The distribution of pores and skeletons within coal reservoirs significantly affects the migration of gases and the occurrence of gas dynamic disasters.To further explore the micro-damage mechanisms in gas-containing coal,a detailed study of the micro-damage process in gas-containing coal was conducted.Atomic force microscopy was employed to con-duct in-situ tests on the surfaces of protruding and non-protruding coal samples before and after loading.The results indic-ate that the surface structure of the coal samples changes after loading,with a reduction in closed pore diameter,damage to some pores,and a tendency for connectivity between adjacent closed pores.Before loading,the pores in coal samples ex-hibit irregular distribution,while after loading,pore connectivity increases,and the number of open pore throats slightly increases.Loading leads to a reduction in the modulus of coal skeleton in protruding coal samples due to pore connectiv-ity,while non-protruding coal samples experience internal structure compaction,resulting in a slight increase in elastic modulus due to their higher strength.Micro-damage types and concepts in coal were defined,and the stress distribution characteristics around coal pores and the coal skeleton were analyzed,revealing the micro-damage mechanisms in gas-containing coal under different conditions.Simultaneously,the factors influencing the closed-cell micro-gas explosion were discussed.The stress at the end of a slender elliptical hole is greater along the hole wall,making it more susceptible to closed-cell micro-gas explosions.Two forms of occurrence of open-pore micro-damage were described,revealing the constraining effect of the"bottleneck effect"on micro-damage.Inherent fractures were identified as the weak link in the coal skeleton,and the evolution of their rupture was analyzed.Utilizing theories such as linear elastic fracture mechanics,elastic-plastic mechanics,and permeation mechanics,criteria for detecting pore damage and coal instability under stress disturbances were established.The micro-damage characteristics of gas-containing coal and the mechanisms inducing coal and gas outbursts were summarized,and the research direction of coal and gas outburst was prospected.
关键词
孔隙/失稳判识/微破坏/煤骨架/煤与瓦斯突出
Key words
pore space/instability discrimination/micro-damage/coal skeleton/coal and gas outburst
维普
万方数据