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Influence of loading and unloading of hydraulic support on the caving property of top coal

  • Huayong Lv (School of Architecture and Engineering, Shangqiu Normal University) ;
  • Fei Liu (College of Emergency Management, Nanjing Tech University) ;
  • Xu Gao (Railway Engineering Research Institute, China Academy of Railway Sciences Corporation Limited) ;
  • Tao Zhou (School of Foreign Languages, Shangqiu Normal University) ;
  • Xiang Yuan (School of Architecture and Engineering, Shangqiu Normal University)
  • Received : 2021.07.06
  • Accepted : 2023.04.28
  • Published : 2023.07.10
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Abstract

The caving property of top coal is a key factor to the success of top coal caving mining. The influence law of cyclic loading and unloading of hydraulic support on top coal caving is of great significance to improve the recovery rate of top coal. The similar simulation methods were used to study the dynamic evolution of the top coal cracks under the multi-cycle action of the support, and the parameters of top coal cracks were analyzed quantitatively in this paper. The results show that the top coal cracks can be divided into horizontal cracks and vertical cracks under the cyclic loading and unloading of the support. With the increase of the times of the support cycles loading and unloading, the load on the support decreases, the fractal dimension of the cracks increases, the number and total length of the top coal cracks increases, and the top coal caving is getting better. With the increase of the times of multi-cycle loading and unloading, the fractal dimension, total crack length and crack rate of top coal show a trend of rapid increase first and then increase slowly. Both the total length of the top coal cracks and the crack rate basically show linear growth with the change of the fractal dimension. The top coal caving can be well improved and the coal resource recovery rate increased through the multi-cycle loading and unloading.

Keywords

Acknowledgement

Authors wish to acknowledge the support from the Innovation and Entrepreneurship Training Program for College Students in Henan Province (Grant No. 202210483014), Henan Province Science and Technology Project (Grant No. 212102310944). The authors would also like to thank the editors and anonymous reviewers for their valuable time and suggestions.

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