A fatigue damage model for sandstone based on acoustic emission and resistivity parameters

Cyclic loads (such as blasting and excavation) may cause disturbance to the rock mass, which can induce fatigue damage in the rock mass within the excavation influence range. To investigate the fatigue damage characteristics of underground engineering sandstone, uniaxial cyclic loading tests were performed under varying cyclic stress amplitudes and frequencies. Acoustic emission (AE) and resistivity monitoring were conducted simultaneously. The results indicate that lower cyclic frequencies and higher cyclic stress amplitudes lead to more severe fatigue damage in the rock. AE and resistivity provide an understanding of damage characteristics from the perspective of crack initiation and crack connection, respectively. By coupling AE and resistivity parameters, a rock fatigue damage variable is established, leading to the development of a fatigue damage body, which is incorporated into the Nishihara rheological model. This integration ultimately results in the formulation of a rock fatigue damage model. A comparison between test results and model predictions shows that the fatigue damage model accurately represents the fatigue damage process of underground engineering sandstone. The findings offer a theoretical foundation for further understanding the fatigue damage evolution in underground engineering sandstone.