Experimental Study on the Size of Rock Fragments Ejected from Boreholes Drilled in Coal Mine Roadway Floors

Borehole drilling is required if floor heave in underground mines to be controlled using bolts through the floor. How well bolt anchored depends, part, on borehole’s quality. A major factor that can reduce borehole quality difficulty of discharging rock fragments from a small-diameter drilled at downward angle. Therefore, fuller understanding sizes will aid attempts achieve smooth fragment discharge. In this study, experiments laboratory and SEM imaging were carried out determine size shape generated when boreholes three sedimentary rocks typically found roadway floors. The results show distribution conformed three-parameter generalized extreme value distribution. mean increased with density larger than 1.5 mm rock’s uniaxial compressive strength. fractal dimension cracks was lower for high-density whose had dimension. When drill rod drills very dense or high-strength rock, increase discharge power should prevent blockages. This paper may provide theoretical basis data reference settings channel optimization.