Experimental study on transient charge signals on raw coalsurface under uniaxial loading

Based on the experimental analysis of the uniaxial compression process of raw coal samples, the change of transient charge on sample surface is studied and the relationship betweene transient charge and loading stress is discussed.The result show that during the main rupture stage of coal samples,the maximum of the transient charge signals appears before the stress peak,and changes suddenly with the abrupt drop of the stress.At the early stage of destruction,the internal friction is the main reason for the charge generation and accumulation.While at the middle and late stages of destruction,a large number of cracks are formed and propagated,which cause the change of charge signals.According to the variation law of the transient charge on the surface of the coal body,it can reflect the damage of the coal body,and the monitoring of the surface charge can provide an important reference for the prediction of coal and rock dynamic disasters.