Deformation and permeability characteristics of raw coal under different gas pressures
Wang Yongfa
Liu Po
Ma Jianhong
Gou Panfeng
Wei Sijiang
Abstract：Objectives To investigate the deformation behavior and permeability evolution of raw coal under different gas pressures,and to clarify the mechanical-seepage coupling characteristics of coal under gas-bearing conditions.Methods Triaxial compression-seepage experiments were conducted on raw coal samples under constant confining pressure and varying gas pressures.The permeability evolution during loading was analyzed.Based on the Mohr-Coulomb strength criterion,the cohesion and internal friction angle of coal un-der different gas pressures were calculated.A six-stage seepage evolution model was established to quantita-tively characterize the relationship between permeability and volumetric strain rate.Results Under constant confining pressure,coal permeability exhibits a distinct V-shaped variation with increasing axial stress.With increasing confining pressure,both the initial permeability and the peak-state permeability decrease exponentially.Increasing gas pressure weakens the mechanical parameters of coal,including cohesion and internal friction angle.According to the monitoring results of axial stress and gas flow during axial loading,the seepage process can be divided into six stages:stable adsorption,attenuation,gradual increase,abrupt increase,steady increase,and rapid surge.After the peak stress,gas permeability shows a linear re-lationship with the volumetric strain rate.Conclusions This study reveals the dynamic evolution of coal per-meability under the coupled effects of axial stress,confining pressure,and gas pressure,and clarifies the influence of gas pressure on coal mechanical properties and the permeability-deformation relationship.The results provide important theoretical support for determining pressure-relief zones,designing gas extraction sequences,and optimizing borehole parameters in protective seam mining.
Keywords：gas pressureraw coaldeformation characteristicspermeability characteristics
Publication Date：2026-03-31
Online Publishing Date：2026-03-04(First online date of this platform, not the publication date of the document)
Pages：8( 148-155 )