Abstract: Experiments on characteristics of infrasonic wave generated by full-regime rock failure under uniaxial loading are carried out with a stiffness material test machine, and the stiffness materials involve granite, limestone, red sandstone, sandstone, phyllite, mudstone. In this study, an advanced digital infrasound emission detecting system to study the characteristics of the infrasonic signals is independently developed. The collected infrasonic signals are processed and analyzed through the wavelet-based denoising method, short-time Fourier transform time-frequency analysis and accumulative ring-down count (ARDC). The results show that: ① The infrasonic wave emission phenomena can apparently appear during the process of uniaxial loading of rocks before rocks fracture. ② The characteristic frequency of prominent infrasonic wave generated by rocks’ fracture typically range 2.0-6.0 Hz. ③ The ARDC of hard rocks, e.g. granite and limestone, are much more than those of soft rocks, e.g. mudstone, in the case of complete structure. Compared with other acoustic signals, infrasound is low-attenuate, cannot be absorbed easily by water and air, and can propagate avoiding huge obstacles due to its long wavelength. Combined with other methods, the further study of the characteristics of infrasonic wave generated by rocks’ microfracture can provide a significant innovate approach and techniques for rock stability monitoring.

Key words: infrasonic wave, rock failure, time-frequency analysis, characteristic frequency, rock stability