Experimental research on the gas pressure sensitivity to the permeability of coal
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Abstract
In order to explore the gas pressure changes caused changes of permeability of coal,leading to the phenomenon of pressure sensitivity.Using the self-developed triaxial seepage equipment with an adjustable outlet pressure,the experimental study of permeability sensitivity of coal sample from 3 mines in Guizhou province under different gases and gas pressure was performed.The results are show that at the lower pressure range (0~0.6 MPa),the permeability decreases significantly when gas pressure increases,the adsorption of coal tends to balance and the rate of descent reduced and leveled off with the rising of gas pressure.When the gas pressure is less than 1.0 MPa,the damage rate of permeabilityDphas a great change,and it increases rapidly showed a significant sensitivity.Under the different gases condition,the sensitiveness coefficient of gas pressure Cpdecreases when the gas pressure increases.The sensitiveness coefficient of gas pressure Spis minimum when filling CH4 under the same condition.The sensitiveness coefficient of gas pressure has the power relationship Spand damage rate of permeability Dphas a better linear correlation.
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