Abstract: In this study, uniaxial cyclic loading tests were carried out on granite specimens to study the relationship between acoustic emission (AE) characteristics and non-uniform deformation of rock materials during the cyclic loading process. The AE signals and the deformation images of the specimen surfaces were collected by using the AE system and CCD camera in the deformation and failure process, respectively. Combined with the digital speckle correlation method, the AE characteristics of specimens were investigated during the evolution process of non-uniform deformation. The research results showed that the minimum point of non-uniform deformation corresponded to the lowest point of unloading stress during each cyclic loading process. However, after the startup of the localisation band, the maximum point of non-uniform deformation lagged behind the vertex of loading stress in each cyclic loading process. There was a good correspondence between the non-uniform deformation evolution and the AE signal. During the cyclic loading process, the first turning and increasing point of non-uniform deformation is the starting point of the increase of AE signal, whereas the maximum point of non-uniform deformation is the starting point of the quiet period of the AE signal. With the increase of cyclic number, the degree of non-uniform deformation is negatively correlated with the Felicity ratio, that is, the greater the non-uniform deformation is, the greater the damage degree is, and the smaller the Felicity ratio is.

Key words: cyclic loading and unloading, non-uniform deformation, acoustic emission signal, localisation band, Felicity ratio