Energy consumption in rock fragmentation at intermediate strain rate

Abstract

In order to determine the relationship among energy consumption of rock and its fragmentation, dynamic strength and strain rate, granite, sandstone and limestone specimens were chosen and tested on large-diameter split Hopkinson pressure bar (SHPB) equipment with half-sine waveform loading at the strain rates ranging from 40 to 150 s⁻¹. With recorded signals, the energy consumption, strain rate and dynamic strength were analyzed. And the fragmentation behaviors of specimens were investigated. The experimental results show that the energy consumption density of rock increases linearly with the total incident energy. The energy consumption density is of an exponent relationship with the average size of rock fragments. The higher the energy consumption density, the more serious the fragmentation, and the better the gradation of fragments. The energy consumption density takes a good logarithm relationship with the dynamic strength of rock. The dynamic strength of rock increases with the increase of strain rate, indicating higher strain rate sensitivity.

Keywords

rock / large-diameter SHPB test / intermediate strain rate / energy consumption density / fragment distribution / dynamic strength

References

[1] LiX. B., LokT. S., ZhaoJ., ZhaoP. J.. Oscillation elimination in the Hopkinson bar apparatus and resultant complete dynamic stress-strain curves for rocks [J]. International Journal of Rock Mechanics and Mining Sciences, 2000, 37(7): 1055-1060

[2] LiX.-b., GuD.-sheng.Rock impact dynamics [M], 1994, Changsha, Central South University of Technology Press

[3] ReddishD. J., StaceL. R., VanichkobchindaP., WhittlesD. N.. Numerical simulation of the dynamic impact breakage testing of rock [J]. International Journal of Rock Mechanics and Mining Sciences, 2005, 42(2): 167-176

[4] WhittlesD. N., KingmanS., LowndesI., JacksonK.. Laboratory and numerical investigation into the characteristics of rock fragmentation [J]. Minerals Engineering, 2006, 19(14): 1418-1429

[5] ZhangZ. X., KouS. Q., JiangL. G., LindqvistP. A.. Effects of loading rate on rock fracture: fracture characteristics and energy partitioning [J]. International Journal of Rock Mechanics and Mining Sciences, 2000, 37(5): 745-762

[6] BohloliB., HovenE.. A laboratory and full-scale study on the fragmentation behavior of rock [J]. Engineering Geology, 2007, 89(1): 1-8

[7] LiX. B., LokT. S., ZhaoJ.. Dynamic characteristics of granite subjected to intermediate loading rate [J]. Rock Mechanics and Rock Engineering, 2005, 38(1): 21-39

[8] TavaresL. M., KingR. P.. Single-particle fracture under impact loading [J]. International Journal of Mineral Processing, 1998, 54(1): 1-28

[9] CouroyerC., NingZ., GhadiriM.. Distinct element analysis of bulk crushing: Effect of particle properties and loading rate [J]. Powder Technology, 2000, 109(1): 241-254

[10] WeichertR.. Theoretical prediction of energy consumption and particle size distribution in grinding and drilling of brittle materials [J]. Particle and Particle Systems Characterization, 1991, 8(1): 55-62

[11] LiX.-b., LaiH.-h., GuD.-sheng.. Energy absorption of rock fragmentation under impulsive loads with different wave forms [J]. Transactions of Nonferrous Metals Society of China, 1992, 2(4): 10-14

[12] FieldJ. E., WalleyS. M., ProudW. G., GoldreinH. T., SiviourC. R.. Review of experimental techniques for high rate deformation and shock studies [J]. International Journal of Impact Engineering, 2004, 30(7): 725-775

[13] LiX.-b., HongL., YinT.-b., ZhouZ.-l., YeZ.-yuan.. Relationship between diameter of split Hopkinson pressure bar and minimum loading rate under rock failure [J]. Journal of Central South University of Technology, 2008, 15(2): 218-223

[14] ZhaoH., GerardG., KlepaczkoJ. R.. On the use of viscoelastic split Hopkinson pressure bar [J]. International Journal of Impact Engineering, 1997, 19(4): 319-330

[15] LiX.-b., GuD.-s., LaiH.-hui.. On the reasonable loading stress waveforms determined by dynamic stress-strain curves of rocks by SHPB [J]. Chinese Journal of Explosion and Shock Waves, 1993, 13(2): 125-130

[16] LokT. S., LiX. B., LiuD., ZhaoP. J.. Testing and response of large diameter brittle materials subjected to high strain rate [J]. Journal of Materials in Civil Engineering, 2001, 14(3): 262-269

[17] LiuD.-s., LiX.-bing.. Dynamic inverse design and experimental study of impact piston [J]. Chinese Journal of Mechanical Engineering, 1998, 34(4): 506-514

[18] LiX.-b., ZhouZ.-l., WangW.-hua.. Construction of ideal striker for SHPB device based on FEM and neural network [J]. Chinese Journal of Rock Mechanics and Engineering, 2005, 24(23): 4215-4218

[19] DaviesE. D. H., HunterS. C.. The dynamic compression testing of solids by the method of the split Hopkinson pressure bar [J]. Journal of the Mechanics and Physics of Solids, 1963, 11(3): 155-179