Study on Energy Absorption Characteristics of Single Free Face Coal under Impact Load

The energy absorption buffer test system is developed, the impact load compression test of single free face coal sample is carried out, and the digital speckle analysis technology is used to obtain the law of the influence of the hole rate, which is the volume of the borehole divided by the volume of the coal sample, on the energy absorption rate and deformation and failure characteristics of coal sample after drilling. The change of the drill layout of two and three holes in coal samples has little effect on the energy absorption performance. The complete coal sample is easy to form vertical main cracks, and the drilled coal sample first forms stress concentration near the borehole, and a large number of cracks appear. The multihole coal samples are easy to form cracks that make the boreholes connected, which converts more impact energy into surface energy and improves the energy absorption rate of coal samples.