Development of a test apparatus for coal adsorption-induced swelling stress to investigate the stress evolution characteristics
ZHANG Zunguo
CHEN Yi
ZHANG Honghu
TANG Chao
Abstract：In order to investigate the dynamical evolution characteristics of the swelling stress dur-ing the CO2 adsorption process in coal,embarking on the key technical challenges such as the air-tightness of the device,the effectiveness of the confinement system and the reliability of the dyna-mometer,a test apparatus for coal adsorption-induced swelling stress has been developed,which in-tegrates the axial confinement system,the data monitoring system,the pore pressure control sys-tem and the temperature control system.The results show that the developed coal adsorption-in-duced swelling stress test device has excellent air-tightness and axial confinement capability,is ca-pable of achieving more than 95％axial deformation of coal samples and enables dynamic testing of gas pressure and coal swelling stress within 10 MPa.The experiments of coal swelling stress under CO2 are conducted based on this device to analyze its dynamical evolution characteristics.The dy-namical evolution curve of adsorption-induced swelling stress in coal during CO2 adsorption over time exhibits three pattern types.When the CO2pressure is low,there is no significant mechanical damage effect due to the adsorbed gas in the coal,resulting in the curve that is primarily character-ized by two stages:The reduction of the compressive stress due to gas injection and the subsequent increase in swelling stress due to gas adsorption,presenting a type-Ⅰ curve with a distinct Lang-muir curve characteristics.As the gas pressure increases,the mechanical damage caused by the"erosion"effect of gas adsorption leads to a decrease in swelling stress,forming a type-Ⅱ curve.Once the stress reduction due to mechanical damage exceeds the stress increase due to adsorption swelling,the swelling stress after adsorption equilibrium is significantly lower than the initial value,presenting a type-Ⅲ curve.A dual Langmuir model for the dynamical evolution of the adsorption-induced swelling stress has been developed,which takes into account the coal mechanical damage,can accurately fit the evolution relationship of the swelling stress over time.
Keywords：gas-solid couplingswelling stressstress evolutiontest apparatusadsorption-in-duced swelling stress model
Publication Date：2026-01-30
Online Publishing Date：2026-01-28(First online date of this platform, not the publication date of the document)
Pages：12( 136-147 )