Cumulative Fatigue Damage Under stepwise Tension-Compression Loading

Rock structures are subjected to cyclic tension-compression loading due to a blasting, earthquake, traffic and injection-production in underground storage case. Therefore study the fatigue behavior of rock samples under this type of loading is required. In this study, the accumulated fatigue damage for a Green Onyx rock sample which consisted of only one mineral composition with two-step high-low sequences of loading levels was investigated under completely reversed loading condition. New apparatus based on the R.R. Moore fatigue test machine is designed to assess this type of loading. A comparison between the predicted behavior of Linear Damage Rule and experimental data was conducted and a new damage model was proposed based on the experimental observation. The results showed a good agreement between the proposed damage model and experimental data.