Gipronickel Institute, Saint-Petersburg, Russia

A. V. Trofimov, Head, Geotechnique Laboratory, Candidate of Engineering Sciences
A. V. Fedoseev, Leading Researcher, Candidate of Engineering Sciences, FedoseevAV@nornik.ru
N. M. Ilchenko, Category I Engineer

NorNickel’s Polar Division, Norilsk, Russia

A. A. Kisel, Chief Engineer, Center for Geodynamic Safety

For the mines at the Oktyabrsky and Talnakh deposits, from the implemented geomechanical research, it is found that the stability of ore and rocks ranges widely, from extreme instability to stability. The lithological diversity also lays emphasis on the accuracy of strength characteristics. A generally accepted value to characterize the strength of rocks is the uniaxial compression strength. In the meanwhile, the tension strength is also a very important determinant of the physical and mechanical properties of rocks since the process of rock failure is, among other things, governed by the action of the tensile load, especially in mechanical and blast-induced loading. In view of the difficult nature of direct tension testing of rock samples, numerous tension tests of rocks were performed using different methods. The world practices use widely indirect tension testing under complex stress states when failure mode of test samples generally depends on the maximal tension component of the stress tensor. The comparative tests of uniaxial compression strength are carried out for lithologically various rocks from the Oktyabrsky and Talnakh deposits. The experimental estimation of the effect of the contact conditions at the loading point of the test samples in the indirect tension testing of rocks is carried out. The destructive load ratios are found for different contact conditions on identical test samples. The uniaxial tension strength coefficients are determined for application conditions of different loading surfaces.

1. Darbinyan T. P., Tsymbalov A. A., Zubov V. P., Kolganov A. V. Impact of rock mass jointing on dilution of disseminated copper–nickel ore in Oktyabrsky Mine. Gornyi Zhurnal. 2023. No. 6. pp. 19–25.
2. Kartashov Yu. M., Matveev B. V., Mikheev G. V., Fadeev A. B. Durability and deformability of rocks. Moscow : Nedra, 1979. 269 p.
3. Litvinskiy G. G., Bikyasheva Yu. N. Patterns of main fracture growth in splitting rock samples. Collection of Scientific Papers of the Donbass State Technical University. Alchevsk, 2013. No. 41. pp. 23–32.
4. Molotnikov V. Ya., Molotnikova A. A. Remarks on the Brazilian research technique for brittle tension strength. Vestnik DGTU. 2014. Vol. 14, No. 4(79). pp. 30–38.
5. Efimov V. P. Testing methods for tension strength and fracture toughness of rocks from test data of cores with axial hole. Fundamentalnye i prikladnye voprosy gornykh nauk. 2019. Vol. 6, No. 2. pp. 90–96.
6. Zhukov V.S. Estimating the strength and elasticity of rocks in the Dagi formation on the Sakhalin shelf. MIAB. 2020. No. 4. pp. 44–57.
7. Efimov V. P. Brazilian tensile strength and its relationship with uniaxial tensile strength. Fundamentalnye i prikladnye voprosy gornykh nauk. 2021. Vol. 8, No. 1. pp. 66–72.
8. Sultanalieva R. M., Konushbaeva A. T., Turdubaeva Ch. B. Determination of strength indicators of rocks under uniaxial compression and tension. Mezhdunarodnyi zhurnal prikladnykh i fundamentalnykh issledovaniy. 2021. No. 5. pp. 61–66.
9. Li D., Wong L. N. Y. The Brazilian disc test for rock mechanics applications: Review and new insights. Rock Mechanics and Rock Engineering. 2013. Vol. 46. pp. 269–287.
10. Perras M. A., Diederichs M. S. A review of the tensile strength of rock: Concepts and testing. Geotechnical and Geological Engineering. 2014. Vol. 35. pp. 525–546.
11. Gong F., Zhang L., Wang S. Loading rate effect of rock material with the direct tensile and three Brazilian disc tests. Hindawi Advances in Civil Engineering. 2019. Vol. 2019. ID 6260351.
12. Rui Li, Lei Liu, Zhihua Zhang, Huaming An. Experimental study of Brazilian tensile strength of concrete under static loads. Proceedings of the 2^nd International Conference on Geoscience and Environmental Chemistry. 2020. E3S Web of Conferences. 2020. Vol. 206. ID 01018.
13. Huang Z., Ren F., Yuan L., Zhang D., Sui Z. et al. Tensile strength and damage characteristics of rock under different test methods. Experimental Technology and Management. 2020. Vol. 37, No. 10. pp. 45–49.
14. Huang Z., Zhang Y., Li Y., Zhang D., Yang T. et al. Determining tensile strength of rock by the direct tensile, Brazilian splitting, and three-point bending methods: A comparative study. Advances in Civil Engineering. 2021. Vol. 2021. ID 5519230.
15. AlAwad M. N. J. Modification of the Brazilian indirect tensile strength formula for better estimation of the tensile strength of rocks and rock-like geomaterials. Journal of King Saud University – Engineering Sciences. 2022. Vol. 34, Iss. 2. pp. 147–154.
16. Suggested methods for determining tensile strength of rock materials. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts. 1978. Vol. 15, Iss. 3. pp. 99–103.
17. Yagodkin G. I., Mokhnachev M. P., Kuntysh M F. Strength and deformability of rocks in loading. Moscow : Nauka, 1971. 148 p.