RESEARCH ON ROCK STRENGTH CRITERION BASED ON SHAPE CHANGE ENERGY DENSITY

The evolution of elastic strain energy density, volume change energy density and shape change energy density of sandstone in the process of conventional triaxial compression test were analyzed. And the rock strength criterion of shape change energy density was established according to the linear relationship between peak shape change energy density and confining pressure. The results indicate that: (1) The volume change energy density and shape change energy density gradually increase in the pre-peak stage and sharply decrease after the peak; (2) The parameters of the shape change energy density strength criterion have clear physical significance, and can be converted into the classical Hoek-Brown criterion by parameter transformation; (3) The calculation results of the shape change energy density strength criterion are basically consistent with the conventional triaxial compression test results of eight different types of rocks. The accuracy and applicability of the criterion were verified.