Determining the optimal dimensions of the pillars under static and dynamic loads in room and pillar mines (Case study: Tabas central coal mine)

نوع مقاله : مقاله پژوهشی

نویسندگان

1 Dept. of Mining Engineering, Isfahan University of Technology, Isfahan, Iran

2 Dept. of Civil Engineering, Yazd University, Yazd, Iran

چکیده

A pillar dimension in room and pillar mining method has been always a technical and economical issue for mining and rock mechanic engineers. The strength of the pillars is usually determined by empirical relationships, which have been determined by experience and the data collected from the coal mines of the United States, South Africa, and China, and which, except in one case, have never been considered seismic loads. This study aims to define the optimum pillar dimension based on the pillar strength derived from a new approach implemented in the numerical modeling by gradually applying an increasing load on the pillar and monitoring its displacement, using the Central section of Tabas coal mine data. The results are compared with the method of Salamon-Munro (1967) which is one of the most commonly used empirical methods. This comparison shows that the strength obtained from the numerical method for pillar widths of less than 15 m is well consistent with the empirical Salamon-Monroe method, whereas the difference between the results of the two methods increases progressively with a pillar width increment. The safety factor of the pillar is then defined by dividing the obtained pillar strength and monitoring critical stresses, under static and dynamic conditions. Tabas (1978) earthquake with 7.4 magnitudes is used for dynamic analyses. The results show that the optimal width of the pillar in the static and dynamic states is 12 and 15 meters, respectively. Moreover, curve fitting with high regression to the results obtained in both static and dynamic states, relations in terms of width to height ratio are presented for use in other areas of the mine with similar geomechanical conditions.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Determining the optimal dimensions of the pillars under static and dynamic loads in room and pillar mines (Case study: Tabas central coal mine)

نویسندگان [English]

  • Milad Heidarnejad 1
  • Amin Azhari 1
  • Mohammad Ahour 2
  • ٍEbrahim Ghasemi 1
1 Dept. of Mining Engineering, Isfahan University of Technology, Isfahan, Iran
2 Dept. of Civil Engineering, Yazd University, Yazd, Iran
چکیده [English]

A pillar dimension in room and pillar mining method has been always a technical and economical issue for mining and rock mechanic engineers. The strength of the pillars is usually determined by empirical relationships, which have been determined by experience and the data collected from the coal mines of the United States, South Africa, and China, and which, except in one case, have never been considered seismic loads. This study aims to define the optimum pillar dimension based on the pillar strength derived from a new approach implemented in the numerical modeling by gradually applying an increasing load on the pillar and monitoring its displacement, using the Central section of Tabas coal mine data. The results are compared with the method of Salamon-Munro (1967) which is one of the most commonly used empirical methods. This comparison shows that the strength obtained from the numerical method for pillar widths of less than 15 m is well consistent with the empirical Salamon-Monroe method, whereas the difference between the results of the two methods increases progressively with a pillar width increment. The safety factor of the pillar is then defined by dividing the obtained pillar strength and monitoring critical stresses, under static and dynamic conditions. Tabas (1978) earthquake with 7.4 magnitudes is used for dynamic analyses. The results show that the optimal width of the pillar in the static and dynamic states is 12 and 15 meters, respectively. Moreover, curve fitting with high regression to the results obtained in both static and dynamic states, relations in terms of width to height ratio are presented for use in other areas of the mine with similar geomechanical conditions.

کلیدواژه‌ها [English]

  • Static analysis
  • Dynamic analysis
  • Room and pillar
  • Numerical modeling
  • Optimal pillar width

مراجع

[1]                Jiang, Yaodong, Et Al. “Assessment And Mitigation Of Coal Bump Risk During Extraction Of An Island Longwall Panel”. International Journal Of Coal Geology,95: 20-33, 2012.‏
[2]                Atai, Mohammad, “Underground Mining, Volume 2: Self-Maintenance Methods”, Shahroud University of Technology Press, 2005 ) In Persian(
[3]                Ghasemi, E., Shahriar, K., Hashemalhosseini, H. (2012). Development of a new method for coal pillars design in room and pillar mines. Journal of Analytical and Numerical Methods in Mining Engineering, 1(2), 15-23.
[4]                Sheorey PR. “Design Of Coal Pillar     Arrays, Chain Pillars”. In: Hudson JA, Et Al., Editors.Comprehensive Rock Engineering, Vol. 2. Oxford: Pergamon. P. 631–70, 1993.
[5]                Galvin, Jim M.; Hebblewhite, Bruce K.; Salamon, Miklos Dg. University Of New South Wales ,“Coal Pillar Strength Determinations For Australian And South African Mining Conditions”. In: Proceedings Of The Second International Workshop On Coal Pillar Mechanics And Design, National Institute For Occupational Safety And Health, Report Ic. P. 63-71, 1999.
[6]                Galvin, Jim, Et Al. “Considerations Associated With The Application Of The Unsw And Other  Pillar Design Formulae. In: Golden Rocks”, The 41st Us Symposium On Rock Mechanics  (Usrms). American Rock Mechanics Association, 2006.‏
[7]                Wang, Hongwei, Et Al. “Numerical Investigation Of The Dynamic Mechanical State Of A Coal Pillar During Longwall Mining Panel Extraction”. Rock Mechanics And Rock Engineering,46.5: 1211-1221, 2013.
[8]                Bieniawski, Z. T. “The Effect Of Specimen Size On Compressive Strength Of Coal”.In: International Journal Of Rock Mechanics And Mining Sciences & Geomechanics Abstracts. Pergamon. P. 325-335, 1968.‏‏
[9]                Salamon, M. D. G.; Ozbay, M. U.; Madden, B. J. “Life And Design Of Bord-And-Pillar Workings  Affected By Pillar Scaling”. Journal Of The Southern African Institute Of Mining And Metallurgy, 98.3: 135-145, 1998.‏
[10]             Ghasemi, E.; Shahriar, K. “A New Coal Pillars Design Method In Order To Enhance Safety Of            The Retreat Mining In Room And Pillar Mines”. Safety Science,  50.3: 579-585,2012.(In Persian).
[11]             Dabagh, A., Fatehi Marji, M., Forghani, H., “Simulation of Subsidence with a Higher Order Displacement Discontinuity Method”. International Journal of Mining Engineering, Volume 4, Issue 7, Page 53-6, (2009), (In Persian).
[12]             Xu, B., Yin, S., Zhang, X., & Wu, J. Research on the Stability of Waterproof Coal Pillar in Steep Seam under Aquifers. An Interdisciplinary Response to Mine Water Challenges - Sui, Sun & Wang ,China University of Mining and Technology Press, Xuzhou, ISBN 978-7-5646-2437-8, (2014).
[13]             Jun De, Q. I., Jing, C. H. A. I., & Zhang, J. (2014). Numerical Design of Pillar Width in the Inclined Coal Seam. Advanced Materials Research, 977. (2014).
[14]             Najafi, M., & Motahhari, M., & Norouzi, M. (2016). Numerical Modeling Of Coal Pillars In Steeply Inclined Coal Seams - Case Study: Hamkar Coal Mine. Journal Of Analytical And Numerical Methods In Mining Engineering, 6(11 ), 27-38, .(In Persian).
[15]             Dehghan, S., Shahriar, K., Maarefvand, P., Goshtasbi, K. (2012). Estimation of Applied Stresses on Pillars in Stope and Rib Pillar mining Method by Numerical and Empirical Methods in Fetr 6 Chromite Mine. Journal of Analytical and Numerical Methods in Mining Engineering, 2(3), 53-61.
[16]             Aydan, Ö. & Kawamoto, T. (2004). “The damage to abandoned lignite mines caused by the 2003 Miyagi-Hokubu earthquake and some considerations on its causes”. 3rd Asian Rock Mechanics Symposium, Kyoto, 525-530. (2004).
[17]             Nishida, N., Esaki, T., Aoki, K. and Kameda, K. (1984)   “Evaluation and prediction of subsidence in old working areas and practical and preventive measures against mining damage to new structures. Proceedings of Third International Symposium on Land Subsidence”, Venice.
[18]             Aydan, Ö., Ohta, Y., Geniş, M., Tokashiki, N., & Ohkubo, K. (2010). Response and stability of underground structures in rock mass during earthquakes. Rock mechanics and rock engineering, 43(6), 857-875.‏
[19]             Tabas Coal Mine. Rock Mechanics Reports.Thecnical Office (2014).
[20]             Itasca, 2005. FLAC3D-Fast Lagrangian Analysis of Continua-User Manuel (dynamic option) (Version 2.1).

فایل ها

سابقه مقاله

  • تاریخ دریافت: 09 مهر 1400
  • تاریخ بازنگری: 13 بهمن 1400
  • تاریخ پذیرش: 02 اسفند 1400

هم رسانی

ارجاع به این مقاله

آمار