Nosov Magnitogorsk State Technical University, Magnitogorsk, Russia:
S. E. Gavrishev, Director of the Institute of Mining and Transport, Head of a Chair, Professor, Doctor of Engineering Sciences, ormpi-cg@mail.ru

V. Yu. Zalyadnov, Associate Professor

Institute of Mining, Ural Branch, Ekaterinburg, Russia:
O. V. Zoteev, Leading Researcher, zoteev.o@mail.ru

The article presents the results of research on the prediction of possible deformations of worked-out slopes in Sibay open pit in extraction of ore reserves occurring beyond the ultimate pit limits using the underground method. Currently, open pit mining has been completed at Sibay copper–zinc–pyrite deposit, and it is planned to continue extraction of the remaining reserves in the pit wall and floor using the underground method. The large pit depth, steep slopes of worked-out pit walls and local deformation of the pit slopes in the course of underground mining of the reserves beyond the ultimate pit limits define the complex geomechanical conditions of further exploitation of the deposit. This requires continuous monitoring of the stability of the pit wall slopes and underground excavations. To forecast possible deformations of the Sibay pit wall slopes, a research has been undertaken, including the analysis of geological and hydrogeological characteristics of the slopes in the areas of planned extraction of the reserves beyond the ultimate pit limits, analysis of the data of instrumental observations and visual survey of the pit slopes; initial data preparation for graphical and analytical calculations of the pit wall stability, and calculation of the stability of the pit walls. The researches have shown that, in general, the Sibay pit walls are characterized by a sufficient margin of stability more than 30%. It is assumed that the existing cases of deformation of individual sections are mainly due to local unfavorable geological conditions, in particular, intensive rock fracturing, tectonic faulting, areas of metasomatic rocks. The condition of the slopes on the lower horizons of the Sibay pit and complicated manifestation of deformation processes requires further monitoring, including systematic surveys, instrumental observations and calculations of rock mass stability in local areas during extraction of ore reserves from the pit walls and floor.

1. Dorabotka zalezhi «Novyy Sibay» Sibayskogo mestorozhdeniya podzemnym sposobom: tekhnologicheskiy reglament. Tom 1 : Poyasnitelnaya zapiska (Shifr 308/07 PR-TR) (Cleaning-up the «Novyi Sibay» deposit (Sibay deposit) using underground mining: technological regulations. Volume 1 : Explanatory note (Code 308/07 PR-TR)). Ekaterinburg : Uralmekhanobr-UMMC, 2008. (in Russian)
2. Nauchnoe soprovozhdenie i nadzor za sostoyaniem ustoychivosti bortov Sibayskogo karera» : otchet o nauchno-issledovatelskoy rabote Uralmekhanobr (Scientific inquiry and observation of the state of stability of Sibay open pit edges» : review about the Scientific and Research work of Uralmekhanobr). Research manager: P. V. Koltsov. Work was carried out by Yu. S. Ivanov. Ekaterinburg, 2009. 97 p.
3. Pravila obespecheniya ustoychivosti otkosov na ugolnykh razrezakh (Rules of slope stability provision on coal strip mines). Saint Petersburg : Research Institute of Mining Geomechanics and Mine Surveying (VNIMI), 1998. 208 p. (in Russian)
4. Metodicheskie ukazaniya po opredeleniyu uglov naklona bortov, otkosov ustupov i otvalov stroyashchikhsya i ekspluatiruemykh karerov (Methodic regulations for the definition of the slope angle of edges, bench slopes and dumps of built and exploited open pits). Leningrad : Research Institute of Mining Geomechanics and Mine Surveying (VNIMI), 1972. 165 p. (in Russian)
5. Kaplunov D. R., Rylnikova M. V. Kombinirovannaya razrabotka rudnykh mestorozhdeniy (Combined ore deposit mining). Moscow : Gornaya kniga, 2012. 344 p.
6. Chen J., Gu D., Li J. Optimization principle of combined surface and underground mining and its applications. Journal of Central South University of Technology. 2003. Vol. 10, No. 3. pp. 222–225.
7. H. Peng, Qingxiang Cai, Li Ma, Wenliang Tang. End-wall slope stability analysis of surface coal mine under the combined open-pit mining with underground mining. EJGE. 2014. Vol. 19, Bund. А. pp. 185–194.
8. Wang N., Wan B. H., Zhang P., Du X. L. Analysis on deformation development of open-pit slope under the influence of underground mining. Legislation, Technology and Practice of Mine Land Reclamation : Proceedings of the Beijing International Symposium on Land Reclamation and Ecological Restoration (LRER 2014), Beijing, China. London : Taylor & Francis Group, 2015. pp. 53–59.

9. Marino G. G., Posluszny G. Progressive mine Instability and subsidence response: a case study. EJGE. 2015. Vol. 20, Bund. 12. pp. 5115–5131.
10. Pikalov V. A., Sokolovskiy A. V., Vasilets V. N., Burmistrov K. V. Obosnovanie effektivnykh parametrov kombinirovannogo otkryto-podzemnogo sposoba razrabotki ugolnykh mestorozhdeniy (Substantiation of efficient parameters for hybrid open pit/underground mining of coal). Gornyi Zhurnal = Mining Journal. 2016. No. 1. pp. 67–72.
11. Melnikov I. T., Zalyadnov V. Yu., Shevtsov N. S., Pavlova E. V., Pogorelov A. Yu., Smyatkin A. N. Avtomatizirovannyy raschet ustoychivosti otkosov bortov karerov (Automated calculation of open pit edge slope stability). Vestnik Magnitogorskogo gosudarstvennogo tekhnicheskogo universiteta imeni G. I. Nosova = Vestnik of Nosov Magnitogorsk State Technical University. 2013. No. 2 (42). pp. 8–12.
12. Gavrishev S. E., Zalyadnov V. Yu., Kravchuk T. S., Pavlova E. V. Otsenka obshchey ustoychivosti bortov Sibayskogo karera pri otrabotke zakonturnykh zapasov rudy podzemnym sposobom (Assessment of the total stability of Sibay open pit edges during the underground mining of edge ore reserves). Marksheyderskoe i geologicheskoe obespechenie gornykh rabot: Sbornik nauchnykh trudov po materialam mezhdunarodnoy nauchno-prakticheskoy konferentsii (Mine surveying and geological provision of mining operations: collection of scientifc proceedings on the materials of international scientific-practical conference). Magnitogorsk : Publishing House of Nosov Magnitogorsk State Technical University, 2013. pp. 155–162.
13. Tsyganov A. V., Osintsev N. A., Gavrishev S. E., Rakhmangulov A. N. Formirovanie tekhnologicheskikh skhem bezopasnoy raboty karerov (Formation of process flowsheets of safe open pit operation). Magnitogorsk : Publishing House of Nosov Magnitogorsk State Technical University, 2014. p. 134.
14. Coal Production and Processing Technology. By editorship of M. R. Riazi, Rajender Gupta. Taylor&Francis Group, LLC, 2016. p. 535.