Long-term stability of a lined rock cavern for compressed air energy storage: thermo-mechanical damage modeling

The long-term stability of a lined rock cavern (LRC) for underground compressed air energy storage is investigated using a thermo-mechanical (TM) damage model. The numerical model is implemented in COMSOL Multiphysics, and TM modeling is verified by the existing analytical solution in the case of no damage. The long-term damage and mechanical responses of the lined cavern are presented. Inhomogeneity and a weak plane are added to the numerical models, and their influences on the stability of the LRC are discussed. Results show that long-term damage occurs within 1 m from the cavern surface. Airtight concrete causes the maximum damage, which occurs in the sealing layer, concrete lining, and host rock, whereas polymer causes the least damage. Compared with the purely thermo-elastic model, the TM damage model obtains larger maximum and minimum principal stresses. In the TM model, the stress of the concrete lining increases and the hoop stress of the host rock decreases with the increase in inclination angle of the weak plane. Moreover, as the inhomogeneity increases, the radial stresses of the concrete and host rock decrease. The maximum hoop stress of the concrete lining in one cycle increases, whereas the maximum hoop stress and maximum hoop strain of the host rock decrease.