Study on Creep Properties of Mudstone Interlayer in Bedded Salt Rock Energy Storage

With regard to the current creep characteristics of mudstone intercalation in the surrounding rock of layered salt rock energy storage, combined with acoustic emission technology, the multi-step creep mechanical behavior of mudstone interlayer was studied. And the damage characteristics from initial loading to stable creep under different stress levels are analyzed. The results show that at low-stress levels, the axial deformation of the interlayer is greater than the lateral deformation. As the increase of the stress level, the lateral deformation becomes more significant, and the corresponding axial and lateral steady-state creep rates both exhibit nonlinear acceleration with the increase of the loading stress. In the initial loading stage of each stress level, the mudstone interlayer releases a large number of AE signals. After the creep stabilization, the AE signals decreased obviously, and a large number of AE signals were released at the last stress level. The improved fractional viscoelastic-plastic model and Nishihara model are used to fit and compare the results of theoretical and experimental creep curves. The fitting results show that the improved creep equation curve is more consistent with the evolution law of the experimental curve. The research results reflected the creep law of mudstone interlayer to a certain extent.