Abstract: Through hightemperature and confining pressure deformation experiments on the five sets of coal samples from the Qinshui Basin, it is clearly seen that the stressstrain intensities of the different coal samples are nearly the same under the conditions of lower temperature and lower pressure and are different under higher temperature and higher pressure. The intensity of higher rank coal such as the No.3 sample is the lowest under certain temperature and pressure (100℃/100 MPa), which might be related to the effect of maceral. The stressstrain intensities of coal samples are negatively related to temperature under hightemperature and highpressure (temperature is larger than 200℃ and pressure is larger than 200 MPa). The stressstrain intensities of coal samples are very low under the conditions of 100℃/100 MPa and 500℃/500 MPa but with intrinsic differences for the two conditions. The stressstrain intensity of coal samples under 100℃/100 MPa condition only represents part of the real intensity of the coal samples when strain (ε) is less than 3% and the persistent stressstrain intensities of coal samples(ε>3%) might show the effect of the confined pressure. But the stressstrain intensity of coal samples under the condition of 500℃/500 MPa is very low, which shows some malleable characteristics of the coal samples resulting from the effect of temperature on the coal samples.

Key words: coal bed gas, deformation experiment, stressstrain curve, maceral