Evaluation of the Energy Consumption and Fractal Characteristics of Different Length-Diameter Ratios of Coal under Dynamic Impact

Coal samples having the same diameter (50 mm) and different length-diameter ratios (l/d), i.e., 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0 were tested under dynamic uniaxial impact compression using Split Hopkinson Pressure Bar (SHPB) experimental system. This study evaluates: (a) The effects of l/d on energy consumption law fractal characteristics coal crushing; (b) stress balance dissipation; (c) density crushing. findings are as follows: (1) show similar stress–strain curve shapes in stages including elastic, plastic, failure stage, which is an “open” shape, proportion plastic stage increases, strain-softening occurs; (2) dissipation ratio shows trend, showing two with increase ratio, increases linearly first overall decreases step-by-step; (3) average particle size while dimension fragmentation linearly, endorses decreasing trend degree; (4) It determined that there a power relationship between density; (5) A new index Crushing Density Energy Efficiency (CDEE) proposed, can be used to characterize rock-breaking efficiency crushing conditions. inversely proportional l/d. research results provide basis for design top caving mining, determination blasting parameters.