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In this paper the macroscopic elastic properties of injected or cemented sands are derived from the characteristics of the constituents and the analysis of the microstructure using a multi‐scale modelling approach. Particular interest is given to the choice of the representative elementary volume, by relying on existing microstructural data. The periodic homogenization is adopted and required numerical solutions are performed by the finite element method. An assessment of the validity of the multi‐scale approach is achieved through comparison with theoretical and experimental results on cemented and injected granular media reported in the literature. The capabilities of the model are also used to investigate the influence of geometrical and mechanical microscale parameters on the macroscopic behaviour of the treated materials. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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Keltoum Chaouche Luc Neppel Claudine Dieulin Nicolas Pujol Bernard Ladouche Eric Martin Dallas Salas Yvan Caballero 《Comptes Rendus Geoscience》2010,342(3):234-243
This study is focused on the western part of the French Mediterranean area, namely the Pyrénées-Orientales and Aude administrative departments. The water resources (surface and groundwater) in the region are sensitive to climate change. The study addresses the question of whether any trend in the annual and monthly series of temperature, rainfall and potential evapotranspiration (PET) already appears at the scale of this region. Two data sources have been used: (a) direct local measurements using the meteorological network; and (b) spatially interpolated data from the French weather service model SAFRAN for the period 1970–2006. The non-parametric Mann–Kendall test was applied to identify significant trends at the local scale and, because of the natural spatial variability of the Mediterranean climate, regional interpretation was also performed. The trends observed in the 13 catchments of interest are consistent with those observed at a larger scale. An increase in annual mean temperature and annual PET was observed throughout the study area, whereas annual precipitation has not exhibited any trend. The monthly scale has revealed strong seasonal variability in trend. The trend for an increase in monthly PET has been observed mainly in the spring, and has not been seen in the coastal areas. A trend for an increase in monthly temperature has been observed in June and in the spring throughout the entire area. Monthly rainfall has been found to decrease in June and increase in November throughout the area. The significant trends observed in rainfall and temperature seem to be consistent between the different data sources. 相似文献
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Michel L. Schlegel Christian Bataillon Keltoum Benhamida Cécile Blanc Denis Menut Jean-Luc Lacour 《Applied Geochemistry》2008
In this study, microscopic and spectroscopic techniques (scanning electron microscopy coupled with energy-dispersive X-ray analysis, Raman microspectroscopy, micro X-ray fluorescence spectroscopy, micro X-ray fine structure adsorption spectroscopy, and micro laser-induced breakdown spectroscopy) were combined to decipher the chemical and mineralogical properties of a saturated Fe–clay interface reacted at 90 °C and 50 bar for 8 months. The results collectively confirm the presence of a corrosion layer and a clay transformation layer. The corrosion layer is made of a magnetite-containing internal sublayer and a Fe-phyllosilicate external sublayer enriched in Na, with traces of goethite presumably resulting from sample reaction with air. The clay transformation layer is made of predominantly Ca-rich siderite (FeCO3). It is depleted in Al and K, suggesting dissolution of rock-forming minerals. The corroded thickness determined from the amount of Fe in corrosion and transformation layers and assuming zero porosity equals 19 ± 9 μm. These data indicate that the interfacial clay was transformed by dissolution of calcite and clay minerals and precipitation of siderite close to the original surface. Silica released upon clay dissolution diffused into the corrosion layer and coprecipitated with oxidized Fe to form Fe-phyllosilicate. 相似文献
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