Structural Engineering and Mechanics

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Numerical simulation on the crack initiation and propagation of coal with combined defects

  • Lv, Huayong (School of Architecture and Engineering, Shangqiu Normal University) ;
  • Cheng, Zhanbo (School of Engineering, University of Warwick) ;
  • Dong, Yaqing (School of Architecture and Engineering, Shangqiu Normal University) ;
  • Zhang, Jing (School of Mathematics and Statistics, Shangqiu Normal University) ;
  • Ma, Yujie (School of Architecture and Engineering, Shangqiu Normal University)
  • Received : 2021.01.31
  • Accepted : 2021.05.30
  • Published : 2021.07.25
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Abstract

There is normally the occurrence of pre-existing cracks and holes in coal mass to influence its mechanical behaviours. And the crack initiation and propagation around the tip of pre-existing cracks can be observed to induce the overall failure of coal mass finally. In this study, two groups of hole with the radius of 10mm connecting one crack with length and width of 20 mm and 1 mm, respectively, were pre-existed in sample to explore the influence of crack angle (from 0 to 90°) on the unconfined compressive strength (UCS), crack initiation and propagation, and failure modes of coal mass with combined faults by using RFPA2D. The results showed that the stress-strain curves of specimen with double-hole-crack exhibit multiple stress drop compared to that of intact coal sample, especially in the post-peak stage. Moreover, UCS decreased firstly with the crack angle increasing to 30° and then increased until the crack angle reaching to 75° following by decreasing with the continuous increase of crack angle to 90°. In addition, the failure mode of double-hole-crack specimen with the crack angle of 0-30° can be regards as the dominated tensile failure combined with shear failure, which was consist with the failure pattern of intact specimen. On the other hand, the failure mode of double-hole-crack specimen with the crack angle of 45-90° is the dominated shear failure combined with tensile failure. Meanwhile, the distribution characteristics of acoustic emission energy can be used to better reflect the deformation and failure process of coal mass with combined defects.

Keywords

Acknowledgement

The authors wish to acknowledge the financial support from National Natural Science Foundation of China under Grant No. 51674264, Research Startup Budget Funding Project of Shangqiu Normal University under Grant No. 700167 and China Scholarship Council (CSC). The authors would also like to thank the editors and anonymous reviewers for their valuable time and suggestions.

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