Advertisement

Experimental Investigation of Blast-Induced Fractures in Rock Cylinders

  • Li Yuan ChiEmail author
  • Zong-Xian Zhang
  • Arne Aalberg
  • Charlie C. Li
Original Paper

Abstract

Fractures in rock cylinders with a central blasthole have been investigated, focusing on the borehole expansion, the crushed zone around the borehole, and the effects of the boundary conditions. Nine small-scale blasting tests were carried out on granite cylinders with diameters of either 228 or 240 mm and lengths of 300 mm, with fully coupled or decoupled explosive charges. The granite cylinders were confined by steel tubes with an inside diameter of 268 mm, where the gap (20 or 14 mm) between was left either empty, filled with gravel or filled with cement grout to simulate various lateral boundary conditions. The fractures around the blasthole were examined on cross-sections of the cylinders. The extent of the crushed zone and the expansion of the borehole were found to depend largely on the decoupling ratio of the charge, both decreasing with an increasing ratio. For small charges, the cylinders confined by gravel fill developed more and longer radial cracks than cylinders confined by the more rigid cement fill. For large charges, a cylinder with an empty gap fragmented into very small pieces, while a cylinder with cement fill broke into large fragments. Hoop strains measured on the steel tubes were smaller for a specimen with gravel fill than for similar specimens with cement fill. For the cylinder with an empty gap, fragment collisions with the steel tube caused significant hoop strains in the confining steel tube. The experimental findings of this investigation may contribute to a better understanding of rock blast fracturing, particularly in the region near the blasthole.

Keywords

Rock fracture Confined blasting Borehole expansion Crushed zone Surface movement 

List of Symbols

Dborehole, Dexp, Dsh

Diameters for the original borehole, the expanded borehole and the outer boundary of crushed zone

P(x)

Material mass passing mesh size x (%)

Rh

Ratio of burden to borehole radius

VB

Burden velocity

b

Undulation parameter

mexp, msh

Expansion ratio, ratio of crushed zone

x, xmax, x50

Fragment size, maximum size, median size

Notes

Acknowledgements

This work was financially supported by the University Centre in Svalbard. The authors wish to thank Professor J. Yang, Mr. Z.Y. Cheng, Mr. Z.S. Zhou, and Mr. Feng at the Beijing Institute of Technology for the support in performing the experiments at the State Key Laboratory of Explosion Science and Technology. The authors also thank the reviewers for their valuable comments and suggestions.

References

  1. Aler J, Du Mouza J, Arnould M (1996) Measurement of the fragmentation efficiency of rock mass blasting and its mining applications. Int J rock Mech Min Sci Geomech Abstr 33:125–139CrossRefGoogle Scholar
  2. Banadaki MMD (2010) Stress-wave induced fracture in rock due to explosive action. University of Toronto, TorontoGoogle Scholar
  3. Bergmann OR, Riggle JW, Wu FC (1973) Model rock blasting-effect of explosives properties and other variables on blasting results. Int J Rock Mech Min Sci 10:585–612.  https://doi.org/10.1016/0148-9062(73)90007-7 CrossRefGoogle Scholar
  4. Brinkmann JR (1990) An experimental study of the effects of shock and gas penetration in blasting. In: Proceedings of the 3rd international symposium on rock fragmentation by blasting, pp 55–66Google Scholar
  5. Chi L, Aalberg A, Zhang ZX et al (2018a) An experimental investigation on dynamic responses of granite blocks under blast loading. In: Li C, Li X, Zhang Z (eds) Proceedings of the 3rd international conference on rock dynamic and applications. Taylor & Francis Group, Trondheim, pp 623–628Google Scholar
  6. Chi LY, Zhang ZX, Aalberg A et al (2018b) Fracture processes in granite blocks under blast loading. Rock Mech Rock Eng.  https://doi.org/10.1007/s00603-018-1620-0 Google Scholar
  7. Chi LY, Zhang Z-X, Aalberg A et al (2019) Measurement of shock pressure and shock-wave attenuation near a blast hole in rock. Int J Impact Eng 125:27–38.  https://doi.org/10.1016/J.IJIMPENG.2018.11.002 CrossRefGoogle Scholar
  8. Cunningham C, Sellers EJ, Szendrei T (2006) Cavity expansion energy applied to rock blasting. In: European federation of explosive engineers conferenceGoogle Scholar
  9. Djordjevic N (1999) A two-component model of blast fragmentation. In: Proceedings of the 6th international symposium on rock fragmentation by blasting, Johannesburg, South Africa, pp 213–219Google Scholar
  10. Dowding CH, Aimone CT (1985) Multiple blast-hole stresses and measured fragmentation. Rock Mech Rock Eng 18:17–36CrossRefGoogle Scholar
  11. Esen S, Onederra I, Bilgin HA (2003) Modelling the size of the crushed zone around a blasthole. Int J Rock Mech Min Sci 40:485–495CrossRefGoogle Scholar
  12. Field JE, Ladegaard-Pedersen A (1971) The importance of the reflected stress wave in rock blasting. Int J Rock Mech Min Sci Geomech Abstr 8:213–226CrossRefGoogle Scholar
  13. Fourney WL (2015) The role of stress waves and fracture mechanics in fragmentation. Blast Fragm 9:83–106Google Scholar
  14. Iverson SR, Hustrulid WA, Johnson JC et al (2009) The extent of blast damage from a fully coupled explosive charge. In: Sanchidrián JA (ed) Proceedings of the 9th international symposium on rock fragmentation by blasting, Fragblast. CRC Press/Balkema, Granada, pp 459–468Google Scholar
  15. Johansson D (2011) Effects of confinement and initiation delay on fragmentation and waste rock compaction: results from small scale tests. Luleå tekniska universitet, LuleåGoogle Scholar
  16. Johansson D, Ouchterlony F (2011) Fragmentation in small-scale confined blasting. Int J Min Miner Eng 3:72–94CrossRefGoogle Scholar
  17. Johansson D, Ouchterlony F (2013) Shock wave interactions in rock blasting: the use of short delays to improve fragmentation in model-scale. Rock Mech rock Eng 46:1–18CrossRefGoogle Scholar
  18. Johansson CH, Persson P-A (1970) Detonics of high explosives. Academic, New YorkGoogle Scholar
  19. Kanchibotla SS, Valery W, Morrell S (1999) Modelling fines in blast fragmentation and its impact on crushing and grinding. In: Explo ‘99–A conference on rock breaking, The Australasian Institute of Mining and Metallurgy, Kalgoorlie, Australia, pp 137–144Google Scholar
  20. Kutter HK, Fairhurst C (1971) On the fracture process in blasting. Int J Rock Mech Min Sci Geomech Abstr 8:181–202.  https://doi.org/10.1016/0148-9062(71)90018-0 CrossRefGoogle Scholar
  21. Lu W, Leng Z, Chen M et al (2016) A modified model to calculate the size of the crushed zone around a blast-hole. J South African Inst Min Metall 116:412–422Google Scholar
  22. O’keefe SG, Thiel DV (1991) Electromagnetic emissions during rock blasting. Geophys Res Lett 18:889–892CrossRefGoogle Scholar
  23. Olsson M, Nyberg U, Fjelborg S (2009) Controlled fragmentation in sublevel caving—first tests. Swebrec Rep 2:27–37 (in Swedish)Google Scholar
  24. Ouchterlony F (2005) The Swebrec© function: linking fragmentation by blasting and crushing. Min Technol 114:29–44CrossRefGoogle Scholar
  25. Persson PA, Ladegaard-Pedersen A, Kihlström B (1969) The influence of borehole diameter on the rock blasting capacity of an extended explosive charge. Int J Rock Mech Min Sci Geomech Abstr 6:277–284CrossRefGoogle Scholar
  26. Petropoulos N, Wimmer M, Johansson D, Nordlund E (2018) Compaction of confining materials in pillar blast tests. Rock Mech Rock Eng 51:1907–1919.  https://doi.org/10.1007/s00603-018-1447-8 CrossRefGoogle Scholar
  27. Rossmanith HP, Uenishi K (2006) The mechanics of spall fracture in rock and concrete. Fragblast 10:111–162CrossRefGoogle Scholar
  28. Saharan MR, Mitri HS, Jethwa JL (2006) Rock fracturing by explosive energy: review of state-of-the-art. Fragblast 10:61–81CrossRefGoogle Scholar
  29. Sanchidrián JA, Segarra P, López LM (2007) Energy components in rock blasting. Int J Rock Mech Min Sci 44:130–147.  https://doi.org/10.1016/j.ijrmms.2006.05.002 CrossRefGoogle Scholar
  30. Segarra P, Sanchidrián JA, López LM (2003) Analysis of bench face movement in quarry blasting. In: Holmberg R (ed) The 2nd world conference on explosives and blasting technique. Balkema, Rotterdam, pp 485–495Google Scholar
  31. Sun C (2013) Damage zone prediction for rock blasting. Department of Mining Engineering, University of Utah, UtahGoogle Scholar
  32. Tilert D, Svedbjörk G, Ouchterlony F et al (2007) Measurement of explosively induced movement and spalling of granite model blocks. Int J Impact Eng 34:1936–1952.  https://doi.org/10.1016/j.ijimpeng.2006.11.006 CrossRefGoogle Scholar
  33. Wang L (2011) Foundations of stress waves. Elsevier, OxfordGoogle Scholar
  34. Wilson WH, Holloway DC (1987) Fragmentation studies in instrumented concrete models. In: 6th ISRM congress. International society for rock mechanicsGoogle Scholar
  35. Wimmer M, Nordqvist A, Ouchterlony F et al (2012) Burden movement in confined drift wall blasting tests studied at the LKAB Kiruna SLC mine. In: International symposium on rock fragmentation by blasting: 24/11/2012–29/11/2012. CRC Press/Balkema, Granada, pp 373–383Google Scholar
  36. Winzer SR, Anderson DA, Ritter AP (1983) Rock fragmentation by explosives. In: Proceedings of the 1st international symposium on rock fragmentation by blasting, Luleå, Sweden, pp 225–249Google Scholar
  37. Zhang ZX (2016) Rock fracture and blasting: theory and applications. Butterworth-Heinemann, OxfordGoogle Scholar
  38. Zhang ZX (2017) Kinetic energy and its applications in mining engineering. Int J Min Sci Technol 27:237–244CrossRefGoogle Scholar
  39. Zhang QB, Zhao J (2014) A review of dynamic experimental techniques and mechanical behaviour of rock materials. Rock Mech Rock Eng 47:1411–1478CrossRefGoogle Scholar
  40. Zhang BP, Zhang QM, Huang FL (2006) Detonation physics. Arms Industry Press, Beijing (in Chinese)Google Scholar

Copyright information

© Springer-Verlag GmbH Austria, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Arctic Technologythe University Centre in Svalbard (UNIS)LongyearbyenNorway
  2. 2.Department of Geoscience and PetroleumNorwegian University of Science and Technology (NTNU)TrondheimNorway
  3. 3.Oulu Mining SchoolUniversity of OuluOuloFinland

Personalised recommendations