Abstract
High in‐situ stress and frequent dynamic disturbances caused by the mining process in deep coal mines can easily induce dynamic disasters such as coal burst. We conducted laboratory experiments to assess the effects of the axial stress loading and dynamic cyclic impact loading on the dynamic mechanical properties of burst‐prone coals by using a modified split Hopkinson pressure bar (SHPB). Comparisons were made using two types of burst‐prone and burst‐resistant coal samples. The mineral components, organic macerals, and dynamic mechanical features of both burst‐prone and burst‐resistant coal samples were comparatively analyzed based on the obtained X‐ray diffraction (XRD), optical microscope observations, and dynamic compressive stress‐strain curves, respectively. The results of the microstructure analysis indicated a larger difference between the minimum and maximum reflectances of vitrinite for burst‐prone coal. Compared to the burst‐resistant coal samples, the burst‐prone coals contained less corpocollinite and fusinite. While applying a high axial static load combined with cyclic impact load, the coal samples showed the characteristics of fatigue damage. The results also demonstrated that preaxial stress affected the burst resistance of coal samples. The greater the preaxial stress was, the less the coal samples could withstand the dynamic cyclic impact load. In comparison to the burst‐resistant coal sample, the burst‐prone coal sample showed a larger dynamic compressive strength and a lower deformation. They were also more positively capable of the propagation and activation of the coal burst. We believe that the results of the study are conducive to further understanding of the distribution of microcomponents of burst‐prone coals. The results are also beneficial for realizing the dynamic mechanical characteristics of burst‐prone coals under the impact of cyclic dynamic load.
Highlights
Coal is China’s basic energy and fuel resource, accounting for 59.0% of total energy consumption in 2019
Coal burst is a dynamic phenomenon characterized by sudden, rapid, and violent destruction, produced by the instantaneous release of elastic deformation energy in the coal mass around the mine roadway or stope [5,6,7,8]. Such coal burst can result in extensive damage to mine equipment (Figure 1(a)) and even can lead to numerous injuries and fatalities. e first recorded coal burst occurred in England in 1738
For more than 200 years, the harm due to coal burst has almost spread in mining countries all over the world. e coal burst disaster in China’s coal mines is extremely serious
Summary
Received 21 December 2020; Revised 29 December 2020; Accepted 4 January 2021; Published 13 January 2021. We conducted laboratory experiments to assess the effects of the axial stress loading and dynamic cyclic impact loading on the dynamic mechanical properties of burst-prone coals by using a modified split Hopkinson pressure bar (SHPB). Comparisons were made using two types of burst-prone and burst-resistant coal samples. E mineral components, organic macerals, and dynamic mechanical features of both burst-prone and burst-resistant coal samples were comparatively analyzed based on the obtained X-ray diffraction (XRD), optical microscope observations, and dynamic compressive stress-strain curves, respectively. E greater the preaxial stress was, the less the coal samples could withstand the dynamic cyclic impact load. In comparison to the burst-resistant coal sample, the burst-prone coal sample showed a larger dynamic compressive strength and a lower deformation. E results are beneficial for realizing the dynamic mechanical characteristics of burst-prone coals under the impact of cyclic dynamic load We believe that the results of the study are conducive to further understanding of the distribution of microcomponents of burst-prone coals. e results are beneficial for realizing the dynamic mechanical characteristics of burst-prone coals under the impact of cyclic dynamic load
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