Natural thermal strains close to surface of rock slopes. Measurement and modeling of the "Rochers de Valabres" case

International audienceNatural temperature variations are often are thought to play a role in slope instabilities. For several years, in situ thermo-mechanical measurements have monitored the "Rochers de Valabres" (Alpes-Maritimes, France) site to examine thermomechanical surface phenomena based on in situ measurements. First, a description of the experimental site is presented in this paper. Eight CSIRO cells grouped in three stations were installed at different depths varying from 0 to 50 cm. To understand CSIRO cell strains under temperature variations, analytical solutions and modelling of the problem of a boreholesitu data were analysed based on these computations. If the order of magnitude of the strain measurements is quite similar to those computed, confirming the computed phenomena, an accurate analysis of the data is difficult due to several instrumental problems: drift, the influence of the temperature on the CSIRO cell itself, and the variation in the time of the gauge behaviour. The influence of the CSIRO cell deformability on the measurements was modelled and confirmed through laboratory tests and modelling.Les variations naturelles de température sont souvent mentionnées pour leur rôle sur les instabilités de pente. Pendant plusieurs années, des mesures thermomécaniques in situ ont été réalisées sur le site des Rochers de Valabres" (Alpes-Maritimes) afin d'étudier les phénomènes thermomécaniques de surface. Le site expérimental est d'abord présenté. 8 cellules CSIRO regroupées en 3 stations ont été installées à des profondeurs variant de 0 à 50 cm. Pour comprendre les déformations des jauges des cellules CSIRO soumises aux variations de température, une solution analytique et des modélisations du problème d'un forage, dans un milieu élastique semi-infini, soumis à des variations de température sont présentés. Les données in situ sont ensuite analysées au regard de ces calculs. L'ordre de grandeur des déformations mesurées est comparable à celles calculées, confirmant les phénomènes pris en compte dans les calculs. L'analyse précise des données est, par contre, plus problématique en raison de l'influence de la température sur la cellule CSIRO ellemême, de problème de dérive et de variation dans le temps du comportement des jauges de mesures. L'influence de la déformabilité de la cellule CSIRO sur la mesure a été modélisée et confirmée par des tests de laboratoire et des modélisation

Outcomes from the french national project drive : Experimental data for the evaluation of hydrogen risks onboard vehicles, the validation of numerical tools and the edition of guidelines

The ever-increasing use of hydrogen in the transport sector requires very high safety standards. However, due to the lack of information regarding the safety level of hydrogen systems, risk assessments tend to be over cautious in determining the consequences of accidental releases and could impose restrictive technical regulations. This drove the National Institute if Industrial Environment and Risks (INERIS) along with the French Atomic Energy Commission (CEA), the French automotive manufacturer PSA PEUGEOT CITROËN and the Research Institute on Unstable Phenomena (IRPHE) to submit with success a project called DRIVE to the National Research Agency

The PREV'AIR system, an operational system for large scale air quality forecasts over Europe : applications at the local scale

International audienceSince Summer 2003, the PREV'AIR system has been delivering through the Internet daily air quality forecasts over Europe. This is the visible part of a wider collaborative project - the PREV'AIR project - launched by the French Ministry for Ecology and Sustainable Development (MEDD), aiming at: (1) Providing technical support on atmospheric pollution management in Europe, in the framework of negotiations on trans-boundary air pollution. (2) Providing large scale national air quality information based on numerical simulations and observations. The PREV'AIR system is a complementary monitoring tool with respect to the local information delivered by the French qualified associations in charge of regional air quality monitoring (AASQA). PREV'AIR relies on a chain of numerical tools: air quality simulation models, modules ensuring the provision of meteorological and air quality input data to these models, modules enabling the extraction and use of the numerical data computed by the system. The outputs of the PREV'AIR system (secondary pollutants forecasts and maps) are archived to build up a large scale air quality simulation data base over Europe

Assessment of the models for the estimation of the CO2 releases toxic effects

Currently, INERIS is involved in European and French projects regarding the CCS chain (carbon capture and storage). Nowadays, some people consider this chain as a future device to fight against the global warming due to high concentration of CO2 in the atmosphere. However, in case of massive accidental leak of CO2, this substance could be the origin of toxic effects for human. Now, carbon dioxide concentrations considered as potentially toxic get close to 10 0000 ppm. To estimate precisely the distances reached by this hazardous level of concentrations, an efficient understanding of the CO2 release phenomena, from the assessment of the mass flow rate to the atmospheric dispersion, is necessary. Whereas the carbon dioxide is often stored and handled under 2-phase or supercritical conditions associated to storage pressure, CO2 ice formation is possible in case of accidental leak in the atmosphere due to specific properties regarding its triple point. Then, this CO2 flakes creation may be followed by the liquid/solid CO2 pool formation on the ground. Due to the important pressure drop of the fluid during the leak, a significant expansion phase, a high rate of air entrainment and a huge temperature drop followed by a dense and cold cloud formation should be considered. Concerning these specific points, a few of atmospheric dispersion softwares take into account the carbon dioxide specific conditions of release. And moreover, some calculations carried out with other software seem to provide different results in terms of hazardous distances for instantaneous or continuous releases. A focus on the models used by the softwares appears interesting to let a better understanding of this difference in the risk assessment context

Monitoring multi-paramètres du mouvement de versant des Ruines de Séchilienne (Isère, 38)

Le mouvement de terrain des Ruines de Séchilienne - localisé sur le versant Sud du Mont Sec (38) - fait l'objet depuis 1985, d'une étude approfondie des mouvements observés et potentiels, ainsi que d'une surveillance continue par le CETE de Lyon. Les mécanismes de déformation et rupture en profondeur de ce versant restent encore mal connus, du fait de leur complexité et du manque de données permettant de les appréhender. Pour progresser dans la compréhension de ces mécanismes, l'INERIS contribue depuis2009 aux investigations menées par forages profonds sur le site. Ainsi, un système d'observation multi-paramètres a été installé en bordure Ouest de la zone active, faisant appel à une plateforme technologique intégrée qui combine des mesures microsismiques, géotechniques, hydrologiques, météorologiques et des mesures de déplacement tridimensionnel. Le bilan des mesures fournit des enseignements complémentaires sur les mouvements et déformations en profondeur. Dans la zone d'étude, ceux-ci présentent des orientations différentes de celles observées en surface : les mesures de déplacement en surface (GPSRTK) indiquent un mouvement vers le Sud-est, alors qu'à 40 et 80 m de profondeur, les mesures d'inclinaison montrent un mouvement vers l'Ouest. Les travaux menés en 2010 confirment les bonnes performances et capacités du réseau d'écoute microsismique qui est capable de détecter des événements de faible énergie à plusieurs centaines de mètres de distance. Depuis novembre 2009, près de 200 événements attribués à l'évolution du versant ont été enregistrés, avec un pic d'activité en novembre 2010 qui coïncide avec une accélération des déplacements de surface. L'article décrit la méthodologie mise en oeuvre par l'INERIS pour répondre aux exigences des systèmes d'alerte précoce multi-paramètres, appliqués aux mouvements de versants. Le site d'étude, les principales caractéristiques du dispositif et les données sont présentés. Des considérations sur le calibrage du système et la qualification des données sont décrites

Data for the evaluation of hydrogen risks onboard vehicles : outcomes from the french project DRIVE

International audienceFrom 2006 to 2009, INERIS alongside with CEA, PSA PEUGEOT CITROËN and IRPHE were involved in a project called DRIVE. Its objective was to provide data on the whole reaction chain leading to a hydrogen hazard onboard a vehicle. Out of the three types of leakages identified by the consortium (permeation, chronic and accidental), the chronic leakage taking place within the engine was judged to be more problematic since it can feature a high probability of occurrence and a significant release flow rate (up to 100 NL/min). Ignition tests carried out within a real and dummy engine compartment showed that pressure effects due to an explosion will be relatively modest provided the averaged hydrogen concentration in this area is limited to 10 % vol/vol, which would correspond to a maximum release flow of 10 NL/min. This maximum concentration could be used as a threshold value for detection or as a target while designing the vehicle. Jet fire experiments were also conducted in the frame of the DRIVE project. It was found that pressure-relief devices (PRDs) might be unsuited to protect humans from the explosion of a tank caused by a bonfire. Other solutions are proposed in this paper

Simulation numérique de la condensation / évaporation et de la coagulation des nanoparticules

National audienceAware of the risks related to nanoparticles (particles which present at least one dimension less than 100 nanometers), INERIS decided in 2009 to create a research program in order to develop a model that would be able to simulate the dynamic of nanoparticles in both confined and free atmospheres. The distinction with usual models is that we need to follow the evolution of the number of particles together with their the mass : in order to simulate the evolution of nanoparticles, the number is much more relevant. A comparative review of algorithms currently used in air quality models and new algorithms adapted to nanoparticles is presented. This first study addresses condensational growth, evaporation and coagulation. The model is to be integrated in chemistry-transport models (CHIMERE) and in CFD models (code_Saturne EdF).Conscient des risques liés aux nanoparticules (particules dont au moins une des dimensions est inférieure à 100 nanomètres), l'INERIS(1) a engagé en 2009 un programme de recherche en collaboration avec le CEREA(2) afin de développer un modèle capable de simuler les transformations des nanoparticules dans les ambiances intérieures (espaces confinés) comme dans l'atmosphère. En effet, les nanoparticules sont notamment susceptibles de coaguler, de grossir par condensation, et de se déposer sur les parois; ce qui modifie leur granulométrie. Une des problématiques liée à la modélisation des nanoparticules est que leur nombre est déterminant devant leur masse, tout au contraire des particules étudiées jusqu'à présent (particules fines ou grossières dont une des dimensions est supérieure à 100 nanomètre). Différents schémas numériques ont été développés pour simuler la condensation/évaporation d'une population de particules, et un noyau de coagulation issu d'algorithmes usuels a été intégré. L'inter-comparaison de ces schémas met en évidence que certains sont plus adaptés que d'autres pour les nanoparticules. Les algorithmes qui sont appropriés pour toutes les tailles de particules sont présentés. A terme, ce modèle de dynamique des nanoparticules a vocation à être intégré dans des modèles de dispersion atmosphérique (CHIMERE) et des modèles CFD (code_Saturne EdF

ARAMIS project : Accidental Risk Assessment Methodology for IndustrieS in the framework of SEVESO II directive

International audienceThis paper presents the ARAMIS project accepted for funding in the 5th Framework Programme of the European Commission, which started on January 2002. The ARAMIS project aims at developing a new risk assessment methodology which allows to evaluate the risk level of an industrial plant by taking into account prevention measures against major accidents and the vulnerability of its environment. The methodology will support the harmonised implementation of the SEVESO II Directive. The project is built to result in the composition of an integrated risk index based on the definition of Reference Scenarios and combining the evaluation of: 1. Scenario consequence severity 2. Safety management effectiveness affecting the probability of occurrence of major accidents 3. Environment vulnerability. The methodology will be validated with case studies. Efforts are given to disseminate the methodology to decision-makers in charge of the control of major accident hazards. Thus the project development will be continuously monitored by a review team gathering risk experts from industry and EU competent authorities in order to ensure the widest acceptance of the approach

Investigation of accidents and sharing information : an expert point of view

International audienceFor long, very large accidents occurred in explosive factories. Later, accidents were reported in flour mills (end of 18th Century), in mines (coal dust and firedamp explosions), in chemical plants, during the transportation of dangerous goods such as fertilizers, explosives ... or even with very common substances such as fuels or grain

Case study of sulphur compounds emissions characterization

International audienceIn order to manage the methane and sulphur compounds emissions of a landfill area with deposits of plasterworks, a flux measurements study was conducted with a mobile laboratory, portable analysers and different chambers. The static chamber was first used in order to locate the methane hot spots. The funnel and the Total Reduced Sulphur (TRS) analyser allow the comparison between emissions of methane and hydrogen sulphide which represent the predominant sulphur compound. In a second stage, the variability of the hydrogen sulphide emissions was monitored with two dynamic chambers and a period of several days. Hydrogen sulphide emissions by cap are much lower than those predicted by the methane flux and the concentration of hydrogen sulphide in landfill gas (LFG)