Study of failure process and failure modes of interstratified rock mass with an emphasis on specimen preparation and image scanning

This paper presents a preparation technique of interstratified rock block the overall mechanical properties of which are similar to the transversely isotropic rocks. Strength criterion and failure modes of the interstratified rock are studied with both theoretical and experimental approaches. A rotary scanner designed by the authors is used to catch the “unrolled” images of rock specimens at different stress level during the uniaxial compression tests. The unrolled images are helpful in the recording and studying of the failure processes and modes of cylindrical rock specimens. Based on the experimental observation, the failure modes of the artificial interstratified rock at different confining pressures and orientation angles, can be classified into two main categories: a) Sliding failure mode, and b) Non-sliding failure mode. The latter includes tensile, splitting, single shear plane and conjugate shear plane sub-failure modes. Failure criterion developed by Tien and Kuo (2001) is used to predict the strength and failure modes of the interstratified rock mass under varied confining pressures. The results show that the Tien-Kuo’s criterion can predict well the failure strength and failure modes of the artificial interstratified rock.