College of Emergency Management and Safety Engineering, China University of Mining & Technology, Beijing, China.
PLoS One. 2020 Mar 9;15(3):e0229824. doi: 10.1371/journal.pone.0229824. eCollection 2020.
Using an analysis of the uniaxial compression process of Datong coal samples, the change of transient charge signals on coal surfaces is observed, and the influence of sampling directions (perpendicular to bedding planes and parallel to bedding planes) on the transient charge signals is studied. The intensity in perpendicular to bedding planes is 4.610.2 MPa, parallel to bedding planes is 2.15.3 MPa. The results show that the change of the charge signals on sample surfaces is instantaneous and pulsing, and such a change is always in accord with stress change and the alternation of positive and negative charge occurring over a short time period. Under uniaxial compression, the surface charge signal characteristics of coal sample in perpendicular to and parallel to the bedding are different. With a higher value of limiting stress, the transient charge signals on coal sample surfaces perpendicular to the bedding exhibit higher strength than those of coal samples oriented parallel to the bedding. However, the number of signal pulses during the failure process, for the samples perpendicular to the bedding, is less than that for the samples oriented parallel to the bedding. According to the variation law for transient charge signals on coal surfaces, we conclude that changes in the transient charge can serve as a tool to characterize crack propagation within coal specimens and provide an important reference for the prediction of coal and rock dynamic disasters.
通过对大同煤样单轴压缩过程的分析，观察到了煤样表面瞬态电荷信号的变化，并研究了采样方向（垂直层面和平行层面）对瞬态电荷信号的影响。垂直层面的强度为 4.610.2 MPa，平行层面的强度为 2.15.3 MPa。结果表明，样品表面电荷信号的变化是瞬时和脉冲式的，这种变化总是与短时间内的应力变化和正负电荷的交替一致。在单轴压缩下，垂直和平行层面煤样的表面电荷信号特征不同。在极限应力较高的情况下，垂直层面煤样表面的瞬态电荷信号强度高于平行层面煤样。然而，在破坏过程中，垂直层面煤样的信号脉冲数少于平行层面煤样。根据煤表面瞬态电荷信号的变化规律，我们得出结论，瞬态电荷的变化可以作为描述煤样内部裂纹扩展的工具，并为煤岩动力灾害的预测提供重要参考。
