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<p>Dynamic impact disasters involving coal and rock pose serious threats to the safety of deep mining operations. To investigate the disasters that occur when roadways traverse coal–rock strata, four coal–rock combinations with identical proportions were subjected to one-sided unloading impact experiments. An anomaly was observed in one specific sample (19–24#), which exhibited significantly higher acoustic emission energy and fragment kinetic energy—reaching 7.85 times the average of the other samples—despite all specimens being collected from the same working face and tested under identical conditions. To investigate this, scanning electron microscope (SEM) analysis was performed at nine positions on both the anomalous sample and a typical sample (15–16#) at magnifications of 1,000 × and 100,000 ×. Porosity and pore characteristics were then quantified using ImageJ software. However, the SEM results revealed no significant structural differences between the two samples. Consequently, small-angle neutron scattering (SANS) was employed to examine nanoscale features, revealing higher porosity in the 1–100&#xa0;nm range and a distinct pore size distribution (PSD) in the anomalous sample. Notably, the PSD of the typical sample was entirely encompassed within that of the anomalous sample. These findings provide a microstructural explanation for the sharp increase in kinetic energy observed during the impact experiments.</p><p><b>Highlights</b><UnorderedList Mark="Bullet"> <ItemContent> <p>This paper offers a new perspective from the view of microstructure to explain the significant increase (7.85 times higher than average) in fragment kinetic energy in true triaxial unloading impact experiments.</p> </ItemContent> <ItemContent> <p>The small-angle neutron scattering was first applied to analyze the influence of the kinetic energy of fragments generated in true triaxial unloading impact experiments.</p> </ItemContent> <ItemContent> <p>The influence of the microstructure of coal fragments generated by true triaxial unloading impact experiments on the kinetic energy of fragments was revealed.</p> </ItemContent> </UnorderedList></p>

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The Influence of Microstructures on the Coal Fragment’s Kinetic Energy Generated by the True Triaxial Unloading Impact Experiments

  • 期刊论文

  • 发表日期：

    2026年2月26日

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  • Shankun Zhao,
  • Yishan Pan,
  • Yubin Ke,
  • Yingjun Li,
  • Bo Hu,
  • Weichen Li,
  • Mingyuan Zhang,
  • Zhenhua Xie

摘要

Dynamic impact disasters involving coal and rock pose serious threats to the safety of deep mining operations. To investigate the disasters that occur when roadways traverse coal–rock strata, four coal–rock combinations with identical proportions were subjected to one-sided unloading impact experiments. An anomaly was observed in one specific sample (19–24#), which exhibited significantly higher acoustic emission energy and fragment kinetic energy—reaching 7.85 times the average of the other samples—despite all specimens being collected from the same working face and tested under identical conditions. To investigate this, scanning electron microscope (SEM) analysis was performed at nine positions on both the anomalous sample and a typical sample (15–16#) at magnifications of 1,000 × and 100,000 ×. Porosity and pore characteristics were then quantified using ImageJ software. However, the SEM results revealed no significant structural differences between the two samples. Consequently, small-angle neutron scattering (SANS) was employed to examine nanoscale features, revealing higher porosity in the 1–100 nm range and a distinct pore size distribution (PSD) in the anomalous sample. Notably, the PSD of the typical sample was entirely encompassed within that of the anomalous sample. These findings provide a microstructural explanation for the sharp increase in kinetic energy observed during the impact experiments.

Highlights

This paper offers a new perspective from the view of microstructure to explain the significant increase (7.85 times higher than average) in fragment kinetic energy in true triaxial unloading impact experiments.

The small-angle neutron scattering was first applied to analyze the influence of the kinetic energy of fragments generated in true triaxial unloading impact experiments.

The influence of the microstructure of coal fragments generated by true triaxial unloading impact experiments on the kinetic energy of fragments was revealed.