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The maximum circumferential stress theory and the effective stress theory were improved based on the boundary collocation method, and then two kinds of failure criterion in the laboratory-scale were established. Moreover, the relationships between rock uniaxial tensile strength and fracture toughness were also developed through the corresponding criteria. Finally, the dimensionless variable which could quantify the uniaxial tensile strength was proposed; meanwhile the influences of crack inclination and crack length on the initial failure angle and the tensile strength of cracked rock mass were analyzed. The results show that both the initial failure angle and the tensile strength increase with the increase of crack inclination, and for specimens containing macroscopic cracks, both the initial failure angle and the tensile strength decrease as the crack length increases which indicates that the specimen scale has a great impact on rock fracture strength. [ABSTRACT FROM AUTHOR]