液氮溶浸时间对原煤力学及破坏形式的影响

    The influence of liquid nitrogen leaching time on raw coal mechanics and failure mode

    • 摘要: 为了研究液氮溶浸处理对煤样单轴和三轴加载力学性质及破坏形式的影响规律,采用三轴实验装置对不同液氮溶浸时间煤样进行单轴、三轴实验。结果表明:是否进行液氮溶浸处理对煤样单轴加载和三轴加载过程中力学特性演化趋势无明显影响,均为随着轴向应变增加,轴向应力先缓慢增加,后直线增大,达到煤样极限后迅速降低;液氮溶浸不同时间煤样单轴加载峰值轴向应力分别为4.28、7.21、2.32、2.34 MPa,三轴加载峰值轴向应力分别为44.31、25.73、37.74、39.78 MPa;随着液氮溶浸时间增加,煤样单轴加载峰值轴向应力呈现出先增大后减小的变化趋势,三轴加载峰值轴向应力呈现出先减小后增大的变化趋势;液氮溶浸煤样在单轴加载和三轴加载后局部破碎更彻底,但液氮溶浸时间越长,煤样破碎后生成的大块煤数量和体积都越多。

       

      Abstract: In order to study the influence of liquid nitrogen leaching treatment on the mechanical properties and failure modes of coal samples under uniaxial and triaxial loading, uniaxial and triaxial tests were carried out on coal samples with different liquid nitrogen leaching time by triaxial test device. The results show that whether liquid nitrogen leaching treatment is carried out has no obvious influence on the evolution trend of mechanical properties of coal samples during uniaxial loading and triaxial loading; with the increase of axial strain, the axial stress increases slowly at first, then increases linearly, and decreases rapidly after reaching the limit of coal samples. The peak axial stress of coal samples under uniaxial loading at different time of liquid nitrogen leaching is 4.28 MPa, 7.21 MPa, 2.32 MPa and 2.34 MPa respectively, and the peak axial stress under triaxial loading is 44.31 MPa, 25.73 MPa, 37.74 MPa and 39.78 MPa respectively. With the increase of liquid nitrogen leaching time, the peak axial stress of coal samples under uniaxial loading shows a trend of increasing first and then decreasing, and the peak axial stress under triaxial loading shows a trend of decreasing first and then increasing. The liquid nitrogen leaching coal sample is partially broken more thoroughly after uniaxial loading and triaxial loading, but the longer the liquid nitrogen leaching time is, the more the number and volume of large coal generated after the coal sample is broken.

       

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