Damage Constitutive Study Of Rock Based On Hoek-Brown Strength Criterion

In underground engineering projects,the failure of rock mass varies under different working conditions.Many scholars believe that the key to the safety of underground projects lies in the study of the mechanical response of rock materials,in which the constitutive evolution relationship of rock damage is an essential link.In this study,it is assumed that rock micro-element strength follows Hoek-Brown strength criterion and three-dimensional Hoek-Brown strength criterion respectively,and rock micro-element damage also follows Weibull probability distribution,forming a rock mass damage constitutive model based on Hoek-Brown strength criterion under cyclic loading-unloading.And the damage constitutive model of rock mass based on three-dimensional Hoek-Brown strength criterion under different confining pressures.By fitting the data of uniaxial cyclic loading-unloading test and triaxial compression test with the proposed rock damage constitutive model,the parameters in the model were analyzed,and the revised expression of the rock damage constitutive model was established.The results show that:（1）In this paper,uniaxial loading test and uniaxial cyclic loading and unloading test were designed.Through the uniaxial loading test,the uniaxial compressive strength of rock specimens was obtained,so as to determine the loading grade and cycle times of uniaxial loading and unloading test.Finally,the change characteristics of the total stress and strain curve were analyzed.（2）The damage constitutive model of rock microelement failure subject to Hoek-Brown strength criterion was established based on the assumption that the rock microelement was subject to Weibull distribution in probability theory,and the damage mechanical strain equivalence theory and the generalized Hooke’s Law were combined.The mathematical fitting between the constitutive model and the uniaxial cyclic loading and unloading test data showed good fitting results.It shows that the damage constitutive model can reflect the mechanical damage characteristics of rock under cyclic loading.Finally,the parametersF₀ and m contained in the expression of constitutive model are analyzed to explore the physical significance of their expression,and then the constitutive model is further modified.（3）The damage constitutive model of rock micro-element failure subject to three-dimensional Hoek-Brown strength criterion was established.The triaxial loading test data were selected for mathematical fitting with the constitutive model,and the fitting correction coefficients were all above 0.90.The fitting parametersF₀ and m were modified to analyze the relationship between the parameters and the confining pressure,and the revised constitutive model expression was obtained.Figure 40 Table 5 Reference 86...