Authors: Thompson, BD; Hunt, T; Malek, F; Grabinsky, MW; Bawden, WF

Purchase Paper

Cite As:
Thompson, BD, Hunt, T, Malek, F, Grabinsky, MW & Bawden, WF 2014, 'In situ behaviour of cemented hydraulic and paste backfills and the use of instrumentation in optimising efficiency', in Y Potvin & T Grice (eds), Proceedings of the Eleventh International Symposium on Mining with Backfill, Australian Centre for Geomechanics, Perth, pp. 337-350.

Download citation as:   ris   bibtex   endnote   text   Zotero


Abstract:
Better understanding of in situ backfill behaviour can allow mines to optimise backfilling efficiency. To this end, a significant quantity of fieldwork has recently been conducted by University of Toronto (U of T) and Mine Design Engineering (MDEng.), focused on in situ measurements in cemented paste backfill. Using these ‘production friendly’ instrumentation approaches, new fieldwork data from two of Vale’s Canadian operations are presented, to demonstrate how instrumentation can be applied to better define the behaviour of cemented hydraulic backfills. Instrumentation consists of clusters of total earth pressure cells, piezometers (for pore pressure) and thermistors that are placed remotely in open stopes, and mounted on barricades. Backfilling with cemented hydraulic fill requires consideration of drainage and potential segregation affects, which are not associated with paste. In situ data demonstrates the transition of the backfill from a fluid to soil-like material at various locations in backfilling stopes. Within a relatively coarse grained (i.e. sand) cemented hydraulic fill, this transition occurred relatively quickly (after three hours). For a sand and tailings blend of cemented hydraulic fill however, the hydrostatic loading condition persisted for between 12 and 24 hours. During backfilling, this information, combined with barricade pressure data, was used to optimise requirements for the post-plug cure period, saving up to three days of stope cycle time. The measurements in hydraulic fill are contrasted with previous fieldwork data from cemented paste backfill. Strength gain mechanics differ between the fill types, through the requirement for drainage in hydraulic fills, whereas cement content and self-desiccation mechanisms appear to dominate in situ measurements in paste. Hydraulic fills exhibit particle size segregation which results in spatial variation in cement content, and so spatially distinct pressure and temperature responses for the interpreted coarse and fine grain zones were measured. A measured low temperature zone was interpreted to represent a coarse grain size fill with an at rest earth pressure coefficient similar to that of a dense sand. A high temperature zone was interpreted to represent a fine grain size fill which features higher cement content. The significantly greater temperature measured in the binder-rich areas are thought to induce ‘thermal expansion’ generated pressure increases. This work demonstrates the potential for instrumentation to feature as part of a considered quality control policy (that includes barricade construction and drainage checks) to safely optimise backfilling efficiency.

References:
Craig, RF 2006, Craig’s Soil Mechanics, London Press.
Falconbridge Ltd. 1990, Backfill alternatives in Ontario mines, vol. 1, DSS File # 09SQ.23440-6-9011, report by Falconbridge Ltd. under auspices of CANMET, Falconbridge Ltd., Sudbury.
Fourie, AB, Helinski M & Fahey, M 2007, ‘Using effective stress theory to characterize the behaviour of backfill’, Proceedings of the 9th International Symposium on Mining with Backfill, FP Hassani & JF Archibald eds, Canadian Institute of Mining, Metallurgy and Petroleum, Westmount, on CD-ROM.
Grabinsky, MW 2010, ‘In situ monitoring for ground truthing paste backfill designs’, Proceedings of the 13th International Seminar on Paste and Thickened Tailings, RJ Jewell & AB Fourie eds, Australian Centre for Geomechanics, Perth, pp. 85-98.
Grabinsky, MW, Cheung, D, Bentz, E, Thompson, BD & Bawden, WF 2013a, ‘Advanced structural analysis of reinforced shotcrete barricades’, Proceedings of the 11th International Symposium on Mining with Backfill, Y Potvin & AG Grice eds, Australian Centre for Geomechanics, Perth, pp. 135-150.
Grabinsky, MW, Thompson, BD, Bawden, WF & Veenstra, RF 2013b, ‘Interpretation of as-placed cemented paste backfill properties from three mines’, Proceedings of the 11th International Symposium on Mining with Backfill, Y Potvin & AG Grice eds, Australian Centre for Geomechanics, Perth, pp. 351-64.
Grice, AG 1998, ‘Stability of hydraulic backfill barricades’, Proceedings of the 6th International Symposium of Mining with Backfill, M Bloss ed, The Australasian Institute of Mining and Metallurgy, Carlton, pp. 117-20.
Hassani, FP & Archibald, JF 1998, Mine backfill, Canadian Institute of Mining, Metallurgy and Petroleum, Westmount, Quebec, on CD-ROM.
Hassani, FP, Fotoohi, K & Doucet, C 1998, ‘Instrumentation and backfill performance in a narrow vein gold mine’, International Journal of Rock Mechanics and Mining Sciences, vol. 35, no. 4-5, paper no. 106.
Helinski, M, Fourie, AB, Fahey, M & Ismail, M 2007, ‘Assessment of the self-desiccation process in cemented mine backfills’, Canadian Geotechnical Journal, vol. 44, no. 10, pp. 1148-56.
Potvin, Y, Thomas, EG & Fourie, AB (eds) 2005, Handbook on Mine Fill, Australian Centre for Geomechanics, Perth, Western Australia.
Revell, MB & Sainsbury, DP 2007, ‘Pastefill bulkhead failures’, in FP Hassani & JF Archibald (eds), Proceedings of the 9th International Symposium on Mining with Backfill, Canadian Institute of Mining, Metallurgy and Petroleum, Westmount, on CD-ROM.
Thompson, BD, Bawden, WF & Grabinsky, MW 2011a, ‘In-situ monitoring of cemented paste backfill pressure to increase backfilling efficiency’, Canadian Institute of Mining Journal, vol. 2, no. 4, pp. 1-10.
Thompson, BD, Grabinsky, MW, Veenstra, RL & Bawden, WF 2011b, ‘In situ pressures in cemented paste backfill – a review of field work from three mines’, in RJ Jewell & AB Fourie (eds), Proceedings of the 14th International Seminar on Paste and Thickened Tailings, Australian Centre for Geomechanics, Perth, Australia, pp. 491-504.
Thompson, BD, Bawden, WF & Grabinsky, MW 2012, ‘In situ measurements of cemented paste backfill at the Cayeli Mine’, Canadian Geotechnical Journal, vol. 49, no. 7, pp. 755-72.
Yumlu, M & Guresci, M 2007, ‘Paste backfill bulkhead monitoring — A case study from Inmet’s Cayeli Mine, Turkey’, in FP Hassani & JF Archibald (eds), Proceedings of the 9th International Symposium on Mining with Backfill, Canadian Institute of Mining, Metallurgy and Petroleum, Westmount, on CD-ROM.
Simms, P & Grabinsky, MW 2009, ‘Direct measurement of matric suction in triaxial tests on early age cemented paste backfill’, Canadian Geotechnical Journal, vol. 46, no. 1, pp. 93-101.
Veenstra, RL, Grabinsky, MW, Bawden, WF & Thompson, BD 2014a, ‘The use of numerical modelling to determine the stress within early-age cemented paste used to backfill an underground stope’, in Y Potvin & AG Grice (eds), Proceedings of the 11th International Symposium on Mining with Backfill, Australian Centre for Geomechanics, Perth.
Veenstra, RL, Grabinsky, MW, Bawden, WF & Thompson, BD 2014b, ‘A numerical analysis of how permeability affects the development of pore water pressure in early-age cemented paste backfill in a backfilled stope’, in Y Potvin & AG Grice (eds), Proceedings of the 11th International Symposium on Mining with Backfill, Australian Centre for Geomechanics, Perth, pp. 83-96.




© Copyright 2019, Australian Centre for Geomechanics (ACG), The University of Western Australia. All rights reserved.
Please direct any queries or error reports to repository-acg@uwa.edu.au