Creep properties and constitutive model of salt rocks under a slow cyclic loading path

The construction of compressed-air energy storage (CAES) plants using the huge space created by salt rock mining is a key means of optimizing China's energy structure. The creep properties of salt rock are vital parameters for ensuring the long-term, stable operation of CAES plants. According to the operation mode of CAES plants, creep tests were conducted on salt rock under the influence of slow loading and unloading. The results indicated that the slow loading and unloading history locally changed the creep development process but did not affect the overall creep process. Additionally, the steady state creep rate of the salt rock depended mainly on the magnitude of external stress. Moreover, the creep test was monitored simultaneously using acoustic emission (AE) technology, and the distribution of the AE absolute energy during the initial loading phase and steady state creep phase satisfied the power law. To more accurately describe the creep characteristics of the salt rock under the influence of slow loading and unloading, a full-process creep constitutive model of salt rock was constructed using state variable, fracture expansion factor, and unloading factor.