Research on Stability of Carbon Fiber Lining for Artificial Caverns with Compressed Air Energy Storage

Compressed air energy storage is a large-capacity, long-term physical energy storage technology. With the advantages of safety, environmental protection and long life, it is moving from demonstration to large-scale commercial application driven by policy support and global energy transformation. Aiming at the problem of structural stability of underground caverns in CAES, the existing research mostly focuses on the mechanical response of unreinforced lining under cyclic internal pressure and in-situ stress field. However, there is a lack of systematic comparative analysis on the long-term dynamic stability of lining reinforced with carbon fiber-reinforced polymer under different cavern burial depths, cavern radii and surrounding rock grades. In this paper, an analysis model considering elastic–plastic mechanical behavior and stability theory is established, and the improvement effect of CFRP reinforcement on the mechanical properties of a cavern lining is systematically evaluated. Firstly, based on the complex variable function method and elastic–plastic theory, the analytical solutions of stress-displacement field of surrounding rock-lining structure under reinforced and unreinforced conditions are derived, respectively. By introducing the CFRP constraint effect, the correction formula of the maximum allowable cyclic internal pressure amplitude to maintain the dynamic stability of the structure is proposed. The accuracy of the numerical simulation is verified by the theoretical model. The results of a parameter sensitivity analysis show that the buried depth of the cavern, the grade of the surrounding rock and the radius of the cavern are the key factors affecting the static stability and dynamic stability of the structure. Compared with the unreinforced condition, CFRP reinforcement reduces the displacement and modifies the stress field of the lining under unfavorable geological conditions. Furthermore, the ratio of in-situ stress to internal pressure considering the reinforcement effect is proposed as a dimensionless evaluation index for cavern layout optimization. The research results provide a theoretical basis and engineering guidance for lining selection and reinforcement design of CAES underground caverns under high stress and complex geological conditions. The present study is based on several idealizations, including a constant thermal condition, perfect interface bonding, and a zero-relaxation excavation-support sequence. These assumptions define the scope of the present mechanical analysis and should be validated in future work.