Abstract: 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.

Key words: coal-rock bodies, burst tendency, charge rate after stress peek, charge coefficient variation, quantitative analysis