Analysis of the deformation characteristics of surrounding rock due to interlayers during cyclic injection-production period of salt cavern hydrogen storage

Underground hydrogen storage in salt caverns represents a crucial technological approach for future hydrogen storage. The stability of the surrounding rock during full-cycle injection and production, especially under varying interlayer properties, is critical for ensuring the stable operation of UHS in bedded salt caverns. This study employed triaxial compression tests to analyze the mechanical properties of salt rock and developed a corresponding creep constitutive model. Finite element analysis software was then used to simulate the full-cycle injection and production processes of salt cavern hydrogen storage, investigating operational patterns, displacement characteristics around the salt cavity, and deformation behaviors of the surrounding rock. The results indicate that under identical strain conditions, higher confining pressure enhances the load-bearing capacity and elastic modulus of salt rock. During the initial operational phase, significant creep deformation may occur, but the salt rock gradually stabilizes over time. As the elastic modulus of interlayers increases, the deformation resistance of the cavern improves, with rigid interlayers effectively reducing maximum cavern displacement. Changes in interlayer elastic modulus have minimal impact on the plastic zones of the storage facility. While the number of interlayers has limited influence on cavern displacement, an increased number of interlayers with lower elastic modulus exacerbates plastic deformation in the adjacent salt rock. These findings provide theoretical guidance for the feasibility analysis and stability evaluation of pilot projects for salt cavern hydrogen storage.