Stability analysis of a compressed air energy storage cavern transformed from a horseshoe‐shaped roadway in an abandoned coal mine

Abstract Compressed air energy storage (CAES) caverns transformed from horseshoe‐shaped roadways in abandoned coal mines still face unclear mechanisms of force transfer, especially in the presence of initial damage in the surrounding rock. The shape and size of the initial damage area as well as their effect on cavern stability remain unclear. Due to the complex geometry and multiphysical couplings, traditional numerical algorithms encounter problems of nonconvergence and low accuracy. These challenges can be addressed through numerical simulations with robust convergence and high accuracy. In this study, the damage area shapes of a CAES cavern are first computed using the concept of damage levels. Then, an iteration algorithm is improved using the generalization α method through the error control and one‐way coupling loop for fully coupling equations. Finally, the stability of the CAES cavern with different damage zone shapes is numerically simulated in the thermodynamic process. It is found that this improved algorithm can greatly enhance numerical convergence and accuracy. The nonuniformity of the elastic modulus has a significant impact on the mechanical responses of the CAES cavern. The cavern shape with different damage zones has significant impacts on cavern stability. The initial damage area can delay the responses of temperature and stress. It induces variations of temperature in the range of approximately 1.2 m and variations of stress in the range of 1.5 m from the damage area.