Experimental study on acoustic waves of different types of debris flow using generalized S transform

The physical model tests in laboratory for debris flow with three types of sub-viscous, intermediate and viscous debris flows are performed. By introducing the window function parameters, a generalized S transform is proposed to analyze the time-frequency characteristics for acoustic signals of different types of debris flows. At the same time, in view of the shortcomings of the traditional Fourier transform, a wavelet packet transform method is used to extract the distribution characteristics of frequency band energy of the acoustic signals. The results show that: (1) Compared with the traditional time-frequency analysis methods, the generalized S transform has excellent time-frequency focus and resolution. (2) With the increase of the bulk density of debris flow, the peak frequency of debris flow moves to low frequency. (3) The signals are decomposed into 8 frequency bands (0 ~ 6.25, 6.25 ~ 12.5, 12.5 ~ 18.75, 18.75 ~ 25, 25 ~ 31.25, 31.25 ~ 37.5, 37.5~43.75, 43.75 ~ 50 Hz) by using the wavelet packet transform, the sub-viscous debris flow is mainly distributed in S6-8, and the intermediate and viscous debris flows are concentrated in S2-4. (4) Comprehensive identification of different types of debris flows can be realized based on the frequency range and frequency band energy of acoustic signals.