Alternative fatigue–creep performance of rock‐backfill composite structure material in mine stopes under high static stress: Disturbed amplitude effect

Abstract

This work aims to investigate the dynamic stress amplitude on the mechanical responses of rock‐backfill composite structure material under alternative low‐cycle fatigue loading and creep loading tests. Results show that deformation, damage propagation, and failure pattern are all impacted by the stress amplitude, and volumetric deformation is the largest for a sample subjected to strong stress disturbance. The equivalent lifetime decreases with the increase of disturbed amplitude. A notable positive interaction between the fatigue damage and time‐dependent damage is found, and they promote each other. Additionally, a novel damage evolution model is proposed by the irreversible radial strain, and the model matches well with the testing data. Moreover, post‐test computed tomography imaging reveals that cracks at rock‐backfill interfaces are relatively easy to be stimulated under low stress disturbance, and it is suggested that tension‐splitting failure is more likely to occur within the surrounding rock, and shear failure seems to occur within the cemented tailings backfill for all the tested samples.