Structural Engineering and Mechanics

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DEM numerical study on mechanical behaviour of coal with different water distribution models

  • Tan, Lihai (School of Resource Environment and Safety Engineering, University of South China) ;
  • Cai, Xin (School of Resources and Safety Engineering, Central South University) ;
  • Ren, Ting (School of Civil, Mining and Environmental Engineering, University of Wollongong) ;
  • Yang, Xiaohan (School of Civil, Mining and Environmental Engineering, University of Wollongong) ;
  • Rui, Yichao (School of Resources and Safety Engineering, Central South University)
  • Received : 2021.05.31
  • Accepted : 2021.09.24
  • Published : 2021.12.10
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Abstract

The mechanical behaviour and stability of coal mining engineering underground is significantly affected by ground water. In this study, nuclear magnetic resonance imaging (NMRI) technique was employed to determine the water distribution characteristics in coal specimens during saturation process, based on which the functional rule for water distribution was proposed. Then, using discrete element method (DEM), an innovative numerical modelling method was developed to simulate water-weakening effect on coal behaviour considering moisture content and water distribution. Three water distribution numerical models, namely surface-wetting model, core-wetting model and uniform-wetting model, were established to explore the water distribution influences. The feasibility and validity of the surface-wetting model were further demonstrated by comparing the simulation results with laboratory results. The investigation reveals that coal mechanical properties are affected by both water saturation coefficient and water distribution condition. For all water distribution models, micro-cracks always initiate and nucleate in the water-rich area and thus lead to distinct macro fracture characteristics. With the increase of water saturation coefficient, the failure of coal tends to be less violent with less cracks and ejected fragments. In addition, the core-wetting specimen is more sensitive to water than specimens with other water distribution models.

Keywords

Acknowledgement

The authors acknowledge the support of the Graduated Students' Research, National Natural Science Foundation of China (51934007, 51874292, 51804303) and Innovation Fund Project of Central South University (2018zzts210). The authors also would like to extend their appreciation to Dr. Chee on for grammar correction.

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