Characteristics investigation on shock wave fracture rock based on Hilbert-Huang transform method using large-scale electric explosion tests

Self-developed electric explosion technology (EET) equipment is used to conduct rock-breaking experiments. A high-speed camera is used to record the expansion of cracks during rock breaking. The Hilbert-Huang transform (HHT) is used to analyze the vibration signals, which reflected the action pattern of shock waves (SWs). Hilbert marginal spectrums, instantaneous energy spectrums, and three-dimensional Hilbert spectrums are used to illustrate the distribution and variation of energy in the time and frequency domains. The experimental results show that SWs energy of 0 to 500 Hz accounts for more than 72% of the total energy, and energy of 0 to 2500 Hz accounts for more than 90% of the total. Energy of SWs has a high base value at the onset of discharge. Energy drops rapidly as discharge time continues. When rocks fracture, there will be obvious instability phenomena, including transfer of energy in frequency, reduction of energy attenuation rate, and reduction of the derivative waves effect.