Abstract: To further understand the mechanical properties of layered rock mass, the contribution of microcracks to the elastic flexibility matrix of rock mass was deduced by using the volume averaging method based on the theory of microscopic damage mechanics; subsequently, the damage evolution equation with damage vector was derived based on the irreversible thermodynamic framework; finally, the damage evolution constitutive model of layered rock mass was established, and the applicability of the constitutive model was verified by comparing the results of numerical calculation with laboratory test. The results of Brazilian disc splitting test manifest that the fracture surface of rock mass samples starts from the loading point. When the bedding dip angle is 0° and 90°, the fracture surface is the approximate plane passing through the loading center and the sample center; otherwise the fracture surface is the curved surface deviating from the loading center. Comparison with laboratory test results verified that the constitutive model developed in this paper could well predict the anisotropic characteristics of progressive failure of layered rock mass.

Key words: microcrack, damage evolution, constitutive model, layered rock mass, Brazilian disc splitting test