2种典型嵌挤骨架配比下混合煤样的渗透特性

Permeability of mixed coal samples with two typical intercalated skeleton ratios

基于轴向压缩位移控制法,利用破碎岩体渗透试验系统,测试了破碎煤样在采用单级嵌挤骨架和级配嵌挤骨架2种配比方式下,承压过程中的渗透特性。结果表明:级配嵌挤骨架煤样压缩过程中,随着20～25 mm含量的增高,渗透率出现明显的平稳变化阶段,说明大煤样颗粒对骨架具有显著的支撑作用,造成煤样内部有效孔隙通道保持平稳;以5～10 mm为主的单级配嵌挤骨架其渗透率远小于其他3组,说明小颗粒煤样对较大煤样颗粒之间的空隙具有良好的充填作用;2种配比方式下,孔压梯度与渗流速度两者之间的二次拟合系数都高达0.94以上,说明煤样压实渗流过程中都满足Forchheimer方程;通过建立的物理模型发现煤样压缩过程中存在侧向约束阻力,其值随轴向压缩位移、渗透压的增大而增大。

Based on the axial compressive displacement control method,the permeability characteristics under pressure of crushing coal samples were tested under the two kinds of mixing modes of single-stage in-frame and cascade-in-frame.The results show that the permeability shows a significant phase of steady change during the compression process of coal samples in the cascades with the increase of 20~25 mm,which indicates that the large particle coal samples have a significant supporting effect on the skeleton,resulting in the pore channel remained stable.The permeability of single-stage in-frame with 5~10 mm is much less than that of the other three groups,which indicates that small particle coal has a good filling effect on the gap between larger coal particles.The two fitting coefficients of pore pressure gradient and seepage velocity are both above 0.94 under the two kinds of proportioning modes,which means that the Forchheimer equation is satisfied during the compaction seepage of coal sample.We have found there is lateral restraint resistance during compression process through the established physical model,its value increases with the axial compression displacement and osmotic pressure.