Experimental investigation on predicting precursory changes in entropy for dominant frequency of rockburst

Rockburst is a dynamic phenomenon accompanied by acoustic emission (AE) activities. It is difficult to predict rockburst accurately. Based on the fast Fourier transform (FFT) method and the information entropy theory, the evolution model of dominant frequency entropy was established. The AE energy, frequency and stress were synthetically considered to predict rockburst. Under the triaxial and the single-face unloading tests, the relationship between AE energy and the development of internal cracks was analyzed. Using the FFT method, the distribution characteristics of AE dominant frequency values were obtained. Based on the information entropy theory, the dominant frequencies evolved patterns were ascertained. It was observed that the evolution models of the dominant frequency entropy were nearly the same and shared a characteristic "undulation-decrease-rise-sharp decrease" pattern. Results show that AE energy will be released suddenly before rockburst. The density of intermediate frequency increased prior to rockburst. The dominant frequency entropy reached a relative maximum value before rockburst, and then decreased sharply. These features could be used as a precursory information for predicting rockburst. The proposed relative maximum value could be as a key point to predict rockburst. This is a meaningful attempt on predicting rockburst.