6 research outputs found

    Fuzzy Reasoning for the analysis of risks in geotechnical engineering Application to a French Case

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    The analysis of risks induced by unstable cliffs is one of the major and important tasks in geotechnieal engineering, This analysis should take into account the fact that some engineering parameters that are necessary for any risk analysts around unstable eliffs are difficult to be quantified and/or they are vague and imprecise. That is why such risk analysis should depend meagerly on the experience of the geotechnical engineer in charge for measurements

    Computer Simulation and Risk Analysis around Abandoned Underground Excavations Application to a French Case

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    International audienceThe Analysis of risks induced by Underground opening or unstable eliffs is one of the major and important tasks in earth science engineering. This analysis should take into account the effect of randomness, it should account also for the probability distributions of different parameters, and above all, the experience of the geotechnical engmeer

    Paramètres d'affaissement pour la hierarchisation des zones à risque dans le bassin ferrifère lorrain

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    International audienceThe consequences of mining collapse on the frame and the infrastructures of surface are directly related to the parameters of subsidence (vertical amplitude, horizontal strain, ..). These parameters are specific to each field even each site. They depend on the nature and the structure of the grounds. In the Lorraine iron-bearing basin, the effects on the surface induced by collapse of mine era by rooms and pillars abandoned are known for 18 cases. The main objective of this research is to determine, by back analysis of subsidence cases due to mining removal of pit props or collapse, the parameters specific to the Lorraine iron-bearing basin in order to use them for the prediction of depressions in zones at the risk of progressive collapse. A comparison of the effects induced by the mining effect with those due to collapses was also carried out. Within the framework of the study, we conform that the cases of subsidence and collapse are very similar. We present, the methodology of back analyzes used to determine subsidence parameters, individually. We describe then, starting from the results obtained, the subsidence parameters of the basin thus determined according to the configuration mining.Les conséquences d'un effondrement minier sur le bâti et les infrastructures de surface sont directement liées aux paramètres d'affaissement (amplitude, déformation...). Ces paramètres sont propres à chaque bassin minier voire chaque site. Ils dépendent de la nature et de la structure des terrains de recouvrement. Dans le bassin ferrifère lorrain, les effets en surface induits par l'effondrement d'exploitations par chambres et piliers abandonnés sont connus pour 18 cas. L'objectif de cette recherche est de déterminer, par le biais d'une rétro-analyse des cas d'affaissements dus à l'exploitation par dépilage ou d'effondrements miniers, les paramètres propres au bassin ferrifère lorrain afin de les utiliser pour la prédiction des affaissements dans des zones à risque d'effondrement progressif". Une comparaison des effets induits par le dépilage à ceux dus aux effondrements a également été réalisée. Dans le cadre de l'étude, nous avons pu exploiter 18 cas d'affaissement ou d'effondrement. Nous présentons, la méthodologie de rétro-analyse utilisée pour déterminer les paramètres d'affaissement, cas par cas. Nous décrivons ensuite, à partir des résultats obtenus, les paramètres de la cuvette d'affaissement ainsi déterminés en fonction de la configuration de l'exploitation

    Towards the determination of surface collapse type over abandoned mines in the Lorraine iron basin

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    Surface collapse is a major problem that follows many active or abandoned underground workings. Collapses result from roof deformation of underground workings, and/or controlled or uncontrolled rock caving. The uncontrolled rock caving could result in surface instability problem and loss of materials and/or human life. Over the past 90 years, ans as a result of underground-uncontrolled rock caving, 16 major accidents "surface collapse" has been reported in the French Lorraine iron basin

    A simplified approach to directly consider intact rock anisotropy in Hoek–Brown failure criterion

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    Many rock types have naturally occurring inherent anisotropic planes, such as bedding planes, foliation, or flow structures. Such characteristic induces directional features and anisotropy in rocks' strength and deformational properties. The Hoek–Brown (H–B) failure criterion is an empirical strength criterion widely applied to rock mechanics and engineering. A direct modification to H–B failure criterion to account for rock anisotropy is considered as the base of the research. Such modification introduced a new definition of the anisotropy as direct parameter named the anisotropic parameter (Kβ). However, the computation of this parameter takes much experimental work and cannot be calculated in a simple way. The aim of this paper is to study the trend of the relation between the degree of anisotropy (Rc) and the minimum value of anisotropic parameter (Kmin), and to predict the Kmin directly from the uniaxial compression tests instead of triaxial tests, and also to decrease the amount of experimental work