Portail des publications scientifiques IMT Mines Alès
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Le concept objet et la modelisation geometrique. Application a la modelisation d'environnement geologique
No full textInternational audienceIn geology and especially when attempting to model the subsurface, the problem of geometric modelling becomes a crucial one. The variety of the geological domain is linked to its very nature. This variety and the imprecision inherent to geological objects increase the complexity of the modelling systems used to represent a geological site. In order to model a geological site, a hierarchical structuration of knowledge is required. Information is then organised around a same entity of data: the "frame'. By simulating a geological site, we give an example of the use of geometric objects in a geological environment
Le concept objet et la modélisation géométrique. Application à la modélisation d'environnement géologique
No full textArticle disponible en texte intégral sur le site e-periodica de la Bibliothèque de l’ETH de Zurich: https://www.e-periodica.ch/digbib/view?pid=bsv-002%3A1990%3A80%3A%3A17#106National audienc
Application combinée de l’analyse structurale, de la géostatistique et de la théorie des blocs clés à l’étude des problèmes de stabilité et de confortement des travaux miniers
No full textInternational audienceThe study presented in this paper aims at the setting up of a methodology which allows the design of mining works, underground or otherwise, taking into account the geological structure of rock masses in which they are located. Three stages of this methodology are presented: the determination of statistical and geostatistical characteristics of the population of fractures; the generation of a field of fractures, with given statistical characteristics, by simulation; the study of the stability of isolated blocks defined by these fractures, by means of the key-block theory. Following the processing of this structural data, rules of action, concerning the conception and execution of the planned structure, will be drawn up.L'étude présentée ici vise la mise en place d'une méthodologie qui permette le dimensionnement d'ouvrages miniers, souterrains ou non, en fonction de la structure géologique du massif rocheux dans lequel ils se trouvent.Trois étapes de cette méthodologie sont exposées sucessivement : – la détermination des caractéristiques statistiques et géostatistiques des populations de fractures ; – la génération, par simulation, d'un champ de fractures de caractéristiques statistiques données ; – l’étude de la stabilité de blocs isolés, définis par ces fractures ; ceci grâce à la théorie des blocs clés.A la suite de cette chaîne de traitement des données structurales, des règles d’action devront être tirées, concernant la conception et l'exécution des ouvrages à réaliser
Optimization software for haulage in surface mining operations
No full textInternational audienceLoading and transport represent quite often the bulk of the extraction cost of surface mining. It is therefore essential to optimize these two operations. For this purpose, this article presents an interactive software of computation which can be utilized to calculate the size of a fleet of vehicles, i.e. to check the performance of a given fleet and to determine the optimum job assignments of the equipment. The architecture of this software is first explained. This is followed by emphasizing some of its features. In particular, the software effects a simulation of the operations of loading and of transport, and a calculation of the haulage times, based on the performance curves of the trucks. The program also makes use of a data base of the plant. An example is presented for the application of the program
An expert-system for the computer-assisted selection of bacterial strains for bioconversions
No full textInternational audienceWe present a rationale for building an expert system for the selection of bacterial strains for bioconversions; the main rule we use is the resemblance rule; this, in association with a data base including a thousand bioconversions, has been tested on steroids and has given good predictions in more than 70% of the cases we have tested
A Statistical Model Of Macroscopic Failure Under Compression
No full textInternational audienceThe behaviour of rocks during compression failure is characterized by the progressive development of axial microcracks. A schematic model in which the heterogeneousness of the microstructure of a rock is simulated by a statistical distribution of fracture energy is proposed. It provides elements for the interpretation of complete stress-strain curves for rocks of Class I
An energy approach to room and pillar exploitations based on post-failure behaviour of pillars
No full textInternational audienceAn energy approach to room and pillar exploitations is proposed by modelling the mechanical behaviour of pillars by a four-parameter model: Young's modulus, compressive strength, negative yield modulus and residual strength. Calculating the mechanical energy of the system leads to the definition of global stability conditions. When a critical extraction ratio is reached, the result is a global instability of the whole exploitation. This phenomenon probably constitutes one of the likely initiating mechanisms of rock burst
Paléomagnétisme et datation du volcanisme permien, triasique et crétacé du Maroc
No full textInternational audiencePaleomagnetism and K–Ar dating of Permian, Triassic, and Cretaceous rocks from Morocco. We have sampled and studied volcanic rocks from the whole of Morocco. Permo-Carboniferous rocks give a magnetic pole situated at 36°N and 238°E (four sites, K = 23, A 95 = 20°). Triassic dolerites dated on plagioclases from 205–180 Ma have a mean pole at 72°N, 218°E (34 sites, K = 17, A 95 = 6°). Middle Jurassic and Lower Cretaceous basalts and dolentes from l'Atlas de Beni Mellal (ages from 170–120 Ma) have a pole at 45°N and 251°E (13 sites, K = 26, A 95 = 8°).The results may be interpreted by clockwise rotation within Morocco. We compare them also with those from other continents.Nous avons prélevé et étudié des échantillons volcaniques répartis sur tout le Maroc. Les formations permo-carbonifères donnent un pôle magnétique situé par 36°N, 238°E (quatre sites : K = 23, A9S = 20°). Les dolérites triasiques datées sur plagioclases de 205–180 Ma donnent un pôle moyen situé par 72°N, 218°E (34 sites, K = 17, A95 = 6°). Les basaltes et dolérites du Jurassique moyen-Crétacé inférieur de l'Atlas de Béni Mellal (âges de 170–120 Ma) ont un pôle situé par 45°N, 251°E(13 sites, K = 26, A95 = 8°).Les résultats peuvent être interprétés par des rotations locales de sens horaire au Maroc. On fait également une comparaison avec les résultats des autres continents