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| Study on characteristics of failure strength and crack propagation of granite rocks containing a single fissure |
| ZHANG Guokai1，2，LI Haibo2，WANG Mingyang1，3，LI Xiaofeng2 |
| (1. School of Mechanical Engineering，Nanjing University of Science and Technology，Nanjing，Jiangsu 210094，China；2. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China；3. State Key Laboratory of Disaster Prevention and Mitigation of Explosion and Impact，
Army Engineering University of PLA，Nanjing，Jiangsu 210007，China) |
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Abstract In order to study the strength characteristics and failure process of fractured rocks，uniaxial compression tests together with AE monitoring were conducted on granites containing a single fissure. The stress-strain data，multi-parameters of AE and video recording were used to analyze the characteristics of crack evolution and their correlations. The results show that the fissure angle has a bigger influence on crack initiation stress and failure strength. The modulus and crack initiation stress increase monotonously with . The stress-strain curves of fractured rocks rise stepwise before the peak strength，and stress drop occurs several times when is small. It?s revealed that the stress drop coincides with the deterioration of modulus，sharp bulge of AE event rate and energy rate. AE event evolution of fractured granites is divided into three stages，with the increase of ，the three-stages characteristic gradually weakens and the brittle failure increases. Moreover，the number of stress drop and AE bulges gradually decrease，but stress levels corresponding to the maximum of AE rate keep increasing. Compared with AE event，the maximum energy rate occurs closer to the peak stress，and AE energy changes more severely. The spatiotemporal evolution of AE hypocenters depicts the three-dimensional propagation region and distribution of cracks. The amplitude of hypocenters occurred at the stable growth period are small，and the number of large-amplitude hypocenters increases rapidly after the high-speed growth period，especially prior to the failure.
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2019, Vol. 38 
