Investigation of Dynamic Failure Mechanism and Microscopic Rupture Mechanism of Shale Rock Using Dynamic Three‐Point Bending Test

ABSTRACT Shale gas extraction relies on understanding reservoir rock fracture. Focusing on Longmaxi shale, this study conducted dynamic three‐point bending tests using a split Hopkinson pressure bar, combined with digital image correlation (DIC) and scanning electron microscopy, to investigate the effect of bedding angle ( α ) on dynamic fracture characteristics. Results show significant anisotropy in failure modes, fracture toughness, energy dissipation, and crack propagation velocity (CPV). Except for the C0 group (Divider) exhibiting pure tensile failure, all other angles display tensile–shear composite failure. Fracture toughness and energy first decrease, then increase, and finally decrease with rising α , whereas CPV shows an opposite trend. DIC reveals stress concentration at the notch tip and captures secondary shear crack propagation at α = 30°. Microscopically, all fractures are mixed transgranular and intergranular; as α increases, the dominant mode shifts from transgranular to intergranular fracture. These findings support hydraulic fracturing design in shale gas reservoirs.