With the aid of MTS815,large scale laser profilometer and SEM testing system,indirect tensile tests,fractography and meso fracture mechanism analysis were carried out on layered marbles taken from transportation tunnel of JinpinⅡ hydropower station.Experimental results indicated that the included angle between tensile stress direction and bedding plane significantly influenced tensile strength and fracture mechanism of marble.The average tensile strength is approximately 6.32 MPa when the direction of tensile stress is parallel to the bedding plane.And the fractography is rough and surface fractal dimension is about 2.14~2.17 in this case.However,the average tensile strength is about 6.32 MPa when the direction of tensile stress is perpendicular to the bedding plane.And the fractography is more smooth and surface fractal dimension is only 2.07~2.10 in this case, which indicates clearly that there is a good corresponding relationship between tensile mechanical properties and fractography in layered marble. For the same kind of rock,the rougher the fracture surface presents,the greater its fractal dimension will be.And it will correspond to a higher tensile strength,vise versa.The meso-fracture mechanism was also studied through SEM. When the tensile stress is parallel to the bedding plane,the intergranular fracture occurs,but the transgranular fracture is relatively less. When the tensile stress is perpendicular to bedding plane,the facture mode changes to mixed fracture mode,namely,coupled intergranular fracture and transgranular fracture. Different micro/meso-fracture modes are the fundamental reasons which induce different fracture morphology and tensile properties in layered marble.
