Study on Acoustic Emission Characteristics and Failure Mode Identification of Beishan Granite

Direct tensile, Brazilian splitting, and triaxial compression tests were carried out for Beishan granite, and acoustic emission events were monitored during the test. Acoustic emission characteristics are analyzed in detail and based on the acoustic emission characteristics, the identification models of rock fracture are established by the Fisher method. The results show that: (1) The strength of the direct tensile test is about 1.23 times that of the Brazilian splitting test; (2) b value of the Brazilian splitting test shows a "W" changing trend, while the b value of the direct tensile test and the triaxial test shows a downward fluctuation trend; (3) AF/RA value of Brazilian splitting test shows stable fluctuation, AF/RA value of direct tensile test experience rising stage, falling stage and small fluctuation stage, AF/RA value of triaxial compression test fluctuates and decreases before the stress reaches the peak, but AF/RA is in a large fluctuation state after the peak; (4) Based on Fisher method, three failure models of test specimens are established, and the accuracy of the modes were further analyzed.