Rapid gas desorption plays a critical role in the development of coal and gas outbursts. This study explores the impacts of rapid gas desorption on structural alterations in deep coal samples from the Sydney Basin, utilizing a novel methodology that integrates advanced computed tomography (CT) scanning for qualitative analysis with void volume measurement for quantitative evaluation. The research thoroughly examines the impact of the rapid desorption of methane (CH₄) and carbon dioxide (CO₂) on the development and expansion of fractures within the coal matrix across a range of equilibrium pressures and saturated contents. The findings indicate that rapid desorption can facilitate the expansion of existing fractures and the creation of new ones, however, the overall structural integrity of the intact coal sample predominantly remains preserved, even under extreme desorption pressures of up to 10 MPa. A notable increase in void volume following the rapid desorption of CH₄ and CO₂ suggests structural alterations due to the formation or expansion of fractures. Notably, CH₄ desorption was observed to have a more significant impact on the coal structure than CO₂, attributed to its higher equilibrium pressures and faster initial desorption rates. Furthermore, the study identifies a direct correlation between gas equilibrium pressure and the extent of fracture volume alteration, highlighting the crucial role of gas pressure in influencing the structural integrity of coal during mining operations. This detailed analysis of the impacts of CH₄ and CO₂ rapid desorption provides profound insights into the mechanisms underlying rapid gas desorption damage to coal structures. It advances the understanding of coal and gas outburst phenomena, offering valuable knowledge for the enhancement of mining safety and the promotion of more sustainable mining practices.
 

methane,carbon dioxide,rapid gas desorption,microstructural alteration,CT scanning,void volume measurement