Abstract: The surrounding rock of a compressed air energy storage (CAES) salt cavern experiences both creep and fatigue during operation. Ensuring the safety of the CAES salt cavern requires studying the mechanical response of salt rock under the combined effect of creep and fatigue. Developing a creep constitutive model that considers cyclic loading and unloading can more accurately predict the long-term stability of the cavern. This paper introduces a fatigue damage body to describe the impact of cyclic loading on the creep characteristics of salt rock. It then integrates this component with an elastic body, Kelvin body, and nonlinear visco-plastic body to propose a new creep-fatigue constitutive model. The model is validated with experimental data, showing good agreement between model predictions and experimental data. The finite difference form of the model is derived and implemented in FLAC3D software for a uniaxial creep simulation experiment. The simulation results for axial strain closely match the experimental data. Finally, a three-dimensional geomechanical model of a domestic CAES salt cavern is established using the proposed creep-fatigue model. The deformation of the salt cavern during long-term operation is analyzed and compared with results from the static Norton Power model, highlighting the differences and improvements provided by the new model.

Key words: creep-fatigue, salt rock, constitutive model, compressed air energy storage (CAES), secondary development