Mechanical characteristics of tensile failure of salt rock

Using MTS815 Flex Text GT rock mechanics test system, PCI-Ⅱ acoustic emission (AE) test system and SMZ1000 stereomicroscope system and CCD real-time camera system, comprehensive studies are carried out through indirect tensile test and direct tensile test on tensile mechanical properties of beddod salt rock. Through the research, the tensile displacement and tress full process curves of different tensile modes, the tensile strength relationship between the indirect tensile test and the direct tensile test and the relationship between the tensile strength and the uniaxial compressive strength are obtained. The studies show that the direct tensile strength is less than the indirect tensile strength, and the direct tensile test result more truly reflects the characteristics of the tensile strength of salt rock. So it is recommended as much as possible to use the direct tensile test method to test the tensile strength of bedded salt rock. The AE test reveals spatial distribution of AE of different tensile failure modes, and the characters of AE spatial distribution reveals the corresponding force status and damage evolution rule leading failure. The rock failure surface morphology of different tensile test methods shows that the rock failure mode of the indirect tensile test is mainly transgranular fracture, but that of the direct tensile test is mainly intergranular fracture. The failure mode differences are main reasons leading to the strength difference of different tensile test methods.