An Investigation into the Creep Behavior of Rock Salt from Slanic Prahova

The rheological behavior of rock salt, particularly creep deformation, significantly influences the stability of underground mining excavations. This study analyzes salt samples from the Slanic Prahova mine to characterize their rheological behavior and assess long-term excavation stability. Uniaxial compression tests revealed an increasing creep rate with increasing applied stress, following both exponential and power-law relationships. Impurities significantly influence the salt's rheological behavior, with higher NaCl content generally improving deformability. Creep mechanisms are complex, involving dislocation, diffusion, and polygonization processes. The salt from Slanic Prahova exhibits pronounced creep (Category 5), and empirical models better describe the observed behavior than constitutive models based on the theory of heredity. Rheological parameters such as modulus of elasticity, yield stress, creep rate, and creep coefficient, as well as the dilatation threshold, were determined. The mechanical properties of salt exhibit significant variability, with creep being the dominant deformation mechanism. Impurities and crystalline structure significantly influence the rheological behavior. The obtained results enable a more precise evaluation of mining excavation stability and highlight the need for more sophisticated numerical models to capture the non-linear behavior of salt.