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To explore the fracture characteristics of rock under the interaction of fatigue load and creep load, fatigue–creep interactive loading experiments were performed on red sandstone with prefabricated cracks. The crack evolution process and failure mode were analyzed using acoustic emission technology and digital image correlation. The results showed that crack growth mainly occurred in the fatigue loading stage; the crack evolution of the sample could be divided into three stages: nucleation and initiation ( SI), stable expansion ( SII), and unstable fracture ( SIII). There were distinct differences in the crack propagation modes of the rock samples with different prefabricated crack angles. The relationship between the crack initiation angle and prefabricated crack angle was analyzed based on the maximum circumferential stress theory. Moreover, with an increase in the prefabricated crack angle, the rock sample gradually changed from compression–shear failure to tension–shear failure.

To study the effect of the upper limit stress on the fatigue characteristics and crack propagation process of jointed rock masses under the interaction of fatigue-creep, a series of fatigue-creep tests with different cyclic stress levels were carried out on jointed sandstone samples. Acoustic emission, scanning electron microscopy, and digital image correlation technologies were used to analyze the fatigue characteristics and crack growth process of the specimen.The results show that as the stress level increases, the deformation of the sample increases, the strength decreases, the elasticity attenuates, and the damage increases. The splitting failure of grains is weakened, the area of fatigue folds increases, and the fracture roughness increases. Besides, the crack propagation process of the sample can be divided into three stages: crack initiation, stable crack growth, and unsteady crack growth. As the stress level increases, the failure mode of the sample gradually changes from brittle to ductile.

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