Reconsolidating salt: Compaction, constitutive modeling, and physical processes

Abstract The proposed use of crushed salt as a functional seal element in the Waste Isolation Pilot Plant (WIPP) shafts has given rise to several technological advances. A large-scale dynamic compaction demonstration using mine-run salt produced a compacted mass having a fractional density of 0.9 and a permeability of 9×10 −14 m 2 . To model evolution of crushed salt from these initial conditions to a high-density, low-permeability seal requires implementation of a suitable constitutive model. Candidate models were evaluated, generalized, and fit to limited data. Refinement of model parameters and definition of the relationship between permeability and density necessitate further experimental work as discussed in this paper. Implementation of a proper constitutive model, inclusion of a reliable permeability/density relationship for reconsolidating crushed salt, and a fundamental understanding of micromechanical processes assure credible design and analyses of the WIPP shaft seal system.