单轴压缩下原煤表面瞬变电荷变化规律试验研究

Experimental study on transient charge signals on raw coal surface under uniaxial loading

基于原煤试样在单轴压缩作用下的失稳破坏试验,研究了原煤破裂过程中表面产生瞬变电荷的现象和变化规律,并分析了瞬变电荷与应力的对应关系。结果表明:原煤试样表面瞬变电荷是瞬时、脉冲信号,会在短时间内出现正负电荷交替变化现象,其变化强度与应力有较好的对应关系。试样发生主破裂过程中,瞬变电荷最大值出现在应力峰值之前,且随着应力的突降而出现急剧变化。在破坏前期,煤体内部摩擦作用是产生电荷变化的主要原因;在破坏中后期,大量裂纹形成、扩展并融合贯通是产生电荷变化的主要原因。根据煤体表面瞬变电荷的变化规律,可以反映煤体受载破坏的情况,对表面瞬变电荷的监测能够为煤岩动力灾害的预测预警提供重要参考。

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.