盐岩拉伸破坏力学特性的试验研究

Mechanical characteristics of tensile failure of salt rock

利用MTS815 Flex Text GT岩石力学试验系统,并利用PCI-Ⅱ声发射测试系统及SMZ1000体视显微镜和CCD实时摄像系统,采用间接拉伸与直接拉伸两种试验方法,对层状盐岩拉伸破坏力学特性进行了综合试验研究。研究获得了两种测试方式的破坏全过程曲线,揭示了间接拉伸、直接拉伸强度相互关系,及其与单轴抗压强度的相互关系。研究表明,直接拉伸试验测得的层状盐岩抗拉强度低于间接拉伸试验,直接拉伸试验得到的结果更加真实反映盐岩的抗拉强度特性,建议尽可能采用直接拉伸试验方法测试盐岩抗拉强度;研究得到了两种拉伸破坏方式的声发射空间分布特征,揭示了与之对应的受力状态和导致破坏的损伤演化规律;不同拉伸破坏方式的岩石断面形貌研究表明,间接拉伸以穿晶断裂为主,直接拉伸以沿晶断裂为主,这种断裂破坏方式的差异是导致不同拉伸测试方式强度差异的原因。

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.