Modelling long-term behaviour of a natural gypsum rock

The model has a limited number of parameters, all accessible from standard laboratory tests. Its description was completed by the procedure of the parameters identification. Then, the predictions of the model have been compared with laboratory results and a good concordance has been found with laboratory data during the first stages of creep. Some discrepancies at the very late stages of the creep are explained by a damage of the rock during the creep. Accordingly, an extension of the model has been proposed that takes into account this damage. Consequently, the extended model fits better laboratory results and allows describing of the accelerated creep.