Blasting vibration characteristics and PPV calculation formula considering cylindrical charge length

The surrounding rock is divided into elastic zone and plastic zone according to the motion and deformation characteristics of medium in rock blasting. Cylindrical charge blasting vibration is framed based on past research related to blasting elastic-plastic theory, and the influence of detonation velocity on cylindrical blasting vibration is considered, especially for long charge length. A superposition model is used to calculate the vibration characteristics of long cylindrical charge blasting while considering the influence of charge length. The analysis results show that when the charge length reaches a certain length, the peak particle velocity (PPV) no longer increases with an increase in charge length, which is not consistent with the traditional theory for PPV calculation. In current practice, the calculation method for spherical charge blasting is used to calculate PPV values for a cylindrical charge. This approach, however, is inaccurate. As such, a new modified PPV calculation formula that considers the characteristics of cylindrical blasting is proposed in this paper after comparing with the spherical blasting PPV calculation method, and the influencing factor of charge length is introduced. The new PPV calculation formula can better characterize cylindrical charge blasting vibration attenuation laws.