Numerical study on accumulative damage characteristics of underground rock caverns for compressed air energy storage

The accumulative damage effects in the surrounding rock of underground caverns for compressed air energy storage (CAES) are obvious in cyclic operation cases. In order to explore the cumulative damage characteristics of the surrounding rock of large-scale rock caverns, based on the damaged theory and FLAC^3D software platform, a routine is developed for the cumulative damaged analysis of the large-scale CAES rock caverns under periodically loading and unloading conditions and validated by a given example. On this basis, the influences of cross-section type of caverns, buried depth and the minimum operating pressure on the cumulative damage characteristics of the surrounding rock are analyzed. The results show that: (1) The cross-section type of cavern, buried depth and the minimum operating pressure are the factors significantly influencing the deformation analysis parameters of the surrounding rock, and the damaged depth in vertical direction is greater than that in horizontal direction. (2) The damage degree of deformation parameters and damage variables of the surrounding rock in damage zone decrease with the increase of the buried depth or the minimum operating pressure. (3) For the cavern with the same cross-section, the difference of damage variables and deformation parameters at the same location in the damage zone of the surrounding rock increases with the numbers of cycles both in the conditions of different burial depths and minimum operation pressures. The accumulative damage characteristics of the surrounding rock of large-scale underground caverns can not be ignored for comprehensive analysis of safety and stability of underground caverns for CAES.