0.36 KN/s, 1 KN/s, 3 KN/s, 5 KN/s, 7 KN/s, and 10 KN/s. The fatigue properties of the salt rock samples are shown in Table 1. Although the fatigue life changes very little as the loading speed changes, there is a relation between the three stages of fatigue damage (the decelerating, uniform, and accelerating phases) [15] and the loading speed. The percentage of each of the three stages changes notably with the change in loading speed. As the loading speed drops, the percentage of the decelerating damage phase and the uniform damage phase decreases while the percentage of the accelerating damage phase increases. Moreover, when the loading speed is reduced, the damage in each cycle propagates much more in all the phases; however, in the accelerating damage phase, the damage is controlled by the crack propagation. Crack propagation is enhanced with increasing loading speed, as shown by Wan [16]; hence, in the accelerating damage stage, the damage increases with increasing loading speed.