Experimental study of isothermal adsorption deformation of transversely isotropic coal

LIANG Bing; JIA Lifeng; SUN Weiji; ZHAO Hang; FANG Shengjie

Abstract：The characteristic of coal is transverse isotropy,while the adsorption deformation on different directions of coal is still unclear.In order to solve the problems,taking 4# coal of Tingnan coal mine as the research object,the isothermal adsorption deformation experiments at 30 ℃ were carried out with CH4 and He as adsorbate by using the self-developed multifunctional measurement test device on gas adsorption/desorption parameters of coal.Based on the experimental results,the gas compression deformation equation,the pure adsorption deformation equation and the deformation equation of transversely isotropic coal were discussed.The results show that the vertical bedding and parallel bedding directions of coal swells when CH4 is adsorbed,and shrinks when He is adsorbed.The parallel bedding direction and vertical bedding direction show the deformation anisotropy in the process of coal adsorption gas.The anisotropy of coal deformation under the effect of gas compression,pure adsorption and the two factors is related to the properties of coal,not the gas pressure and theadsorbate.The average relative error of the theoretical calculation results and experimental results on parallel bedding direction is 7.08％ and vertical bedding direction is 14.63％.The deformation equation of transversely isotropic coal can express the relationship between gas pressure and adsorption swelling deformation and also describe adsorption deformation on vertical bedding and parallel bedding direction.