The permeability of a rock mass affects the site selection and construction of underground high-pressure gas storage for compressed-air energy storage. This study investigates the permeability evolution of sandstone under high-pressure gas during the cycle of confining and axial pressures. Nitrogen permeation tests were conducted at different inlet pressures using the steady-state method. The initial steady-state flow, seepage in the circulation, and steady-state flow after circulation were measured continuously in three stages. The effects of the loading and unloading rates and load-holding time on the seepage flow were analyzed. The results indicate that the flow rate and displacement changed with periodic changes in the axial and confining pressures during the cycle. The higher the inlet pressure, the greater was the difference between the peak and trough of the flow in the cycle, and the greater was the difference between the flow after the cycle and the initial flow. When the inlet pressure was 10 MPa, the steady-state flow rate increased from 284 ml/min to 336 ml/min (18%). When the inlet pressure was 2 MPa, the evolution range of the seepage flow in the sample was similar for different load-holding times. The loading and unloading rates had a significant influence on the flow waveform in the circulation process but little influence on the wave height. With an increase in the number of cycles, the porosity of the samples first decreased rapidly and then increased slowly. This study provides a reference for construction and operation of compressed-air energy-storage systems.

Given the significant impact of damage on the deformation and stability of surrounding rock in shallowly buried metro stations, understanding the behaviors of rocks, with the blasting vibration effect considered, is crucial. This study examines the blasting damage mechanism, including an analysis of damage factors and radii. The results revealed a nonlinear decreasing relationship between the damage factor and the distance from the blasting source. Hence, equations for the radii of the surrounding rock's crushing and crack zones are established under the influence of blasting shock and stress waves. On-site acoustic testing indicated that the surrounding rock suffers severe damage within a 0–0.6 m range from the blasting source. A damage disturbance zone exists within a 0.7–1.7 m range while the rock remains intact within a 1.7–4.7 m range. The on-site measured radius of the crushing zone differs by 9.59% from the theoretical value, and the crack zone's radius deviates by 16.47%. In addition, a simulation model is developed to investigate the stability of surrounding rock under different rock span ratio (RSR). For shallowly buried, large-span hard rock stations, the findings suggested that with RSR between 0.15 and 0.25, a smaller ratio correlates with increased settlement of the surrounding rock, higher horizontal stress values, and larger plastic zone areas post-excavation, confirming the evaluation index's rationality and scientific validity.

Based on a certain Qingdao metro station, a large‐scale three‐dimensional model test has been carried out to investigate the stability of the surrounding rock masses (hard rock) and a large‐span metro station under different excavation methods and technologies. The model test includes an entire section excavation, an arch‐cover excavation, and a primary support arch‐cover excavation. Compared with the entire section excavation, the primary support arch‐cover method can effectively control the vault settlement and clearance convergence deformation of the surrounding rock masses, reducing them by 15–30%. The deformation itself goes through three stages: slow, abrupt, and stable. The excavation of the “middle hole” creates a drastic change in the tunnel vault during the arch‐cover excavation; however, the timely application of supports can effectively constrain the range of disturbance caused by the excavation and weaken the degree of load agglomeration of the surrounding rock masses.