Pneumatic fracturing is the process of generation of fractures or extension of existing fractures in soils and rocks through the injection of high-pressure air into boreholes. Based on an analysis of the characteristics of the propagation of pneumatic fracture, the applicable conditions of the mathematical models are evaluated, taking consideration of the interaction between gas and soil. The results indicate that the gas permeability coefficient of soils may have significant impact on the propagation of pneumatic fracturing. With the gas permeability coefficient of soil increasing, the maximum width and radius of fractures would decrease exponentially. It is also shown that increase of gas volume may result in increases of the maximum width and radius of fractures, especially the maximum width of fractures. It is also revealed that the soil elastic modulus is linearly positively correlated with the radius of fractures, and inversely exponentially related with the maximum width of fractures.%气压劈裂是指土体在高压气体作用下产生裂隙并发展的过程。在分析气压劈裂裂隙扩展特性的基础上，考虑气体与土体相互作用机理，提出气压劈裂裂隙扩展模型适用条件；同时进行气压劈裂裂隙扩展模型中关键影响因素参数分析。参数分析结果表明，土体的透气性对于气压劈裂效果有显著的影响，裂隙最大宽度和裂隙半径随着土体中气体渗透系数的增大而减小，呈指数关系；喷气量的增加可以增大裂隙最大宽度和裂隙半径，尤其对增大裂隙宽度效果更为明显；喷气深度的改变对于裂隙半径影响显著，呈线性正相关性；裂隙最大宽度随着弹性模量的增大而减小，呈指数关系，当模量增大到一定程度时，裂隙宽度趋于极限值，裂隙半径与弹性模量呈线性正相关关系。
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