通过分析计算炮孔周边径向裂纹尖端的应力强度因子，认为：爆生气体驱动的裂纹扩展可分为稳定扩展和非稳定间断扩展两阶段。在稳定扩展阶段，裂纹扩展速度由Ｇｒｉｆｆｉｔｈ理论确定；在间断扩展阶段，裂纹的平均扩展速度完全取决于焊生气体在裂纹中的一维膨胀流动速度。 By analyzing and calculating the stress intensity factor of the radial crack tip around the blasting hole, it is considered that the crack propagation driven by the blasting gas can be divided into two stages of steady expansion and unsteady discontinuous expansion. The crack growth rate is determined by Griffith theory in the steady-state expansion stage. The average propagation speed of the crack in the intermittent expansion stage depends entirely on the one-dimensional expansion flow rate of the welding gas in the crack.