Experimental and analytical study on key factors of rock breaking under a single indenter

Abstract

AbstractRock breaking under impact load has a wide application prospect in hard‐rock roadway excavation because of its environmental protection and strong rock‐breaking ability, but the key factors affecting the rock‐breaking effect are not clear enough. Based on a percussive penetration experimental system (PHPB) into rock by combining the Hopkinson Pressure Bar and a detachable indenter, the effects of impact velocity, waveform and rock strength on the force‐penetration curves, percussive efficiency, and crushing work ratio are studied by model simplification, experimental analysis, and theoretical verification. The results show that the peak percussive force and percussive depth are linearly related to the impact velocity; the penetrative coefficient and crushing work ratio are decayed exponentially with the increase of the thickness‐width ratio of the specimens; the rectangular wave can significantly improve the penetration efficiency; the newly established shear‐tensile model with a double‐V structure can accurately predict each stage of rock breaking, which is consistent with the experimental results. The conclusions can be used to speed up the project progress in mechanical excavation of hard‐rock roadway.