COAL DEFORMATION TEST UNDER HIGH TEMPERATURE AND CONFINING PRESSNTE

The deformation behaviour of different ranks of coal was discussed based on characteristics of stress and strain curves of coals tested under different temperature and confining pressure.Temperature and confining pressure are considered to be two important influencing factors.In the middle stage of coal metamorphism increase of the confining pressure will increase to a certain extent the strength of coal.However,the influence of temperature is even more important.For high rank of coal,the temperature is predominant in the stage of low strain,and the confining pressure will gradually become predominant in the stage of high strain.In addition,under specific conditions the gas produced and released from coal will greatly affect the deformation behaviour of coal.