Gipronickel Institute LLC, St. Petersburg, Russia
A. V. Trofimov, Head of the Geotechnical Laboratory, Candidate of Technical Sciences, e-mail: TrofimovAV@nornik.ru
A. P. Kirkin, Researcher, Geotechnical Laboratory, Candidate of Technical Sciences, e-mail: KirkinAP@nornik.ru
A. A. Shutov, Leading Engineer, Geotechnical Laboratory, e-mail: ShutovAA@nornik.ru

Polar Division of PJSC MMC Norilsk Nickel, Moscow, Russia

A. A. Kormnov, Chief Project Engineer, Project Office for Integrated Development of the Skalisty Mine, Candidate of Technical Sciences, e-mail: KormnovAA@nornik.ru

The opening of mineral deposits developed by underground mining, due to the complexity of mining and geological conditions, requires complex geomechanical surveys. Such studies usually include field work to measure the stress-strain state of the rock mass. The data obtained make it possible to assess the influence of tectonic faults on the formation of the stress field in the rock massif and ensure competent planning of mining operations. In world practice, overcoring is the most widely used method, which consists in measuring the core deformations during its drilling-out. This method is quite accurate, but very labor-intensive. The article presents the results of measuring the stress-strain state of the rock mass using the overcoring method in the conditions of the Komsomolsky, Oktyabrsky and Skalisty mines (the Verkhnyaya shaft and the Glubokaya shaft), developing the Oktyabrskoe and Talnakhskoe deposits of copper-nickel sulfide ores. The obtained results indicate the predominance of the subvertical component of the stress tensor in the field of the Oktyabrsky, Komsomolsky mines and the Skalisty mine`s Verkhnyaya shaft , which allows to conclude that the stress field is gravitational. At the same time, increased values of the subhorizontal components of the stress tensor were observed, which is due to both the block structure of the massif and the influence of mining operations. In the conditions of the Skalisty mine`s Glubokaya shaft, the subhorizontal component predominates, which indicates a tectonic stress field. The reasons for this difference from the stress field of other mines should be considered to be both the greater depth of operations (over 1.5 km) and the influence of the Norilsk-Kharaelakh fault.
The following took part in the work: A. E. Rumyantsev, A. A. Davydov, M. S. Popov, V. A. Popov, M. Sh. Uzhakhov, K. E. Breus.

1. Darbinyan T. P., Tsymbalov A. A., Zubov V. P., Kolganov A. V. Imact of rock mass jointing on dilution of disseminated copper-nickel ore in Oktyabrsky Mine. Gornyi Zhurnal. 2023. No. 6. pp. 19–25.
2. Zatsepin M.A., Gospodarikov A.P. Approaches to numerical modeling of dynamic rock fracture in drilling and blasting. Gornyi Zhurnal. 2023. No. 9. pp. 21–27.
3. Aynbinder I. I., Kaplunov D. R. Risk-oriented approach to the selection of geotechnologies for underground mining at great depths. Gorny informatsionno-analiticheskiy byulleten. 2019. No. 4. pp. 5–19. DOI: 10.25018/0236-1493- 2019-04-0-5-19
4. Leontiev A. V. Review of instrumental stress monitoring data in the Tashtagol deposit massif. Problemy nedropolzovaniya. 2018. No. 3. pp. 44–52.
5. Semenova I. E., Zemtsovskiy A. V., Pavlov D. A. Complex geomechanical studies of the rock massif of the burst hazardous deposit Oleniy Ruchey during underground mining operations. Gorny informatsionno-analiticheskiy byulleten. 2014. No. 4. pp. 46–55.
6. Sergunin M. P., Eremenko V. A. Determination of parameters of the initial stress state field at the Zapolyarny mine. Gorny informatsionno-analiticheskiy byulleten. 2019. No. 4. pp. 63–74.
7. Gischig V. S., Doetsch J., Maurer H., Krietsch H. et al. On the link between stress field and small-scale hydraulic fracture growth in anisotropic rock derived from microseismicity. Solid Earth. 2018. Vol. 9. pp. 39–61.
8. Subrahmanyam D. S. Evaluation of hydraulic fracturing and overcoring methods to compare the in situ stress parameters in porous rock mass. Geotechnical and Geological Engineering. 2019. Vol. 37, Iss. 6. pp. 4777–4787.
9. Lyashenko V. I. Development of scientific and technical bases for monitoring the state of a rock massif of complex-structure deposits. Message 1. Gorny informatsionno-analiticheskiy byulleten. 2017. No. 2. pp. 109–135.
10. Guido S., Acerbis R., Sossi G. Practice of the Doorstopper stress measurement method during the last 30 years in Italy. IOP Conference Series: Earth and Environmental Science. 2021. Vol. 833. Art. 012167.
11. Melnikov D. N. Measurement of stresses in the Zhdanov deposit`s rock massif by overcoring method (end version). Vestnik Kolskogo nauchnogo tsentra RAN. 2019. No. 1. pp. 57–61.
12. ASTM D4623-2016 Standard test method for determination of in situ stress in rock mass by overcoring method – three component borehole deformation gauge. 2024. Available at: https://docs.cntd.ru/document/440173059
13. Gray I. Stress in the ground. Drilling for geology II extended abstracts. Australian Institute of Geoscientists, Brisbane, Bulletin. 2017. No. 64. pp. 157–175.
14. Li Y., Fu S., Qiao L., Liu Z., Zhang Y. Development of twin temperature compensation and high-level biaxial pressurization calibration techniques for CSIRO In-Situ Stress. Measurement in Depth, Rock Mechanics and Rock Engineering. 2019. Vol. 52, Iss. 4. pp. 1115–1131.
15. Salvini R., Ermini A., DeLucia V., Beltramone L. et al. Stress–strain investigation of the rock mass based on overcoring with CSIRO HI Cell test and numerical modeling: A case study from an Italian underground marble quarry. Geosciences. 2022. Vol. 12. p. 441. DOI: 10.3390/geosciences12120441
16. Feng Y., Gao K., Lacasse S. Bayesian partial pooling to reduce uncertainty in overcoring rock stress estimation. Journal of Rock Mechanics and Geotechnical Engineering. 2024. Vol. 16, Iss. 4. pp. 1192–1201. DOI: 10.1016/j.jrmge.2023.05.003
17. Trofimov A. V., Kirkin A. P., Rumyantsev A. E., Yavarov A. V. Use of numerical modeling to determine optimum overcoring parameters in rock stressstrain state analysis. Tsvetnye Metally. 2020. No. 12. pp. 22–27.
18. Marysyuk V. P., Trofimov A. V., Kirkin A. P., Shutov A. A. Stress-strain determination in Oktyabrsky mine SS-1 skip shaft area by overcoring. Gornyi Zhurnal. 2024. No. 3. pp. 34–40.
19. Ask D. Analysis of overcoring stress data. Analysis of overcoring rock stress measurements preformed using the CSIRO HI at the Äspö HRL. Sweden, Äspö Hard Rock Laboratory, 2003. 266 p.