Journal of Experiental Mechanicals

节理煤体低温损伤机理及影响范围研究

Research on low temperature damage mechanism and influence scope of intermittent joint coal body

Received:December 01, 2021 Revised:March 22, 2022

英文关键词:joint water saturation cyclic cold loading single-cycle heat transfer influence scope

基金项目:国家自然科学基金青年基金资助项目(51704142)；国家重点研发计划(2017YFC1503102)；辽宁省博士科研启动基金计划项目(2019-BS-115)

Author Name	Affiliation
LI Hewan*	Department of Mechanics and Science Engineering, Liaoning Technical University, Fuxin 123000, Liaoning, China
LIU Jian	Department of Mechanics and Science Engineering, Liaoning Technical University, Fuxin 123000, Liaoning, China
WANG Laigui	Department of Mechanics and Science Engineering, Liaoning Technical University, Fuxin 123000, Liaoning, China
REN Tianjiao	Department of Mechanics and Science Engineering, Liaoning Technical University, Fuxin 123000, Liaoning, China

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中文摘要:

节理普遍存在于地下煤储层中,是煤层气存储和运移的主要通道。为了研究冻融作用下煤体自身含水饱和度的不同,对节理结构损伤和液氮作为煤体的制冷剂逆传热至-45℃作用范围的影响,利用低温保存箱为不同含水饱和度煤样提供-45℃低温环境,对煤样进行循环冻融交叉实验；并建立以液氮作为制冷剂的传热模型,进行单周期低温加载数值模拟。结果表明：(1)煤样表面以及内部节理扩展量随着低温循环冻融周期的增加而逐渐增大,单轴抗压强度逐渐降低；煤样表面维度逐渐从二维向三维转化、表面及内部节理结构损伤程度加剧；(2)煤样节理结构损伤程度随含水饱和度的增加而增大,100%饱和度时,煤样循环冻融41周期后破碎；(3)单周期传热模型随着含水饱和度的升高,影响范围变小,且传热时间变长,100%含水饱和度下煤体传热至-45℃的传热半径仅为2.77m,所用时间为2531.2s,表明含水饱和度制约着传热半径及传热时间,含水饱和度越高,制约越明显。

英文摘要:

Joints commonly exist in underground coal reservoirs and are the main space for CBM storage and migration. In order to study the damage mechanism of the different water saturation of the coal body on the joint structure under the action of freezing and thawing and the influence range of the reverse heat transfer of liquid nitrogen as the refrigerant of the coal body to -45℃, a low-temperature storage box was used for coal with different water saturation. The samples were provided with a low temperature environment of -45℃, and the cyclic freeze-thaw cross experiment was carried out on the coal samples; a heat transfer model with liquid nitrogen as the refrigerant was established, and a single-cycle low-temperature loading numerical simulation was carried out. The results show that: (1) With the increase of the freeze-thaw cycle of the low temperature cycle, the expansion amount of the coal sample surface and internal joints gradually increases, and the uniaxial compressive strength gradually decreases; The damage degree is aggravated. (2) The damage degree of the coal sample structure increases with the increase of the water saturation. When the saturation is 100%, the coal sample freeze-thaw cycle is 41T, and the coal sample is more likely to be damaged or even destroyed. (3) As the water saturation increases in single cycle, the heat transfer radius becomes smaller and the heat transfer time becomes longer. Under 100% water saturation, the heat transfer radius of the coal body to -45℃ is only 2.77m. The time is 2531.2s, indicating that the water saturation restricts the heat transfer radius and heat transfer time. The higher the water saturation, the more obvious the restriction. The experimental and simulation results can provide a theoretical basis for predicting and efficiently exploiting coalbed methane in practical engineering.

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