Effect of Clay Minerals on Tensile Failure Characteristics of Shale

The effects of mass fraction, elastic modulus, and the spatial distribution of clay minerals on the failure behaviors of shale under the Brazilian disc split are investigated in this study based on a developed PFC2D model. The feasibility of this established numerical model is validated by the load-displacement curves and fracture morphology of shale in the laboratory test. The influences of the mass fraction, elastic modulus, and spatial distribution of clay minerals on the tensile strength and failure behaviors of shale are comprehensively analyzed using the developed numerical model. The results show that the clay content has the strongest influence on the tensile strength of shale. The number of matrix cracks is sensitive to the clay distribution, and the complexity of the matrix fracture network in shale shows a positive correlation with the clay content. In addition, the variation of the clay modulus has a linear correlation with the macro elastic modulus of shale.