A damage constitutive model for shear behavior of joints based on determination of the yield point

Abstract Rock joints, a ubiquitous geological phenomenon, greatly affect the mechanical properties of rock masses for engineering purposes. The shear constitutive model of rock joints plays an important role in the research in this field, both experimentally and theoretically. However, most existing constitutive models utilize too many parameters with unclear physical significance and cannot reflect the overall process of shearing due to the absence of prepeak and postpeak deformation. Therefore, this paper focuses on the characteristics of joints entering strain hardening after the yield point during shearing. Based on the statistical damage theory and the combination of macro- and microdeformation characteristics, a new damage constitutive model was established to accurately depict the deformation of the whole joint shearing process. In addition, a quantitative analysis method based on the shear stress difference is proposed to determine the yield point, which is of great significance to improve the capability of this proposed model and is easy to program, effectively avoiding subjective factors. It can be deduced that the new model can describe the deformation characteristics and damage evolution law of the whole joint shearing process, and it has a simple model form as well as few parameters with reasonable physical meaning. The new model was adopted to fit the experimental data from previous studies. The results indicate that the new model shows great consistency with the experiments, which reflects the feasibility and capability of this proposed model.