CH4吸附-解吸过程中煤体的应变特性研究OA

In order to clarify the deformation law of the coal body in the adsorption-desorption process and reveal its intrinsic domin-ant mechanism,a study on the strain characteristics of the coal body in the CH4 adsorption-desorption process was carried out.The isothermal CH4 adsorption-desorption experimental test of the coal body was carried out at room temperature on an independently constructed experimental platform.Using He as the reference gas,the transient and residual strains during CH4 adsorption-desorp-tion process were systematically analyzed in the pore pressure range of 1.0-5.0 MPa,and the deformation law of coal body during the interaction between coal and gas was studied in depth.The results show that coal has complex pore structure and strong adsorption capacity,CH4 adsorption causes swelling and deformation of the coal body,and desorption leads to contraction of the coal body,which triggers a series of coupled effects of stress change and seepage behavior.In the CH4 adsorption-desorption process,the pore pressure and coal body strain showed a positive correlation trend.With the increase of pore pressure,the volumetric strain induced by CH4 adsorption on the coal body increases significantly,and the residual strain after desorption also increases.Compared with He,the adsorption swelling strain produced by CH4 under the same pressure condition is 1.77-3.52 times,and the desorption residual strain is 2.02-3.36 times,indicating that CH4 adsorption-desorption has an obvious irreversible deformation characteristic on the coal body.The swelling deformation caused by CH4 adsorption is mainly dominated by the filling and swelling elastic deformation of the pore-crack structure,the adsorption swelling deformation of the coal matrix,and the pore damage deformation induced by the ad-sorption stress,while the residual deformation after desorption is mainly controlled by the micro-damage effect caused by the release of pore pressure,the reorganization behavior of the coal molecular structure during desorption,and the irreversible deformation of the pore structure,among other factors.