三轴条件下煤体受压破裂电荷感应信号试验研究

为研究煤体破裂程度与其释放电荷之间的联系以提高矿山动力灾害预测准确率,利用自主研制的电荷传感器对某矿原煤试件在三轴情况下进行电荷感应试验,分析相邻侧面不同破裂程度下煤体电荷感应信号的变化特征,将信号进行快速傅里叶变换处理,在频域内研究不同孔隙瓦斯压力条件下电荷感应信号的变化规律,在此基础上对电荷累积量与声发射振铃总计数、总能量进行了对比分析。试验结果表明:同一煤体相邻两表面破裂程度越严重,其电荷感应信号越丰富; 在围压不变情况下,随着孔隙压力的增大,煤体变形破裂过程中电荷感应信号频率的最大幅值波峰有逐渐向低频方向移动的趋势,煤体破裂电荷感应信号频率波动低于200Hz,幅值最大点频率在50Hz以内; 电荷累积量曲线在煤体应力达到峰值后,表现出跳跃式增长趋势,但电荷感应信号的量级相对较小。

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.