Understanding the evolution mechanism and classification criteria of tensile -shear cracks in rock failure process from acoustic emission (AE) characteristics

• Five failure stages of rock were divided by accumulative AE hits line method, and crack closure stress ( σ cc ), crack initiation stress ( σ ci ) and crack damage stress ( σ cd ) were determined. • A criterion for crack classification is proposed based on AE spectral parameters (Ad, FW), and a straight line dividing tensile and shear cracks was obtained in the density map of RA-AF.. • Based on the evolution characteristics of crack scale and type, the failure modes of different rocks were determined and verified by the failure images. This study aimed to investigate the crack evolution and failure mechanism of rocks by conducting uniaxial compression tests (UCT) and Brazilian indirect tension tests (BITT)…