Linking Pore Structure Parameters with Coal Strength and Initial Gas Desorption for Outburst Risk Identification: A Preliminary, Region-Specific Threshold Framework
摘要
To investigate the pore-structure differences between outburst-prone tectonic coal and non-outburst-prone raw coal and their associations with gas dynamic behavior, six coal samples from Jiujia and Laodonghe coal mines were analyzed using firmness coefficient testing, initial speed of methane emission testing, and low-temperature N2 adsorption–desorption experiment (LPGA-N2 adsorption). Pore volume composition, specific surface area, and pore-size distribution were comparatively evaluated, and their relationships with coal firmness and initial methane release behavior were examined. The results show that, within the present six-sample dataset, outburst-prone coals generally exhibit lower firmness coefficients and higher initial methane emission rates than raw coals, with an inverse trend observed between f and ΔP. Compared with raw coals, outburst-prone coals are characterized by lower total pore volume, higher mesopore proportion, and markedly higher t-plot internal specific surface area, suggesting a pore-structure reorganization pattern of volume reduction and surface-area amplification under tectonic deformation. Linear fitting between pore parameters and the conventional engineering indices f and ΔP was used to derive corresponding pore-structure threshold ranges, from which a preliminary pore-parameter threshold framework was proposed. The results suggest that rapid gas release is related not only to pore volume, but also to pore refinement and possible short-range transport advantages inferred from the pore system. The proposed framework is intended as a preliminary, region-specific interpretation of pore-parameter thresholds under the present mining conditions. Broader applicability will require further calibration and validation using larger, statistically strengthened datasets from more diverse geological settings.