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Abstract The tests on methane flow regularities of complete stress-strain processes of coal samples are performed by AG–250kNI rock mechanics testing system combined with self-developed coal triaxial creep and gas seepage equipment. The characteristics and principles for gas seepage in complete stress-strain processes of coal samples are obtained. The results show that the strain-gas seepage velocity curves are similar to stress-strain curves of coal samples，but hysteretic nature is found in strain-gas seepage velocity curve，which shows that the character of gas seepage is determined by damage evolution of coal sample during the process of loading. The lasting durations for both the adsorption-desorption processes and seepage processes of gas are the reason of hysteretic nature in strain-gas seepage velocity curve. The confining pressure shows hindering effect on gas seepage through the changes of internal structure caused by compression effect of confining pressure. The results of two kinds of coal samples composed of different particle sizes and powders show that the difference of gas seepage characters is large，and the coal sample composed of larger particle size and powder is more easily to be influenced by external conditions.
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Received: 19 April 2009
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