Correlations between strain localisation evolution and acoustic emission characteristics of granite subjected to uniaxial compression

Strain localisation reflects the precursory characteristics of rock failure, tracking its evolution is crucial for the early warning of catastrophic rock events. To explore the correspondence between monitoring indicators and strain localisation, uniaxial compression tests are conducted on granite specimens using acoustic emission (AE) monitoring and the digital image correlation (DIC) method in this study. The response of AE rate and fracture mode to the initiation and accelerated evolution of strain localization is examined. The behavior of the strain localization band during AE quiet period is discussed. Furthermore, the energy–stress transfer process along the strain localization band is elucidated. The results indicate that: (1) After the initiation of strain localization, stress concentrates in the compacted localized region, accompanied by a sharp drop in AE rate. During the accelerated evolution stage of strain localisation, AE rate surges and the proportion of shear-mode fracture considerably increases. (2) During AE quiet period, localisation evolution continues and considerable changes occur in the displacement and strain fields. At its end, the shear stress along the localised band sharply drops. The accelerated evolution of strain localization begins in the quiet period. (3) The reduction in strain energy density of the surrounding rock precedes the drop in shear stress along the localised band. When the whole structure reaches its potential energy limit, the surrounding rock strain energy, localisation band shear stress and AE event rate all decrease sharply, resulting in specimen failure.