PFC^2D-based investigation on the mechanical behavior of anisotropic shale under Brazilian splitting containing two parallel cracks

Abstract

A validated particle flow code (PFC^2D)-based model was developed to investigate the indirect tensile mechanical behavior of shale containing two central parallel cracks under Brazilian splitting test conditions. The results show that preexisting cracks have a significant and insignificant influence on the tensile strength of shale under LPL and LVL conditions, respectively. When L≥10 mm, changing the L and H values has little effect on the tensile strength of shale. However, the inclusion of preexisting cracks have a positive effect on reducing the anisotropy of the shale specimens, and in the case of an L/D ratio of 0.3, the shale anisotropy is the lowest. Four failure modes were formed at different β and θ values under LPL conditions. In the case of β≥60°, the failure mode is mainly affected by β, and when β≤45°, the failure mode is more complicated than in the case of β≥60°. Only three major failure modes were observed under LVL conditions; in the case of 45°≤β≤75° and θ≤30°, the most complex failure mode occurred.

Graphical abstract

Keywords

anisotropy / preexisting cracks / tensile strength / mechanical behavior / PFC^2D

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Higher Education Press