基于声发射信号主频和熵值的岩石破裂前兆试验研究

EXPERIMENTAL STUDY ON PRECURSOR OF ROCK BURST BASED ON ACOUSTIC EMISSION SIGNAL DOMINANT-FREQUENCY AND ENTROPY

对干燥和饱水煤矸石进行单轴压缩声发射试验,基于频谱分析和信息熵理论,分析其破裂全过程声发射信号的主频和熵值变化,研究煤矸石变形破坏声发射前兆规律。研究结果表明:干燥和饱水煤矸石声发射信号均有2个主频带,分别为20 k Hz左右和30~60 k Hz,主频在破裂前均发生突变,出现接近0和100 k Hz的主频值;干燥煤矸石熵值集中在0.5~2.0,无突变性,饱水煤矸石熵值集中在0.0~0.5,具有突变性。利用声发射信号熵值对煤矸石系统进行稳定性评价,出现大于1的熵值预示着煤矸石失稳的危险性增强;以密集出现接近0和100 k Hz的突变主频值作为煤矸石破裂的前兆特征;由于实际矿山岩体的饱水特性,以及其变形破坏的复杂性,实际应用时,可将声发射信号主频和熵值2个参数相结合。利用饱水煤矸石声发射信号主频和熵值的突变特征,得到基于声发射场的煤岩动力灾害综合预警信息。试验结果为岩石损伤演化机制及破裂预测研究提供新的手段和依据,对于实际矿山煤岩动力灾害的声发射监测预警具有重要理论研究意义。

The uniaxial compression acoustic emission tests of dry and saturated coal gangue were performed. The acoustic emission precursor laws of deformation and failure of coal gangue were researched based on the dominant-frequency and entropy changing of acoustic emission signal. The results show that drying and saturated coal gangue have two dominant-frequency bands of about 20 k Hz and 30–60 k Hz. The acoustic emission signal dominant-frequency of coal gangue has a mutation before the rupture of rock,and it is close to 0 and 100 k Hz. The entropy of dry coal gangue concentrates in 0.5 to 2.0 without a mutation;and the entropy of saturated coal gangue concentrates in 0.0 to 0.5 and has a mutation. Acoustic emission signal entropy can evaluate the stability of coal gangue. when the entropy is greater than 1.0,it indicates the increasing of risk of the instability of coal gangue. The dominant-frequency focusing on about 0 and 100 k Hz can be seen as a precursory characteristic of coal gangue rupture. Due to the saturated characteristic of the actual mining rock,as well as the complexity of its deformation and destruction,the dominant-frequency and entropy can be combined used to obtain an early warning information of coal dynamic disaster based on acoustic field parameter variation. The experimental results provide a new method and basis for research on rock damage evolution mechanism and rupture forecast,which has an important theoretical study significance for acoustic emission monitoring and early warning for the actual mining dynamic disaster of coal.