Study on Nonlinear Damage Creep Model for Rocks under Cyclic Loading and Unloading

To determine the nonlinear creep characteristics of rocks under cyclic loading and unloading conditions, a Kelvin model damage viscoplastic are proposed. The models connected in series with linear elastic body to establish model. differential constitutive equations proposed one-dimensional three-dimensional stress states derived based on mechanics elasticity theory. then obtained superposition principle, simple feasible method for determining parameters is determined. Finally, step test data lherzolite limestone used verify rationality feasibility results show that theoretical curves consistent experimental which indicates can not only properties but also transient steady-state stages particularly within accelerating stage.