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The thermal effect of coal adsorption/desorption gas is very important for understanding the evolution of coal temperature and interaction between coal and gas during coal and gas outburst. The pressure difference between the high gas pressure area in front of the working face and the low gas pressure area near the coal wall may affect the adsorption/desorption thermal effect. In order to reveal the characteristics of the coal adsorption/desorption gas thermal effect at different pressure differences, a thermo-hydro-mechanicalcoupled experimental system of coal and gas was designed. Taking no.3 coal from Xinjing Mine as the research object, the characteristics of the coal adsorption/desorption gas thermal effect under different pressure differences are studied by using the cycle-step experiment method. It is found that coal adsorbs gas to release heat, while coal desorbs gas to absorb heat. Also, the temperature variation and temperature accumulation caused by adsorption are greater than those caused by desorption. Under the same pressure difference, the temperature increase rate during the adsorption changes from large to small, and the temperature variation gradually decreases; the temperature decrease rate during the desorption changes from small to large, and the temperature variation gradually increases; desorption is the reverse process of adsorption. The relation between temperature variation and gas pressure is linear, and the increasing range of temperature variation gradually decreases with the increase of pressure difference. The relation between temperature accumulation and gas pressure conforms to an exponential function, and the decreasing range of temperature accumulation gradually decreases with the increase of pressure difference. The greater the pressure difference, the greater is the energy variation caused by the adsorption/ desorption thermal effect. The experimental results of different pressure differences can reflect the characteristics of the coal adsorption/desorption gas thermal effect under different geological structures or outburst types.

This paper studies the anisotropic characteristics of shale and the difference in mechanical performance between deep shale and outcrop shale. The outcrop shale was collected from the Shuanghe section in Changning County, southern Sichuan, and the deep shale was collected from the Wells Yi201 and Lu202. Study their basic mechanical parameters, failure modes, and wave velocity responses through laboratory tests. Research shows that with the increase of bedding angle, the deformation mode has the trend from elastic deformation to plastic deformation in high-stress state. When the bedding angles are 0°, 30°, and 45°, the weak bedding surface plays a leading role in the formation of the failure surface trend. As the bedding angle increases to 60° and 90°, its influence is weakened. The tensile strength, elastic modulus, and wave velocity decrease with the increase of bedding angle. The compressive strength and Poisson’s ratio have the law of U-type change, there are higher values at 0° and 90°, and the lowest values are at 30°. The brittleness index first increases and then decreases with the increase of the bedding angle. The tensile strength and Poisson’s ratio of outcrop shale and deep shale are close, but the compressive strength of deep shale is only 1/3 of outcrop shale, the elastic modulus is only 3/4 of outcrop shale, and the failure of deep shale is accompanied by instability failure.

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