1.School of Safety Science and Engineering, Henan Polytechnic University, Jiaozuo , China;2.Hebei Provincial Key Lab of Mine DisasterPrevention,North China Institute of Science and Technology,Sanhe,China;3.State and Local Joint Engineering Lab of Gas Drainage andSurrounding Rock Control in Deep Mine,Henan Polytechnic University,Jiaozuo China;4.Collaborative Innovation Center of Coal SafetyProduction,Henan Polytechnic University, Jiaozuo , China

为了研究液氮对含水煤岩的作用机制，利用自行研制的自增压式液氮冷浸装置对不同含水饱和度煤样进行液氮冷浸试验，对比分析了液氮冷浸前后煤样渗透率变化规律和微观孔、裂隙发育情况，并从理论角度解释了液氮冷浸对含水煤样的损伤机制。结果表明，经液氮冷浸后，煤样渗透率随含水饱和度的增大而增大，增加幅度成指数型增长且增加幅度在70.6%~1 254.9%；在煤样饱水情况下，液氮对煤岩的影响以水冰相变造成的体积膨胀为主，其微观结构破坏程度远高于干燥煤样，煤样出现裂隙延伸、裂隙加宽等现象，增透效果更好。

In order to study the action mechanism of the liquid nitrogen to the water bearing coal and rock, a self developed self pressurized liquid nitrogen cold immersion device was applied to the liquid nitrogen cold immersion test on the coal samples with different water bearing saturation and a comparison analysis was conducted on the permeability variation law and micropore, pore development condition of the coal samples before and after the liquid nitrogen cold immersion. From a view of the theory, the paper had an explanation on the damage mechanism of the water bearing coal samples by the liquid nitrogen cold immersion. The results showed that after the liquid nitrogen cold immersion, the permeability of the coal samples would be increased with the water bearing saturation increased. The increased amplitude would be in an index type increasing and the increased amplitude was ranging from 70.6% to 1 254.9%. Under the saturation condition of the coal samples, the liquid nitrogen affected to the coal and rock would be the water-ice phase change to make the volume expansion mainly. The failure degree of the micro-structure would be higher than the dry coal samples. The coal sample would have the pore extension, pore widening and other phenomenon and the permeability effect would be better.