Study on the propagation and multifractal characteristics of stress waves in coal based on electric potential and DIC characterization

An essential theoretical foundation for preventing coal and rock dynamic disasters is understanding the propagation of stress waves within coal and dynamic monitoring of the stress conditions of coal. A split Hopkinson pressure bar and electric potential (EP) test system is utilized in this work to conduct the EP test experiment. The EP response and surface displacement characteristics of the stress wave propagation process were investigated, the evolution law between the EP parameters and displacement parameters was analysed, and the multifractal characteristics of the EP, surface displacement and stress wave were revealed. The findings demonstrate how the EP can accurately depict the propagation process of the stress wave, and both show significant attenuation characteristics. The multi parameter evolution of the EP is highly consistent with the variations in the surface displacement of the specimen. The multifractal characteristics of the EP response can be used to quantitatively characterize the stress anomalies within the specimen, in which the abrupt increase and decrease in Δα and Δf(α) can be used as the key indicators for identifying the stress anomalies within the coal. The findings of this work have important theoretical implications for the stability and safety of deep coal mining since they offer fresh ideas for real-time dynamic monitoring of the stress conditions of the coal seams utilizing EP test techniques.