Experimental study on ULF electromagnetic induction during coal and rock damage failure process
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.
Keywords：coal and rockdamage and failureelectromagnetic inductionULF
Publication Date：2012-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：7( 1658-1664 )