Etude de la localisation de la déformation à l'aide de modèles second gradient

Cette étude explore le comportement des matériaux en régime de post-localisation, elle traite de certains aspects qui doivent être pris en compte dès lors que l'on cherche à modéliser le phénomène de localisation. On ne peut plus se restreindre à trouver une solution à un problème donné, on doit aussi se poser la question de l'existence éventuelle de plusieurs solutions au même problème. En effet, déterminer la solution la plus critique au problème de l'ingénieur peut nécessiter d'explorer différentes solutions. Puis des résultats avec localisation sont présentés pour différents régimes de comportement dans les géomatériaux, régime fragile ou ductile, montrant des similitudes avec les observations expérimentales de laboratoire

The Alestle - Vol. 57 No. 30 - 01/11/2005

Vol. 57 No. 3

MECHANICAL BEHAVIOUR AND RUPTURE IN CLAYEY ROCKS STUDIED BY X-RAY MICRO-TOMOGRAPHY AND 3D-DIGITAL IMAGE CORRELATION

International audienceThe mechanical behaviour and the rupture of clayey rocks have been experimentally studied by performing in situ triaxial tests on a synchrotron beamline i.e. performing X-ray micro tomography scans under mechanical loading. The 3D images obtained at different steps of the test were then analysed by 3D-Digital Image Correlation method in order to measure incremental strain fields. The results allow to clearly detect the onset of shear strain localization and to characterize its development in a 3D complex pattern

A biaxial apparatus for the study of heterogeneous and intermittent strains in granular materials

We present an experimental apparatus specifically designed to investigate the precursors of failure in granular materials. A sample of granular material is placed between a latex membrane and a glass plate. A confining effective pressure is applied by applying vacuum to the sample. Displacement-controlled compression is applied in the vertical direction, while the specimen deforms in plane strain. A Diffusing Wave Spectroscopy visualization setup gives access to the measurement of deformations near the glass plate. After describing the different parts of this experimental setup, we present a demonstration experiment where extremely small (of order $10^{-5}$) heterogeneous strains are measured during the loading process

Experimental characterisation of (localised) Deformation Phenomena in Granular Geomaterials from Sample Down to Inter-and Intra-grain Scales

AbstractThis paper outlines some recent advances in the full-field experimental characterisation of the mechanics of granular geomaterials (in particular, sands) using a range of methods that provide characterisation at different scales, from the sample-scale down to the inter- and intra-grain scale. The techniques used are “full-field” approaches involving in-situ x-ray micro-tomography, 3D-volumetric digital image analysis/correlation and grain ID-tracking, in-situ 3D x-ray diffraction and in-situ, spatially-resolved neutron diffraction. These methods provide new data on the mechanics of sand at different scales, including continuum measures of strain, porosity, and fabric plus discrete measures of particle kinematics and force transmission. The results of such measurements might be used to advance higher-order continuum theories, and provide the necessary input parameters, or to calibrate discrete grain-scale simulations of sand behaviour to explore loading paths that are inaccessible in the laboratory

Caractérisation expérimentale de la déformation et de la rupture localisée dans une argilite

Nous présentons une étude expérimentale de caractérisation de la rupture par localisation de la déformation dans une roche argileuse. Des essais triaxiaux ont été effectués sur une ligne de lumière de l'ESRF pour obtenir des reconstructions microtomographiques en volume à différents stades de l'essai. Une mesure du champ de la déformation a été faite en associant aux images obtenues une méthode de corrélation d'images en volume. Ces résultats permettent d'identifier très clairement le seuil d'initiation de la localisation, et le mode de déformation dans les bandes

Analisis Integrasi Padi Ikan Dalam Perspektif Agro Ekonomi

This study aimed to obtain information integration rice fish viewed from the perspective of agroeconomics. This study is motivated by the growth rate of rice production which likely to decline, decline in soil fertility due to continuous intensification. The method used was a survey method by taking the case of rice - fish farming in Solokan Jeruk District Bandung Regency West Java Province. Purposive sampling is used in this research. The expected benefit is to increase rice production, fish seed supply, income and welfare of farmers and the development of efficient utilization of paddy fields. The results showed the integration of fish rice as seen as agro-economic was positively gave the benefit for both farmers and for agricultural land itself. Keywords: rice, agro-econom

Experimental Investigation of the Emergence of Strain Localization in Geomaterials

International audienc