Explosively Induced Fracture and Fragmentation in Copper Porphyry.
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Experiments were conducted to obtain an understanding of the nature and processes of rock fragmentation near a borehole in rock blasting. Ten controlled impact experiments on quartz monzonite were performed using the inclined-plane wave generator to induce a uniaxial compressive wave. Particle size distribution and microcrack density in quartz grains were determined as a function of stress levels (between 1.6 Gpa (16 kb) and 7.3 Gpa (73 kb)) and pulse durations (between 1.1 Us and 6.9 Us). Both shock pressure and pulse duration were shown to have a strong effect on both particle size and microcrack density. Although the effect of pressure is well recognized, the effect of pulse duration indicates that the ultimate fragmentation increases with the time of application of a plane wave pulse. At high pulse durations, both the degree of fragmentation and microcracking are more sensitive to change in pressure than at low pulse durations. The degree of fragmentation increases rapidly as the microcrack density is increased.
CP; Final Contract Report;
For Reference Only At Bureau Libraries
New Mexico Inst. of Ming. & Tech.