Research on Fractal Characteristics and Energy Dissipation Law of Gas-Bearing Coal under Dynamic and Static Loads

Abstract

In this study, the fractal characteristics and energy dissipation behavior of gas-bearing coal are explored under both dynamic and static loads. Multifactor coupling mechanical tests are conducted using visualized static and dynamic loading experiment systems. The effects of impact velocity, axial compressive stress ratio, and initial gas pressure on energy dissipation and fragmentation characteristics of gas-bearing coal are analyzed. An internal correlation between the debris fractal and the energy dissipation density is clarified considering the fact that debris distribution has prominent fractal characteristics in the log–logarithmic coordinates. It is discovered that the fractal dimension experiences exponential growth with the strain rate in the impact velocity group, while showing that it rises linearly in the gas pressure group. There exists a critical axial compressive stress ratio that causes the formation of the debris fractal segment in the axial compressive stress ratio group. The debris fractal dimension change with the energy dissipation density is divided into two stages, and it is found that the dissipated energy value and its ratio decrease with the rise of initial gas pressure; debris fractal exhibits a quadratic decreasing relationship to the density of energy dissipation. Furthermore, by considering the dimension of the strain rate, the relationship of the aforementioned three indicators are uniformly quantified and compared. The research results reinforce the fundamentals of gas-bearing coal dynamics and provide a theoretical reference for further research on gas composite dynamic disasters in mines.