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Plasticité et endommagement des roches ductiles. Application au sel gemme

Abstract : Elastoplastic short term behaviour and damage mechanisms of rocksalt are studied experimentally and theoretically. Review of previous works on rocksalt deformation mechanisms shows the role of different physical factors on ductile or brittle behaviour of rocksalt. Mechanical properties of salt are compared with those of other geomaterials. Experimental methods for identification of geomaterial damage are reviewed. Compression and extension axisymmetric triaxial tests are performed. Volume change measurements are carried out during the tests. Under deviatoric loading, volumetric strain denotes the material damage state, especially damage initiation. Variation of elastic parameters is analysed. It is small, and it is not taken into account in the constitutive law. A simple analysis of internal stresses using a self-consistent model allows to explain that damage appears earlier under extension loading than under compression. Kinematic and isotropic hardenings are then discussed. An elastic-plastic model is proposed. It considers isotropic hardening and non associated flow rule with plastic distortion as a hardening parameter. Model parameters are fitted on the basis of experimental results related to the evolution of dilatancy angle. A 3D generalisation (using three invariants of stress tensor) is proposed. The constitutive model takes into account behaviour difference between extension and compression loadings. An application to circular cavities is given.
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Submitted on : Wednesday, November 3, 2010 - 6:20:45 PM
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  • HAL Id : tel-00529724, version 1

Citation

Luc Thorel. Plasticité et endommagement des roches ductiles. Application au sel gemme. Géologie appliquée. Ecole Nationale des Ponts et Chaussées, 1994. Français. ⟨tel-00529724⟩

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