Objective The construction of underground chambers involves complex geological conditions such as weak surrounding rocks, fractured zones, and faults. The poor stability of surrounding rocks in these areas makes them prone to collapses and sliding. Therefore, studying the stability of chamber surrounding rocks holds significant theoretical and engineering importance. This study aims to examine the influence of the Mohr-Coulomb and Hoek-Brown strength criteria on the construction stability of underground chambers for compressed air energy storage (CAES), and to explore the differences in chamber stability under the two criteria and their implications for design.

Method Based on the FLAC3D numerical simulation method, this study investigated a sealed underground chamber of a CAES power station in Inner Mongolia. The Mohr-Coulomb and Hoek-Brown strength criteria were applied to analyze the displacement and plastic zone distribution of the surrounding rock under pressure. Through simulation, the differences in the effects of the two strength criteria on rock deformation and plastic zones were compared, and the performances of three chamber types—a large tank chamber, a circular tunnel, and a horseshoe-shaped tunnel—were further evaluated.

Result The simulation results show that the analyses based on the Mohr-Coulomb and Hoek-Brown criteria are generally consistent. The large tank chamber demonstrates superior performance, particularly in stress distribution and plastic zone control, indicating better stability and safety. In contrast, the circular and horseshoe-shaped tunnels exhibit relatively lower stability, especially under high-pressure gas storage conditions.

Conclusion This study provides meaningful guidance for the optimized design and construction of underground chambers, particularly under high-pressure storage conditions, and confirms the advantages of the large tank chamber. The findings indicate that the large tank chamber can effectively control rock deformation and reduce the risk of plastic failure, showing promising application potential. These results offer a theoretical basis for CAES chamber design and practical insights for engineering applications.