Numerical Analyses of the Influence of Blast-Induced Damaged Rock Around Shallow Tunnels in Brittle Rock

Original Paper
First Online:
Received:
Accepted:

Abstract

Most of the railway tunnels in Sweden are shallow-seated (<20 m of rock cover) and are located in hard brittle rock masses. The majority of these tunnels are excavated by drilling and blasting, which, consequently, result in the development of a blast-induced damaged zone around the tunnel boundary. Theoretically, the presence of this zone, with its reduced strength and stiffness, will affect the overall performance of the tunnel, as well as its construction and maintenance. The Swedish Railroad Administration, therefore, uses a set of guidelines based on peak particle velocity models and perimeter blasting to regulate the extent of damage due to blasting. However, the real effects of the damage caused by blasting around a shallow tunnel and their criticality to the overall performance of the tunnel are yet to be quantified and, therefore, remain the subject of research and investigation. This paper presents a numerical parametric study of blast-induced damage in rock. By varying the strength and stiffness of the blast-induced damaged zone and other relevant parameters, the near-field rock mass response was evaluated in terms of the effects on induced boundary stresses and ground deformation. The continuum method of numerical analysis was used. The input parameters, particularly those relating to strength and stiffness, were estimated using a systematic approach related to the fact that, at shallow depths, the stress and geologic conditions may be highly anisotropic. Due to the lack of data on the post-failure characteristics of the rock mass, the traditional Mohr–Coulomb yield criterion was assumed and used. The results clearly indicate that, as expected, the presence of the blast-induced damage zone does affect the behaviour of the boundary stresses and ground deformation. Potential failure types occurring around the tunnel boundary and their mechanisms have also been identified.

Keywords

Blast-induced damaged zone Overbreak Inherent rock properties Brittle rock Rock mass strength and stiffness Shallow tunnels Numerical analyses 

List of Symbols

For Undamaged Rock Mass

σi

intact compressive strength (MPa)

σm

compressive strength of the undamaged rock mass (MPa)

Em

deformation modulus of the undamaged rock mass (GPa)

ϕm

frictional strength of the undamaged rock mass (°)

cm

cohesive strength of the undamaged rock mass (MPa)

σtm

tensile strength of the undamaged rock mass (MPa)

For Damaged Rock Mass

D

disturbance factor

σd

compressive strength of the damaged rock mass (MPa)

Ed

deformation modulus of the damaged rock mass at the tunnel boundary (GPa)

Ed(ij)

deformation modulus of the damaged rock mass at point i, j (GPa)

ϕd

frictional strength of the damaged rock mass (°)

cd

cohesive strength of the damaged rock mass (MPa)

σtd

tensile strength of the damaged rock mass (MPa)

Ld

total thickness of the damaged rock zone (m)

Ld(ij)

thickness of the damaged rock zone at point i, j (m)

σdUB

upper bound compressive strength of the damaged rock mass

σdBC

base case compressive strength of the damaged rock mass

σdLB

lower bound compressive strength of the damaged rock mass

cdUB

upper bound cohesive strength of the damaged rock mass

cdBC

base case cohesive strength of the damaged rock mass

cdLB

lower bound cohesive strength of the damaged rock mass

Other Notations

σθ − σr

induced differential or deviatoric stress

σθ

tangential stress (induced)

σr

radial stress (induced)

σ3max

maximum confining stress

σ3min

minimum confining stress

σnmax

maximum normal stress derived from normal stress–shear stress envelope

σnmin

minimum normal stress derived from normal stress–shear stress envelope

τmax

maximum shear stress derived from normal stress–shear stress envelope

τmin

minimum shear stress derived from normal stress–shear stress envelope

This is a preview of subscription content, log in to check access.

Notes

Acknowledgements

The authors wish to acknowledge the Swedish Railroad Administration (Banverket) for funding this study, and Mr. Peter Lundman and Dr. Finn Ouchterlony for discussing the tunnel and rock excavation guidelines in Sweden. Doctors Evert Hoek and Mark Diederichs are sincerely acknowledged for their communications regarding the use of the Hoek–Brown criterion for shallow excavations and the use of disturbance factor descriptions for estimating the deformation modulus for the damaged rock.

References

  1. AnläggningsAMA-98 (1999) General materials and works description for construction work, section CBC: Bergschakt (in Swedish). Svensk Byggtjäanst, StockholmGoogle Scholar
  2. Banverket (2002) BV Tunnel. Standard BVS 585.40. BanverketGoogle Scholar
  3. Barla G, Barla M, Repetto L (1999) Continuum and discontinuum modelling for design analysis of tunnels. In: Proceedings of the 9th international congress on rock mechanics, Paris, France, August 1999Google Scholar
  4. Brown ET (ed) (1981) ISRM commission on standardization of laboratory and field tests. Suggested methods for the quantitative description of discontinuities in rock masses. Pergamon PressGoogle Scholar
  5. Cundall PA, Potyondi DO, Lee CA (1996) Micromechanics-based models for fracture and breakout around the mine-by tunnel. In: Martino JB, Martin CD (eds) Proceedings of the excavation disturbed zone (EDZ) workshop—designing the excavation disturbed zone for a nuclear waste repository in hard rock, Winnipeg, Manitoba, Canada, September 1996, pp 113–122Google Scholar
  6. da Gama CD (ed) (1998) Quantification of rock damage for tunnel excavation by blasting. Tunnels and metropolises. Balkema, Rotterdam, pp 451–456Google Scholar
  7. de la Vergne JN (2003) Hard rock miner’s handbook. McIntosh engineering, Tempe, AZ, p 262Google Scholar
  8. Diederichs MS (2003) Rock fracture and collapse under low confinement conditions. Rock Mech Rock Eng 36(5):339–381CrossRefGoogle Scholar
  9. Diederichs MS (2005) Personal communicationGoogle Scholar
  10. Diederichs MS, Kaiser PK (1999) Tensile strength and abutment relaxation as failure control mechanisms in underground excavations. Int J Rock Mech Min Sci 36(1):69–96CrossRefGoogle Scholar
  11. Farmer IW (1968) Engineering properties of rocks. E. & F.N. Spon Ltd., p 180Google Scholar
  12. Feng X-T, Zhang Z, Sheng Q (2000) Estimating mechanical rock mass parameters relating to the Three Gorges Project permanent shiplock using an intelligent displacement back analysis method. Int J Rock Mech Min Sci 37(7):1039–1054CrossRefGoogle Scholar
  13. Fjellborg S, Olsson M (1996) Long drift rounds with large cut holes at LKAB. SveBeFo Report No. 27, Swedish Rock Engineering Research, StockholmGoogle Scholar
  14. Forsyth WW, Moss AE (eds) (1991) Investigation of development blasting practices. CANMET-MRL, pp 91–143Google Scholar
  15. Hajiabdolmajid V, Kaiser PK, Martin CD (2002) Modeling brittle failure of rock. Int J Rock Mech Min Sci 39(6):731–741CrossRefGoogle Scholar
  16. Hoek E (2007) Practical rock engineering. Available online at: http://www.rocscience.com/hoek/PracticalRockEngineering.asp
  17. Hoek E, Diederichs MS (2006) Empirical estimation of rock mass modulus. Int J Rock Mech Min Sci 43(2):203–215CrossRefGoogle Scholar
  18. Hoek E, Kaiser PK, Bawden WF (1995) Support for underground excavations in hard rock. A.A. Balkema, Rotterdam, p 215Google Scholar
  19. Hoek E, Carranza-Toress C, Corkum B (2002) Hoek–Brown failure criterion—2002 edition. In: Proceedings of 5th North American rock mechanics symposium and the 17th Tunnelling Association of Canada conference (NARMS-TAC 2002), University of Toronto, Canada, July 2002, pp 267–271Google Scholar
  20. Holmberg R (1982) Charge calculation for tunneling. In: Hustrulid W (ed) Underground mining methods handbook. Society of Mining Metallurgy and Exploration, Littleton, pp 1580–1589Google Scholar
  21. Holmberg R, Persson P-A (1980) Design of tunnel perimeter blasthole patterns to prevent rock damage. Trans Inst Min Metall 89:A37–A40Google Scholar
  22. Hustrulid W (1994) The “practical” blast damage zone in drift driving at the Kiruna mine. In: Proceedings of the seminar Skadezon vid tunneldrivning, SveBeFo, StockholmGoogle Scholar
  23. Itasca (2002) FLAC version 4.00. Itasca Consulting Group, MinneapolisGoogle Scholar
  24. Ladegaard-Pedersen A, Daly JW (1975) A review of factors affecting damage in blasting. Mechanical Engineering Department, University of MarylandGoogle Scholar
  25. Lundman P (2004) Personal communicationGoogle Scholar
  26. MacKown AF (1986) Perimeter controlled blasting for underground excavations in fractured and weathered rocks. Bull Assoc Eng Geol XXIII(4):461–478Google Scholar
  27. Malmgren L, Saiang D, Töyrä J, Bodare A (2007) The excavation disturbed zone (EDZ) at Kiirunavaara mine, Sweden—by seismic measurements. J Appl Geophys 61(1):1–15CrossRefGoogle Scholar
  28. Martin CD, Read RS, Martino JB (1997) Observations of brittle failure around a circular test tunnel. Int J Rock Mech Min Sci 34(7):1065–1073CrossRefGoogle Scholar
  29. Martino JB (2003) The 2002 international EDZ workshop: the excavation damaged zone—cause and effects, Atomic Energy of Canada LimitedGoogle Scholar
  30. Martino JB, Martin CD (1996) Proceedings of the excavation disturbed zone workshop, ManitobaGoogle Scholar
  31. Nyberg U, Fjellborg S (2002) Controlled drifting and estimating blast damage. In: Holmberg R (ed) Proceedings first world conference on explosives and blasting technique. Balkema, Rotterdam, pp 207–216Google Scholar
  32. Olsson M, Bergqvist I (1993) Crack lengths from explosives in small diameter holes. SveBeFo Report No. 3, Swedish Rock Engineering Research, StockholmGoogle Scholar
  33. Olsson M, Bergqvist I (1995) Crack propagation in rock from multiple hole blasting—part 1. SveBeFo Report No. 18, Swedish Rock Engineering Research, StockholmGoogle Scholar
  34. Olsson M, Bergqvist I (1997) Crack propagation in rock from multiple hole blasting—summary of work during the period 1993–96. SveBeFo Report No. 32, Swedish Rock Engineering Research, StockholmGoogle Scholar
  35. Olsson M, Ouchterlony F (2003) New formula for blast induced damage in the remaning rock. SveBeFo Report No. 65, Swedish Rock Engineering Research, StockholmGoogle Scholar
  36. Oriad LL (1982) Blasting effect and their control. In: Hustrulid W (ed) Underground mining methods handbook. Society of Mining Engineers of AIME, New York, pp 1590–1603Google Scholar
  37. Ouchterlony F (1997) Prediction of crack lengths in rock after cautious blasting with zero inter-hole delay. SveBeFo Report No. 31, Swedish Rock Engineering Research, StockholmGoogle Scholar
  38. Ouchterlony F, Olsson M, Bergqvist I (2001) Towards new Swedish recommendations for cautious perimeter blasting. Explo 2001. Hunter Valley, NSWGoogle Scholar
  39. Pelli F, Kaiser PK, Morgenstern NR (1991) The influence of near face behaviour on monitoring of deep tunnels. Can Geotech J 28(2):226–238CrossRefGoogle Scholar
  40. Persson P-A, Holmberg R, Lee J (1996) Rock blasting and explosives engineering. CRC Press, Tokyo, pp 265–285Google Scholar
  41. Plis MN, Fletcher LR, Stachura VJ, Sterk PV (1991) Overbreak control in VCR stopes at Homestake mine. In: 17th Conference on explosives and blasting research, ISEE, pp 1–9Google Scholar
  42. Priest SD (2005) Determination of shear strength and three-dimensional yield strength for the Hoek–Brown criterion. Rock Mech Rock Eng 38(4):299–327CrossRefGoogle Scholar
  43. Pusch R, Stanfors R (1992) The zone of disturbance around blasted tunnels at depth. Int J Rock Mech Min Sci Geomech Abstr 29(5):447–456CrossRefGoogle Scholar
  44. Raina AK, Chakraborty AK, Ramulu M, Jethwa JL (2000) Rock mass damage from underground blasting, a literature review, and lab- and full scale tests to estimate crack depth by ultrasonic method. FRAGBLAST Int J Blast Fragm 4:103–125CrossRefGoogle Scholar
  45. Ricketts TE (1988) Estimating underground mine damage produced by blasting. In: 4th Mini symposium on explosive and blasting research, Society of Explosive Engineers, Anaheim, CA, pp 1–15 Google Scholar
  46. Robertson AM (1973) Determination of joint populations and their significance for tunnel stability. Trans Soc Min Eng AIME 254(2):135–139Google Scholar
  47. Rocscience (2002) RocLab, Rocscience Inc.Google Scholar
  48. Saiang D (2004) Damaged rock zone around excavation boundaries and its interaction with shotcrete. Licentiate Thesis, Luleå University of Technology, p 121Google Scholar
  49. Saiang D, Malmgren L, Nordlund E (2005) Laboratory tests on shotcrete-rock joints in direct shear, tension and compression. Rock Mech Rock Eng 38(4):275–297CrossRefGoogle Scholar
  50. Sato T, Kikuchi T, Sugihara K (2000) In-situ experiments on an excavation disturbed zone induced by mechanical excavation in Neogene sedimentary rock at Tono mine, central Japan. Eng Geol 56(1–2):97–108CrossRefGoogle Scholar
  51. Sheng Q, Yue ZQ, Lee CF, Tham LG, Zhou H (2002) Estimating the excavation disturbed zone in the permanent shiplock slopes of the Three Gorges Project, China. Int J Rock Mech Min Sci 39(2):165–184CrossRefGoogle Scholar
  52. Sjöberg J, Perman F, Leaner M, Saiang D (2006) Three-dimensional analysis of tunnel intersections for a train tunnel under Stockholm. In: Proceedings of the 2006 North American Tunneling conference, Chicago, Illinois, June 2006Google Scholar
  53. Stephansson O (1993) Rock stress in the Fennoscandian shield. In: Hudson JA (ed) Comprehensive rock engineering. Pergamon Press, Oxford, pp 445–459Google Scholar
  54. Tang B, Mitri HS (2001) Numerical modelling of rock preconditioning by destress blasting. J Ground Improv 5(2):57–67CrossRefGoogle Scholar
  55. Töyrä J (2006) Behaviour and stability of shallow underground constructions. Licentiate Thesis, Luleå University of Technology, Luleå, p 135Google Scholar
  56. Whittaker BN, Singh RN, Sun G (1992) Rock fracture mechanics—principles, design and applications. Developments in geotechnical engineering, vol 71. Elsevier, Amsterdam, p 568Google Scholar
  57. Yang RL, Rocque P, Katsabanis P, Bawden WF (1993) Blast damage study by measurement of blast vibration and damage in the area adjacent to blast hole. In: Rossmanith HP (ed) Rock fragmentation by blasting. Balkema, RotterdamGoogle Scholar

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  1. 1.Division of Rock MechanicsLuleå University of TechnologyLuleåSweden

Personalised recommendations