Abstract: Further study of the mechanism and law of salt rock deformation and breakage has great significance for the safety and stability of the gas storage. Based on the triaxial compression test under different confining pressures, a new elastoplastic damage model with improved Mohr-Coulomb criterion is presented in the framework of the irreversible thermodynamics and nonlinear continuum mechanics, which can depict the confining pressure effect, hardening and softening behaviours of salt rock. In this model, the mechanical damage criterion and hardening function highly depend on the stress state. The solution process for the coupled model is studied using finite element method and the corresponding computer code is developed on the ABAQUS solver. The numerical simulation under various stress states shows that the numerical simulations perfectly agree with the experimental data; and the proposed model is able to effectively depict the main features of mechanical behaviors of salt rock.

Key words: salt rock, confining pressure, mechanical model, damage criterion, improved Mohr-Coulomb criterion