284 / 2018-04-27 08:59:28

Effect of bedding direction on transient charge on Datong coal sample surface

coal,bedding direction,uniaxial compression,transient charge

矿山动力灾害 > 岩爆冲击

According to analysis of the uniaxial compression process of Datong coal samples, the change of transient charge signals on coal surface is observed and the influence of sampling directions (perpendicular to beddings and parallel to beddings) on the transient charge signals is studied. The results show that the change of the charge signals on sample surface is instantaneous and pulsing, and such a change is always in accord with stress change and alternation of positive and negative charge occur in a short time. The bedding direction (perpendicular to and parallel to beddings) has a significant influence on the uniaxial strength and sample surface charge signals. With a higher value of the limiting stress, the transient charge signals on surface of the coal samples perpendicular to beddings exhibit higher strength than that of the coal samples parallel to beddings. However, the amount of signal pulses during the failure process for the samples perpendicular to beddings is less than that of the samples parallel to beddings. During the loading process, a large number of cracks are formed, propagated and converged in the coal matrix under the act of uniaxial load which leads to the generation and accumulation of transient charge. According to the variation law of the transient charge signals on coal surface, it is concluded that the change of transient charge can serve as a tool to characterize the crack propagation within coal specimen and provide an important reference for the prediction of coal and rock dynamic disasters.