Stability analysis method for underground lined storage cavern group in compressed air energy storage power station

The burial depth issue of compressed air energy storage (CAES) caverns significantly influences initial site selection and overall stability assessment, serving as a critical aspect in the design of artificial gas storage caverns. To investigate the uplift failure mode of tunnel-type gas storage reservoirs for CAES, we propose a multi-cavern conical failure model based on the single-cavern limit equilibrium framework. The model accounts for rock-mass friction and cohesion, as well as interactions between adjacent caverns. We introduce parameters describing the equivalent slip surface and its inclination angle ω. By enforcing equality of the inter-block force (Ea) between the central and lateral blocks, we derive a governing equation for ω. Solving this equation yields the safe burial depth. Research findings demonstrate that the calculation results of multi-cavern model, which considers the influence of adjacent caverns, are more reasonable compared to those of the single-cavern model. To further explore the response characteristics of the multi-cavern model to design parameters, we conduct a systematic analysis of the impacts of cohesion, horizontal in-situ stress coefficient, cavern diameter, and cavern spacing on buried depth. The results indicate that burial depth is negatively correlated with cohesion and decreases as cohesion increases. In contrast, burial depth is positively correlated with the horizontal in-situ stress coefficient and increases as this coefficient rises. Burial depth also increases with cavern diameter but decreases as the spacing between adjacent caverns increases. Notably, when the spacing between adjacent caverns exceeds four times the cavern diameter, the multi- cavern effect can be neglected.