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Numerical Simulation of Rock Breakage Modes under Confining Pressures in Deep Mining: An Experimental Investigation

The cutting efficiency in underground excavations relies on the optimum parameters of the cutting tool and the cutting process. However, the optimization of the cutting tool design and the cutting process is a challenge and requires knowledge about the tool-rock interaction. This paper aims to investigate the tool-rock interaction using a rock cutting mathematical model. The confining pressure was considered in the rock cutting model with conical cutters and the discrete element method was adopted to calculate the dynamics of the rock breakage of this model. Graded particle assemblies were created, calibrated, and compressed in the horizontal direction with a certain confining pressure. Afterwards, the initiation and propagation of cracks during the rock cutting processes were recorded. A series of small-scale rock cutting tests were also carried out to verify the numerical model. The analysis results demonstrate that: 1) the confining pressure induced larger cutting force than that in the unconfined condition; 2) with increase of the confining pressure, the rock failure mode experienced predominantly brittle to predominantly ductile failure; and 3) there was a critical confining pressure/compressive strength ratio of 0.53 when the transition of failure mode occurred.