Analysis for mechanical characteristics and failure models of coal specimens with non-penetrating single crack

Huayong Lv, Yuesong Tang, Lingfei Zhang, Zhanbo Cheng and Yaning Zhang

Abstract

It is normal to observe the presence of numerous cracks in coal body. And it has significantly effective on the mechanical characteristics and realistic failure models of coal mass. Therefore, this paper is to investigate the influence of crack parameters on coal body by comprehensive using theoretical analysis, laboratory experiments and numerical simulation through prepared briquette specimens. Different from intact coal body possessing single peak in stress-strain curve, other specimens with crack angle can be illustrated to own double peaks. Moreover, the unconfined compressive strength (UCS) of specimens decreases and follow by increasing with the increase of crack angle. It seems to like a parabolic shape with an upward opening. And it can be demonstrated that the minimum UCS is obtained in crack angle 45o. In terms of failure types, it is interesting to note that there is a changing trend from tensile failure to tensile-shear mixing failure with tension dominant follow by shear dominant with the increase of crack angle. However, the changing characteristics of UCS and failure forms can be explained by elastic-plastic and fracture mechanics. Lastly, the results of numerical simulations are good consistent with the experimental results. It provides experimental and theoretical foundations to reveal fracture mechanism of coal body with non-penetrating single crack further.

Key Words

unconfined compressive strength; non-penetrating single crack; crack angle; failure form

Address

Huayong Lv: 1.) School of Resource and Safety Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China 2.) State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Xuzhou 221116, China 3.) Coal Industry Engineering Research Center of Top-coal Caving Mining, Beijing 100083, China Yuesong Tang, Lingfei Zhang and Yaning Zhang: .) School of Resource and Safety Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China 2.) Coal Industry Engineering Research Center of Top-coal Caving Mining, Beijing 100083, China Zhanbo Cheng: 1.) School of Resource and Safety Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China 2.) Coal Industry Engineering Research Center of Top-coal Caving Mining, Beijing 100083, China 3.) School of Engineering, University of Warwick, Coventry CV47AL, U.K.

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