Creep-seepage Law And Microscopic Response Characteristics Of Coal Containing Gas

Rheological property is one of the inherent characteristic of coal,which affecting the coal and rock dynamic disasters in the underground production process such as coal and gas outburst,rock burst,and even having a decisive influence on decay of coal and gas outburst.Creep is the main form of the coal rheological property.The creep damage and failure of loaded coal with time are determined by the rheological property.Therefore,the research of creep-seepage characteristics and microstructure response characteristics of gas bearing coal under high stress condition is an important part of revealing the dynamic phenomenon of coal in deep mining.It also provides the theoretical basis and means for prevention and control of underground coal dynamic disasters and has a significance to reduce casualties and property losses in the process of coal mining and protect the normal operation of production In the process of coal mining.This paper takes raw coal samples with containing gas as the object of the research,Mainly adopting laboratory simulation experiments and theoretical analysis and other research methods,and carry out creep-seepage tests of coal samples containing gas under different gas pressures and confining pressures by RLW-500 G creep testing machine and gas adsorption-desorption-seepage experiment system to research the creep-seepage laws and creep instability phenomenon of loaded raw coal samples with containing gas.The results show that in the experimental process of creep-seepage tests of coals containing gas,the permeability of coal contain gas firstly decreases and next stabilizes with the increase of axial load,when entering a non-steady-state creep stage,since a large number of micro-damage accumulate of coal as well as some macro cracks appear,the permeability of coal gradually increases,and it becomes the maximum as soon as instability of coal occurs;the increase of confining pressure leads to the augment of strength and density of the coal sample In the experimental process of creep-seepage tests of coals containing gas,and the add of axial stress to unsteady stage of coal samples,moreover decreases the longitudinal strain at the beginning of creep damage,Permeability decreases with the increase of confining pressure in the whole process.With the increase of gas pressure,but the permeability of Coal samples increases,the AE signal(count)intensity and density of the coal damage anddestructions is basically same in the process of creep failure.Meanwhile,combined with existing creep model and theory of creep-seepage,Considering the response characteristics of microstructure of coal containing gas during creep process,this paper establishes and verifies the creep model and damage evolution equation of coal containing gas for studying on the law of creep damage and instability of coal containing gas in the process of creep-seepage process.Besides,combined with some research experimental methods such as acoustic emission monitoring system and Scanning electron microscope and high pressure mercury test,this paper superficially discusses the influences of the creep-seepage process on the microstructure of coal samples.Results shows that the process of creep-seepage promotes coal samples to twist and fold,to damage as tension joint and shear joint,and produce a large number of macro cracks and micro cracks,at the same time weakly changes these pore structure its pore size less than 100 nm,but some pore structure its pore size larger than 1000 nm changed greatly,and it's the main reason of coal sample instability and change of permeability.To a certain extent,the experimental study qualitatively and quantitatively researches and analysis the influence law of creep-seepage process on the microstructure characteristics of coal samples,and reveals creep-seepage law and Microstructure response characteristics of loaded raw coal with containing gas.