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| Experimental study on the relationship between mode I static fracture toughness and newly added surface area after crushing |
| CAI Zenghui1,2,HUANG Gun1,2,ZHENG Jie1,2,CHENG Qiang1,2,GENG Weile1,2 |
| (1. State Key Laboratory of Coal Mine Disaster Dynamic and Control,Chongqing University,Chongqing 400044,China;2. School of Resources and Safety Engineering,Chongqing University,Chongqing 400044,China) |
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Abstract Three-point bending tests and grinding tests were carried out with notched semi-circular bend(NSCB) and 1–2 mm/0.425–1 mm particle size samples,and theoretical analysis was performed based on fracture mechanics and rock fragmentation. The theoretical analysis shows that the second power of the fracture toughness is directly proportional to the reciprocal of the newly added surface area after crushing. The fitting results on the test data also indicate that there is a good proportion between the second power of the fracture toughness and the reciprocal of the newly added surface area of the 1–2 mm/0.425–1 mm particle size samples after grinding,and the correlation coefficient R2 are 0.974 and 0.878 respectively,which shows that the fracture toughness of coal can be estimated by the newly added surface area calculated easily and then the surface energy can be obtained. The research not only provides a new test method for the determination of the fracture toughness of coal but also provides an experimental basis for further understanding of the energy dissipation in the process of outburst.
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