Thermo-Mechanical Analytical Solution and Parametric Sensitivity Analysis of a CAES Prestressed-Lined Rock Cavern

Abstract: Underground compressed air energy storage (CAES) caverns are subjected to severe cyclic thermo-mechanical coupling loads during operation, making traditional lining structures prone to hoop tensile failure. To actively regulate the stress state of the lining, this paper introduces the concept of a prestressed lining into CAES caverns. Based on thermoelasticity and multi-layered thick-walled cylinder theory, an analytical solution for the mechanical response of a prestressed lined cavern under thermo-mechanical coupling was derived. Complete distribution patterns of the temperature field, stress field, and displacement field were obtained. The rationality of the model was verified through numerical simulations using COMSOL Multiphysics. The research indicates that prestressing can significantly improve the hoop stress state of the lining. Under high internal pressure, the hoop stress in both the steel liner and the inner wall of the concrete lining transitions from tension to compression. However, this also leads to a corresponding increase in the hoop tensile stress and radial displacement at the inner wall of the surrounding rock, indicating a partial transfer of load to the surrounding rock. Hoop stress is significantly affected by thermo-mechanical coupling, under high pressure, thermal stress is dominant (accounting for 94.16% to 168%) and effectively counteracts the mechanical tensile stress. Radial stress, on the other hand, is consistently dominated by mechanical loading (accounting for over 95%), with thermal effects being negligible. Radial deformation is primarily caused by mechanical loading, with thermal displacement contributing a relatively low proportion. Parameter sensitivity analysis shows that the hoop stress at key interfaces of the steel liner and concrete lining is mainly controlled by in-situ stress, the elastic modulus of the surrounding rock, the prestress level, the cavern radius, and the maximum internal pressure. The influence of the surrounding rock's Poisson's ratio is relatively minor. The effects of lining thickness, steel liner thickness, and the elastic modulus of the concrete on the hoop stress are generally insignificant.