Experimental investigation and damage modeling of salt rock subjected to fatigue loading

Damage evolution salt rock under fatigue loading at different stress amplitudes, loading frequencies, and loading rates was investigated in the laboratory. Under conditions of fatigue loading, damage of salt rock can be divided into three stages: initial damage, constant-velocity damage, and accelerated damage. The results of the fatigue tests indicate that higher stress amplitudes, higher loading frequency, and higher loading rate lead to decreased fatigue lifetime. Based on the experiments, a model for the prediction of fatigue life versus stresses, frequency, and loading rate was proposed. Comparison between the model and the experimental results shows that fatigue lifetime can be estimated and predicted from this model. Based on the three-stage damage trend, the cumulative fatigue damage is numerically predicted by considering a double term power damage model. The proposed model captures the characteristics of damage evolution in salt rock under fatigue loading, with the parameters of the model obtained from experimental data.