Damage Deformation and Acoustic Emission Characteristics of Raw Coal under Different Moisture Contents

Coal seam with different moisture contents considerably affects coal mining and gas extraction. The coal seam with moisture contents has unique damage deformation characteristics that differ from dry coal. Therefore, the damage deformation characteristics of coal seam with different moisture contents need to be investigated to enhance the effects of coal mining and gas extraction. To explore the damage and deformation laws and acoustic emission (AE) characteristics of coal samples with different moisture contents, coal samples with different moisture contents were prepared for triaxial compression AE localization tests, and the stress-strain characteristic parameters and AE counts, cumulative AE counts, AE energy, and cumulative AE energy of coal samples were prepared. The damage models of coal samples with different moisture contents were established based on AE counts, and the damage and deformation laws were analyzed. Results show that the peak intensities of coal samples decrease with the increase in moisture contents, the dry coal sample mainly undergoes shear failure, and the water-containing coal samples are pronounced by lateral splitting. The peak and cumulative AE counts of the coal samples decreased as the moisture contents increased. The peak and cumulative AE energies of coal samples decreased with the increase in moisture contents. The damage model established based on AE counts has a high degree of fit. Moreover, the damage amount of the coal samples increased with the moisture contents. The conclusions obtained in this study have practical guiding significance for demonstrating the mechanism and process of coal body dynamic disasters in actual engineering.