Research on Energy Characteristics of Shaft Blasting Vibration Based on Wavelet Packet

Analyzing the time-frequency and energy variation characteristics of blasting vibration signals is helpful to understand the propagation law of blasting seismic waves and guide the optimization of blasting parameters. The study is based on the field-measured tunnel shaft blasting vibration signal data and uses wavelet packets to extract the energy frequency band characteristics of the vibration signal. The distribution of blasting vibration signal energy in each frequency band and the change law with vertical distance are analyzed, and the regression analysis of shaft blasting vibration energy is carried out according to the principle of dimensional analysis. The results show that the main frequency band of the shaft blasting vibration signal is distributed within 0-300 Hz, and the variation trend of blasting vibration energy in different frequency bands is different. The results show that the vibration energy of shaft blasting accounts for 99% of the energy in the 0-300 Hz frequency band, and the vibration energy in the vertical direction accounts for the most. The energy is concentrated in the low frequency band, and the average proportion of energy in the frequency range of 0-30 Hz at 25 m, 31 m, and 41 m from the explosion source is 86.21%, 49.67%, and 39.10%, which is not conducive to the safety of structures. The energy attenuation coefficient of the shaft is about twice that of the tunnel, and seismic wave propagation has an elevation amplification effect.