Countermeasure Method for Stope Instability in Crown Pillar Area of Cut and Fill Underground Mine
- 1 Department of Earth Resources Engineering, Kyushu University, Fukuoka, Japan
- 2 Department of Earth Resources Engineering, Kyushu University, Fukuoka, Japan
- 3 Department of Earth Resources Engineering, Kyushu University, Fukuoka, Japan
- 4 Department of Earth Resources Engineering, Kyushu University, Fukuoka, Japan
- 5 Department of Earth Resources Engineering, Kyushu University, Fukuoka, Japan
- 6 Department of Mining Engineering, Institut Teknologi Bandung, Bandung, Indonesia
Abstract
Maintaining stability as well as optimizing recovery of crown pillar, a pillar separating surface area with the uppermost stope in overhand cut and fill underground mining method, is important. Failures in stope may lead to crown pillar failures and cause surface subsidence. Increasing crown pillar thickness will increase crown pillar stability yet reduce mining recovery because part of crown pillar is formed by ore body. Preventing stope failure is the key to maintain stability and optimize recovery of crown pillar. Therefore, it is important to study countermeasure method for stope failure especially in crown pillar area. An attempt has been made to investigate the effectiveness of various countermeasures for stope failure in crown pillar area by means of parametric study. The result shows active type support system is effective for supporting stope in high vertical stress condition while the passive one needs to be installed if the stope is opened in high horizontal stress condition. In general, more supporting capacity from both type support systems is needed if the stope is opened in more severe geological condition. Another countermeasures, sill pillar and surface pile, are introduced for stope instability in crown pillar and non-crown pillar area. Sill pillar is an abandoned slice of unstable stope based on stability analysis. Sill pillar is very effective to stabilize stope both in crown pillar and non-crown pillar area, especially for stope in high horizontal stress condition. Sill pillar application in model with stress ratio 2 can optimize 20 meter thickness of crown pillar into 5 meter. Another proposed countermeasure is surface pile. Surface pile can be installed from the surface to improve stability of crown pillar and stope. The most effective use of surface pile is found in simulation of model with stress ratio 0.75 where surface pile can optimize 15 meter thickness of crown pillar into 5 meter.
- Hartman, H.L. (1987) Introductory Mining Engineering. Wiley-Interscience, New York.
- Bell, F.G., Stacey, T.R. and Genske, D.D. (2000) Mining Subsidence and Its Effect on the Environment: Some Differing Examples. Environmental Geology, 40, 135-152. http://dx.doi.org/10.1007/s002540000140
- Marinos, P. and Hoek, E. (2000) GSI: A Geologically Friendly Tool for Rock Mass Strength Estimation. Proceedings of the International Conference on Geotechnical and Geological Engineering, Lancaster, 1422-1446.
- Hoek, E. and Brown, E.T. (1988) The Hoek-Brown Failure Criterion—A 1988 Update. Proceedings of the 15th Canadian Rock Mechanics Symposium, Civil Engineering Department, University of Toronto, Toronto, 31-38.
- Hoek, E. (1990) Estimating Mohr-Coulomb Friction and Cohesion Values from the Hoek-Brown Failure Criterion. International Journal of Rock Mechanics and Mining Science & Geomechanics Abstracts, 27, 227-229. http://dx.doi.org/10.1016/0148-9062(90)94333-O
- Hoek, E. and Diederichs, M.S. (2006) Empirical Estimation of Rock Mass Modulus. International Journal of Rock Mechanics and Mining Sciences, 43, 203-215. http://dx.doi.org/10.1016/j.ijrmms.2005.06.005
- Hoek, E. and Wood, D.F. (1987) Support in Underground Hard Rock Mines. Bulletin Canadian Institute of Mining, Metallurgy and Petroleum, 35, 1-6.
- Hoek, E., Kaiser, P.K. and Bawden W.F. (2000) Support of Underground Excavation in Hard Rock. A.A. Balkema, Rotterdam. http://dx.doi.org/10.1201/b16978