Mechanical properties of rubber sealing material in lined rock cavern for compressed air energy storage considering thermo-mechanical coupling effect

Polymer rubber are considered viable sealing materials for lined rock caverns (LRC) in compressed air energy storage (CAES) systems. However, the mechanical stability and long-term durability of the rubber sealing layer are substantially impacted by the air temperature and pressure within the cavern. In this study, a hyperelastic damage constitutive model was proposed to characterize the mechanical behavior of the rubber sealing layer. Aging and mechanical experiments were conducted to investigate the uniaxial tensile and cyclic loading characteristics of aged and unaged rubber samples, along with the microscopic damage behavior. Based on the stress- strain curve from uniaxial tensile tests and load-displacement curve obtained from cyclic loading tests, the parameters of the rubber constitutive model for damaged and undamaged rubber were determined using the inverse analysis method. Additionally, temperature and pressure within the cavern, along with stress on the structural layers, were compared and analyzed via numerical simulation when using steel and rubber as sealing layers for the LRC. The long-term evolution of stress, strain, displacement, and damage state in the rubber sealing layer was evaluated under three conditions: no damage, pressure-induced damage, and coupled pressure- temperature damage. The results indicate that the rubber sealing layer reduces energy waste and mitigates stress induced by temperature and pressure within each structural layer compared to the steel sealing layer. However, the mechanical properties of the rubber sealing layer gradually deteriorate due to temperature and pressure, while displacement increases and stress decreases as operational cycles accumulate during CAES operation.