煤体吸附膨胀变形模型理论研究

为了深入探讨煤体吸附瓦斯发生膨胀变形效应的力学行为，基于煤-气吸附界面的表面自由能变化等于煤体弹性能的变化基本假设，从理论上推导了煤体吸附膨胀模型中吸附膨胀变形表达式和吸附膨胀应力表达式，模型中各参数的物理意义明确。通过已有的试验数据分别从低气体压、中气体压和高气体压3个角度对吸附变形模型的适用性和正确性进行了验证。模拟结果表明，模型预测数据与已有的试验数据吻合度较高，能够很好地描述不同气体在不同压力条件下的煤体吸附膨胀差异性，拟合精度均较高；在综合考虑吸附膨胀应力和气体压力对煤体吸附膨胀变形影响前提下，忽略吸附气体体积Va对煤体吸附膨胀变形的影响。

Theoretical study of deformation model of coal swelling induced by gas adsorption

In order to investigate the swelling effect of coal induced by gas adsorption, based on the assumption that the surface energy change caused by gas adsorption is equal to the change in elastic energy of the coal, a theoretical model is developed to describe gas adsorption induced swelling. The formulas of adsorptive expansion stress and strain of coal are derived. The model also is tested by experimental results of gas adsorption induced coal swelling from three aspects, such as low pressure, medium pressure and high pressure. The results show that the model agrees well with experimental data of coal deformation induced by the gas adsorption. It is shown that the model is able to describe the differences in swelling behaviour with respect to gas species and at different levels of gas pressures. It is also shown that the volume of the adsorption gas can be ignored when the effects of gas pressure on coal deformation is considered.