A New Solution to Assess the Required Strength of Mine Backfill with a Vertical Exposure
Publication: International Journal of Geomechanics
Volume 17, Issue 10
Abstract
Backfilling is commonly applied to aid pillar recovery in open stope mines. The backfill must then remain self-standing in the primary stope when mining an adjacent secondary stope. The design of exposed fill is often based on a solution proposed by Mitchell and coworkers over 30 years ago. Several modifications of this solution have later been reported. These solutions have been partly validated against a few physical model test results, and they have also been compared with numerical simulations. The analyses have shown that these solutions cannot completely capture the response of the exposed backfill, particularly when the required cohesion of the cemented backfill is relatively large. New simulation results presented here indicate that the sliding plane tends to change from planar at small fill cohesion to spoon shaped [three-dimensional (3D)] at larger cohesion. In the former case, the failure mechanism is controlled by shear stress along the sliding plane near the base of the stope; this corresponds well to existing analytical models. In the latter case, however, failure of the backfill is controlled by both shear (near the base) and tensile (near the top) stresses. This feature is not represented by existing analytical models. In this paper, a new analytical solution is proposed for assessing the stability of exposed cemented backfill with a vertical face. An instability criterion is also introduced for estimating the critical strength of side-exposed backfill. Additional numerical simulations are then conducted to validate the proposed analytical solution. The results show that the newly developed solution correlates well with the numerical simulations for representative stope geometry and backfill strength. This new solution is thus regarded as an improvement over existing solutions. Further calculations are made to illustrate the effect of key parameters on the stability of side-exposed fill. A discussion follows on the limitations and effect of various influence factors on the design of exposed cemented backfill.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The authors would like to acknowledge the financial support from the Natural Sciences and Engineering Research Council of Canada (NSERC 402318), Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST 2013-0029), Fonds de recherche du Québec–Nature et Technologies (FRQNT 2015-MI-191676), and the industrial partners of the Research Institute on Mines and Environment (RIME UQAT-Polytechnique; http://rime-irme.ca).
References
Alexander, E., and Fabjanczyk, M. (1982). “Extraction design using open slopes for pillar recovery in the 1100 orebody at Mount Isa.” Proc., Design and Operation of Caving and Sublevel Stoping Mines, SME, New York, 437–458.
Askew, J., McCarthy, P. L., and Fitzgerald, D. J. (1978). “Backfill research for pillar extraction at ZC/NBHC.” Proc., 12th Canadian. Rock Mechanics Symp. on Mining with Backfill, CIM, Montreal, Canada, 100–110.
Aubertin, M., et al. (2003). “Interaction between backfill and rock mass in narrow stopes.” Proc., Soil and Rock America 2003, P. J. Culligan, H. H. Einstein, and A. J. Whittle, eds., Vol. 1, Verlag Glückauf Essen (VGE), Essen, Germany, 1157–1164.
Barrett, J. R., Coulthard, M. A., and Dight, P. M. (1978). “Determination of fill stability.” Proc., 12th Canadian Rock Mechanics Symp. on Mining with Backfill, CIM, Montreal, Canada, 85–91.
Barrett, J. R., and Cowling, R. (1980). “Investigations of cemented fill stability in 1100 orebody, Mount Isa Mines, Ltd., Queensland, Australia.” IMM Trans. Sect. A: Min. Ind., 89, A118–A128.
Bloss, M. L. (1992). “Prediction of cemented rock fill stability–design procedures and modelling techniques.” Ph.D. thesis, Univ. of Queensland, Brisbane, Australia.
Bloss, M. L., Cowling, R., and Meek, J. L. (1993). “A procedure for the design of stable cemented fill exposures.” Proc., MINEFILL’93, 5th Int. Symp. on Mining with Backfill, Southern African Institute of Mining and Metallurgy, Johannesburg, South Africa, 3–8.
Bowles, J. E. (1984). Physical and geotechnical properties of soils, 2nd Ed., McGraw-Hill, New York.
Coulthard, M. A. (1980). “Numerical analysis of fill pillar stability: Three dimensional linearly elastic finite element calculations.” Technical Rep., Div. of Applied Geomechanics, Commonwealth Scientific and Industrial Research Organization, Mt. Waverley, VC, Australia.
Coulthard, M. A. (1999). “Applications of numerical modelling in underground mining and construction.” Geotech. Geol. Eng., 17(3), 373–385.
Coulthard, M. A., and Dight, P. M. (1980). “Numerical analysis of failed cemented fill at ZC/NBHC Mine, Broken Hill.” Proc., 3rd Australia-New Zealand Geomech. Conf., Institution of Professional Engineers New Zealand, Wellington, New Zealand, 2-145–2-151.
Cowling, R., and Gonano, L. P. (1976). “Cemented rockfill practice at Mount Isa Mines Limited.” Proc., Symp. on Influence of Excavation Design and Ground Support on Underground Mining Efficiency and Costs, Australian Mineral Industries Research Association, Parkville, VC, Australia.
Cundall, P., Shillabeer, J. H., and Herget, G. (1978). “Modelling to predict rock fill stability in transverse pillar extraction.” Proc., 12th Canadian Rock Mechanics Symp. on Mining with Backfill, CIM, Montreal, Canada, 92–99.
Dight, P. M., and Coulthard, M. A. (1980). “Numerical analysis of fill pillar stability–two-dimensional analysis of exposures.” Technical Rep. CSIRO, Div. of Applied Geomechanics, Commonwealth Scientific and Industrial Research Organization, Mt. Waverley, VC, Australia.
Dirige, A. P. E., and De Souza, E. (2000). “Centrifuge physical modelling of paste fill designs for improved cost performance.” Proc., The Millennium 2000 CIM Conf., CIM, Montreal, Canada.
Dirige, A. P. E., and De Souza, E. (2013). “Mechanics of failure of paste backfill face exposure during adjacent mining.” Proc., 23rd World Mining Congress, CIM, Montreal, Canada.
Dirige, A. P. E., McNearny, R. L., and Thompson, D. S. (2009). “The effect of stope inclination and wall rock roughness on back-fill free face stability.” Proc., Rock Engineering in Difficult Conditions, 3rd Canada-US Rock Mechanics Symp. (CD-ROM), M. Diederichs and G. Grasselli, eds., Omnipress, Madison, WI.
Duncan, J. M., and Bursey, A. (2013). “Soil modulus correlations.” Foundation of engineering in the face of uncertainty: Honoring Fred H. Kulhawy, James L. Withiam, K. K. Phoon, and M. H. Hussein, eds., Geotechnical special publication 229, ASCE, Reston, VA, 321–336.
Duncan, J. M., and Wright, S. G. (2005). Soil strength and slope stability, John Wiley & Sons, New York.
El Mkadmi, N., Aubertin, M., and Li, L. (2014). “Effect of drainage and sequential filling on the behavior of backfill in mine stopes.” Can. Geotech. J., 51(1), 1–15.
Emad, M. Z., Mitri, H., and Henning, J. G. (2012). “Effect of blast vibrations on the stability of cemented rockfill.” Int. J. Min. Reclam. Environ., 26(3), 233–243.
Emad, M. Z., Mitri, H., and Kelly, C. (2014). “Effect of blast-induced vibrations on fill failure in vertical block mining with delayed backfill.” Can. Geotech. J., 51(9), 975–983.
Emad, M. Z., Mitri, H., and Kelly, C. (2015). “In-situ blast vibration monitoring in cemented rockfill stope-a case study.” Int. J. Min. Reclam. Environ., 1–18.
Falaknaz, N. (2014). “Analysis of geomechanical behavior of two adjacent backfilled stopes based on two and three dimensional numerical simulations.” Ph.D. thesis, Mineral Engineering, Polytechnique Montréal, Montréal.
Falaknaz, N., Aubertin, M., and Li, L. (2015a). “Evaluation of the stress state in two adjacent backfilled stopes within an elasto-plastic rock mass.” Geotech. Geol. Eng., 1–24.
Falaknaz, N., Aubertin, M., and Li, L. (2015b). “Numerical analyses of the stress state in two neighboring stopes excavated and backfilled in sequence.” Int. J. Geomech., 04015005.
Falaknaz, N., Aubertin, M., and Li, L. (2015c). “Numerical investigation of the geomechanical response of adjacent backfilled stopes.” Can. Geotech. J., 52(10), 1507–1525.
Falaknaz, N., Aubertin, M., and Li, L. (2015d). “On the stability of exposed backfill in mine stopes.” Proc., 68th Canadian Geotechnical Conf., Quebec City, Canada.
Fall, M., and Nasir, O. (2010). “Mechanical behaviour of the interface between cemented tailings backfill and retaining structures under shear loads.” Geotech. Geol. Eng., 28(6), 779–790.
Itasca. (2013). FLAC3D: Fast Lagrangian analysis of continua in 3 dimensions; user’s guide, version 5.01, Itasca Consulting Group, Minneapolis, MN.
Jahanbakhshzadeh, A. (2016). “Analyse du comportement géomécanique des remblais miniers dans des excavations souterraines inclinées.” Ph.D. thesis, Mineral Engineering, Polytechnique Montréal, Montréal.
Jones, T. O. (1972). “Pillar recovery in a section of the 650 orebody floor pillar using cemented fill.” Proc., The Aus. IMM Regional Conf., Australasian Institute of Mining and Metallurgy, Carlton, VC, Australia.
Karim, R., Simangunsong, G. M., Sulistianto, B., and Lopulalan, A. (2013). “Stability analysis of paste fill as stope wall using analytical method and numerical modeling in the Kencana underground gold mining with long hole stope method.” Procedia Earth Planet. Sci., 6, 474–484.
Koupouli, N. J., Belem, T., Rivard, P., and Effenguet, H. (2016). “Direct shear tests on cemented paste backfill-rock wall and cemented paste backfill-backfill interfaces.” J. Rock Mech. Geotech. Eng., 8(4), 472–479.
Leahy, F. J., and Cowling, R. (1978). “Stope fill developments at Mount Isa.” Proc., 12th Canadian Rock Mechanics Symp. on Mining with Backfill, CIM, Montreal, Canada, 21–29.
Li, L. (2014a). “Analytical solution for determining the required strength of a side-exposed mine backfill containing a plug.” Can. Geotech. J., 51(5), 508–519.
Li, L. (2014b). “Generalized solution for mining backfill design.” Int. J. Geomech., 04014006.
Li, L., and Aubertin, M. (2009a). “A three-dimensional analysis of the total and effective stresses in submerged backfilled stopes.” Geotech. Geol. Eng., 27(4), 559–569.
Li, L., and Aubertin, M. (2009b). “Numerical investigation of the stress state in inclined backfilled stopes.” Int. J. Geomech., 52–62.
Li, L., and Aubertin, M. (2012). “A modified solution to assess the required strength of exposed backfill in mine stopes.” Can. Geotech. J., 49(8), 994–1002.
Li, L., and Aubertin, M. (2014). “An improved method to assess the required strength of cemented backfill in underground stopes with an open face.” Int. J. Min. Sci. Technol., 24(4), 549–558.
Li, L., Aubertin, M., and Belem, T. (2005). “Formulation of a three dimensional analytical solution to evaluate stresses in backfilled vertical narrow openings.” Can. Geotech. J., 42(6), 1705–1717.
Li, L., Aubertin, M., and Shirazi, A. (2010). “Implementation and application of a new elastoplastic model based on a multiaxial criterion to assess the stress state near underground openings.” Int. J. Geomech., 13–21.
Li, L., Aubertin, M., Simon, R., Bussière, B., and Belem, T. (2003). “Modelling arching effects in narrow backfilled stopes with FLAC.” Proc., 3rd Int. Symp. on FLAC & FLAC3D numerical modelling in Geomechanics, CRC Press, Boca Raton, FL, 211–219.
Libby, D. J., and Smith, J. D. (1975). “Development of a sub-level mining method with delayed pillar recovery at Sherritts Fox mine, Manitoba: 9F.” IMM Bull. Trans. Aus., 84(818), A40–A46.
Liu, G., Li, L., Yang, X., and Guo, L. (2016a). “A numerical analysis of the stress distribution in backfilled stopes considering nonplanar interfaces between the backfill and rock walls.” Int. J. Geotech. Eng., 10(3), 271–282.
Liu, G., Li, L., Yang, X., and Guo, L. (2016b). “Numerical modelling of the stability of cemented backfill with a vertical face exposed: A revisit to Mitchell’s physical model tests.” Int. J. Min. Sci. Technol., 26(6), 1135–1144.
Liu, G., Li, L., Yang, X., and Guo, L. (2017). “Numerical analysis of stress distribution in backfilled stopes considering interfaces between the backfill and rock walls.” Int. J. Geomech., 06016014.
McCarthy, D. F. (2002). Essentials of soil mechanics and foundations: Basic geotechnics, 6th Ed., Prentice Hall, Englewood Cliffs, NJ.
Mitchell, R. J. (1986). “Centrifuge model tests on backfill stability.” Can. Geotech. J., 23(3), 341–345.
Mitchell, R. J., Olsen, R. S., and Smith, J. D. (1982). “Model studies on cemented tailings used in mine backfill.” Can. Geotech. J., 19(1), 14–28.
Mitchell, R. J., and Wong, B. C. (1982). “Behaviour of cemented tailings sands.” Can. Geotech. J., 19(3), 289–295.
Pierce, M. E. (1997). “Laboratory and numerical analysis of the strength and deformation behaviour of paste backfill.” Master thesis, Queen’s Univ., Kingston, ON, Canada.
Pierce, M. E. (2001). “Stability analysis of paste back fill exposes at Brunswick Mine.” Proc., 2nd Int. FLAC Symp., Swets & Zeitlinger Publishers, Lisse, Netherlands, 147–156.
Potvin, Y., Thomas, E., and Fourie, A. (2005). Handbook on mine fill, Australian Centre for Geomechanics, Perth, Australia.
Sainsbury, D. P., and Urie, R. (2007). “Stability analysis of horizontal and vertical paste fill exposures at the Raleigh Mine.” Proc., 9th Int. Symp. on Mining with Backfill, CIM, Montreal, Canada.
Smith, J. D., Dejongh, C. L., and Mitchell, R. J. (1983). “Large scale model tests to determine backfill strength requirements for pillar recovery at the Black Mountain Mine.” Proc., Int. Symp. on Mining with Backfill, Balkema, Rotterdam, Netherlands, 413–423.
Thompson, B. D., Grabinsky, M. W., and Bawden, W. F. (2012). “In-situ measurements of cemented paste backfill at the Cayeli Mine.” Can. Geotech. J., 49(7), 755–772.
Yang, K. H., and Liu, C. N. (2007). “Finite element analysis of earth pressures for narrow retaining walls.” J. Geoeng., 2(2), 43–52.
Yang, P. Y. (2016). “Investigation of the geomechanical behavior of mine backfill and its interaction with rock walls and barricades.” Ph.D. thesis, Mineral Engineering, Polytechnique Montréal, Montréal.
Yang, P. Y., Li, L., Aubertin, M., Brochu-Baekelmans, M., and Ouellet, S. (2017). “Stability analyses of waste rock barricades designed to retain paste backfill.” Int. J. Geomech., 04016079.
Zou, D. H., and Nadarajah, N. (2006). “Optimizing backfill design for ground support and cost saving.” Proc., 41st U.S. Rock Mechanics Symp.: 50 Years of Rock Mechanics, American Rock Mechanics Association, Alexandria, VA.
Information & Authors
Information
Published In
International Journal of Geomechanics
Volume 17 • Issue 10 • October 2017
Copyright
© 2017 American Society of Civil Engineers.
History
Received: Sep 28, 2016
Accepted: Apr 24, 2017
Published online: Jul 21, 2017
Published in print: Oct 1, 2017
Discussion open until: Dec 21, 2017
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.