煤田地质与勘探

2024, v.52;No.316(04) 21-34

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不同围压与饱和度下含瓦斯水合物煤体能量变化规律
Laws of changes in the energy of gas hydrate-bearing coals under different confining pressures and saturations

祝威,高霞,张保勇,吴强
ZHU Wei,GAO Xia,ZHANG Baoyong,WU Qiang

摘要(Abstract)：

突出煤层瓦斯水合固化是一项新型降低瓦斯压力增强煤体强度的防突技术，不同围压、饱和度下含瓦斯水合物煤体破坏特性及能量耗散规律尚不明确，无法为现场深部煤与瓦斯突出等动力灾害预防提供理论依据。基于三轴压缩试验获取的偏应力-应变曲线，计算并分析不同围压(12、16、20 MPa)、饱和度(20%、50%、80%)下含瓦斯水合物煤体三轴压缩过程中能量变化规律。研究表明：(1)含瓦斯水合物煤体三轴压缩过程中总能量、弹性能及耗散能均随着轴向应变增加而增大，外界做功在弹性阶段和屈服阶段前期主要转化为弹性能，在屈服阶段后期和强化阶段主要转化为耗散能。(2)当围压从12 MPa增加到20 MPa、饱和度从20%增加到80%，其临界破坏点总能量不断增大，增幅分别为120.30%和81.60%，储能极限与临界破坏点耗散能也随围压增加而增大，增幅分别为174.89%和110.73%，含瓦斯水合物煤体在高围压和高饱和度下吸收能量的能力、抵抗变形破坏的能力及损伤所消耗的能量的量均高于低围压，越不容易破坏。(3)能耗比随着轴向应变增加匀速增大，饱和度50%和80%时，临界轴向应变随围压的增加而增大，但随着饱和度增大临界轴向应变对围压的敏感性降低。(4)围压16、20 MPa下，储能极限随着储能系数的增加而增大，储能系数与储能极限同等具有表征含瓦斯水合物煤体储存弹性能的能力。(5)煤体中水合物生成能够有效降低瓦斯压力，提高煤体峰值强度、临界破坏点总能量、储能极限及临界破坏点耗散能，整体提升幅度21.11%～42.11%，有利于提升煤体抵抗外力破坏的能力。研究成果揭示了含瓦斯水合物煤体受载损伤能量变化规律，可为深部煤与瓦斯突出等动力灾害的防治提供一定的理论指导。
Gas hydration for the solidification of coal seams susceptible to outbursts is a novel technology used to prevent coal and gas outbursts by reducing gas pressure and enhancing coal strength. However, an unclear understanding of the failure characteristics and the energy dissipation law of gas hydrate-bearing coals under different confining pressures and saturations leads to the lack of a theoretical basis for the prevention of dynamic disasters such as field coal and gas outbursts in deep mines. Based on the deviatoric stress-strain curves obtained using triaxial compression tests, this study calculated and analyzed the laws of changes in energy of gas hydrate-bearing coals during triaxial compression under different confining pressures(12, 16, and 20 MPa) and saturations(20%, 50%, and 80%). The results are as follows:(1) The total energy, elastic energy, and dissipation energy of gas hydrate-bearing coals increased with an increase in the axial strain during triaxial compression. The external work was mainly converted into the elastic energy in the elastic stage and the early yield stage and was primarily converted into the dissipation energy in the late yield stage and the reinforcement stage.(2) In cases where the confining pressure increased from 12 MPa to 20 MPa and the saturation increased from 20% to 80%, the total energy at the critical failure point increased constantly, with increased amplitude of120.30% and 81.60%, respectively. The energy storage limit and the dissipation energy at the critical failure point also increased with the confining pressure, with increased amplitude of 174.89% and 110.73%, respectively. Therefore, the gas hydrate-bearing coals were less likely to fail under a high confining pressure and saturation due to their enhanced abilities to absorb energy and resist deformations and failure, as well as elevated energy consumed by damage, compared to a low confining pressure.(3) The ratio of dissipated energy to elastic energy increased with the axial strain. Under saturations of 50% and 80%, the critical axial strain increased with the confining pressure, but its sensitivity to the confining pressure decreased with an increase in the saturation.(4) Under confining pressures of 16 MPa and 20 MPa,the energy storage limit increased with the energy storage coefficient. Both the energy storage coefficient and the energy storage limit exhibited comparable abilities to characterize gas hydrate-bearing coals' storage capacity of elastic energy.(5) Hydrate formation in coals effectively reduced the gas pressure and enhanced the peak strength of coals, the total energy at the critical failure point, the energy storage limit, and the dissipation energy at the critical failure point, with the overall increased amplitude ranging between 21.11% and 42.11%. These are conducive to improving the coals' ability to resist damage by external forces. The results of this study reveal the laws of changes in the energy of gas hydrate-bearing coals subjected to damage by external loads, serving as a theoretical guide for the prevention and control of dynamic disasters such as coal and gas outbursts in deep coal mines.

关键词(KeyWords)： 煤与瓦斯突出;含瓦斯水合物煤体;三轴压缩试验;能量特征
coal and gas outburst;gas hydrate-bearing coal;triaxial compression test;energy characteristic

Abstract:

Keywords:

基金项目(Foundation): 国家自然科学基金联合基金项目(U21A20111);国家自然科学基金面上项目(51974112,51674108)

作者(Author): 祝威,高霞,张保勇,吴强
ZHU Wei,GAO Xia,ZHANG Baoyong,WU Qiang

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