Study on the Creep Model of Sandstone Considering Hardening and Damage Effects

In order to study the influence of the combined action ofthe hardening effect and damage effect on the creep characteristics of rock, based on the Nishihara model, the hardening function which can reflect the yield strength strengthening with time and the damage variable which can reflect the deterioration of mechanical properties in the process of rock creep are introduced. The mechanism of hardening and damage in the three stages of instantaneous strain and creep deformation is analyzed, and the creep model of sandstone considering the hardening effect and damage effect is established. Finally, the rationality and correctness of the model are verified by comparing the model curve with the test curve. The results show that: The creep model curve of sandstone with hardening and damage effects shows a high degree of agreement with the test curve, and the correlation coefficient is over 0.90. Compared with the degree of agreement between the Nishihara model and the test curve, the constructed model curve can not only describe the creep curve containing accelerated creep more accurately, and it can also well describe the variation of decay creep and stable creep. Therefore, the established model comprehensively reflects the combined influence mechanism of the hardening effect and damage effect of rock in the whole process of creep deformation.