Effect of the upper limit stress on the fatigue properties and crack propagation processes of sandstones containing pre‐existing crack under fatigue‐creep interaction

Abstract

AbstractTo 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.