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过程工程学报 ›› 2022, Vol. 22 ›› Issue (12): 1676-1682.DOI: 10.12034/j.issn.1009-606X.221382CSTR: 32067.14.jproeng.221382

• 研究论文 • 上一篇    下一篇

吸附CO2煤体的力学性能劣化机制

朱川曲， 马合意*， 赵鹏涛   

  1. 湖南科技大学资源环境与安全工程学院，湖南 湘潭 411201
  • 收稿日期:2021-11-22 修回日期:2022-02-22 出版日期:2022-12-28 发布日期:2022-12-30
  • 通讯作者: 马合意 mhy6069@163.com
  • 基金资助:
    国家自然科学基金

Degradation mechanism of mechanical properties for CO2 adsorbed coal

Chuanqu ZHU,  Heyi MA*,  Pengtao ZHAO   

  1. School of Resource & Environment and Safety Engineering, Hunan University of Science and Technology, Xiangtan, Hunan 411201, China
  • Received:2021-11-22 Revised:2022-02-22 Online:2022-12-28 Published:2022-12-30

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摘要： 准确了解CO2吸附诱发煤层力学性质的变化是安全实施CO2封存的必要条件。通过进行不同CO2吸附平衡压力下煤样试件的三轴压缩试验，考察了CO2吸附后煤体力学性能的变化规律。结果表明，吸附CO2降低了煤质的表面能，进而降低了煤体整体强度；CO2吸附后引起煤体的塑性效应，导致煤体弹性模量减小；煤体的强度和弹性模量随着CO2吸附平衡压力增大而降低，其变化量可以用Langmuir型曲线描述，相关系数均达到0.99以上。高阶煤(无烟煤)强度和弹性模量均远大于低阶煤(长焰煤)，而吸附CO2后高阶煤的强度和弹性模量降低百分比更高。

关键词: CO2吸附, 吸附平衡压力, 强度和弹性模量, 煤阶, 三轴压缩

Abstract: It is necessary to understand accurately mechanical properties of coal seam induced by CO2 adsorption for the safe and successful implementation of CO2 storage. Through the triaxial compression test of coal samples (long flame coal and anthracite) under different CO2 adsorption equilibrium pressure, the change law of coal mechanical properties after CO2 adsorption is revealed. The research results show that the triaxial stress-strain curves of coal with CO2 adsorption is similar to that of coal without CO2 adsorption, however, after CO2 is adsorbed in coal, it causes the structural reorganization and expansion of the coal, which reduces the surface energy of the coal, and then leads to the obvious reduction of the compressive strength. The higher the CO2 adsorption equilibrium pressure, the greater the reduction of surface energy, and the smaller the tensile strength leading to the formation of coal cracks. CO2 adsorption causes the plastic effect of coal. This plasticization is due to the increase of segment mobility in coal polymer structure caused by CO2 adsorption, which softens the coal, and then leads to the decrease of elastic modulus of coal with the increase of CO2 adsorption equilibrium pressure. In addition, the rearrangement of polymer structure after CO2 adsorption leads to the free volume expansion of coal, the toughness of coal structure is enhanced and the elastic modulus is reduced. The degradation of mechanical properties (strength and elastic modulus) of coal caused by CO2 adsorption can be described by Langmuir curve, and the correlation coefficients are all above 0.99. In the same stress environment, the strength and elastic modulus of high rank coal are higher than that of low rank coal, it is mainly due to the existence of developed cleat system in high rank coal, which provides more conditions for CO2 adsorption. And the decrease percentage of strength and elastic modulus of high rank coal is larger than that of low rank coal after CO2 adsorption.

Key words: CO2 capture, adsorption equilibrium pressure, strength and elastic modulus, coal rank, triaxial compression