冲击倾向性煤体力-电感应规律试验研究

Experimental study on the mechanical charge induction law of the coal bumping proneness

为提高冲击地压预测的准确性,应用自行研发的多通道电荷感应监测系统,对单轴压缩条件下冲击倾向性煤体变形破坏过程中力-电感应规律进行了试验研究。结果表明：冲击倾向性煤体的单轴抗压强度大,破坏失稳时间短,煤体失稳具有显著的突发性特点;冲击倾向性煤体的电荷波动幅值大于无冲击倾向性煤体的电荷波动幅值;冲击倾向性煤体的单位时间电荷量大于无冲击倾向性煤体的单位时间电荷量;冲击倾向性煤体表面累积的自由电荷总量和单位时间内从煤体表面逃逸出来的自由电荷数多于无冲击倾向性煤体的表面累积的自由电荷总量和单位时间内从煤体表面逃逸出来的自由电荷数;冲击倾向性煤体力-电感应规律曲线中存在一个冲击失稳的超前预警时间区域,该区域可为预测煤体发生冲击失稳做好预报准备。

The paper is intended to do an experimental study on the mechanical-charge induction law in the process of deformation and destruction of the bump-prone coal body under the condition of uniaxial suppression by using our self-developed multi-channel charge induction monitoring system. The results of our experimental study show that： since the uniaxial compressive load of the bump instability of the coal body is great, it tends to lead to the sbort-term abrupt bumping and the coal-seam instability, which can be thought of great significance for the coal bump characteristics. However, with the continuous increase of the load applied to the coal, greater impact of the instability would occur on the entire coal body when the expanding speed of the main crack takes place inside the coal body, which can even exceed the critical speed and lead to the charge fluctuation of the coal bumping. At the same time, the charge fluctuation amplitude of the bumping coal can also be remarkably greater than that of the unbumping prone coal seam. The number of the free charges escaping from the bump-prone coal surface in the unit time can also be greater than that of the free charges escaping from unbumping coal surface in the unit time. The charge fluctuation amplitude and the charge per unit time of bump proneness may also tend to increase with the impact energy index, for they are also increasing with the uniaxial compressive strength. Thus, the rock-burst and the other dynamic disasters can be predicted and prevented by monitoring the change of the charge number fluctuation. And, so can the charge number per unit time, the free charge number of the coal surface accumulation and that of free charge escaping from the coal. Therefore, there exists a warning time area of the impact buckling. Therefore, the curve of the bump-prone coal induced by the mechanical-charge can be used as a signal for a kind of advanced warning area of the impact buckling.