Geotechnical Appraisal of the Thar Open Cut\ud Mining Project

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Singh, R N ; Pathan, A G ; Reddish, D D J ; ATKINS, Anthony (2011)
  • Publisher: Australasian Institute of Mining and Metallurgy
  • Subject: J100 | H100

This paper is concerned with a slope stability appraisal of the proposed open cut mining\ud operations in the Thar lignite field in Sindh, Pakistan. The Thar coalfield covers an area of approximately\ud 9 000 km2 and is estimated to contain 193 billion tonnes of lignite resources. The design of safe high wall\ud slopes is necessary to ensure mine safety and overall economical viability of the mining operations. In the\ud Thar lignite field, the presence of three main aquifers induces pore pressure in the rock mass surrounding\ud the lignite seams and makes high wall slopes potentially unsafe. It is, therefore, necessary to dewater the\ud rock mass before commencing mining excavations. A proposed mine dewatering scheme to facilitate\ud rock mass dewatering surrounding the mining excavations and a description of the slope stability analysis\ud of the high wall using the software “SLIDE” version 5 is outlined. Three computer models with slope\ud angles of 28o, 29o and 30o, incorporating a plane failure mode, were analyzed to investigate the stability of\ud pit slopes. The generalized stratigraphy of borehole RE-25 has been used for the development of the\ud computer models. The main conclusions of this study are that the slope angle of 28o is quite acceptable\ud for a Stability Factor (SF) ≤ 1.3 whereas the excavated slopes with slope angles ≥ 29o are not safe\ud against the plane failure for SF>1.3. This assessment was followed by a slope stability analysis\ud incorporating circular failure modes. Five models incorporating various slope angles ranging from 23o to\ud 27o and one model incorporating combined slope angles of 23o in dune sand and 26o in the rest of the\ud strata were developed and analysed. The main conclusions from this study are that the dune sand layer\ud (having a thickness of 48 m) is acceptable for a SF of 1.3 at slope angle ≤ 23o, while the rest of the strata\ud is acceptable for SF=1.3 at slope angles ≤ 26o. The overburden to lignite extraction ratio for this slope\ud design has been calculated as 3:1 or 3 m3 of overburden over 1 t of lignite.
  • References (11)
    11 references, page 1 of 2

    Deep Rock Drilling, 2010, Eight exploration blocks in Thar Lignite Field, One outline Map, Private communication.

    Pathan, A G, Halepota, G R, Shah, M A and Singh, R N, 2007. Stability analysis and dewatering of the proposed open cut lignite mine at Thar Coalfield, Pakistan, International Coal Conference, Karachi, 30-31 October, pp 19.

    Pathan, A G, Singh, R N and Shah A A, 2006. Hydrogeological studies and the design of mine dewatering system for the proposed open cut lignite mine at Thar, Sindh, Pakistan., International Conference on new technology for surface and underground mining', Kolkata, India 15-17 December, Journal of Mines, Metals and Fuels, Special issue, II ISSN 0033-2755, pp 362-369.

    Pathan, A G and Singh R N, 2008, Report on the visit of professor A. G. Pathan, of Mehran University of Engineering and Technology to the NCG, University of Nottingham, 6th July to 29th July 2008, pp 26.

    Ahmad M and Farzana, N, 2001. Prospects of development of nuclear power in the emerging Electricity market in Pakistan, 18th Congress of World Energy Council, Buenos Aires, 2001, pp 10.

    R W E, 2004. Power International, Thar Mining Project, Bankable feasibility studies and assessment report, for Sindh Coal Authority, Province Sindh, Pakistan, Vol 1, pp 58-130.

    Shah, A A, 2007. Four exploration blocks of the THAR Coalfield, Sindh, Pakistan, Private communication, One Outline Map.

    Singh, Raghu N, Anthony S Atkins, A S, Abdul G, Pathan, 2010. Water resources assessment associated with lignite operations in Thar, Sindh, Pakistan, Archives of Mining Sciences, Krakow, Poland, 55, No 3, pp 377-392.

    Thomas, R E, Shah, A A, Khan, S A and Tgar, M A, 1994. Analytical results on coal samples collected from drilling activities in the Thar Desert, Sindh, Pakistan, U.S. Geological Survey Open File Report 94-557, pp 440.

    Warrick, P D and Thomas R E, 1995. The regional stratigraphic and settings of the Paleocene-Eocene coal bearing rocks of South Sindh, American Association of Petroleum Geologists, Annual Convention, March 5-8, Houston, pp 124. http://www.gsp.gov.pk/Systematic. Evaluation and appraisal of coal resources of four specific tracks in Thar coalfield, Mithi District, Sindh, 2005-06.

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