Australian Mining Consultants Pty Ltd. – АМС (Perth, Australia):

Lushnikov V. N., Leading Mining Engineer
Sandy M. P., Director

Institute of Comprehensive Exploitation of Mineral Resources (Russian Academy of Sciences) (Moscow, Russia):
Eremenko V. A., Leading Researcher, Doctor of Engineering Sciences, e-mail: eremenko@ngs.ru

«Yakutniproalmaz» Institute (Mirny, Russia):

Kovalenko A. A., Chief Engineer – First Deputy Director

«ALROSA» JSC (Mirny, Russia):

Ivanov I. A., Academic Secretary of Advisory Committee on Innovations, Candidate of Engineering Sciences

Understanding of processes and development scales of rock failure zone around the underground mine working is an important aspect during the assessment of rock massif stability and choice of the type of support for guaranteeing of mine personnel work safety. The following basic reasons of rock failure zone formation around the underground mine workings are defined:
-cracking, caused by blasts;
-brittle fracture of unmined massif under the influence of high concentration of stresses around the mine working;
-shear fracture of massif along the heterogeneities and neogenic cracks.
Drilling of measuring (observation) wells and drilling with selection and analysis of core-sample (or exploration (test) drilling) are the most acceptable methods of measuring of rock failure zone sizes during the underground mining. The staff of Australian Mining Consultants Pty Ltd (АМС) have developed the easy way of calibration of tensile elastic strain by the depth of rock failure zone range, mapped by means of tape-measure. The drafts of measured distances to cracks are combined with the contours of tensile strains, obtained by three-dimensional modeling by boundary elements method, using the Map3D program. Correspondence of tensile strains' contours to the drafts of distances to cracks is defined by variation of rocks' elastic properties (E and ). Criterion of fracture by tensile mechanism for certain mine area is defined as a result of carrying out of such calibration. Formation of rock failure zone around chambers, working excavation and worked-out area is complex, because, as a rule, ore bodies mining is carried out simultaneously on several floors in different order. Development of easy calibrated models makes it possible to do the mine operations planning with minimization of development processes of rock failure zones. This article shows the experience of numerical models calibration, which has the following content:
- measurement and mapping of cracks in wells in the massif around mine working, chamber and working excavation;
- comparison of obtained pictures of fracture in the form of system of cracks with contours of tensile strains, calculated by numerical modeling.
Correctly calibrated models make it possible to carry out the reliable forecast of the depth of rock failure zone range on the stage of projecting of mining operations.

1. Sato T., Kikuchi T., Sugihara K. In situ experiments on an excavation disturbed zone induced by mechanical excavation in Neogene sedimentary rock at Tono mine, Central Japan. Engineering Geology, 2000, 56(12), pp. 97–108.
2. Mostkov V. M. USSR experience in construction of hydraulic tunnels. Electric Power Research Institute (Report) EPRIEL. Pergamon Press, New York, 1979, pp. 81–88.
3. Sandy M., Sharrock G., Albrecht J., Vakili A. Managing the transition from low stress to high stress conditions. In Proceedings of the 2^nd Australasian Ground Control in Mining Conference. Sydney, 23–24 November, 2010.
4. Wiles T. D. Evidence based model calibration for reliable predictions. In Proceedings of the 4^th International Seminar on Deep and High Stress Mining. Perth, November 7–9, 2007.
5. Terzaghi K., Peck R. B. subsoil mechanics in engineering practice. Wiley, New York, 1967.
6. Coulomb C. A. Essai sur une application des regles de maximis et minimis a quelques problemes de statique, relatifs a l’architecture. Memoires de mathematique et de physique, presentes l’Academie Royale des Sciences par divers savans. 1779, Vol. 7, pp. 343–382.
7. Griffith A. A. Theory of rupture. In Proceedings of the 1^st International Congress of Applied Mechanics, (Delft Biezeno, C. B. and Burges, J. M., eds). 1924, pp. 55–63.
8. Hoek E., Brown E. T. Underground excavations in rock. London: Institute of Mining and Metallurgy, 1980.
9. Sheorey P. R., Biswas A. K., Choubey V. D. An empirical failure criterion for rocks and jointed rock masses. Engineering Geology, 1989, Vol. 26, pp. 141–159.
10. Fairhurst C., Cook N. G. W. The phenomenon of rock splitting parallel to the direction of maximum compression in the neighbourhood of a surface. In Proceedings of the 1^st Congress of the International Society for Rock Mechanics. Lisbon, September 25 – October 1, 1966, Vol. 1, pp. 687–692.
11. Kuijpers J. Fracturing around highly stressed excavations in brittle rock. Journal of the South African Institute of Mining and Metallurgy, 2000, Vol. 100, pp. 325–332.
12. Ndlovu X., Stacey T. R. Observations and analyses of roof guttering in a coal mine. Journal of the South African Institute of Mining and Metallurgy, 2007, Vol. 107, pp. 477–491.
13. Stacey T. R. A simple extension strain criterion for fracture of brittle rock. International Journal of Rock Mechanics and Mining Sciences, 1981, Vol. 18, pp. 469–474.
14. Wiles T. D. Evidence based model calibration for reliable predictions. In Proceedings of the 4^th International Seminar on Deep and High Stress Mining. Perth, November 7–9, 2007.
15. Wiles T. D. Map3D program. 2013. Available at: http://www.map3d.com/ (accessed: October 20, 2013).
16. Sandy M. P., Lushnikov V. N., Eremenko V. A., Bukher R. Gornyi Zhurnal – Mining Journal, 2013, No. 10, pp. 73–78.
17. Eremenko V. A., Lushnikov V. N., Sandy M. P., Milkin D. A., Milshin E. A. Gornyi Zhurnal – Mining Journal, 2013, No. 7, pp. 59–66.
18. Eremenko V. A., Razumov E. A., Zayatdinov D. F. Gornyy informatsionno-analiticheskiy byulleten – Mining Informational and Analytical Bulletin, 2012, No. 12, pp. 38–45.
19. Eremenko V. A., Gakhova L. N., Semenyakin E. N. Fiziko-tekhnicheskie problemy razrabotki poleznykh iskopaemykh – Journal of Mining Science, 2012, No. 2, pp. 80–87.
20. Kurlenya M. V., Baryshnikov V. D., Gakhova L. N. Fiziko-tekhnicheskie problemy razrabotki poleznykh iskopaemykh – Journal of Mining Science, 2012, No. 4, pp. 20–28.