This research is motivated by the increasing need for geostorage facilities, mainly: nuclear waste disposals, high-pressure gas reservoirs and carbon dioxide sequestration systems. A new constitutive model is formulated to account for anisotropic damage due to tensile cracks and healing due to Diffusive Mass Transfer (DMT). The damage variable is the difference between the second-order crack density tensor and a scalar viscoplastic healing variable. The viscoplastic healing variable is needed to model the effects of DMT on the reduction of damage-induced deformation. Contrary to the damage and healing models proposed previously for salt rock, the proposed framework accounts for crack-induced anisotropy, and anisotropy is treated in both damage and healing evolution laws. Compression, extension and compression loading and unloading cycles have been simulated with Theta-Stock Finite Element code. The results illustrate well the influence of anisotropic damage on stiffness degradation and residual strain development. An algorithm has also been written to study the trends of the coupled damage and healing model for a stress path comprising an isotropic compression, and axial compression, a healing period and an unloading phase. The results match the theoretical expectations, and show that the proposed model can predict anisotropic damage and healing.
Saving energy resources and reducing carbon emissions can be achieved by resorting to geo-storage, a technique consisting in injecting fluids or disposing solids in the bedrock . Salt cavities are often used to store highpressure gas that can be used to activate turbines at peak hours. Rock salt is also an attractive host rock for deep waste disposals, due to favorable creep characteristics and low gas permeability, which helps ensure containment. However, these same creep properties can induce crack damage in the vicinity of deep cavities and repositories and significantly compromise security.