Authors: Gupte, SS
Editors: Dight, PM
Conference: First Asia Pacific Slope Stability in Mining Conference, 6–8 September, Brisbane
Published: Australian Centre for Geomechanics, Proceedings of the First Asia Pacific Slope Stability in Mining Conference, pp.557-570, Perth
In India, accelerated demand of coal resulted in rapid development of open pit mines. This has resulted into adoption of stripping ratios ranging between 1:15 to 1:25 and mine depths of open pit mines greater than 300 m, from topographic surface, being reached. All this requires removal of huge quantities of overburden material needing to be accommodated in properly planned and designed containment systems within the worked out part of the mine. In any open pit mining venture, transportation cost is approximately 40% of the mineral mining cost. In-pit dumping of overburden material is always preferred to minimise the cost of transportation. However, destabilisation of internal dumps, as seen in the recent past, hampers the smooth functioning of mining operations and severely affects economics. To ensure long-term stability, vis-à-vis enhanced capacity of internal dumps, scientific understanding and practical know-how is necessary.
In this study, detailed stability analysis of internal dumps was done at one of the coal mines of Western Coalfields Limited, India. Pertinent physico-mechanical properties of the dump material were determined and used as inputs for numerical simulation. Four different methods were used in simulating and analysing the existing and optimised dump slopes. Stability analysis of dump slopes was carried out for monsoon season of the year, when dump material possesses least shear strength. Factor of Safety determined by different analytical techniques is presented. Also, distribution of stresses, strains, plastic points, tensile zones along with various failure surfaces were determined. Based on the results of numerical modelling, an increase of nearly 22% of the existing dump capacity is recommended, whilst maintaining a safe range of Factor of Safety.
Gupte, SS 2016, 'Optimisation of internal dump capacity and stability analysis in a coal mine — a case study', in PM Dight (ed.), Proceedings of the First Asia Pacific Slope Stability in Mining Conference
, Australian Centre for Geomechanics, Perth, pp. 557-570.
Aruna, M 2009, ‘A comparison of limit equilibrium method of slope stability analysis with finite element modeling’, Journal of Mines, Metals and Fuels, pp. 455–460.
Bishop, AW 1955, ‘The use of the slip circle in the stability analysis of slopes’, Geotechnique, vol. 5, no. 1, pp. 7–17.
British Columbia Mine Waste Rock Pile Research Committee 1991, Investigation and Design Manual, Interim Guidelines, Canada.
Brown, ET, Bray, JW, Ladanyi, B & Hoek, E 1983, ‘Characteristic line calculations for rock tunnels’, Journal of Geotechnical Engineering Division, American Society of Civil Engineers, vol. 109, pp. 15–39.
Cheng, YM, Lansivaara, T & Wei, WB 2007, ‘Two-dimensional slope stability analysis by limit equilibrium and strength reduction methods’, Computers and Geotechnics, vol. 34, pp. 137–150.
Coates, DF & Yu, YS 1977, Pit Slope Manual, CANMET Report 77-1, p. 137.
Courant, R 1943, ‘Variational methods for the solution of problems of equilibrium and vibrations’, Bulletin of American Mathematical Society, vol. 49, no. 1, pp. 1–23.
Dawson, EM, Roth, WH & Drescher, A 1999, ‘Slope stability analysis by strength reduction’, Geotechnique, vol. 49, no. 6, pp. 835–840.
DGMS (Director General of Mines Safety) 2010, ‘Design, control and monitoring of pit and dump slopes in opencast mines’, Director General of Mines Safety, Circular no. 02, Dhanbad, India.
Douglass, PM & Bailey, MJ 1981 ‘Evaluation of surface coal mine spoil pile failures’, in The Third International Conference on Stability in Open Pit Mining, Vancouver, pp. 815–836.
Duncan, CW & Christopher, WM 2001, Rock Slope Engineering: Civil and Mining, CRC Press.
Fellenius, W 1936, ‘Calculation of the stability of earth dams’, Transactions of the 2nd Congress on Large Dams, International Commission on Large Dams, Washington, vol. 4, pp. 445–462.
Griffiths, DV & Lane, PA 1999, ‘Slope stability analysis by finite elements’, Geotechnique, vol. 49, no. 3, pp. 387–403.
Hammah, RE, Yacoub, TE, Corkum, B & Curran, JH 2005, ‘A comparison of finite element slope stability analysis with conventional limit-equilibrium investigation’, in 58th Canadian Geotechnical Conference and 6th Joint CGS and IAHCNC Groundwater Specialty Conference: Conference Proceedings, Canadian Geotechnical Society, GeoSask Saskatoon, Canada.
Hoek, E & Bray, J 1981, Rock slope engineering (3rd edition), The Institute of Mining and Metallurgy, London.
ISRM (International Society for Rock Mechanics) 1972, ‘Suggested methods for determining water content, porosity, density, absorption and related properties and swelling and slake durability index properties’, International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, pp. 1–12.
ISRM (International Society for Rock Mechanics) 1977, ‘Suggested methods for determining the strength of rock materials in triaxial compression’, International Journal of Rock Mechanics Mining Sciences Geomechanics Abstracts, vol. 15, pp. 47–51.
ISRM (International Society for Rock Mechanics) 1981, ‘Rock characterization testing and monitoring’, ISRM suggested method. International Society of Rock Mechanics, p. 211.
Itasca 2005, FLAC/Slope, version 5.0, Itasca Consulting Group, Minneapolis.
Janbu, N 1954, ‘Stability analysis of slopes with dimensionless parameters’, Harvard Soil Mechanics Series 46, Harvard University Press, Cambridge.
Janbu, N 1957, ‘Earth pressure and bearing capacity calculations by generalized procedure of slices’, in Proceedings of the 4th International Conference on Soil Mechanics and Foundation Engineering, vol. 2, pp. 207–212.
Janbu, N 1968, Slope stability computations, soil mechanics and foundation engineering report, The Technical University of Norway, Trondheim, Norway.
Janbu, N 1973, Slope stability computations: Embankment Dam Engineering – Casagrande, John Wiley and Sons, New York.
Jiang, GL & Magnan, JP 1997, ‘Stability analysis of embankments: comparison of limit analysis with methods of slices’, Geotechnique, vol. 47, no. 4, pp. 857–872.
Jing, L 2003, ‘A review of techniques, advances and outstanding issues in numerical modeling for rock mechanics and rock engineering’, International Journal of Rock Mechanics and Mining Sciences, vol. 40, pp. 283–353.
Kasmer, O, Ulsay, R & Gokceoglu, C 2006, ‘Spoil pile instabilities with reference to a strip coal mine in Turkey: mechanisms and assessment of deformations’, Environmental Geology, vol. 49, pp. 570–585.
Khandelwal, NK, Mozumdar, BK 1987, ‘Stability of overburden dumps’, Journal of Mines, Metals and Fuels, vol. 35, no. 6, pp. 253–261.
Mansour, ZS & Kalantari, B 2011, ‘Traditional methods vs. finite difference method for computing safety factors of slope stability’ Electronic Journal of Geotechnical Engineering, vol. 16, pp. 1119–1130.
Ranjan, P & Singh, SK 2004, ‘Slope stability of overburden dump, Jayant colliery, Northern Coalfields Ltd., Madhya Pradesh, India’, Minetech, vol. 25, no. 4, pp. 3–16.
Rassam, DW & Williams, DJ 1999, ‘3-dimensional effects on slope stability of high waste rock dumps’, International Journal of Surface Mining, Reclamation and Environment, vol. 13, pp. 19–24.
Richards, BG 1982, ‘The finite element analysis of mine spoil slopes using slip elements to simulate strain softening yield behaviour’, Civil Engineering Transactions, Institute of Engineers, Australia, vol. 24, pp. 69–76.
Richards, BG, Coulthard, MA & Toh, CT 1981, ‘Analysis of slope stability at Goonyalla Mine’, Canadian Geotechnical Journal, vol. 18, pp. 179–194.
Singh, TN 2011, ‘Assessment of coal mine waste dump behavior using numerical modeling’, in Fuenkajorn & Phien-wej (eds.), Rock Mechanics, Thailand, pp. 25–36.
Singh, TN, Pradhan, SP & Vishal, V 2013, ‘Stability of slopes in a fire-prone mine in Jharia coalfield, India’, Arabian Journal of Geosciences, coi: 10.1007/s12517-011-0341-4.
Singh, TN, Gulati, A, Dontha, L & Bhardwaj, V 2008, ‘Evaluating cut slope failure by numerical analysis - A Case Study’, Natural Hazards, vol. 47, pp. 263–279.
Spencer, E 1967, ‘A method of analysis of the stability of embankments assuming parallel inter-slice forces’, Geotechnique, vol. 17, no. 1, pp. 11–26.
Taylor, DW 1937, ‘Stability of earth slopes’, Journal of the Boston Society of Civil Engineers, vol. 24, no. 3, pp. 197–247.
Trivedi, R, Vishal, V, Pradhan, SP, Singh, TN & Jhanwar, JC 2012, ‘Slope stability analysis in limestone mines’, International Journal of Earth Sciences & Engineering, vol. 5, no. 4, pp. 759–766.
Tutluoglu, L, Oge, IF & Karpuz, C 2011, ‘Two and three dimensional analysis of a slope failure in a lignite mine’, Computers & Geosciences, vol. 37, pp. 232–240.
Ulusay, R & Aksoy, H 1994, ‘Assessment of the failure mechanism of a highwall slope under spoil pile loadings at a coal mine’, Engineering Geology, vol. 38, pp. 117–134.
Umrao, RK, Singh, R, Ahmad, M & Singh, TN 2011, ‘Stability analysis of cut slopes using continuous slope mass rating and kinematic analysis in Rudraprayag District, Uttarakhand’, Geomaterials, vol. 1, pp. 79–87.
Vishal, V, Pradhan, SP & Singh, TN 2010a, ‘Mine sustainable development vis-a-vis dump stability for a large open cast mine’, in Proceedings of the International Conference on Earth Sciences and Engineering, pp. 1–7.
Vishal, V, Pradhan, SP & Singh, TN 2010b, ‘Instability analysis of mine slope by finite element method approach’, International Journal of Earth Sciences & Engineering, vol. 3, no. 06, pp. 11–23.
Zienkiewicz, OC & Cheung, YK 1967, ‘The finite element method in structural and continuum mechanics’, McGraw-Hill, London, p. 274.