Experimental Investigation of Hard Rock Breaking Using a Conical Pick Assisted by Abrasive Water Jet

Rock breaking using conical picks is a complex process affected by several factors; its performance is directly related to the excavation rate of rock tunnels, which is important in terms of the economic benefits and social impact of a project. This study investigates the effects of cutting depth and water pressure on rock breaking performance using a conical pick assisted by an abrasive water jet (AWJ). To measure the weakening effect of the AWJ on rock strength and evaluate the practical application of this approach, further analyses of a secondary cut of rock with a fracture pit and rock breaking economy are included in this study. The results show that a conical pick can efficiently break hard rock when assisted by the strong impact of an AWJ; the cutting resistance and specific energy (SE) decrease with the use of the AWJ. With a fracture pit and surrounding tiny cracks, the cutting resistance during the secondary cut is further reduced and rock fragments become smaller. In addition, with a decrease in cutting depth and an increase in water pressure, the stability of the cutting resistance is improved, reducing conical pick costs resulting from impact fracture and wear. According to the rock breaking economy analysis of the proposed approach, there is an optimal cutting depth under certain conditions that can provide a reference for practical application.