力热耦合条件下煤岩渗透率模型研究

Research on model for permeability of coal under stress and temperature coupling condition

为研究随采深增加煤岩的渗流变化趋势,利用含瓦斯煤热-流-固耦合三轴伺服渗流装置,进行不同温度下孔隙压力改变的渗流试验,建立力热耦合作用下考虑滑脱效应的煤岩渗透率模型,采用试验数据验证模型的有效性。研究结果表明:在孔隙压力增大过程中,瓦斯流量逐渐增加,随温度升高体积应变、径向应变均呈降低趋势,轴向应变呈先降低后升高趋势;随孔隙压力增大,煤岩渗透率先逐渐减小后趋于平缓,且随温度升高,煤岩渗透率呈增大趋势;考虑力热耦合作用下煤岩渗透率模型计算出的渗透率与试验所测结果吻合较好;在低孔隙压力下滑脱效应较明显,随着孔隙压力增大,滑脱效应逐渐减弱。

In order to study the variation trend in seepage of coal with increasing depth of mining,seepage experiments were carried out by using a piece of triaxial servo-controlled seepage equipment for thermo-fluid-solid coupling of coal containing methane. A permeability model considering slippage effect under the stress and temperature coupling condition was built. The model was verified by experimental data. That there is a negative correlation between the volumetric strain and the radial strain,and the axial strain show the opposite trend of decreasing and increasing with the increase of temperature,that the permeability first decreases and then tends to be gentle with the increase of pore pressure,and it shows an increasing trend with the increase of temperature. The permeability calculated by the permeability model of coal under the coupling condition between stress and thermal conforms with the experimental results,andthat under the low porosity pressure,the slippage effect is more obvious,and it is weakened with the increase of pore pressure.