【摘要】 利用建立的煤岩声-电信号测试系统,对强度较低的煤岩试样进行了单轴压缩、剪切加载破坏实验,测试研究了ULF(1 kHz)、VLF(5 kHz)、LF(300 kHz)等频段电磁辐射及42.3 kHz声发射(AE)信号规律,并初步探讨了煤岩变形破坏ULF电磁信号的产生机理。结果表明:煤岩材料在单轴压缩和剪切变形破裂过程中能够产生ULF频段的电磁信号;与LF及VLF电磁信号相比,ULF信号与应力的相关性更好;同时,ULF信号与应力及AE相比存在一定程度的超前性,一般超前应力及AE信号5～10 s。实验室测得的煤岩变形破裂产生的ULF电磁信号,主要是由电荷运动产生的感应场变化引起的,煤岩材料中含有的少量金属矿物成分导致的压磁效应也是其来源之一。煤岩ULF电磁信号的研究不仅扩展了煤岩电磁辐射技术的研究范围,而且由于其在传播距离和抗干扰能力方面的优势,有望对远距离和较大尺度范围的煤岩动力灾害监测技术实现突破。更多还原

【Abstract】 The rules of electromagnetic signals of ULF(1 kHz),VLF(5 kHz),and LF(300 kHz),as well as acoustic emission(AE)(42.3 kHz) were studied under two ways of loading including uniaxial compression and shearing with the establishment of acoustic-electric signals test system of coal and rock,and the generating mechanism of ULF electromagnetic signals was preliminarily discussed.The results show that coal and rock under uniaxial compression and shearing can produce ULF electromagnetic signals,which has a better correlation to stress than LF and VLF signals.ULF signals displays a certain degree of advance to stress and AE signals,producing 5~10 s earlier than the two parameters.The ULF electromagnetic signals measured in laboratory mainly induced by the changes of induction field due to the motion of electric charges,and the piezomagnetic effect caused by a small amount of metal mineral composition in coal and rock is another source.This study extends the research scope of EMR of coal and rock.Meanwhile,with the advantages in transmission distance and anti-jamming capability,the study is expected to achieve a breakthrough in long-range and large-scale monitoring for coal and rock dynamic disasters.更多还原