组合煤岩冲击倾向电荷判据试验研究

Experimental study on the charge criterion of coal-rock bodies burst tendency

针对深部煤层冲击倾向指标评价冲击危险出现的差异现象,开展了煤、岩石和组合试样冲击倾向指标试验研究,对组合煤岩试样破裂过程的电荷信号进行监测。试验结果表明:顶、底板岩石对煤体的冲击倾向有显著影响,岩石厚度越大,冲击倾向指标越高;组合试样破裂过程的力-电荷变化具有一致性,冲击倾向性强的组合试样,其应力强化直至破坏阶段的电荷信号幅值相差显著。由此提出了组合煤岩峰后电荷变化率冲击倾向判据。回采面的电荷监测表明,冲击危险发生过程获得的电荷变异系数迅速升高和衰减以及试验获取的峰后电荷变化率的量化分析结果相一致,从而验证了峰后电荷变化率作为冲击倾向判据的正确性,为形成深部开采条件下组合煤岩冲击危险及发生几率的电荷预测方法提供了试验指导,为煤岩体失稳破坏预测、矿井动力显现预警提供了试验依据。

Experimental studies were carried out on coal specimens, rock specimens and coal-rock specimens to solve the invalidity of burst tendency index on evaluating burst danger in the deep coal seam. The charge signal was monitored in the fracture process of coal-rock specimen to explore the corresponding relation of force-charge and the charge burst tendency of coal-rock specimens. The results show that roof and floor rocks significantly influence burst tendency of the coal seam. The greater the thickness of rock is, the higher the measured burst tendency index of coal-rock is. It is found that force change of coal-rock specimens was consistent with charge change in the fracturing process of specimens. Moreover, the stronger burst tendency of the coal-rock specimens is, the greater the charge signal amplitudes vary in its stress intensification until failure. Thus, the charge rate burst tendency criterion after the stress peak was proposed. The monitoring results of charge in stope face show that the rapid rise and attenuation of charge coefficient variation in the process of rock burst occurrence are consistent with quantitative analysis results on charge change rate after the stress peak. The validity of the charge rate after stress peek as burst tendency criterion was further verified. Therefore, this study provides experimental instruction for the formation of charge prediction method to pre-judge burst danger and its occurrence probability, and offers the experimental basis for failure prediction of coal and rock mass and early warning of mine power appearance.