FDEM-based collaborative optimization of sealing structure and lining preset joint design in underground lined rock caverns

Underground lined rock caverns (LRCs) used for compressed air energy storage are highly susceptible to cracking and the development of leakage pathways under cyclic high-pressure loading. Therefore, sealing performance and crack control are critical design challenges. This study employs the finite-discrete element method (FDEM) to develop an integrated rock-lining-sealing layer model, to systematically compare flat steel plate and wave-arch liners, as well as to analyze the influence of preset joint design parameters on crack evolution and sealing behavior. The results indicate that flat steel plate liners exhibit elevated stress levels, numerous cracks, and poor structural integrity, while preset joints provide only limited mitigation. In contrast, wave-arch liners significantly reduce peak stress and redistribute cracking, concentrating damage beneath arches, thereby lowering crack density, albeit with locally larger crack widths. A combined wave-arch and preset joint design further uniform crack propagation and alleviates liner stress. Increasing the number of wave arches and preset joints improves stress uniformity and crack control. However, the maximum crack width exhibits a “decrease-increase” trend, accompanied by a transition in liner stress mode from tension-dominated to bending-shear dominated behavior. When joints are placed at arch bottoms, cracks develop uniformly along the preset paths; when combined with waterproofing and drainage measures, leakage risks can be effectively managed. Overall, the wave-arch and preset joint composite design offers notable advantages in guiding crack development, releasing strain, and enhancing sealing reliability, providing a robust reference for coordinated optimization of sealing and lining design in underground LRCs.