Impact of Desiccation on Monotonic and Cyclic Shear Strength of Thickened Gold Tailings
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 140, Issue 9
Abstract
Various forms of thickened or high-density tailings, characterized by exhibition of a yield stress that facilitates deposition in gently sloped stacks, are increasingly used for a variety of mining operations. Although this technology reduces reliance on containment by dams and the associated risk of catastrophic failure, regulators are concerned with remobilization of such unbounded deposits by earthquakes or extreme rainfalls. Therefore, the monotonic and cyclic shear strength of thickened tailings layers are of significant interest. Thickened tailings experience a particular stress history during deposition, which may include desiccation, rewetting, and subsequent consolidation by burial under new tailings. The effect of this stress history on their shear response is investigated using a Norwegian Geotechnical Institute (NGI)-type simple shear device. Samples are alternately mechanically overconsolidated or subjected to desiccation and subsequent rewetting because of burial by fresh tailings before consolidation. The two sets of data, one overconsolidated by load, the other by matric suction, were compared using the suction stress concept to quantify an equivalent overconsolidation ratio (OCR) caused by desiccation. However, the effects of mechanical overconsolidation and desiccation were found to be qualitatively different for both the monotonic and cyclic responses; therefore, it is not possible to quantify the effects of desiccation using mechanical overconsolidation and one stress-state variable. Desiccated samples exhibited much weaker strength at phase transformation but more strain hardening compared with mechanically overconsolidated samples at the same OCR. For the desiccated samples, both monotonic strength at phase transformation and cyclic resistance continuously increased with increasing desiccation to air entry value (AEV). Past the AEV, a much smaller increase in strength was observed. Even a small amount of desiccation changed the monotonic response of the tailings from contractive to dilative behavior.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
Support from Golder Associates, the Natural Science and Engineering Research Council of Canada (NSERC), and the Canadian Foundation for Innovation (CFI) is gratefully acknowledged.
References
Al-Tarhouni, M., Simms, P., and Sivathayalan, S. (2011). “Cyclic behaviour of reconstituted and desiccated–rewet thickened gold tailings in simple shear.” Can. Geotech. J., 48(7), 1044–1060.
ASTM. (2000a). “Standard test methods for liquid limit, plastic limit, and plasticity index of soils.” D4318-10, West Conshohocken, PA.
ASTM. (2000b). “Standard test methods for specific gravity of soil solids by water pycnometer.” D854-10, West Conshohocken, PA.
ASTM. (2007). “Standard test method for particle-size analysis of soils.” D422-63, West Conshohocken, PA.
Bishop, A. W. (1959). “The principle of effective stress.” Teknisk Ukeblad, 106(39), 859–863.
Boulanger, R. W., and Idriss, I. M. (2004). “Evaluation of the potential for liquefaction or cyclic failure of silts and clays.” Rep. No. UCD/CGM-04/01, Center for Geotechnical Modeling, Univ. of California, Davis, CA.
Bryan, R., Simms, P., and Verburg, R. (2010). “Coupling oxidation to transient drying during multilayer deposition of thickened gold tailings.” Miner. Eng., 23(14), 1101–1112.
Bussiere, B. (2007). “Colloquium 2004: Hydrogeotechnical properties of hard rock tailings from metal mines and emerging geoenvironmental disposal approaches.” Can. Geotech. J., 44(9), 1019–1052.
Cooper, R. A., and Smith, M. E. (2011). Case study: operation of three paste disposal facilities. Proc., 14th Int. Seminar on Paste and Thickened Tailings, Australian Centre for Geomechanics, Crawley, Australia, 261–270.
Daliri, F. (2013). “The influence of desiccation and overconsolidation on monotonic and cyclic shear response of thickened gold tailings.” Ph.D. dissertation, Carleton Univ., Ottawa.
Dyvik, R., Berre, T., Lacasse, S., and Raadim, B. (1987). “Comparison of truly undrained and constant volume direct simple shear tests.” Geotechnique, 37(1), 3–10.
Ellison, K. C., and Andrade, J. E. (2009). “Liquefaction mapping in finite-element simulations.” J. Geotech. Geoenviron. Eng., 1693–1701.
Fisseha, B., Bryan, R., and Simms, P. (2010). “Evaporation, unsaturated flow, and salt accumulation in multilayer deposits of ‘paste’ gold tailings.” J. Geotech. Geoenviron. Eng., 1703–1712.
Fredlund, D. G. (2006). “Unsaturated soil mechanics in engineering practice.” J. Geotech. Geoenviron. Eng., 286–321.
Fredlund, D. G., and Morgenstern, N. R. (1977). “Stress state variables for unsaturated soils.” J. Geotech. Engrg. Div., 103(5), 447–466.
International Commission on Large Dams. (2001). “Tailings dams: Risk of dangerous occurrences. Lessons learnt from practical experiences.” Bulletin 121, Paris.
Ishihara, K., Tatsuoka, F., and Yasuda, S. (1975). “Undrained deformation and liquefaction of sand under cyclic stresses.” Soils Found., 15(1), 29–44.
Lu, N., Godt, J. W., and Wu, D. T. (2010). “A closed-form equation for effective stress in unsaturated soil.” Water Resour. Res., 46(5).
Lu, N., and Likos, W. J. (2006). “Suction stress characteristic curve for unsaturated soil.” J. Geotech. Geoenviron. Eng., 131–142.
McPhail, G., and Brent, C. (2007). “Osborne high density discharge: An update from 2004.” Proc., 10th Int. Seminar on Paste and Thickened Tailings, A. Fourie and R. Jewell, eds., Australian Centre for Geomechanics, Crawley, Australia, 339–350.
National Research Council (NRC). (1985). Liquefaction of soils during earthquakes, National Academy Press, Washington, DC.
Robinsky, E. I. (1975). “Thickened discharge: A new approach to tailings disposal.” Can. Min. Metall. Bull., 68(764), 47–53.
Robinsky, E. I. (1999). Thickened tailings disposal in the mining industry, E. I. Robinsky Associates, Toronto.
Seed, H. B., and Idriss, I. M. (1982). Ground motions and soil liquefaction during earthquakes, Earthquake Engineering Research Institute (EERI), Berkeley, CA.
Shuttleworth, J. A., Thomson, B. J., and Wates, J. A. (2005). “Surface paste disposal at Bulyanhulu—Practical lessons learned.” Proc., 8th Int. Seminar on Paste and Thickened Tailings, R. Jewell and S. Barrera, eds., Australian Centre for Geomechanics, Crawley, Australia, 20–22.
Simms, P., Dunmola, A., and Bryan, R. (2010). “Generic modeling of desiccation for cyclic deposition of thickened tailings to maximize density and to minimize oxidation.” Proc., 13th Int. Seminar on Paste and Thickened Tailings, R. Jewell and A. Fourie, eds., Australian Centre for Geomechanics, Crawley, Australia, 293–303.
Simms, P., Grabinsky, M., and Zhan, G. (2007). “Modelling evaporation of paste tailings from the Bulyanhulu mine.” Can. Geotech. J., 44(12), 1417–1432.
Simms, P., and Grabinsky, M. W. (2004). “A simple method for estimating rates of drying and desaturation of paste tailings during surface deposition.” Proc., 11th Annual Conf. on Tailings and Mine Waste, Taylor & Francis, London, 287–292.
Simms, P., Sivathayalan, S., and Daliri, F. (2013). “Desiccation in dewatering and strength development of high-density hard rock tailings.” Proc., 16th Int. Seminar on Paste and Thickened Tailings, R. Jewell and A. Fourie, eds., Australian Centre for Geomechanics, Crawley, Australia, 75–86.
Simms, P. H., and Yanful, E. K. (2004). “Estimation of soil–water characteristic curve of clayey till using measured pore-size distributions.” J. Environ. Eng., 847–854.
Simms, P. H., and Yanful, E. K. (2005). “A pore-network model for hydro-mechanical coupling in unsaturated compacted clayey soils.” Can. Geotech. J., 42(2), 499–514.
Vaid, Y. P., and Chern, J. C. (1985). “Cyclic and monotonic undrained response of saturated sands.” Proc., Advances in the Art of Testing Soils under Cyclic Conditions, V. Khosla, ed., ASCE, Reston, VA, 120–147.
Vaid, Y. P., and Sivathayalan, S. (1996). “Static and cyclic liquefaction potential of Fraser Delta sand in simple shear and triaxial tests.” Can. Geotech. Journal, 33(2), 281–289.
Wijewickreme, D., and Sanin, M. (2004). “Cyclic shear loading response of Fraser river delta silt.” Proc., 13th World Conf. on Earthquake Engineering, Canadian Association for Earthquake Engineering, Vancouver, BC, Canada.
Williams, M. P. A., Seddon, K. D., and Fitton, T. G. (2008). “Surface disposal of paste and thickened tailings: Brief history and current confronting issues.” Proc., 11th Int. Seminar on Paste and Thickened Tailings, A. Fourie, R. Jewell, P. Slatter, and A. Paterson, eds., Australian Centre for Geomechanics, Crawley, Australia, 293–303.
Information & Authors
Information
Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 140 • Issue 9 • September 2014
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Jun 12, 2012
Accepted: May 5, 2014
Published online: Jun 13, 2014
Published in print: Sep 1, 2014
Discussion open until: Nov 13, 2014
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.