Research on fractal characteristics and energy dissipation law in the process of coal fragmentation

The DDL600 electronic universal testing machine and the self-developed crushing rock compaction device are used to crush the gradation under different relative humidity by using the staged loading method. The coal sample is subjected to a uniaxial confined compression test. The particle size fractal dimension is calculated by screening and weighing each particle size coal sample, and the particle size distribution characteristics of the broken coal sample under various levels of axial stress are analyzed, and the energy dissipation model is used to calculate the energy dissipation rate of crushing, and explore the law of energy dissipation rate of crushed coal samples during the loading process. The results show that: the fractal dimension and the loading stress satisfy the logarithmic relationship during the crushing process of the coal sample. The influence of the initial gradation on the change of the fractal dimension decreases with the increase of the loading stress, and the increase of relative humidity will reduce the fractal dimension. The relative humidity reduces the energy dissipation of the coal sample by reducing the occurrence of fragmentation, and the energy dissipation rate varies from 30% to 42%; the energy dissipation rate of coal samples increases first and then decreases with the fractal dimension, and the higher the humidity, the smaller the fractal dimension when the energy dissipation rate reaches the peak, and the more prominent the change of energy consumption rate.