Quantitative Evaluation Methods of Brittle Failure Characteristics of Coal: A Case Study of Hard Coal in China
Coal brittleness is one of the important indexes to characterize the post-peak characteristics of coal, which is closely related to the efficiency of underground coal mining and the degree of coal disaster. In this paper, the compression characteristics of coal are studied by laboratory experiment, which is characterized by relatively long nonlinear elastic stage, smaller plastic stage and stress drops in post-peak stage. On this basis, the existing brittleness evaluation methods are summarized, and the applicability of 11 indexes of 6 physical parameters to the quantitative evaluation methods of coal brittleness are analyzed and discussed. The results show that: (1) for the coal is a complexity heterogeneous medium with hole and fracture, there are different degrees of limitation on the methods of coal brittleness quantitative evaluation,which can be used to roughly estimate the brittleness of coal, but it can not accurately characterize its brittle characteristics. (2) Based on the whole process stress–strain curve, the brittleness degree index B5 is more suitable for the brittleness characterization of coal by quantitatively considering the relative size and absolute rate of post-peak stress drop.
KeywordsCoal Brittleness characteristics Quantitative evaluation Stress–strain curve
The research was supported by the Beijing Natural Science Foundation (8174072), the National Natural Science Foundation (51627804), the National Key R & D Programme of China (2016YFC0801400), an Open Project of The Research Centre of Coal Resources Safe Mining and Clean Coal Utilisation, Liaoning (LNTU16KF08), The State Key Laboratory of Coal Resources and Safe Mining (China University of Mining and Technology) under Grant Nos SKLCRSM16KFB07 and SKLCRSM16DCB01, and The National Natural Science Foundation of China under Grant No. 41272347: this support is gratefully acknowledged.
- Gao B, Huigui Li, Lin Li et al (2014) Study of acoustic emission and fractal characteristics of soft and hard coal samples with same group. Chin J Rock Mechan Eng 33(S2):3498–3504Google Scholar
- He J, Pan J, Wang A (2014) Acoustic emission characteristics of coal specimen under triaxial cyclic loading and unloading. J China Coal Soc 39(01):84–90Google Scholar
- Liu K, Liu Q, Yuanguang Zhu et al (2013) Experimental study of coal considering directivity effect of bedding plane under Brazilian splitting and uniaxial compression. Chin J Rock Mechan Eng 32(02):308–316Google Scholar
- Liu Q, Liu K, Lu X et al (2014) Study of mechanical properties of raw coal under high stress with triaxial compression. Chin J Rock Mechan Eng 33(01):3429–3438Google Scholar
- Su Chengdong, Gao B, Hua Nan et al (2009) Experimental study on acoustic emission characteristics during deformation and failure processes of coal samples under different stress paths. Chin J Rock Mechan Eng 28(04):757–766Google Scholar
- Su Chengdong, Tang Xu, Xiaoming Ni (2012) Study on correlation among point load strength, compression and tensile strength of coal samples. J Min Saf Eng 29(04):511–515Google Scholar
- Su Chengdong, Xiaoxiang Chen, Ruifu Yuan (2014) Analysis of aeformation and strength characteristics of coal samples under uniaxial compression of stepped relaxation. Chin J Rock Mechan Eng 33(06):1135–1141Google Scholar
- Sun CM, Cao SG, Li Y (2017) Mesomechanics coal experiment and an elastic-brittle damage model based on texture features. Int J Min Sci Technol. OnlineGoogle Scholar
- Zhou H, Men Men Fanzhen, Chuanqing Zhang et al (2014) Quantitative evaluation of rock brittleness based on stress–strain curve. Chin J Rock Mechan Eng 33(06):1114–1122Google Scholar