Experimental investigation of multiple rock indentations on hard rock using a conical cutter at different cutting depths

To apply roadheaders to deep hard rock mines, one must investigate the influence of multiple rock indentations and cutting depths on rock breakage. In this study, multiple rock indentations using a conical cutter were performed on hard rock samples at different cutting depths. The relationship between the cutting depth and the parameters reflecting the rock cuttability was regressed. The experimental results of the single and multiple rock indentations were compared. They showed that the failure pattern affects the cutting parameters. In the case of partial splitting, the cutting parameters increase with the increase of the cutting depth. Meanwhile, in the case of complete splitting, the force and the work required to break the rock did not show any obvious relationship with the cutting depth, but were directly proportional to the area of the formed fracture surface. Moreover, the free and fracture surfaces formed by multiple rock indentations facilitated the subsequent rock breakage.