In order to improve the rock damage constitutive model and parameter determination method under high temperature

based on the effective stress theory

the Weibull distribution function is introduced. Under the condition that the micro-element strength obeys the Hoek-brown criterion

the influence of residual strength is considered

the damage variables are modified

the damage correction coefficient is introduced

and a statistical constitutive model that can reflect the damage characteristics of rocks under high-temperature action is established. Considering the damage threshold factor in the rock damage process

the present constitutive model takes the form of a piecewise function. The conventional mechanical parameters are obtained by testing. Based on the process of solving the parameters of the constitutive model

the values of the constitutive model parameters are determined and the relationship between the values of the model parameters and the temperature is fitted. Finally

the theoretical curve of the model is verified. The results show that the theoretical curve of the proposed statistical damage constitutive model for high-temperature rocks has a good similarity with the test curve

and it is closer to the test curve and reflects the reasonableness of the constitutive model. At the same time

the theoretical curve of the model has a high degree of coincidence with the triaxial test curve

which indicates that the constitutive model can reflect the characteristics of the full stress-strain curve of the rock and can reflect the applicability of the model. The model provides a reference for rock strength estimation and rock thermal damage softening.