Frequency spectrum analysis on micro-seismic signal of rock bursts induced by dynamic disturbance

Blasting and breaking of hard roof are main inducing causes of rock bursts in coal mines with danger of rock burst, and it is important to find out the frequency spectrum distribution laws of these dynamic stress waves and rock burst waves for researching the mechanism of rock burst. In this paper, Fourier transform as a micro-seismic signal conversion method of amplitude-time character to amplitude-frequency character is used to analyze the frequency spectrum characters of micro-seismic signal of blasting, hard roof breaking and rock bursts induced by the dynamic disturbance in order to find out the difference and relativity of different signals. The results indicate that blasting and breaking of hard roof are high frequency signals, and the peak values of dominant frequency of the signals are single. However, the results indicate that the rock bursts induced by the dynamic disturbance are low frequency signals, and there are two obvious peak values in the amplitude-frequency curve witch shows that the signals of rock bursts are superposition of low frequency signals and high frequency signals. The research conclusions prove that dynamic disturbance is necessary condition for rock bursts, and the conclusions provide a new way to research the mechanism of rock bursts.