Abstract: The construction of compressed air energy storage power stations in salt caverns is one of the important means to solve the problem of wind/solar energy generation, grid connection and grid peak regulation. In recent years, in order to make full use of the bedded salt formations in China, the option of building horizontal caverns has been proposed. However, horizontal caverns bring us not only more cavern space but also larger roofs, which may become a gas leakage channel due to deformation, failure and even cracking. In this study, the argillaceous anhydrite layer above bedded salt formations is identified as the key roof which controls the stability of horizontal cavern, and its stress state and possible types of instability are analyzed. Additionally, based on the linear planning method, a feasible range of internal pressures and the depths of the cavern for compressed air energy storage are determined. Finally, stability and influent factors are analyzed in detail by numerical simulation. The results reveal that (1) the maximum operating internal pressure is the main determinant of the stability of key roof. The maximum internal pressure should be less than 75% of the original gravitational stress, but not less than 60%. (2) The increase of the cavern dimensions will enlarge the displacement and plastic zone of the key roof, and change the volume shrinkage of the cavern, which requires comprehensive optimization. (3) Increasing the thickness of the protective salt layer can reduce the subsidence and the plastic zone volume of the key roof but increase the volume shrinkage, which is also not conducive to the full utilization of bedded salt resources.

Key words: bedded salt formations, compressed air energy storage, horizontal cavern, key roof, stability