Experimental Test of the validity of "Isotropic" Approximation for the Mechanical Behaviour of Clay

P. Evesque: Lab MSSM, UMR 8579 CNRS, Ecole Centrale Paris, 92295 Châtenay-Malabry, France, evesque@mssmat.ecp.fr

M. Hattab : LPMM/ISGMP,UMR 7554 CNRS, Université de Metz, île de Saulcy, 57045 METZ cedex 01, France, hattab@lpmm.univ-metz.fr

Abstract: Experimental data from axially symmetric compression test at constant mean pressure p=(s₁+s₂+s₃)/3 on kaolinite clay are used to study the validity of an "isotropic" modelling as a function of the over-consolidation ratio (OCR).The isotropic assumption is found to be quite good for 2<OCR<3 and/or in the range of small deformation for OCR>4. For very large OCR (OCR >10), anisotropic response is observed at few percents axial deformation. Relation with anisotropic distribution of local force is made.

Pacs # : 5.40 ; 45.70 ; 62.20 ; 83.70.Fn

poudres & grains 12 (1), 5-10 (février 2001)