| 王来贵*,甘超超,李和万,潘纪伟.液氮作用下煤样结构损伤规律研究[J].实验力学,2020,35(1):109~117 |
| 液氮作用下煤样结构损伤规律研究 |
| Study on the law of coal-sample structural damage under liquid nitrogen |
| 投稿时间：2018-06-20 修订日期：2018-09-03 |
| DOI：10.7520/1001-4888-18-150 |
| 中文关键词: 液氮 CT 长焰煤 裂隙 结构损伤 |
| 英文关键词:liquid nitrogen CT long flame coal fissure structural damage |
| 基金项目:国家自然科学基金(51474121, 51274110)资助 |
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| 中文摘要: |
| 为研究液氮浸泡对低渗煤体结构损伤增透的影响，对不同尺寸煤样进行周期性液氮浸泡实验。通过CT扫描观测煤样浸泡前后内部孔隙、裂隙变化情况，采用高倍照相机观测煤样表面形貌，利用超声测速仪测定煤样波速变化，分析液氮浸泡周期对不同尺寸煤样内部结构损伤规律的影响，提出了液氮作用下煤样损伤模型，解释了液氮作用下煤样损伤机理。结果表明：同尺寸煤样，其内部孔隙率、表面裂隙尺寸及波速衰减率随液氮作用周期数的增加而增大，煤样损伤加剧；同周期浸泡条件下，随着煤样尺寸的增大，液氮作用后的煤样孔隙率逐渐降低；液氮作用周期为1T时，煤样孔隙率增加相对显著，损伤效果明显，1T后煤样孔隙率增加幅度逐渐减小；液氮的超低温作用使煤岩基质收缩，煤岩内部产生新微孔隙，多次作用后，微孔隙发育、扩展和贯通使煤岩出现宏观裂纹并发生破坏。 |
| 英文摘要: |
| In order to study the effect of liquid nitrogen soaking on the structural damage of low permeability coal, periodic liquid nitrogen immersion experiments were carried out on different sizes of coal samples. The changes of internal pores and cracks of coal samples before and after soaking were observed by the CT scanning. The surface morphology of coal samples was observed by the high resolution camera, and the change of coal wave velocity was measured by the ultrasonic velocimeter. The effect of liquid nitrogen soaking cycle on the internal structural damage of coal samples with different sizes was analyzed. A damage model of coal samples under liquid nitrogen was presented, and the damage mechanism of coal samples under liquid nitrogen was explained. The results showed that the internal porosity, surface crack size and wave velocity decay rate of the same size coal sample as well as the damage degree of the same size coal sample increased with the increase of the number of liquid nitrogen cycles. With the increase of coal sample size, the porosity of coal samples decreased gradually after soaked in liquid nitrogen during the same period. When the liquid nitrogen cycle was 1T, the porosity of coal samples increased significantly, and the damage effect was obtained obviously. When the liquid nitrogen cycle exceeded 1T, the increase of coal sample porosity decreased gradually. The ultra-low temperature effect of liquid nitrogen made the coal rock matrix shrinking, and the new micro-pores were produced inside the coal rock. After many times of interaction, the micro-pore gap was developed, expanded and penetrated to make the coal rock crack and finally destroy. |
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