Abstract: Compressed air energy storage (CAES) is a key technology for the consumption of renewable energy and peak shaving of power grid. Artificial cavern gas storage has promising application prospects because it is less constrained by site selection and offers better controllability of construction quality. However, the lining and surrounding rock are subjected to significant tensile stress during high-pressure operation. When the maximum tensile stress exceeds the material’s critical strength, tensile failure occurs. To address this issue, the reinforcement ratio of the lining must usually be increased, or the chamber size and storage pressure must be reduced. However, these measures increase construction costs and limit storage capacity. In this study, an optimized structure is proposed in which the lining is placed inside the sealing layer. From the inside outward, the structure consists of the lining, sealing layer, leveling layer, initial support, and surrounding rock. Numerical simulations and analyses are conducted based on a thermo-mechanical coupling model. The results show that the sealing layer temperature in the optimized structure is significantly lower than that in the traditional structure because of the protective effect of the lining. When using steel plate as the sealing material, the maximum temperature is reduced by 46.08%. In terms of stress, the entire lining structure is subjected to circumferential tension and radial compression. After structural optimization, the maximum tensile stresses in the sealing layer, concrete lining, and surrounding rock are reduced by 16.00%, 28.19%, and 24.73%, respectively. Furthermore, the load-sharing results show that more than 70% of the pressure is borne by the surrounding rock in both structures. In terms of deformation, the maximum displacement occurs at the top of the lining. The overall displacement variation of the optimized structure is relatively small. Further analysis examines the lining structure’s mechanical response under high, medium, and low in situ stress levels. Compared with the traditional structure, the optimized structure reduces the sealing layer’s maximum first principal stress by 40.26%, 32.01%, and 22.46% under high, medium, and low in situ stress levels, respectively. This reduction demonstrates the optimized structure’s effectiveness in mitigating circumferential tensile stress in the sealing layer. Surrounding rock grade and deformation modulus significantly influence the structure’s mechanical response. For gas storage sites, surrounding rock of Grade III or higher is selected. Moreover, the mechanical properties of four kinds of sealing layer materials are compared. The steel plate and fiber-reinforced plastic (FRP) are subjected to circumferential tension and radial compression, whereas flexible concrete and rubber are in compression. Steel plate is recommended for traditional structure, whereas flexible concrete is recommended as the sealing material for optimized structure, because it minimizes stress and deformation in the surrounding rock. In summary, for artificial cavern gas storage, the optimized structure proposed in this study is more conducive to structural stability than the traditional structure. The findings provide valuable guidance for the design of artificial cavern lining structures in compressed air energy storage applications.

Key words: compressed air energy storage, artificial cavern, lining structure, combined bearing of lining and surrounding rock, design optimization