Objective During the operation of a salt cavern used for compressed air energy storage, the surrounding rock is subjected to cyclic pressure fluctuations over a prolonged period. These fluctuations tend to induce irreversible deformation, energy dissipation, and cumulative fatigue damage, thereby impairing the long-term stability of the storage cavern. An experimental study involving uniaxial cyclic loading-unloading tests is conducted to reveal the effects of loading rate on the cyclic mechanical response, energy evolution, and accumulation of low-cycle fatigue damage in salt rock.

Methods Salt rock from the Feicheng Salt Mine in Tai’an, Shandong Province, China, is investigated. Uniaxial compression tests are conducted to determine the compressive strength of the salt rock. The lower and upper cyclic stress limits are set at 20％ and 80％ of the mean compressive strength, respectively. Three cyclic loading–unloading rates are applied: 0.25 kN/s, 0.50 kN/s, and 1.00 kN/s. Sixty loading–unloading cycles are performed at each rate. The total input energy, elastic strain energy, and dissipated energy for each cycle are derived from the stress–strain curves. Their evolution patterns are then analyzed. A damage variable is defined using dissipated energy, and an energy-driven damage evolution model is formulated.

Results The stress–strain curves of salt rock exhibit pronounced hysteresis at all loading rates, accompanied by residual strain accumulation. These features indicate irreversible deformation and energy dissipation in the specimens. During the initial cycles, the total input energy per cycle and dissipated energy per cycle decrease rapidly, whereas the elastic strain energy per cycle gradually increases. All energy parameters then tend to stabilize. Both cumulative total energy and cumulative elastic strain energy increase approximately linearly with the number of cycles, with only small differences among the loading rates. In contrast, cumulative dissipated energy shows a stronger dependence on loading rate. For a given number of cycles, cumulative dissipated energy was found to decrease with increasing load rate. The damage variable defined using dissipated energy captures the nonlinear progression of low-cycle fatigue damage in salt rock from rapid growth through steady accumulation to late-stage acceleration.

Conclusion Loading rate significantly affects the accumulation of dissipated energy and the evolution of low-cycle fatigue damage in salt rock during cyclic loading and unloading. Lower loading rates are more conducive to internal structural adjustment and the development of irreversible damage. The energy-driven damage evolution model shows good agreement with the test results. It can serve as a reference for future studies on damage evolution in salt rock under triaxial cyclic loading-unloading and cyclic loading-creep coupling conditions.