based on the Integrated Biological Responses (IBR) developed by Beliaeff and Burgeot (2002). The results showed that Acer 35EC reduced cholinesterase activity in muscle of treated fish of both sexes. Females displayed high levels of testosterone and 11-Keto-testosterone after 56 days of exposure. Regarding immune biomarkers, intracellular superoxide anion production decreased in both sexes after 56 days of exposure. Oxidative stress biomarkers were not influenced by Acer-35EC exposure, regardless of sex and concentration. However, liver of females exposed to 1 and 10% of LC50- 96 h value was significantly (p < 0.05) affected after 28 and 56 days of exposure, while no histological differences were recorded in kidney between control and exposed fish. After 28 and 56 days of exposure, significant differences in the ovarian development were observed as the diameter of vitellogenic oocytes in exposed females differed from the one of the control females, indicating an increase in oocyte growth during the 1st month of exposure to Acer-35EC, followed by a regression during the 2nd exposure period. No differences were recorded in male gonads. Based on a large set of biomarkers, the insecticide Acer-35EC seems to impair different physiological functions in Nile tilapia juveniles on a time-dependent manner, with a stronger impact on females than in males