Journals →  Gornyi Zhurnal →  2020 →  #10 →  Back

PHYSICS OF ROCKS AND PROCESSES
ArticleName Estimate of change in specific cohesion between fracture surfaces by back-calculation: A case study of open pit mine Zhelezny of Kovdor Mining and Processing Plant
DOI 10.17580/gzh.2020.10.06
ArticleAuthor Agarkov I. B., Ignatenko I. M., Dunaev V. A., Kryuchkov I. S.
ArticleAuthorData

Belgorod State University, Belgorod, Russia:

I. B. Agarkov, Senior Lecturer, agarkov@bsu.edu.ru
I. M. Ignatenko, Director of the Institute of Earth Sciences, Candidate of Engineering Sciences
V. A. Dunaev, Professor, Doctor of Geological and Mineralogical Sciences
I. S. Kryuchkov, Post-Graduate Student

Abstract

This article presents the back-calculation data on bench deformations in open pit mine Zhelezny of Kovdor Mining and Processing Plant. The calculations are performed for 105 rock falls divided into six groups with respect to volume (m3): 0–200 is group 1; >200–500 is group 2; >500–1000 is group 3; >1000–5000 is group 4; >5000–10000 is group 5; >10000 is group 6. The computational method was the single-factor analysis of change in specific cohesion between the surfaces of deformation-limiting fractures. The internal friction angle is assumed to be constant as it is the least of all changeable and is correlatable with laboratory test data. Actual rock falls were simulated in GIS GEOMIX. The simulation correctness was ensured by the high-accuracy referencing and orientation measurements of fractures using 3D models constructed based on laser scanning and drone photography. For all sampled rocks, it is found that specific cohesion between fracture surfaces grows with increasing volume of rock falls. Specific cohesion in case of small volume rock falls (0–200 м3) in all types of rocks, except for olivinite, is approximately the same and ranges as 0.0021–0.011 MPa; for olivinite, this value is higher by 20 % at least. Higher rate slipping along fractures is typical of fenite (almost in all groups, specific cohesion is lower by 10–90 % than in other rock types), which is governed by supergene mineralization of fenites and by down water flow in fractures. The low and approximately equal values of specific cohesion (0.0058–0.0094 MPa) are observed in group 0–200 m3, which is conditioned by the action of blasting on deformation of benches.
The study is carried out under State Contract No. 075-03-2020-474/1 от 05.03.2020.

keywords Kovdor magnetite–apatite ore deposit, benches, deformations, simulation, limit equilibrium equation, actual rock falls, back-calculation, fractures, specific cohesion, internal friction angle
References

1. Dunaev A. V. Types and conditions of deformation of permanent benches in open pit mining of Kovdor apatite–magnetite deposit. Izv. TulGU. Ser. Geomechanincs. Mechanics of Underground Structures : VI International Conference Proceedings. Tula, 2009. pp. 56–59.
2. Zhirov D. V., Melikhova G. S., Rybin V. V., Sokharev V. A., Klimov S. A. Peculiarities of the Engineering-Geological Studies of Rock Masses for Designing / Redesigning Deep Open Pits Exemplified with the Kovdor Deposit of Magnetite and Apatite Ores (Kovdor Alkaline-Ultrabasic Massif, NE of the Fennoscandian Shield). Part 1. Vestnik Kolskogo nauchnogo tsentra RAN. 2016. No. 1. pp. 15–25.
3. Fisenko G. L. Stability of pit and dump edges. 2nd enlarged and revised edition. Moscow : Nedra, 1965. 378 p.
4. Makarov A. B., Khormazabal E., Livinskiy I. S., Spirin V. I., Soluyanov N. O. Back analysis of shear strength of joints based on bench wedge failures. Marksheyderiya i nedropolzovanie. 2016. No. 4(84). pp. 44–48.
5. Galchenko Yu. P., Eremenko V. A. Model representation of anthropogenically modified subsoil as a new object in lithosphere. Eurasian Mining. 2019. No. 2. pp. 3–8. DOI: 10.17580/em.2019.02.01
6. Chernyshev S. N. Rock jointing and influence on slope stability. Moscow : Nedra, 1984. 111 p.
7. Seryi S. S., Ermolov V. A., Dunaev A. V. Engineering-geological zoning of hard rock masses and prediction of deformations in open pit benches. GIAB. 2008. No. 5. pp. 157–164.
8. Popov I. I., Okatov R. P. Struggle with landslides on open pits. Moscow : Nedra, 1980. 239 p.
9. Wyllie D. C. Rock Slope Engineering: Civil Applications. 5th ed. Boca Raton : CRC Press, 2018. 568 p.
10. Shpakov P. S. Back-calculation in slope stability analysis for open pit mines. Modern Mining, Education, Science and Industry : Symposium Proceedings. Moscow : MGGU, 1996. pp. 88–92.
11. Musah Abdulai, Mostafa Sharifzadeh. Uncertainty and Reliability Analysis of Open Pit Rock Slopes: A Critical Review of Methods of Analysis. Geotechnical and Geological Engineering. 2019. Vol. 37, Iss. 3. pp. 1223–1247.
12. Miller S. M. Modeling Shear Strength at Low Normal Stresses for Enhanced Rock Slope Engineering. Proceedings of the 39th Highway Geology Symposium. Salt Lake City, 1988. pp. 346–356.
13. Seryi S. S., Agarkov I. B., Konovalov A. V., Agarkov N. B. Remote assessment of orientation of fractures in pit’s slopes using laser scanners. Marksheyderiya i nedropolzovanie. 2016. No. 3(83). pp. 54–57.
14. Yanitskiy E. B., Ignatenko I. M., Dunaev A. V. Photographic techniques in the analysis of rock mass structure and bench stability in open pit mines. Geologiya, geografiya i globalnaya energiya. 2009. No. 1(32). pp. 31–37.
15. Methodical regulations for definition of edge slope angles, bench slopes and dumps of constructed and exploited pits. Leningrad : VNIMI, 1972. 168 p.
16. Afanasev B. V. Mineral reserves of the alkaline–ultrabasic rock masses of the Kola Peninsula. Saint-Petersburg : Roza vetrov, 2011. 224 p.
17. Badulin A. P., Alyabeva O. D. Effect of waveliness of weakened surfaces in rock mass on slope stability. Innovative Geotechnologies for Metallic and Nonmetallic Ore Deposits : IV International Conference Proceedings. Yekaterinburg : Izdatelstvo UGGU, 2015. pp. 112–115.
18. Ignatenko I. M., Yanitsky E. B., Dunaev V. A., Kabelko S. G. Jointing of rock mass in open pit at the Zhelezny mine of the Kovdor Mining and Processing Plant. Gornyi Zhurnal. 2019. No. 10. pp. 11–15. DOI: 10.17580/gzh.2019.10.01
19. Schlotfeldt P., Elmo D., Panton B. Overhanging rock slope by design: An integ rated approach using rock mass strength characterisation, large-scale numerical modelling and limit equilibrium methods. Journal of Rock Mechanics and Geotechnical Engineering. 2018. Vol. 10, Iss. 1. pp. 72–90.
20. Regassa B., Nengxiong Xu, Gang Mei. An equivalent discontinuous modeling method of jointed rock masses for DEM simulation of mining-induced rock movements. International Journal of Rock Mechanics and Mining Sciences. 2018. Vol. 108. pp. 1–14.

Language of full-text russian
Full content Buy
Back