Study on nonlinear creep model of soft rock

Based on the component model,the damage and hardening variables were introduced into the creep model to express the nonlinear creep behavior of soft rock.A new nonlinear creep equation was established for soft rock.The Maxwell chains was equivalent to a linear damage Hooker body,the Kelvin chain was equivalent to a linear hardening Newton body,and the Burgers chain was a model describing linear damage and hardening for creep of rock.With the development of the creep of soft rock,the variation of rock microstructure had influence upon mechanical behavior.These changes were explained by nonlinear damage and hardening variables.The nonlinear creep model was established,which could describe three phases of soft rock creep.The results of model agreed with those of test perfectly.