Study of Coal and Magnetite Collapse Process and Precursor Based on Acoustic Emission Flicker Noise Spectroscopy

Rock-burst prediction is an important issue faced by deep coal mining operations and holds significant significance for ensuring the safety of workers and the sustainable development of mines. This study investigates the crack-propagation behavior of coal and magnetite under uniaxial compression, introduces the characteristic parameter γ within the framework of the flicker noise spectrum (FNS), analyzes the trends in the variation of acoustic emission (AE) b-value and γ-value, and explores the relationship between these two parameters. Experimental results reveal that the proportion of tensile cracks is significantly higher than shear cracks during the loading process, shear failure becomes the main factor as the specimen approaches failure. Both the b-value and γ-value are proven to effectively reflect the damage evolution process of coal and magnetite and exhibit noticeable changes prior to collapse. Specifically, the peak γ-value serves as a precursor indicator for coal and magnetite collapse. Furthermore, this study uncovers a negative linear relationship between the b-value and γ-value. By delving into the feature parameter γ of AE signals, this research offers a new perspective and approach for predicting the instability of coal and magnetite formations and monitoring dynamic hazards. It contributes to a better understanding of the damage evolution process of coal and magnetite formations and provides valuable guidance and reference for preventing and mitigating dynamic hazards associated with coal and magnetite.