Macro- and meso- failure mechanism analysis for shale-like brittle materials under uniaxial compression

Understanding the failure mechanisms of the widespread shale-like brittle materials is of great significance to engineering safety. In this research, the discrete element model which can reflect the real rock mechanical properties and failure mode of shale specimens with different bedding angles has been reconstructed. First, microcrack has been introduced to characterize the meso-damage. The relationship between the microscopic crack numbers in the material and the macroscopic stress has been revealed. In addition, the relative movement between different deformed blocks has been analyzed by introducing the residual velocity field. The control factor of material failure varies with the bedding angle (beta) in the macro scale. It manifests from the bedding plane and the matrix synergistically control the failure mode of rocks to mainly the bedding plane and then back to the bedding plane and the matrix synergistically control the rock failure mode. The competitiveness of the shear and tensile damages in the failure mechanism varies with the bedding angle in the meso scale. When 30 < 75, Shear damage dominates the failure mechanism. The established numerical model is capable of predicting the mechanical behavior of brittle rock, which may have guiding merits to the application of shale-like brittle materials.

Automated summary

Understanding the failure mechanisms of shale-like brittle materials is crucial for engineering safety. This research reconstructed a discrete element model that reflects the real rock properties and failure modes of shale specimens with different bedding angles. It revealed the relationship between micro-crack numbers and macroscopic stress, as well as analyzed the relative movement between deformed blocks. The model can predict the mechanical behavior of brittle rock and guide the application of shale-like brittle materials.