Abstract: To investigate the contact mechanical characteristics between the sealing plug and surrounding rock in compressed air energy storage caverns, a contact mechanical analysis model suitable for wedge-shaped sealing plugs was established based on the Winkler elastic foundation assumption. By deriving the mechanical equilibrium equations of plug-rock interactions, a second-order nonlinear ordinary differential equation describing the horizontal displacement of the sealing plug was obtained. The contact pressure and displacement distributions were solved using a numerical boundary-value problem method (MATLAB bvp4c). Considering typical engineering parameters, systematic analyses were performed on boundary constraints, geometric dimensions, material properties, and contact parameters to identify the key mechanical factors under high internal air pressure. The results show that the boundary constraint conditions significantly influence the distribution of the contact response between the plugging structure and surrounding rock. Under free-boundary conditions, both the contact pressure and displacement increase gradually along the axial direction, whereas with increasing boundary stiffness, their distributions first increase and then decrease. Among the geometric parameters, the inclined-edge angle θ is the key factor governing the contact mechanical behavior of the plugging structure. An increase in the maximum convex radius R₀ increases θ, resulting in an increase and eventual stabilization of the contact pressure and displacement while effectively reducing the horizontal displacement of the plugging structure. In contrast, an increase in the plug length L₀ reduces θ, weakens the contact interaction, and increases horizontal displacement. Furthermore, increasing the friction coefficient and surrounding rock resistance coefficient reduces the contact and horizontal displacements and enhances the antisliding stability of the plugging structure; however, the influence of these factors has a diminishing marginal effect. Finally, by controlling the horizontal displacement as the optimization target, parametric optimization was performed for R₀, L₀, and L_m（horizontal distance from the left end face of the plug to the point of maximum bulging）, and an optimal combination of R₀=12.0, ₀=10.5, and L_m=3.8 m was identified within the prescribed parameter ranges.

Key words: compressed air energy storage, wedge-shaped plug, contact pressure, optimized design