不同冷条件的循环冻融作用对煤样结构损伤的影响

Effect of Freeze-thaw Cycles under Different Cold Conditions on Structural Damageof Coal Samples

为了增加煤体的渗透性,提高煤层气的抽采量。采用循环冻融的方式对煤样进行物理增透,以温度作为实验的唯一变量,探究最优、最高效增透煤样的冷条件;揭示不同冷条件的循环冻融作用对煤样结构损伤的影响规律。研究结果表明:随着阶梯低温的降低,煤样结构冻融损伤程度逐渐增大;不同冷条件温度冻融煤样损伤速率不同,温度低于-33℃或高于-15℃后损伤速率均变缓,-33℃的冷条件温度循环冻融效果最优,循环冻融后孔隙量达2.242;通过理论推导所得的损伤因子计算结果与实验所得结果较为一致,表明理论推导与实验结果真实有效。温度及冻融周期均是煤样损伤的重要原因,实验结果可对绿色能源开采等方面提供重要理论支撑。

In order to increase the permeability of coal body and increase the extraction volume of coalbed methane, the method of cyclic freeze-thaw is used to physically increase the permeability of coal samples. Taking temperature as the only variable in the experiment, the cooling method of the optimal and most efficient permeability-enhancing coal samples is explored conditions;revealing the effect of cyclic freezing and thawing under different cold conditions on the structural damage of coal samples. The research results show that: with the decrease of the step low temperature, the degree of freeze-thaw damage of the coal sample structure gradually increases;the damage rate of the freeze-thaw coal samples at different cold conditions is different, and the temperature is lower than-33℃ or higher than-15℃, the damage rate was slowed down after freeze-thaw cycle, the cold condition temperature of-33°C has the best freeze-thaw effect, and the pore volume reaches 2.242 after freeze-thaw cycle;the calculation results of the damage factor obtained by theoretical derivation are in good agreement with the experimental results, indicating that the theoretical derivation is true and effective.Both temperature and freeze-thaw cycle are important reasons for the damage of coal samples. The experimental results can provide important theoretical support for green energy mining.