Driving mechanisms and control technologies for coupled gas and coal spontaneous combustion disasters in deep mines dominated by fracture scale effects

CHENG Jianwei

doi:10.13347/j.cnki.mkaq.20251395

Abstract：During deep resource extraction,various disasters often exhibit characteristics of group occurrence and interrelation,with severe interactions and overlapping effects,making traditional prevention and control methods increasingly inadequate.Focusing on the core scientific issues of disaster prevention and control in deep mining stopes,this study systematically analyzes the manifesta-tions and distribution characteristics of multi-scale fractures in deep mine stopes.By introducing the Knudsen number to delineate different flow regimes,such as free molecular flow,slip flow,and continuous medium flow,it reveals the dominant influence of frac-ture scale on the transition from laminar to turbulent flow,frictional heating,and convective heat transfer efficiency.Combining Darcy and Forchheimer seepage models with convective heat transfer relations,a multi-level transmission chain of"fracture scale-permeability-flow velocity-heat flux density-temperature field"is constructed.The heat transfer enhancement coefficients under laminar and turbulent conditions are derived,elucidating the regulatory mechanism of fracture scale on flow regimes and heat-mass transfer from a mathematical modeling perspective.The research shows that during the coupling process of stress field,seepage field,fracture field,and temperature field in the incubation of deep mine disasters,the fracture field serves as the dominant primary field,while the others are secondary fields regulated by it.Based on this,a new perspective is proposed:"the fracture field is the funda-mental driver of disaster evolution,and scale effects are the dominant controlling parameter in disaster incubation".Taking the coupled disaster of gas and coal spontaneous combustion in typical deep mine scenarios as an example,a disaster prevention and control technical approach centered on actively regulating fracture scale is proposed.Through the application of liquid-phase sealing materials and inorganic grouting leakage-plugging materials,the area prone to spontaneous combustion defined by both seepage ve-locity and oxygen concentration is significantly reduced,seepage velocity within the region noticeably decreases,and air leakage around gas extraction boreholes is improved.Under optimal grouting conditions,the area of the composite hazardous zone is re-duced by 746 m2,and the flow field structure in the goaf is further optimized.Engineering practices demonstrate that liquid-phase sealing materials and inorganic grouting leakage-plugging filling materials can regulate the scale distribution of the fracture field,al-ter the mass and heat transfer characteristics of the flow field,and enable active intervention in and control of disaster evolution pathways.