北山花岗岩直接拉伸与巴西劈裂试验研究

Study on direct tensile and Brazilian splitting test of Beishan granite

以甘肃北山预选场区地下实验室深部花岗岩为研究对象,采用直接拉伸与巴西劈裂两种试验方法,对岩样的拉伸力学特性进行了综合试验研究。研究表明,直接拉伸试验测得的花岗岩抗拉强度低于巴西劈裂试验,两者比值为0. 71,直接拉伸试验得到的结果更加真实反映花岗岩的抗拉强度特性。两种拉伸破坏方式的岩石断面扫描研究表明,直接拉伸以晶间断裂为主,为典型脆性拉断破坏;巴西劈裂以穿晶断裂为主,存在剪切破坏。

Taking deep granite in underground laboratory of Beishan pre-selection site in Gansu province as research object,comprehensive studies are carried out through Brazilian splitting test and direct tensile test on tensile mechanical properties of granite. The studies show that the direct tensile strength is less than the Brazilian splitting strength,and the ratio of the two is 0. 71. The direct tensile test result more truly reflects the characteristics of the tensile strength of granite. The scanning of rock failure surface 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 results of cross section scanning of rock under two kinds of tension failure modes show that intergranular fracture is the main mode of direct tension,which is typical brittle fracture. Transgranular fracture is dominant in Brazilian splitting,and shear failure exists.