Forced vibration analysis of rock mass under millisecond delay blasting

The frequency spectrum analysis of blasting vibration is the basis of blasting vibration control. Based on the blasting vibration data of the dam foundation blasting excavation of Baihetan hydropower station, the frequency spectrum analysis is carried out by means of MATLAB. Under the action of delayed blasting of the same segment, the data at both sides of the detonation zone are processed by the prony-reference complex exponential method. The results show that the vibration frequencies are two sets of resonant frequencies, and the vibration of rock mass is a forced one. The two groups of resonant frequencies are not equal. Through numerical simulation and analysis, it is found that the resonant frequency is shifted due to the Doppler effect which is generated by the relative motion of the seismic source. On the contrary, the data processing results also verify the feasibility of using the modal identification method to accurately calculate the resonance frequency of blasting vibration in the case of Doppler effect. Based on this, the vibration frequency of delayed detonation is used as the fundamental one, and then the frequency shift generated by the Doppler effect is used to achieve the directional frequency alteration and vibration control around explosive sources.