EXPERIMENTAL STUDY OF CHARACTERISTICS ABOUT COAL CHARGE INDUCTION SIGNAL UNDER TRIAXIAL STRESS CONDITION

This paper looks for the links between the coal fracture degree and the electricity released by the raw coal sample to improve the forecasting accuracy of mine dynamic disaster. The self-developed charge sensor is used to conduct charge induction test with the raw coal sample under triaxial compression. It analyzes the charge induction signal variation characteristics of coal with different fracture degrees in adjacent sides. Using FFT method, the spectrum of the charge-induced signal is processed to study the change rules of the spectrum caused by different gas pore pressures in frequency domain. The charge accumulation quantity is analyzed comparing with the cumulative ringing counts and the total acoustic emission energy on this basis. The research results show that the more serious the coal fracture degree is,the charge induction signal is more abundant. As the pore pressure increases, the largest peak of the charge induction signal frequency amplitude moves to low frequencies under the fixed confining pressure. The frequency of the charge induction signal is generally in 200Hz below. The frequency of the large amplitude appears less than 50Hz under the triaxial compressions. The charge accumulation quantity shows greater jump growth trend. The cumulative amount of the charge induction signal amplitude is smaller in comparison with the cumulative ringing counts and the total acoustic emission energy.