Evolution characteristics of induction charge signals in the process of unstable failure and post-peak failure of coal mass

In this paper, an experimental study of the evolution of the charge induced by uniaxial compression of coal mass is carried out. The charge-noise signals are analyzed in the fre-quency-domain based on the Fourier Transform, and the high frequency noise signal is re-moved through low-pass filtering. On this basis, the coal is mainly studied ontime-domain evolution of the effective signals to induced charge in the stage of unstable failure and post-peak failure of coal mass. The results have shown that the induced charge signals after noise reduction have higher correlation with the stress-strain curves. The lower the loading speed is, the more sufficient the specimen to break, and the more uniform the distribution of high amplitude induced charge signals at each mechanical stage, while the higher the loading speed is, the more concentratedin the post-peakstage the high amplitude induced charge signals are; The cluster degree of induced charge signals of the sudden change is lower in the stable rupture stage. But in the unstable failurestage, the amplitude fluctuation and the number of abrupt changes of inducted charge signals increase obviously, and the cluster degree increases correspondingly. In the post-peak failure stage, the mutation signals of high amplitude appear continuously, and the cluster degree changes qualitatively. The mutation degree of high amplitude signals abruptly changes most violently and the variation coefficient of induced charge signals in this stage is even more than an order of magnitude in the unstable rupture stage. The variation characteristics of high amplitude of induced charge signals can effectively evaluate the stability of coal and rock mass. © 2020, Editorial Board of Journal of Mining & Safety Engineering. All right reserved.