Non-linear rock creep model based on hardening and damage effect

Rock creep process is the result that the internal stresses of rock constantly adjusts,hardening and damage effect gradually grow and take mutual effect.By means of classic element combination modeling ideas,the rock initial yield strength was regarded as the stress threshold of the creep hardening,and rock's long-term strength served as the stress threshold of damage softening,introduced hardening function and damage variable that could reflect the effect of rock hardening and damage effect.Established nonlinear creep model of rock that could comprehensively reflect the creep mechanism.The fitted results of the test data show that nonlinear rheological model not only can effectively describe the creep process of rocks,but also can reflect creep hardening and damage softening mechanism in the creep process of rocks.