Micro-macro approach for the rock salt behaviour

Rock salt is considered as a pure aggregate of halite (mineral NaCl) crysta ls and its behaviour is investigated by a micro-macro approach. The behavio ur of the polycrystalline aggregate is deduced from the properties of the c onstituent halite crystals. A model For the elastoplastic behaviour ui hali te crystal has been deduced from experimental data available in the literat ure. The basic equations of the micro-macro model for the polycrystalline m edium and the calculation method are then presented and the elastoplastic b ehaviour of rock salt is investigated by this method. The hardening effects obtained for the polycrystal are found to be very different from those obt ained for FCC metal polycrystals. The differences are explained as a conseq uence of differences of families of glide systems in these crystals. Finall y, the internal stresses in the polycrystal are studied in order to elucida te the origin of cracking and damage of the rock salt. (C) 2000 Editions sc ientifiques et medicales Elsevier SAS.