Mechanism of the Crack Formation Induced by Pre-split Blasting and Design Method for the Pre-split Blasting Hole Space

The pre-split crack initiation mechanism during the pre-split blasting is still a controversial topic.The clarification of the crack initiation mechanism during the pre-split blasting is of great significance for the engineering design.Comparative analysis indicates that the crack propagation velocity and the blasting-induced gas dissipation velocity change under different decoupling charging coefficients.The comparison of the magnitude of the two velocities shows that the crack propagation is caused by both the blasting stress wave and blasting-induced gas dissipation.It is thus concluded that the pre-split blasting mechanism is characterized by a dynamic process depending on the time and charging parameters.According to the blasting stress wave and blasting-induced gas dissipation induced stress distribution of the hole surrounding,a design method of the pre-split blasting hole space and a calculation equation based on the dynamic compressive and tensile strengths of the rockmass are proposed.