Experimental study on elastic modulus of medium- high rank coals and its influencing factors

Elastic modulus of cal is one of the most sgnificant mechanical paramneters.in ths paper a total of 25 cores from the southern Qinshui and southeastern Ordos Basins were caried out on thestess- tain at dfrent conining stress condittons.Based on the stre-strain curve,the elastic modulus of cal was obtained.Furthermore,the controling factors of elastic modulus of coal were comprehensivly analyzed. The resuis showed that th elastic modulus of coal had a strong hetercgeneity and is affected by pore-fracture.coal composttons coal qualtyconfining stress and fuid nediaetc. The elstic modulus ofcoal reduced due to the developmentof pore-fracture wihin cal . with the increase in vtrnite virite and fived carbon contents,the elasic modulus decreased.Howeve,the elastic modulus would increasswith incvemental inertinite and intrtite conterts and ash yilad. The elastic modulus increases resuting fron the compression and closure of pore- fracture caused by theincrease in confining sress.Theresistance of coal defomation is induced by the adsorption and volume force from water which resuits in the decrease in th elastic modulus. Based on the multiple infuencing factors,the elastic modulus distribution of coal reservoir in- situ can be predicted.