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不同加载速率下原煤与型煤的力学渗流特性对比研究

Comparative Study on Mechanical and Permeability Characteristics of Raw Coal and Briquettes under Different Loading Rates

  • 摘要: 以原煤、型煤煤样为研究对象,在三轴压缩变形过程中进行渗流试验,研究了不同加载速率下煤样的力学渗流特性。研究结果表明:加载速率对原煤的弹性模量影响较大,而型煤的弹性模量变化较小,且随着加载速率的增大,原煤、型煤的峰值应力均呈现先增大后减小的趋势;在破坏阶段,型煤的破坏呈现延性特征,而原煤的破坏是突发性的,更接近于现场煤与瓦斯突出的破坏过程;同一加载速率下,型煤和原煤的渗透率虽然都随着应力的增大先减小后增大,但前期型煤的渗透率降低幅度远远大于原煤,且型煤为剪切滑移破坏形式,峰后渗透率低于初始渗透率,而原煤为剪张破坏形式,峰后渗透率激增;随着加载速率的增大,煤样渗透率呈现更明显的“V”字形走势。

     

    Abstract: Taking raw coal and briquette samples as research objects, the seepage test was carried out in the process of triaxial compression deformation, and the mechanical seepage characteristics of coal samples under different loading rates were studied. The results show that the loading rate has a great influence on the elastic modulus of the raw coal, while the elastic modulus of the briquette has a small change,moreover, with the increase of the loading rate, the peak stress of the raw coal and briquette increases first and then decreases; in the destruction stage, the destruction of briquette shows ductility characteristics, while the destruction of raw coal is sudden, which is closer to the destruction process of coal and gas outburst on site; at the same loading rate, although the permeability of both briquette and raw coal decreases first and then increases with the increase of stress, the permeability of briquette decreases more than that of raw coal in the early stage, and the briquette is in the form of shear slip failure, the post-peak permeability is lower than the initial permeability, while the raw coal is in the form of shear and tension failure, and the post-peak permeability increases sharply; with the increase of loading rate, the permeability of coal sample shows a more obvious "V" pattern.

     

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