ABSTRACT
The constitutive model used to describe the deformation of crushed salt is presented. Two mechanisms — dislocation creep and grain boundary diffusional pressure solution — are combined to form the basis for the constitutive model governing the deformation. The constitutive model is generalized to represent three-dimensional states of stress. Upon complete consolidation, the crushed-salt model reproduces the multimechanism deformation (M-D) model typically used for the Waste Isolation Pilot Plant (WIPP) host geological formation salt. Parameter values are determined through nonlinear least-squares model fitting to an experimental database. Using the fitted parameter values, the constitutive model is validated against constant strain-rate tests. Shaft seal problems are analyzed to demonstrate model-predicted consolidation of the shaft seal crushed-salt component. Based on the fitting statistics, the ability of the model to predict the test data, and the ability of the model to predict load paths and test data outside of the fitted database, the model appears to capture the creep consolidation behavior of crushed salt reasonably well.
