煤吸附解吸气体变形的力学模型研究

A mechanical model of coal strain induced by gas sorption/desorption

针对煤吸附/解吸气体过程中变形随时间变化的力学行为,对煤体孔隙度方程的隐函数求导,将具有时变性的孔隙度方程引入有效应力系数中,由此建立煤吸附/解吸气体变形问题的力学模型。模型的数值计算结果表明:煤样吸附/解吸气体产生膨胀/收缩变形,变形随时间的增加而增大,直到气体在煤中吸附/解吸达到平衡,煤样的变形才稳定不变;气体压力对煤样的吸附/解吸变形平衡时间及平衡变形量产生影响,气体压力越大,吸附/解吸变形平衡所用的时间越短,平衡时煤样体积应变越大;煤样吸附变形与气体吸附性相关,吸附性更强的CO2气体比CH4气体促使煤样产生更大的膨胀变形。模拟结果与以往实验研究结论一致,证明建立的力学模型能反映煤吸附/解吸气体的变形特征。

To investigate the time variation of the coal strain due to the gas sorption/desorption,in this work,a model of coal strain induced by the gas sorption/desorption is presented by means of deriving the implicit function of coal porosity included in the effective stress coefficient.Numerical results indicate that the variation of coal swelling/shrinkage due to the gas sorption/de-sorption increases with the time.The coal strain is a constant in the sorption/desorption equilibrium.The gas pressure around coal samples has an effect on the equilibrium time and the coal volumetric strain of sorption/desorption.Given a higher gas pres-sure,the greater coal samples due to sorption swell and the shorter the deformation coal samples last.The adsorbability of gas al-so influences the coal strain induced by sorption.Coal adsorbing CO2 swells greater than that adsorbing CH4 .The numerical re-sults are in agreement with previous experimental conclusions.Therefore this model reflects the features of the coal strain due to sorption/desorption.