Study on permeability characteristics of coal body under mining influence in working face of single thick coal seam

Yuan Jiguang; Cui Chongbin; Chen Qiaojun; Wang Chaoqian

doi:10.19896/j.cnki.mtkj.2025.02.012

Abstract：In order to deeply reveal the influence of mining action on the permeability characteristics of the coal body,the conventional triaxial loading seepage experiments of the coal body under different conditions of confining pressure and pore water pressure were car-ried out systematically with the No.8 coal seam(a single thick seam)of Malan Mine as the object of the study,and the evolution law of the permeability characteristics of the coal body under the influence of mining was comprehensively explored,as well as the mecha-nism of its mechanical response.The results show that the increase of the confining pressure increases the strength of the coal body,and the peak permeability decreases at the time of damage;the increase of the pore water pressure decreases the strength of the coal body,and the peak permeability increases at the time of damage.Based on the rate of stress change,a triaxial segmented loading and unloa-ding experimental path was designed.It was found that in the slow pressurization zone,the coal body stress increased from 10.45 MPa to 11.68 MPa,and the permeability decreased nonlinearly to 0.16 × 10-3 μm2 due to the closure of fissures;in the rapid pressurization zone,the coal body stress increased to 19.24 MPa,and the permeability decreased firstly and then increased nonlinearly to 0.42 × 10-3μm2;in the rapid depressurization zone,the coal body stress dropped suddenly,and the volume expansion was significant,and the per-meability continued to increase to 0.87 × 10-3 μm2.0.87 × 10-3 μm2.Based on the experimental data,the relationship between the permeability and axial stress of the coal body under the influence of mining was fitted,the results of this study can provide a scientific theoretical basis for the study of permeability characteristics in the coal seam mining area.