Numerical Analysis of the 650,000 m2 Åknes Rock Slope based on Measured Displacements and Geotechnical Data

  • Vidar Kveldsvik
  • Herbert H. Einstein
  • Bjørn Nilsen
  • Lars Harald Blikra
Original Paper

Abstract

The unstable 650,000 m2 Åknes rock slope (Western Norway) poses a hazard, as a sudden failure may cause a destructive tsunami in the fjord. In this study the slope was divided into blocks based on displacements measured at the slope surface. Discontinuous deformation analysis (DDA) showed that three or four blocks in the upper half may be considered as potential subareas that may fail catastrophically. The lower half may be divided into two or three blocks, but more limited data introduces more uncertainty into block definition. The Universal Distinct Element code (UDEC) was used for two-dimensional (2D) stability analyses. By varying fracture geometry, fracture friction, and groundwater conditions within reasonable limits based on site-specific data a number of possible models were compared. The conclusions show that models that were unstable to great depths were in closer agreement with shear strength parameters derived from an earlier study than models that were unstable to smaller depths. The length (depth) of the outcropping fracture, along which shear displacements are shown to occur, plays an important role. A (shallow) slide at 30 m, in which displacements have been documented by borehole measurements, will reduce the stability at greater depths. Increased groundwater pressure is demonstrated to be less critical for very deep slope instability. The results of the DDA and UDEC modelling will be useful for planning of future investigations, interpretation of the subsequent results, further development of the early warning system and in the tsunami modelling.

Keywords

Landslides Displacement analysis Numerical modelling DDA-Backward UDEC 

Notes

Acknowledgments

The work presented here is part of ongoing projects funded by the Research Council of Norway through the International Centre for Geohazards (ICG), the Geological Survey of Norway (NGU), Norwegian Geotechnical Institute (NGI), Norwegian University of Science and Technology (NTNU), National Fund for Natural Damage Assistance and Møre & Romsdal County, and the Aaknes/Tafjord project. The DDA-Backward analysis was done while the first author stayed at University of California, Berkeley. The first author wishes to thank Prof. Nicholas Sitar for hosting the stay and for useful discussions during the work. Thanks are also due to Dr. Gen-Hua Shi who suggested doing the DDA-Backward analysis and who taught the method.

References

  1. Barton N, Bandis S (1990) Review of predictive capabilities of JRC-JCS model in engineering practice. In: Proc Int. Symp. on Rock Joints, Loen, Norway, Balkema, pp. 603–610Google Scholar
  2. Barton N, Choubey V (1977) The shear strength of rock joints in theory and practice. Rock Mech 10:1–54CrossRefGoogle Scholar
  3. Bhasin R, Kaynia AM (2004) Static and dynamic simulation of a 700 m high rock slope in western Norway. Eng Geol 71:213–226CrossRefGoogle Scholar
  4. Blikra LH, Longva O, Harbitz C, Løvholt F (2005) Quantification of rock-avalanche and tsunami hazard in Storfjorden, western Norway. In: Senneset K, Flaate K, Larsen JO (eds) Landslide and Avalanches ICFL 2005 Norway. Taylor & Francis, London, pp 57–63Google Scholar
  5. Blikra LH, Longva O, Braathen A, Anda E, Dehls JF, Stalsberg K (2006) Rock-slope failures in Norwegian fjord areas: examples, spatial distribution and temporal patterns. In: Evans SG, Mugnozza GS, Strom A, Hermanns RL (eds) Landslides from Massive Rock Slope Failure. NATO Science Series. IV. Earth and Environmental Sciences, vol 49, pp 475–496. Springer, DordrechtGoogle Scholar
  6. Blikra LH (2008) The Åknes rockslide; monitoring, threshold values and early-warning. In: Proceedings of the 10th International Symposium on Landslides and Engineered Slopes, Xi’an, China (In print)Google Scholar
  7. Braathen A, Blikra LH, Berg SS, Karlsen F (2004) Rock-slope failures of Norway; type, geometry, deformation mechanisms and stability. Norwegian J Geol (NGT) 84:67–88Google Scholar
  8. Chang QT (1994) Nonlinear dynamic discontinuous deformation analysis with finite element meshed block systems. Ph.D. thesis, University of California, BerkeleyGoogle Scholar
  9. Crosta GB, Agliardi F (2003) Failure forecast for large rock slides by surface displacement measurements. Can Geotech J 40:176–191CrossRefGoogle Scholar
  10. Cundall PA (1980) UDEC—a generalized distinct element program for modelling jointed rock. Report PCAR-1-80, Peter Cundall Associates, European Research Office, US Army Corps of EngineersGoogle Scholar
  11. Derron M-H, Blikra LH, Jaboyedoff M (2005) High resolution digital elevation model analysis for landslide hazard assessment (Åkerneset, Norway). In: Senneset, Flaate K, Larsen JO (eds) Landslide and Avalanches ICFL 2005 Norway. Taylor & Francis Group, London, pp 101–106Google Scholar
  12. Eiken T (2007) Personal communication. University of Oslo, NorwayGoogle Scholar
  13. Eberhardt E, Stead D, Coggan JS (2004a) Numerical analysis of initiation and progressive failure in natural rock slopes—the 1991 Randa rockslide. Int J Rock Mech Mining Sci 41(1):69–87CrossRefGoogle Scholar
  14. Eberhardt E, Spillmann T, Maurer H, Willenberg H, Loew S, Stead D (2004b) The Randa Rockslide Laboratory: establishing brittle and ductile instability mechanisms using numerical modelling and microseismicity. In: Lacerda A et al. (eds) Proc. 9th Int. Symp. on Landslides. Rio de Janeiro. Balkema, Leiden, pp 481–487Google Scholar
  15. Evans SG, Mugnozza GS, Strom AL, Hermanns RL, Ischuk A, Vinnichenko S (2006) Landslides from massive rock slope failure and associated phenomena. In: Evans SG, Mugnozza GS, Strom A, Hermanns RL (eds) Landslides from Massive Rock Slope Failure. NATO Science Series. IV. Earth and Environmental Sciences, vol 49. Springer, Dordrecht, pp 3–52Google Scholar
  16. Fritz HM, Hager WH, Minor H-E (2001) Lituya Bay case: rockslide impact and wave run-up. Sci Tsunami Hazards 19(1):3–22Google Scholar
  17. Fukuzono T (1985) A new method for predicting the failure time of a slope. In: Proceedings of the 4th International Conference and Field Workshop on Landslides, Tokyo, Tokyo University Press, pp 145–150Google Scholar
  18. Ganerød GV, Grøneng G, Rønning JS, Dalsegg E, Elvebakk H, Tønnesen JF, Kveldsvik V, Eiken T, Blikra LH, Braathen A (2008) Geological model of the Åknes rock slide, western Norway. Eng Geol (in print)Google Scholar
  19. Govi M, Gulla G, Nicoletti PG (2002) Val Pola rock avalanche of July 28, 1987, in Valtellina (Central Italian Alps). In: Evans SG, DeGraff JV (eds) Catastrophic landslides: effects, occurrence and mechanisms. Geol. Soc. Am. Rev. Eng. Geol., vol XV, pp 71–89Google Scholar
  20. Hart RD (1993) An introduction to distinct element modelling for rock engineering. In: Hudson JA (ed) Comprehensive Rock Engineering: Principles, Practice and Projects, vol 2. Pergamon Press, Oxford, pp 245–261Google Scholar
  21. Jing L (1998) Formulation of discontinuous deformation analysis (DDA)—an implicit discrete element model for block systems. Eng Geol 49:371–81CrossRefGoogle Scholar
  22. Jing L (2003) A review of techniques, advances and outstanding issues in numerical modelling for rock mechanics and rock engineering. Int J Rock Mech Mining Sci 40(7–8):283–353CrossRefGoogle Scholar
  23. Kilburn CRJ, Petley DN (2003) Forecasting giant, catastrophic slope collapse: lessons from Vajont, Northern Italy. Geomorphology 54:21–32CrossRefGoogle Scholar
  24. Kveldsvik V, Eiken T, Ganerød GV, Grøneng G, Ragvin N (2006) Evaluation of movement data and ground conditions for the Åknes rock slide. In: Proceedings of International Symposium on Stability of Rock Slopes in Open Pit Mine and Civil Engineering, pp 279–299. The South African Institute of Mining and Metallurgy (SAIMM)Google Scholar
  25. Kveldsvik V, Einstein HH, Nadim F, Nilsen B (2007) Alternative approaches for analyses of a 100,000 m3 rock slide based on Barton–Bandis shear strength criterion. Landslides. http://ejournals.ebsco.com/direct.asp?ArticleID = 414B898789CF80825C7D. doi:10.1007/s10346-007-0096-x
  26. MacLaughlin MM, Sitar N (1995) DDA for Windows: Discontinuous deformation analysis for the windows PC environment. Geotechnical engineering report no. UCB/GT/95-04, University of California, Berkeley, CaliforniaGoogle Scholar
  27. MacLaughlin MM, Berger EA (2003) A decade of DDA validation. In: Lu M (ed) Development and Application of Discontinuous Modelling for Rock Engineering. Proc. of the 6th International Conf. on Analysis of Discontinuous Deformation, Trondheim, Norway, pp 13–31. Balkema, Rotterdam, ISBN 90 5809 610 6Google Scholar
  28. MacLaughlin MM, Doolin DM (2006) Review of validation of the discontinuous deformation analysis (DDA) method. Int J Numer Anal Methods Geomech 30(4):271–305CrossRefGoogle Scholar
  29. Müller-Salzburg L (1987) The Vajont catastrophe—a personal review. Eng Geol 24:493–512CrossRefGoogle Scholar
  30. Petley DN, Bulmer MH, Murphy W (2002) Patterns of movement in rotational and translational landslides. Geology 30(8):719–722CrossRefGoogle Scholar
  31. Segalini A, Giani GP (2004) Numerical model for the analysis of the evolution mechanics of the Grossgufer rock slide. Rock Mech Rock Eng 37(2):151–168CrossRefGoogle Scholar
  32. Shi GH, Goodman RE (1985) Two dimensional discontinuous deformation analysis. Int J Numer Anal Methods Geomech 9:541–556CrossRefGoogle Scholar
  33. Shi GH (1988) Discontinuous deformation analysis: a new numerical model for the statics and dynamics of block systems. Ph.D. Dissertation, Department of Civil Engineering, University of California, BerkeleyGoogle Scholar
  34. Shi G, Goodman RE (1989) Discontiuous deformation analysis—a new numerical method for the statics and dynamics of deformable block structures. In: Mustoe G et al. (eds) Proceedings of the 1st U.S. Conf. on Discrete Element Methods, Golden, Colorado. CSM Press, Golden, 16 ppGoogle Scholar
  35. Shimizu N, Kakihara H, Terato H, Nakagawa K (1996) A back analysis for predicting deformational behaviour of discontinuous rock mass. In: Aubertin M, Hassani F, Mitri H (eds) Proceedings of the Second North American Rock Mechanics Symposium, Montreal, Canada, pp 2001–2008Google Scholar
  36. Shyu K (1993) Nodal-based discontinuous deformation analysis. Ph.D. thesis, University of California, BerkeleyGoogle Scholar
  37. Sitar N, MacLaughlin MM, Doolin DM (2005) Influence of kinematics on landslide mobility and failure mode. J Geotech Geoenviron Eng 131(6):716–728CrossRefGoogle Scholar
  38. Stead D, Eberhardt E, Coggan JS (2006) Developments in the characterization of complex rock slope deformation and failure using numerical techniques. Eng Geol 83:217–235CrossRefGoogle Scholar
  39. Ter-Stepanian G (1966) Types of depth creep of slopes in rock masses. In: Proceedings of the first congress of the International Society of Rock Mechanics, Lisboa 1966, pp 157–160Google Scholar
  40. Varga AA (2006) Gravitational creep of rock slopes as pre-collapse deformation and some problems in its modelling. In: Evans SG, Mugnozza GS, Strom A, Hermanns RL (eds) Landslides from Massive Rock Slope Failure. NATO Science Series. IV. Earth and Environmental Sciences, vol 49. Springer, Dordrecht, pp 103–110Google Scholar
  41. Voight B (1989) A relation to describe rate-dependent material failure. Science 243:200–203CrossRefGoogle Scholar
  42. Yeung MR, Blair SC (1999) Analysis of large block test data using DDA method. In: Amadei B (ed) ICADD-3: Third International Conference on Analysis of Discontinuous Deformation. From Theory to Practice. American Rock Mechanics Association, Balkema, Rotterdam, Washington DC, pp 141–150Google Scholar
  43. Yeung MR, Blair SC (2000) DDA back analysis of large block test data. In: Seattle WA, Girard J, Liebman M, Breeds C, Doe T (eds) Proceedings of Pacific Rocks, The Fourth North American Rock Mechanics Symposium. Balkema, Rotterdam, pp 934–944Google Scholar

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Vidar Kveldsvik
    • 1
    • 2
  • Herbert H. Einstein
    • 3
  • Bjørn Nilsen
    • 2
  • Lars Harald Blikra
    • 2
    • 4
  1. 1.Norwegian Geotechnical Institute/International Centre for GeohazardsOsloNorway
  2. 2.Norwegian University of Science and TechnologyTrondheimNorway
  3. 3.Department of Civil and Environmental EngineeringMassachusetts Institute of TechnologyMAUSA
  4. 4.Geological Survey of NorwayTrondheimNorway

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