Abstract
The damage evolution of coal is accompanied by the generation of acoustic emission (AE) signal. Through the analysis and research of the AE response characteristics of coal deformation and failure, it is helpful to reveal the initiation, propagation, and fracture evolution of microcracks in coal. In this work, taking the anthracite coal as research object, the basic mechanical parameters of the coal samples were obtained by ultrasonic tests and uniaxial compression experiments. Meanwhile, the AE response characteristics of coal samples during uniaxial compression were obtained through AE experiments. The results show that when the density is low, the wave velocity of the coal sample decreases with the increase of density. When the density is higher than a certain value, the wave velocity of the coal sample increases with the increase of density. Through the measurement of ultrasonic wave velocity, it is found that there is some nonuniformity and anisotropy in raw coal samples. The ring counts, energy counts, and AE events with time in uniaxial compression process have approximately normal distribution. The AE events are concentrated in the elastic stage and yield stage, and the energy amplitude of AE events is higher in the plastic stage. Compared with the ring counts and energy counts, the AE events have a good positioning function, which can better reflect the evolution of internal cracks of coal samples during uniaxial compression.
Highlights
With the coal resources gradually entering the deep mining stage, under the complex environment of “three-high and one-disturbance,” the coal and rock are more prone to fracture and lose stability, leading to more dynamic disasters such as rockburst and coal and gas outburst [1,2,3,4]
When these microstructures are stressed, the deformation, stress concentration, and failure will occur, and the stored strain energy will be released in the form of elastic waves, which is the acoustic emission (AE) phenomenon of the coal and rock under stress [10,11,12]. e AE signal during the failure of the coal reflects the microscopic destruction of coal and is closely related to the evolution of coal damage. rough the in-depth analysis of the AE signals during the coal damage, the deformation and fracture process of the internal microstructures of coal can be inversed, which is helpful to reveal the evolution law of coal damage and provide references for full understanding of the mechanism, forecasting, and early warning of coal-gas outburst, rockburst, and coal-gas compound dynamic disaster
A lot of early warning researches on AE to coal and rock dynamic disasters are based on coal-gas outburst and rockburst, and few studies about AE focus on the early warning of coal-gas compound dynamic disaster
Summary
With the coal resources gradually entering the deep mining stage, under the complex environment of “three-high and one-disturbance,” the coal and rock are more prone to fracture and lose stability, leading to more dynamic disasters such as rockburst and coal and gas outburst [1,2,3,4]. Rough the in-depth analysis of the AE signals during the coal damage, the deformation and fracture process of the internal microstructures of coal can be inversed, which is helpful to reveal the evolution law of coal damage and provide references for full understanding of the mechanism, forecasting, and early warning of coal-gas outburst, rockburst, and coal-gas compound dynamic disaster. A lot of early warning researches on AE to coal and rock dynamic disasters are based on coal-gas outburst and rockburst, and few studies about AE focus on the early warning of coal-gas compound dynamic disaster. The AE response characteristics of raw coal samples in uniaxial compression process were obtained by AE experiment, which provides theoretical guidance for AE monitoring and early warning of failure of coal and rock dynamic disasters
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