分阶段卸载条件下突出煤变形特征与渗流特性

发布时间：2018-10-10 07:41

【摘要】：为研究下保护层开采过程中采动应力作用下含瓦斯突出煤的渗流特性,利用自制的三轴渗流试验机,进行了恒定轴压卸围压、增大轴压卸围压、轴压围压同时卸载等3种不同加卸载条件下的分阶段卸围压煤样瓦斯渗流试验。试验结果表明:试验中煤样的变形具有明显的阶梯状特性,煤样未破坏时,应变增量随着围压卸载速率的增大而增大。随着围压的卸载,恒定轴压卸围压组和增大轴压卸围压组煤样的偏应力不断增大,其渗透率则呈现出先减小后增大的趋势,而轴压和围压同时卸载组煤样的渗透率则随着围压的卸载,呈现出不断增大的趋势。煤样体积应变变化量较大时,渗透率变化量也大。从能量的角度分析渗透率的变化,发现煤样渗透率均随能量耗散率的增大而呈指数增大。
[Abstract]:In order to study the percolation characteristics of gas-bearing outburst coal under the mining dynamic stress of the lower protective layer, a triaxial percolation testing machine is used to carry out constant axial pressure relief and increase the axial pressure. The gas seepage test of coal sample under three different loading and unloading conditions, such as axial pressure and simultaneously unloading, is carried out in different stages. The test results show that the deformation of coal samples has obvious ladder characteristics in the test, and the strain increment increases with the increase of confining pressure unloading rate when the coal sample is not destroyed. With the unloading of confining pressure, the deviation stress of the coal samples of the constant axial pressure unloading group and the increasing axial pressure unloading group increases continuously, while the permeability of the coal sample decreases first and then increases. However, the permeability of coal samples under axial pressure and confining pressure at the same time increases with the unloading of confining pressure. When the volume strain variation of coal sample is large, the permeability change is also large. By analyzing the change of permeability from the angle of energy, it is found that the permeability of coal samples increases exponentially with the increase of energy dissipation rate.
【作者单位】：重庆大学煤矿灾害动力学与控制国家重点实验室;
【基金】：高等学校博士学科点专项科研基金资助项目(20130191130003) 重庆市基础与前沿研究计划资助项目(cstc2015jcyj A90011) 国家科技重大专项资助项目(2016ZX05045001-005)
【分类号】：TD712

【参考文献】