Authors: Napa-García, GF; Navarro Torres, VF
Show More

Citation as:   ris   bibtex   endnote   text   Zotero

Pillar stability is an active research topic, and is important in the safety evaluation of underground mining projects. Commonly, pillar stability is evaluated using empirical formulations based on specific case studies and rock mass conditions. Numerical modelling could be a very useful tool given its ability to represent a wide range of field situations, as well as material behaviour. However, the evaluation of the safety factor using numerical models may be a challenging task when a large number of runs is required to yield a reliable estimate, e.g. strength reduction or load testing. In this context, a fast and accurate method of measuring pillar safety is desirable. The failure strain proposed by Sakurai (1981) was studied to understand and propose its use when adapted to room and pillar stability by means of numerical modelling. The commercial software package FLAC3D was used to evaluate the continuum mechanics problem. A wide range of parameters involved in the calculation were explored. Results suggest that the failure strain seems to be a promising tool when used correctly. Considerable time saving can be made without losing accuracy. Keywords: safety, pillar stability, numerical modelling, FLAC3D, failure strain

Keywords: safety, pillar stability, numerical modelling, FLAC3D, failure strain

Napa-García, GF & Navarro Torres, VF 2017, 'Applicability of failure strain for the stability evaluation of square pillars in room and pillar mining', in M Hudyma & Y Potvin (eds), Proceedings of the First International Conference on Underground Mining Technology, Australian Centre for Geomechanics, Perth, pp. 557-565.

Aydan, O, Akagi, T & Kawamoto, T 1993, ‘A method for the prediction of the squeezing potential of rock around tunnels’, Assessment and Prevention of Failure Phenomena in Rock Engineering, A.A. Balkema, Rotterdam, pp. 767–774.
Bullock, RL 2011, ‘Room-and-pillar mining in hard rock’, in P Darling (ed.), SME Mining Engineering Handbook, 3rd edn, Society for Mining, Metallurgy, and Exploration, Englewood, pp. 1327–1338.
Cai, M, Kaiser, PK, Tasaka, Y & Minami, M 2007, ‘Determination of residual strength parameters of jointed rock masses using the GSI system’, International Journal of Rock Mechanics & Mining Sciences, vol. 44, pp. 247–265.
Corkum, AG & Board, MP 2016, ‘Numerical analysis of longwall mining layout at Solvay Mine, Wyoming’, International Journal of Rock Mechanics & Mining Sciences, vol. 89, pp. 94–108.
Deng, J, Yue, ZQ, Tham, LG & Zhu, HH 2003, ‘Pillar design by combining finite element methods, neural networks and reliability:
A case study of the Feng Huangshan copper mine, China’, International Journal of Rock Mechanics and Mining Sciences,
vol. 40, no. 4, pp. 585–599.
Gao, W & Mingming, G 2016, ‘Stability of a coal pillar for strip mining based on an elastic-plastic analysis’, International Journal of Rock Mechanics and Mining Sciences, vol. 87, pp. 23–28.
Hoek, E & Brown, ET 1997, ‘Practical estimates of rock mass strength’, International Journal of Rock Mechanics and Mining, vol. 34, no. 8, pp. 1165–1186.
Hoek, E, Carlos C-T & Corkum, B 2002, ‘Hoek-Brown failure criterion – 2002 edition’, in R Hammah (ed.), Proceedings of the 5th North American Rock Mechanics Symposium and the 17th Tunnelling Association of Canada Conference, University of Toronto Press, Toronto, pp. 267–273.
Idris, MA, Saiang, D & Nordlund, E 2015, ‘Stochastic assessment of pillar stability at Laisvall mine using artificial neural network’, Tunnelling and Underground Space Technology, vol. 49, pp. 307–319.
Itasca Consulting Group, Inc. 2012, FLAC3D, version 5.01, Itasca Consulting Group, Inc., Minneapolis.
Itasca Consulting Group, Inc. 2017, FLAC3D Version 6 User’s Manual, Itasca Consulting Group, Inc., Minneapolis.
Jaiswal, A & Shrivastva, BK 2009, ‘Numerical simulation of coal pillar strength’, International Journal of Rock Mechanics and Mining Sciences, vol. 46, no. 4, pp. 779–788.
Kortnik, J 2009, ‘Optimization of the high safety pillars for the underground excavation of natural stone blocks’, Acta Geotechnica Slovenica, vol. 6, no. 1, pp. 35–48.
Laubscher, DH 1990, ‘A geomechanics classification system for the rating of rock mass in mine design’, Journal of the South African Institute of Mining and Metallurgy, vol. 90, no. 10, pp. 257–273.
Lunder, PJ & Pakalnis, RC 1997, ‘A determination of the strength of hard-rock mine pillars’, CIM Bulletin, vol. 90, no. 1014.
Navarro Torres, VF, Da Gama, CD, Costa E Silva, M, Falcão Neves, P & Xie, Q 2011, ‘Comparative stability analyses of traditional and selective room-and-pillar mining techniques for sub-horizontal tungsten veins’, International Journal of Minerals, Metallurgy and Materials, vol. 18, no. 1, pp. 1–8.
Obert, L & Duvall, WI 1967, Rock Mechanics and the Design of Structures in Rock, John Wiley & Sons, Hoboken.
Pariseau, WG & Eitani, IM 1981, ‘Comparisons between finite element calculations and field measurements of room closure and pillar stress during retreat mining’, International Journal of Rock Mechanics and Mining Sciences, vol. 18, no. 4, pp. 305–319.
Ribacchi, R 2000, ‘Mechanical tests on pervasively jointed rock material: Insight into rock mass behaviour’, Rock Mechanics and Rock Engineering, vol. 33, no. 4, pp. 243–266.
Russo, G, Kalamaras, GS & Grasso, P 1998, ‘A discussion on the concepts of geomechanical classes behavior categories and technical classes for an underground project’, Gallerie E Grandi Opere Sotterranee, vol. 54, pp. 40–51.
Sakurai, S 1981, ‘Direct strain evaluation technique in construction of underground opening’, Proceedings of the 22nd US Symposium on Rock Mechanics, American Rock Mechanics Association, Alexandria, pp. 278–282.
Sakurai, S 1997, ‘Strength parameters of rocks determined from back analysis of measured displacements’, Proceedings of the First Asian Rock Mechanics Symposium, International Society for Rock Mechanics, Lisbon.
Sakurai, S 1999, ‘Interpretation of field measurements in tunneling practice’, Proceedings of the 9th ISRM Congress, International Society for Rock Mechanics, Lisbon, pp. 1517–1523.
Sakurai, S, Kawashima, I & Otani, T 1993, ‘A criterion for assessing the stability of tunnels’, in L Ribeiro, E Sousa & NF Grossman (eds), Proceedings of the ISRM International Symposium: EUROCK ’93, vol.2, A.A. Balkema, Rotterdam, pp. 929–973.
The MathWorks Inc. 2016, MATLAB, version R2016a, The MathWorks Inc., Natick, viewed 20 July 2017,
Yan-lin, Z & Wen, W 2014, ‘Thickness reduction method of the pillar size set safely and its application’, Electronic Journal of Geotechnical Engineering, vol. 19, no. Z6, pp. 18291–18304.

© Copyright 2018, Australian Centre for Geomechanics (ACG), The University of Western Australia. All rights reserved.
Please direct any queries to or error reports to