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Abstract Triaxial seepage tests of briquettes and row coal specimens are implemented by self-developed triaxial seepage test system. The complete stress-strain curves under different confining pressures are obtained. Seepage velocity and transverse deformation in the whole test process are automatically collected by flowmeter and ring extensormeter. The different destructional forms of two types of samples are analyzed by microscopic damage mechanics theory；and the relation of seepage velocity and the process of deformation and destroy is presented. The sensitivity of seepage velocity is effected by the external variables；and the coal and gas outbursts are also discussed. The results show that the complete stress-strain curves of two kinds of samples could be divided into five stages. It has a good relationship with the curve of seepage velocity-axial strain. Due to different structural characteristics，the two types of coal specimens have different damage mechanisms under axial pressure. Seepage velocity-axial strain curves have great difference，especially in the destructional phase. The deformation of briquettes will affect seepage velocity in the first two stages，but it will have certain effects on coal in the whole compression process. The seepage velocity of briquettes is sensitive to axial pressure and axial strain，but it is sensitive only to transverse strain and volume strain for row coal. The five stages in the compression stress-strain- seepage curves of row coal could be explained by four stages(preparation，initialization，development，and completion) of coal and gas outbursts processes. The variety of seepage velocity in coal bed could be used for forecasting coal and gas outburst indirectly. The results have a certain referential value for exploring the real laws of gas migration.
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Received: 01 December 2009
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