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Abstract The mechanical properties of raw coal specimens containing gas from the B10 seam of －780 m elevation in Huainan coal mine were studied under the conventional high stress triaxial compression by using the modified adsorption-penetration-mechanical coupling test system. The deviatoric stress-axial strain curves of the raw coal containing gas have the stages of elastic deformation，yielding，post-peak brittle failure or strain softening. The elastic period shows the fluctuation associated with strain-softening and strain-hardening. The post peak brittle failure feature is apparent. Under the same initial gas pressure，with the increase of the initial effective confining pressure，the trend of transition between the brittle and ductile is weak. Increasing the initial gas pressure can result in more significant brittle failure if the initial effective confining pressure is kept constant. The deviatoric stress-lateral strain curve has the linear elastic stage which is very smooth. The deviatoric stress-volume strain curve of raw coal containing gas shows dilation under the low effective confining pressure in the pre-peak region. With the increase of the effective confining pressure，the volume dilation delayed. The peak strength increases linearly with increase in confining pressure or gas pressure. The common failure mode for the coal specimens is shear failure and the cohesion and friction angle are 14.02 MPa and 25.93º，respectively.
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2017, Vol. 36 
