Evolution law of coal mechanical properties in gas emission process

In this paper, taking gas emission process of coal containing different pressure gas in fixed-stress environment as the research object, and taking the axial and transverse strains in gas emission process as study parameters, the coal sample deformation law in gas emission process was studied systematically. The results show that in a certain external stress environment, the evolution law of both the axial strain and transverse strain in gas emission process present obvious nonlinear characteristics. The axial strain of coal sample law presents three-step style, and there exits one point of gas emission speed make the axial strain start to increase in a larger rate, while the relationship between gas emission speed and axial strain can be expressed by improved power function The total transverse strain also shows obvious nonlinear characteristics at the end of experiment. The size of gas pressure has obvious effect on axial strain and transverse strain in process of gas emission, which mainly is manifested in the sensitivity between strain appear point and gas emission speed, and the correlation between total strain, strain formation process, and gas emission speed, etc.