冻融循环对煤体孔隙结构的改造特征

为了提高瓦斯抽采效果,探究冻融循环实验对煤体孔隙的改造特征;将真空饱水的无烟煤样放置在冷冻箱(-20℃)中,利用核磁共振T;图谱分析不同冻融循环次数后的致裂效果,研究了煤样冻融前后孔隙结构的变化。结果表明:第1~第3次的冻融循环过程中T;图谱面积增幅较大,且在第3次冻融循环中达到最大值42.41%;第4~第9次冻融循环的T;图谱面积增幅不断减小,冻融循环煤体致裂效果不断减小;在第3次冻融循环过程中,孔隙结构变化最大;综合分析认为3次冻融循环为最佳冻融次数。

Transformation characteristics of pore structure of coal by freezing-thawing cycle

In order to improve the effect of the gas extraction,to explore the transformation characteristics of freezing and thawing cycle of coal pore,vacuum full anthracite coal samples of water are placed in cooler(-20℃),the nuclear magnetic resonance T;spectrum was used to analyze the cracking effect of different freezing-thawing cycles,and the pore structure changes of coal samples before and after freezing-thawing were studied.The results showed that the T;spectrum area increased greatly during the first to third freeze-thaw cycles,and reached the maximum value of 42.41%in the third freeze-thaw cycle.The increase of T;spectrum area of 4 to 9 freeze-thaw cycles decreases continuously,and the cracking effect of freeze-thaw cycles decreases continuously.In the process of the third freeze-thaw cycle,the change of pore structure is the largest,and the comprehensive analysis shows that the third freeze-thaw cycle is the best number of freeze-thaw cycles.