考虑温度作用下煤岩渗透特性及吸附膨胀的试验研究

利用含瓦斯煤热-流-固耦合三轴伺服渗流装置,为模拟采深增加导致的渗透特性变化,开展不同温度下孔隙压力升高过程中煤岩渗透特性的试验研究,建立考虑温度作用的吸附膨胀模型,探讨温度和孔隙压力综合作用对煤岩吸附膨胀效应的影响。结果表明:随孔隙压力升高,轴向应变在较低温度下(30,40℃)逐渐下降,在较高温度下(50,60℃)逐渐上升,在各个温度下径向应变、体积应变逐渐降低;随孔隙压力升高,煤岩渗透率先减小后略有增高,不同温度下通入氦气与甲烷气体的煤岩渗透率变化趋势相同且前者渗透率大于后者;随温度升高滑脱效应导致的渗透率变化量(Δkb)逐渐增大,煤岩吸附膨胀导致的渗透率变化量(Δks)随孔隙压力升高先急剧下降后趋于平缓,且随温度升高变化量逐渐增大;在相同孔隙压力下,考虑温度作用吸附膨胀引起的渗透率变化量均高于不考虑温度作用的变化量,且前者总减小量要大于不考虑温度时总减小量。

Experimental study on permeability characteristics and adsorption swelling of coal considering temperature effect

Using the triaxial servo-controlled seepage equipment for the thermo-fluid-solid coupling of coal containing methane to simulate the changes of permeability characteristics caused by the increase of depth of mining,an experimental study on the permeability during the process of loading tests under different temperatures was carried out,and a adsorption swelling model considering the effect of temperature was developed to study the influence of temperature and pore pressure on the swelling of coal.The results are shown as follows:① With the increase of pore pressure,the axial strain decreases at lower temperature (30,40 ℃) and increases at higher temperature (50,60 ℃).In addition,the radial strain and volumetric strain decrease with the increase of pore pressure；② With the increase of pore pressure,the permeability of coal decreases first and then increases slightly.The trend of the permeability of helium at different temperatures is similar to that of methane and the permeability is higher than that of methane；③ The variable quantity of permeability caused by slippage effect (Δkb) increases with the increase of temperature.The variation of permeability caused by adsorption swelling (Δks) decreases with the increase of pore pressure and then tends to be gentle.With the increase of temperature,Δks increases gradually；and ④ Under the same pore pressure,Δks considering the effect of temperature is higher than that without considering the temperature.During the loading process,the total amount of reduction of Δks considering the effect of temperature is greater than that neglecting it.