Research on time-frequency characteristics for blasting vibration signal of CO2 blasting by frequency slice wavelet transform

—With the advancement of theoretical and practical research for high pressure gas fracturing technology, carbon dioxide (CO2) fracturing technology will have broad application prospects in the national economic construction, the study on attenuation law of peak particle velocity (PPV) with distance and time-frequency characteristics for blasting vibration signal of CO2 fracturing technology will be of great significance. On behalf of speeding up the excavation progress and studying the vibration effect of carbon dioxide blasting, liquid carbon dioxide phase change fracturing is used as the blasting source to bench excavation of mountain. The regressive analysis about propagation characteristics of blasting vibration signal along the horizontal radial, horizontal tangential and vertical direction was expressed by power function formula. The peak particle velocity of residential building is in the safety range during the CO2 blasting, which show the excellent control effect on CO2 blasting damage for near building. In terms of altogether 9 blasting vibration data along the horizontal radial, horizontal tangential and vertical direction recorded from 3 vibration monitoring points at a distance of 5 m, 15 m and 30 m away from the borehole, the dominating frequency of particle vibration produced by carbon dioxide blasting varies form 4.4 Hz to 63.7 Hz; In the process of analyzing CO2 blasting vibration signal, FSWT has good time and frequency resolution, it shows that the vibration intensity of CO2 blasting vibration sub-band signal decreases with the increase of frequency, the main energy concentrates in the range of 0-100 Hz, the CO2 blasting vibration signal in the frequency range of 0-20 Hz is more obvious and reach 92.9% of the total energy, meanwhile, the CO2 blasting vibration energy within 20-100 Hz is relatively small with 6.4% energy percentage. The analysis results can provide reference for similar design and construction of carbon dioxide blasting. © 2020, International Association of Engineers. All rights reserved.