Discrete Element Modeling of the Effects of Cutting Parameters and Rock Properties on Rock Fragmentation

Rock properties (e.g., brittleness, fracture toughness, hardness, compressive strength and tensile strength), cutting parameters (e.g., cutting depth, attack angle, wedge angle, cutting velocity) and confining stress are closely related to rock fragmentation behaviors in the design and application of excavation and mining machinery. To investigate the influence mechanism of those factors on rock fragmentation, a series of linear cutting numerical tests were conducted using the discrete element method. Numerical models with different rock mechanical parameters were calibrated by changing the cohesion strength-to-tensile strength ratio of the linear parallel bond model in PFC2D. The effects of cutting parameters on rock fragmentation were studied using orthogonal test and range analysis. The numerical results indicated that the strength ratio had a dominant effect on the specific energy and that the cutting depth and attack angle had a dominant effect on the mean cutting force. The cutting velocity significantly influenced the specific energy, and a higher cutting velocity should be adopted in actual rock cutting. In addition, a cutting force prediction model was proposed that considered factors such as the compressive strength, wedge angle, attack angle and cutting depth. Moreover, the introduction of more rock mechanical parameters into the evaluation indicators can reflect a greater number of fragmentation characteristics.