Experimental study on short-term creep crack evolution and acoustic emission characteristics of salt rock after heat treatment at different temperatures

The construction of salt cavern storage engineering is an important national strategic requirement in China. However, temperature has always been an important factor affecting the creep deformation of the surrounding rock of salt cavern storage. So, the influence of temperature on the creep damage behavior of salt rock was studied through indoor experiments, and the crack evolution and acoustic emission (AE) characteristics during the creep process were discussed. Firstly, the research results indicate that a high temperature of 200 ℃ causes thermal damage to salt rock, while a high temperature of 100 ℃ enhances the self-healing ability of salt rock. Secondly, the IET function curves based on AE rate-process theory during the creep process can be divided into four obvious stages. Thirdly, during the entire creep process, the probability of low-energy AE events at 200 ℃ is the highest, followed by 25 ℃, and lowest at 100 ℃. This result is similar to the occurrence of AEs, that is, the probability of high amplitude AEs occurring at 200 ℃ is lowest, followed by 25 ℃ and the highest at 100 ℃. Fourthly, the proportion of tensile cracks during the creep process of salt rock exceeds 70%, and the proportion of tensile cracks is highest at 25 ℃, followed by 200 ℃, and lowest at 100 ℃. Finally, a nonlinear viscoelastic-plastic creep model considering damage was constructed and validated. This research work plays an important role in the stability assessment and prediction of deep salt cavern storage engineering.