Dynamic mechanical properties and damage constitutive modelling of paste phyllite under triaxial impact testing

Abstract

Understanding the dynamic mechanical properties and damage mechanisms of the surrounding rock during blasting and mining is crucial for preventing engineering accidents. In this study, triaxial and uniaxial impact compression experiments were conducted on paste phyllite using a Split Hopkinson Pressure Bar (SHPB) device under various confining pressures and strain rates. The effects of confining pressure and strain rate on the dynamic mechanical properties of paste phyllite, including stress-strain behaviour, dynamic compressive strength, and energy evolution characteristics, were investigated. The results reveal that the stress-strain curve in the triaxial state exhibits more prominent plasticity characteristics compared to the uniaxial state. The dynamic compressive strength and energy vary to different extents with increasing confining pressure and strain rate. As the confining pressure increases, the microscopic damage characteristics of the rock gradually transition from mixed tensile-shear cracks to predominantly shear cracks. Furthermore, the influence factor of confining pressure and the plasticity element were incorporated into the Zhu-Wang-Tang (ZWT) constitutive model. A dynamic damage constitutive model considering the effects of confining pressure and plasticity was established and validated using experimental data. The model demonstrated good agreement with the experimental results and could predict the stress-strain behaviour.

Keywords

• Dynamic constitutive modelling
• triaxial compression test
• dynamic mechanical properties
• SHPB