Insights into Thermal Strain Mismatch-Induced Interlayer Load Redistribution in the Bearing Mechanism of a Lined Rock Cavern for Compressed Air Energy Storage

The coupled thermo-mechanical response of a refined lined rock cavern (LRC) model for a real compressed air energy storage (CAES) plant is numerically investigated. The simulation captures inelastic mechanical behaviors of the steel liner, stiffening rings, concrete lining, and surrounding rock during cyclic charging (high temperature and pressure) and discharging (low temperature and pressure) operations. A key challenge is identified that the tensile stress in the reinforcement reaches 477.2 MPa during the high-temperature and high-pressure stage, while that in the steel liner reaches 350.5 MPa during the low-temperature and low-pressure stage, because cooling shrinkage significantly increases the elastic strain in the steel liner of a multilayer LRC. This phenomenon means that the elastic strain is relatively smaller during the charging stage although the total strain is large because of the high fraction of steel thermal expansion. This interlayer load redistribution in the bearing mechanism is attributed to thermal strain mismatch. To overcome this lining design challenge, the selection of plant sites with a horizontal in-situ stress coefficient between 1.0 and 2.9 is recommended. The tensile stresses in the reinforcement and steel liner can be reduced to 274.8 MPa and 186.9 MPa, respectively.