Rock mechanical properties experiments with low-frequency circulation disturbance under different stress amplitudes

The rock mechanics experiments were designed under different stress amplitudes. The results showed that the elastic modulus reinforcement effect was appeared when the disturbance stress amplitude was small. The rock sam- ples were damaged only when the stress was greater than stress limit threshold value. The disturbance stress amplitude level influenced the destruction of rock significantly. The cycle numbers were reduced rapidly under the high stress amplitude. The specimens’ failure pattern was shear failure when the stress amplitude was low and the failure pattern was complex when the stress amplitude was high. The strain damage model was established under circulation disturb- ance. By analyzing the change law of damage variable under different stress amplitudes,the rock damage can be divid- ed into a rapid growth stage and stable stage of development and rapid increase stage. The cycle number of develop- ment stage was reduced development with the increase of stress amplitude disturbance. The damage variable rate in- creased significantly and the strain of rock increased rapidly with the increase of stress amplitude disturbance.