Abstract: To simulate the deformation behavior of rocks under cyclic loading and unloading, a cyclic loading-unloading model is developed based on Drucker-Prager (D-P) yield criterion and the subloading surface theory. Tensile strength and stress angle effect are considered in this model. By introducing the corner model into the traditional D-P yield criterion, and referring the D-P-Y yield criterion proposed by Yin Youquan, a modified D-P yield criterion is put forward on the basis of strength characteristics of rocks under triaxial compression and tension. According to the modified yield criterion and the subloading surface theory, a subloading surface model for rock under cyclic loading and unloading is proposed. Numerical verification of this model is conducted by programing. The results show that the subloading surface model can be used to represent the Mansingh reaction and the ratchet effect of rock. As the tensile strength decreases, the deformation of rock increases, and the rate of increase is gradually improved, which demonstrates that the modified model can be used to well reflect the effect of tensile strength on the deformation of rock under cyclic loading and unloading.

Key words: stress angle effect, tensile shear region, modified Drucker-Prager criterion, subloading surface, cyclic loading-unloading