Influence of initiation modes on vibration frequency induced by single-hole blasting

To further reveal the blasting vibration frequency distribution characteristics induced by different initiation modes of the single borehole cylindrical charge, the PPV and Fourier dominant frequency formula under different initiation modes such as top initiation, bottom initiation, mid-point initiation, and two-point initiation are derived based on the Heelan equivalent unit short-column charge model. The results show that the dominant frequency distribution characteristics near the explosion source are as follows: two-point initiation > mid-point initiation > bottom initiation > top initiation; in the middle and far zones from the explosion source, the difference of dominant frequency induced by various initiation modes is insignificant; the attenuation curves of the dominant frequency of radial and vertical vibration abruptly change at the distance away from the blasting center of 20-50 m and 20-30 m, respectively. However, the curves of centroid frequency under different initiation modes attenuate smoothly with increasing distance, and the distribution rule is two-point initiation > mid-point initiation > bottom initiation > top initiation. In general, the influence of initiation mode on the particle vibration dominant frequency and centroid frequency is gradually weakened with increasing distance. Finally, the theoretical calculation is verified by the experimental data.