Jantzer, I & Knutsson, S 2010, 'Critical gradients for tailings dam design', in R Jewell & AB Fourie (eds), Proceedings of the First International Seminar on the Reduction of Risk in the Management of Tailings and Mine Waste
, Australian Centre for Geomechanics, Perth, pp. 23-33, https://doi.org/10.36487/ACG_rep/1008_03_Jantzer
Knowledge on tailings dam design is often derived from conventional earth and rockfill dams that are
designed for relatively short service periods. Tailings dams often differ in both structural design and service
life, where a long-term stability of 1,000 years or more is demanded. One of the most important factors
related to tailings dam stability and performance in long-term perspective is the prevention of failure from
internal erosion, i.e. particle migration initiated by seepage pressure.
Internal erosion is a process not yet completely understood; it is related to the seepage rate, which in turn is
connected to the hydraulic gradient, the internal structure, particle size distribution, etc. The hydraulic
gradient is therefore crucial for embankment stability and prevention of particle migration for a given
material. A basic research question is: does a maximum hydraulic gradient in a given material exist, below
which internal erosion cannot be initiated? If so, what maximum gradient can we allow for a tailings dam
construction in order to prevent internal erosion with respect to the long-term stability of the construction?
The maximum, or critical, gradient is often related to slope stability problems, heave, or blow out. Such
critical values differ from a critical hydraulic gradient for internal erosion problems taking place inside the
soil matrix. To be able to apply critical values on internal erosion problems, clear definitions and
information on the origin of a given critical hydraulic gradient is needed. This paper presents a detailed
literature survey on reported values of critical hydraulic gradients for the initiation of piping. These values
are derived from laboratory tests and from experiences of conventional dam constructions, i.e. they have to
be looked upon in a limited time perspective. This paper discusses the use of these values for tailings dams
To take the long-term aspect into account, natural analogies to dam constructions have been analysed. These
structures are formations from the last glaciations that have fulfilled the task of damming water. Such
structures are especially interesting with regard to their obvious stability against internal erosion over long
time periods. Natural analogies to dam constructions in Sweden are analysed to some extent and presented
in this paper. Results show that they are stable under a hydraulic gradient between 0.02 and 0.05. Current
guidelines on tailings dam design in Sweden allows a hydraulic gradient where neither the long-term
stability of the construction, nor the possible degradation of the construction material is taken into account.
To ensure a long-term stability of tailings dam constructions, a more thorough understanding of the critical
hydraulic gradient is needed, and a modification of the present design guidelines is suggested.
Agrell, H. (2002) Naturligt dämda sjöar – analogier av dammkonstruktioner, Uppdragsrapport för Svarliden Guld AB,
Geological Survey of Sweden SGU, Uppsala, Sweden (in Swedish).
Bjelkevik, A. (2005a) Water Cover Closure Design for Tailings Dams, State of the Art Report, Research Report, Luleå
University of Technology, Luleå, Sweden.
Bjelkevik, A. (2005b) Stability of Tailings Dams. Focus on Water Cover Closure, Licentiate Thesis, Luleå University of
Technology, Luleå, Sweden, 2005, 85 p.
Chapuis, R.P. (1992) Similarity of internal stability criteria for granular soils, Canadian Geotechnical Journal, Vol. 29,
Davies, M.P. (2002) Tailings Impoundment Failures: Are Geotechnical Engineers Listening? Geotechnical News,
September 2002, pp. 31–36.
den Adel, H., Bakker, K.J. and Klein Breteler, M. (1988) Internal Stability of Minestone, in Proceedings International
Symposium on Modelling Soil–Water–Structure Interaction, International Association for Hydraulic Research
(IAHR), Netherlands, Balkema, Rotterdam, pp. 225–231.
Fannin, R.J. and Moffat, R. (2006) A large permeameter for study of internal stability in cohesionless soils,
Geotechnical Testing Journal, Vol. 29, No. 4, pp. 273–279.
Fell, R., MacGregor, P., Stapledon, D. and Bell, G. (2005) Geotechnical Engineering of Dams, A.A. Balkema, Leiden.
Foster, M., Fell, R. and Spannagle, M. (2000) The statistics of embankment dam failures and accidents, Canadian
Geotechnical Journal, Vol. 37, pp. 1000–1024.
Jantzer, I. (2009) Critical hydraulic gradients in tailings dams – Comparison to natural analogies, Licentiate thesis,
Luleå University of Technology, Luleå, Sweden.
Jantzer, I., Bjelkevik, A. and Pousette, K. (2008) Material properties of tailings from Swedish mines, Nordic
Geotechnical Meeting NGM 15, Sandefjord, Norway, 3–6 September 2008, pp. 229–235.
Kenney, T.C. and Lau, D. (1985) Internal stability of granular filters, Canadian Geotechnical Journal, Vol. 22,
Lafleur, J. (1984) Filter testing of broadly graded cohesionless tills, Canadian Geotechnical Journal, Vol. 21,
Lafleur, J., Mlynarek, J. and Rollin, A.L. (1989) Filtration of broadly graded cohesionless soils, Journal of Geotechnical
Engineering, Vol. 115, No. 12, pp. 1747–1768.
Mansour, B.G.S. (2005) Investigations on Design and Rehabilitation Options for River Barrages with Special Respect
to Piping, Doctoral Thesis, Mitteilungen des Instituts für Grundbau, Bodenmechanik und Energiewasserbau,
Universität Hannover, Heft 62.
Mitchell, J.K. and Soga, K. (2005) Fundamentals of soil behaviour, John Wiley and Sons, Inc., Hoboken, New Jersey.
Design and Analysis
Mine Waste 2010, Perth, Australia 33
Mueller–Kirchenbauer, H., Rankl, M. and Schlötzer, C. (1993) Mechanism for regressive erosion beneath dams and
barrages, in Proceedings Filters in geotechnical and hydraulic engineering, J. Brauns, M. Heibaum, and U.
Schuler (eds), A.A. Balkema, Rotterdam, pp. 369–376.
Perzlmaier, S., Muckenthaler, P. and Koelewijn, A.R. (2007) Hydraulic Criteria for Internal Erosion in Cohesionless
Soil, in Proceedings Assessment of the Risk of Internal Erosion of Water Retaining Structures: Dams, Dykes and
Levees – Intermediate Report of the European Working Group of ICOLD, Contributions to the Symposium in
Freising, Germany, September 2007.
Richards, K.S. and Reddy, K.R. (2009) True Triaxial Piping Test Apparatus for Evaluation of Piping Potential in Earth
Structures, Geotechnical Testing Journal, Vol. 33, No. 1, pp. 83–95.
Saucke, U. (2006) Nachweis der Sicherheit gegen innere Erosion fuer Körnige Erdstoffe, Geotechnik 29, 2006 No. 1,
Sherard, J.L., Dunnigan, L.P. and Talbot, J.R. (1984) Basic properties of sand and gravel filters, Journal of
Geotechnical Engineering, Vol. 110, No. 6, pp. 684–700.
Sherard, J.L., Steele, E.F., Decker, R.S. and Dunnigan, L.P. (1976) Pinhole Test for Identifying Dispersive Soils,
Journal of the Soil Mechanics and Foundations Division, Vol. 102, No. 1, pp. 69–85.
Skempton, A.W. and Brogan, J.M. (1994) Experiments on piping in sandy gravels, Géotechnique, Vol. 44, No. 3,
Terzaghi, K., Peck, R.B. and Mesri, G. (1996) Soil mechanics in engineering practice, Third Edition, John Wiley &
Sons Inc., New York.
Tomlinson, S.S. and Vaid, Y.P. (2000) Seepage forces and confining pressure effects on piping erosion, Canadian
Geotechnical Journal, Vol. 37, pp. 1–13.
Wan, C.F. and Fell, R. (2004a) Investigation of Rate of Erosion of Soils in Embankment Dams, Journal of Geotechnical
and Geoenvironmental Engineering, Vol. 130, No. 4, pp. 373–380.
Wan, C.F. and Fell, R. (2004b) Experimental investigation of internal instability of soils in embankment dams and their
foundations, NICIV Report No. R429, University of South Wales, Sydney, Australia.
Weijers, J. and Sellmeijer, J. (1993) A new model to deal with the piping mechanism, in Proceedings Filters in
geotechnical and hydraulic engineering, J. Brauns, M. Heibaum, and U. Schuler (eds), A.A. Balkema,
Rotterdam, pp. 349–355.
Zhang, L.M. and Chen, Q. (2006) Seepage failure mechanism of the Gouhou rockfill dam during reservoir water
infiltration, Soils and Foundations, Vol. 46, No. 5, pp. 557–568.
Ziems, J. (1969) Beitrag zur Kontakterosion nichtbindiger Erdstoffe, Doctoral Thesis at Technische Univeristät
Dresden, Germany (In German).
Critical gradients for tailings dam design I. Jantzer and S. Knutsson
34 Mine Waste 2010, Perth, Australia