Study of triaxial energy strength criterion for brittle rock materials

Based on rock properties of unequal compression and tensile strengths and the strength influence of intermediate principal stress,from the viewpoint of releasable elastic energy,a rock triaxial energy strength criterion taking account of the influence of intermediate principal stress on elastic energy release after rock failure was deduced and set up.The rationality and reliability of the proposed strength criterion was further validated by a lot of testing data from thick-walled rock cylinder experiments and rock true triaxial experiments in published literatures and also analyzed from the physical implications of strength criterion parameters.Research results show that the proposed triaxial energy strength criterion can be suitable for various complex stress states in thick-walled rock cylinder experiments and rock true triaxial experiments.The influence of intermediate principal stress for granite and limestone is heavier than that of red sandstone and middle-fine sandstone;as for the same kind of rock materials,the influence coefficient of intermediate principal stress is varied with stress states,the general variation trend is that the influence coefficient is increased and then decreased with the development of intermediate principal stress.Rock energy strength criterion is in close correlation with stress states and rock material physical properties.