In the context of global decarbonization, underground hydrogen storage in salt caverns offers an effective pathway for large-scale utilization of surplus wind and solar energy. However, the sealing performance and long-term stability of salt caverns in deep, high-temperature bedded salt formations, which are widely distributed in China, remain major challenges due to the coupled effects of temperature, mechanical damage, and seepage. This study investigates the seepage and dilatancy behavior of salt cavern hydrogen storage through high-temperature seepage-coupled triaxial compression tests and fully coupled thermo–hydro–mechanical numerical simulations. A temperature-dependent permeability evolution model is developed to characterize damage-induced permeability evolution under geothermal conditions, together with a temperature-dependent dilatancy criterion. The results indicate that permeability evolution fundamentally alters the seepage structure of the surrounding rock, resulting in a significant expansion of the pore pressure influence zone. The pore pressure attenuation along the seepage direction exhibits a distinct three-stage pattern, corresponding to damaged, transitional, and undisturbed zones. Compared with conventional fixed-permeability models, the proposed model significantly redistributes hydrogen leakage among different lithologies, reducing leakage from mudstone while increasing leakage from salt rock and interlayers. Higher temperatures strongly promote dilatancy. Elevated temperatures enhance pore pressure accumulation, reduce effective stress, and promote the expansion of dilatant zones, thereby amplifying permeability evolution and leakage potential. In addition, higher interlayer stiffness effectively suppresses the propagation of low-safety-factor zones into deeper formations. This study highlights the necessity of incorporating permeability evolution in leakage risk assessment and guides the design and safety evaluation of salt cavern hydrogen storage in deep, high-temperature bedded salt formations.
Ji et al. (Mon,) studied this question.