Experimental Research on Electrical Parameters Variation of Loaded Coal

Experiment on electrical parameters variation of different destruction type coals under uniaxial compression are studied. The results show that electrical parameters’ change curves of the loaded raw coal samples and briquette have a very good consistency; the consistency of dielectric constant curve and coal stress - strain curve is better than the resistivity curve. The resistivity curve of loaded coal in general is “concave” shape with the stress - strain curves, and the dielectric constant curve is “convex” shape generally. Compared to the initial electrical parameter values of the coal samples, the electrical parameter change rate of raw coal samples and briquette are generally higher than 13%, up to 165%, the electrical parameter change rate of raw coal samples is generally higher than briquette. The electrical parameter change of loaded coal and its stress have significantly coherence, electrical parameters variation of loaded coal better reflects the formation, development and transfixion of micro-fractures, and the characteristics of changes in internal structure in the failure process of coal rock. In the case of uniaxial compression, coal is dominated by electronic conductivity in the I, II phases, and ionic conductivity in III, IV phases, the dielectric constant changes of loaded coal have a close relation with its changes in the structure, cracks closure and cracked degree.