## 4 Discussion  
The data pertaining to displacement, obtained from the numerical simulation of single-cavity vertical gas storage reservoir monitoring points, were subjected to processing using Origin 2018 software, with the objective of obtaining the rule of change. The changes in vertical displacement at monitoring points T and B and the top and bottom plates of the cavity are shown in Figure 5, respectively. From Figure 7, a trend can be clearly observed: as the number of mudstone interlayers increases, the displacement of the top and bottom plates of the reservoir increases. This trend reflects the relatively weaker nature of the mudstone interlayer in the surrounding rock. The increase in the number of interlayers under the same cyclic air pressure directly leads to an increase in displacement deformation. The explanation for this phenomenon can be attributed to the role of mudstone interlayers in the reservoir structure. Mudstone interlayers typically have lower strength and higher deformability and are, therefore, more susceptible to displacement and deformation when subjected to external pressures. When the number of mudstone entrapments increases, the relative proportion of mudstone entrapment in the gas storage structure increases, and the effects of their displacement and deformation increase accordingly. It is, therefore, imperative that the impact of the quantity of mudstone inclusions on the stability of the surrounding rock is given due consideration at all stages of the design and operational phases of a gas storage reservoir. Appropriate support and reinforcement measures are implemented to mitigate the adverse effects of mudstone interlayers on the structural stability of gas storage reservoirs, thereby ensuring the safe operation of the  
Figure 7: Vertical Displacement of Monitoring Points T and B: (**a**) The top plate; (**b**) The base plate slab. reservoirs. These findings have significant implications for the optimisation of reservoir operation strategies, the reduction of surrounding rock deformation, and the improvement of long-term reservoir stability. The deformation of the surrounding rock can be effectively mitigated through the implementation of a rationalised air pressure peaking strategy and the regulation of the air pressure action time, thereby enhancing the performance and safety of the gas storage reservoir. From Figure 8, the changes in horizontal displacement show a similar pattern to the vertical displacement, which is due to the contraction of the cavity under the influence of the circulating air pressure. It is worth noting that the displacement changes on the left and right sides are nearly symmetrical, which means that the trend of changes on the left and right sides is similar when the cavity is affected. Similar to the vertical displacement, the effect of the number of interlayers on the horizontal displacement change is also consistent. When the number of mudstone inclusions is increased, it leads to greater horizontal displacement changes, which suggests a positive correlation between the number of inclusions and displacement changes. The volumetric shrinkage of a cavity is defined as the extent to which its volume decreases due to deformation of the surrounding rock under specific conditions. The volume change of the cavity is calculated and monitored using FLAC3D, and the resulting data are instrumental in comprehending the deformation of the cavity under disparate operational conditions, as well as in appraising the stability and performance of the gas  
Figure 8: Horizontal Displacement of Monitoring Points L and R: (**a**) The left plate; (**b**) The right plate slab. storage reservoir. Figure 9 illustrates the variation in cavity volume shrinkage at different air pressure cycling frequencies. As can be seen from the above figure, the volumetric shrinkage of the gas storage reservoirs all show a nearly exponential and steady increase for different numbers of mudstone interlayers.