Complex function solutions for mechanical response of compressed air energy storage caverns under full smooth contact and constant stiffness sliding contact conditions between lining and surrounding rock

Based on the complex function theory and power series method, an analytical calculation method of mechanical responses for compressed air energy storage (CAES) caverns under non-hydrostatic ground stress fields are established under the full smooth contact and constant stiffness sliding contact conditions between lining and surrounding rock. A displacement release coefficient η is introduced to account for the support delay effect during cavern construction, and the superposition method is employed to consider the influence of thermal strain in the operational stage. Numerical simulations are conducted to validate the proposed analytical solutions, and the stress distribution and load transfer of CAES caverns under different influencing factors are analyzed with an engineering case study. Results show that the lining-surrounding rock contact condition exerts a significant influence on stress in lining, but has a relatively minor effect on stress in surrounding rock. Compared with full smooth contact, both the range of the circumferential tensile zone and the magnitude of tensile stress in the lining increase significantly under constant stiffness sliding contact, whereas the circumferential tensile stress in the surrounding rock decreases slightly. The load transfer ratio , defined as the proportion of the load transferred from lining to surrounding rock under high internal pressure, increases with the rise in the elastic modulus ratio of surrounding rock to lining, and decreases with the increase in η. Increasing and reducing η are effective approaches to enhance the load sharing ratio of the surrounding rock and mitigate the circumferential tensile stress in the lining induced by high internal pressure. Reducing the sliding stiffness at the lining-surrounding rock interface can substantially decrease the tensile stress within lining, with only a slight increase in the tensile stress of surrounding rock over a small zone.