Safe burial depth of underground lined gas storage caverns: An analysis integrating elastoplasticity and ultimate equilibrium

Existing analytical models for the safe burial depth design of compressed air energy storage (CAES) caverns typically assume that the operational air pressure is directly transmitted to the surrounding rock wall, neglecting the load-sharing effect of the lining, which leads to overly conservative burial depth estimates. Meanwhile, most previous studies have focused on hydrostatic in-situ stress conditions, leaving the influence of the lateral pressure coefficient on the spatial distribution of plastic zones largely unexplored. This study establishes a dual-criterion analytical framework integrating the Elastoplastic Analysis Method (EPM) and the Ultimate Equilibrium Method (UEM) for determining the safe burial depth of lined CAES caverns. By coupling thick-walled cylinder theory with the Kirsch solution, the load-sharing effect of the lining is explicitly quantified, and a quantitative relationship between the operational air pressure and the cavern wall pressure is established. The results show that a 7%–21.8% difference exists between the wall pressure and the operational pressure. The safe burial depth is highly sensitive to the lateral pressure coefficient, rock mass quality, and cavern operating pressure. The lateral pressure coefficient governs the spatial evolution of elastoplastic zones in the surrounding rock and the initiation location of plastic failure. A dual-criterion control mechanism for the safe burial depth is established: under low pressure, the UEM governs the anti-uplift stability of the overlying rock mass; under high pressure, the EPM governs the prevention of plastic yielding in the surrounding rock. These findings demonstrate that explicitly accounting for the lining load-sharing effect and non-hydrostatic stress conditions is essential for the rational design of safe burial depth in CAES caverns.