A Numerical Simulation for Damage Mechanical Behavior of Brazilian Splitting Test of Deep Shales

In order to investigate the mechanism between shale texture characteristics and tensile strength, a three-dimensional Brazilian splitting test numerical model was established by the cohesive element method. The effects of texture angle and strength on damage modes and tensile strength were studied, and the crack growth behavior was accurately analyzed using acoustic emission distribution characteristics. The results indicate that the numerical simulation outcomes of the Brazilian splitting test were basically in accordance with the experimental results. The cohesive element method can be used to predict the shale’s damage behavior. The damage modes of shale specimens are classified into six categories under the coupling of texture angle and strength. For shale specimens with central damage, the acoustic emission (AE) energy-displacement curves are dominated by a single-peak distribution type. For shale specimens with tension-shear mixed damage, the AE energy-displacement curves are dominated by a multiple-peak distribution type. The tensile strength of shale specimens is significantly anisotropic. As the texture strength increases, and the primary crack approaches the loading diameter direction, the tensile strength of the specimens gets higher under the same texture angle. The results of the study also reveal the damage mechanisms in deep shales and provide theoretical basis for the fracturing design for shale reservoirs.