Energy mutual feedback mechanism between surrounding rock and coal seam in deep coal-gas compound dynamic disasters

WANG Kai; SUN Jiazhi; DU Feng; ZUO Xiaohuan; ZHAO Yu; FENG Chengtao; WANG Chaolin

doi:10.13247/j.cnki.jcumt.20250182

Abstract：Coal-gas compound dynamic disasters(hereinafter referred to as"compound disas-ter")is a catastrophic behavior in which the energy of the"gas-containing coal seam-surround-ing rock"system is violently released under deep mining disturbance.At present,there is still a lack of in-depth analysis on the interaction of energy between coal seams and surrounding rocks,especially the mechanism of surrounding rocks in compound disaster.By conducting physical simulation experiments on the instability of gas-containing coal rock structures under different geo-stress and coal rock strength differences,the energy conversion law of compound disaster was analyzed,and the mechanism of the elastic performance of surrounding rocks was mainly explored.A critical criterion model for rock instability was constructed based on dis-turbance response criteria,and the critical conditions for rock instability and the effect of rock energy accumulation on compound disaster were quantitatively determined.The experimental results show that the evolution of disasters is dominated by the energy feedback path between the surrounding rock and coal,which is manifested as:under high geo-stress and low roof strength conditions,the surrounding rock accumulates higher residual elastic performance due to enhanced energy storage capacity;The residual elastic energy of the two promotes mutual destruction through the bidirectional transmission mechanism of"coal-surrounding rock",leading to an increase in the degree of damage to the coal and roof,which in turn makes it easi-er for the ejected holes to expand upwards,ultimately significantly enhancing the intensity and risk of disasters.Theoretical results indicate that both low strength and high impact prone sur-rounding rocks are prone to instability under disturbance due to weak energy storage capacity and low threshold for plastic zone expansion,and are more likely to exacerbate coal damage through energy transfer;Although enhancing the strength of coal and rock can increase the critical stress of surrounding rock instability,the impact tendency increases synchronously,which may in turn reduce the critical value of instability and form a contradiction in prevention and control.Although the increase in support strength can only enhance the energy storage ca-pacity of the surrounding rock to a limited extent,it mainly releases elastic energy in a control-lable area by constraining deformation,reducing the risk of energy transfer to the coal body.Although increasing the excavation radius will significantly expand the plastic zone radius and elastic energy storage,it will not directly increase the risk of disasters.However,when disas-ters occur,the concentrated release of a large amount of elastic energy may increase the inten-sity of the disaster.The research proposes a"medium modification unloading energy dissipa-tion"prevention and control strategy,providing theoretical basis for the prediction and preven-tion of deep compound disaster.