Perm Federal Research Center, Ural Branch, Russian Academy of Sciences, Perm, Russia:

A. A. Baryakh, Director, Corresponding Member of the Russian Academy of Sciences, Doctor of Engineering Sciences

Mining Institute, Perm Federal Research Center, Ural Branch, Russian Academy of Sciences, Perm, Russia:
S. Yu. Devyatkov, Leading Engineer, sd@mi-perm.ru

Salt deposit development is always associated with the risk of waterproof stratum failure resulting in hazardous fresh water inflow in mine openings. One of the main consequences of mine flooding due to high solubility of salts is the intensification of mined rock mass deformation that is frequently accompanied by sinkhole formation at the site of water breakthrough. The sinkhole formation as a phenomenon can be described as a transition of static deformation that manifests in earth surface subsidence into dynamic phase in form of failure. The sinkholes sizes could reach hundreds of meters and their formation presents real danger for life activity, leads to considerable financial losses and negative social-economic and ecological aftermaths. With the use of methods of mathematical modeling based on retrospective estimations of processes that accompanied First Berezniki Potash (BKPRU-1) mine flooding the conditions for sinkhole formation on earth surface were defined in the paper. Failure dynamics in the strata overlying salt rocks in the course of growth of a water conducting channel in the waterproof layers was studied. In all model variants, stress state of rock mass was analyzed. Failure dynamics in the strata overlying salt rocks in the course of growth of a water conducting channel in the waterproof layers was studied. In all model variants, stress state of rock mass was analyzed. Formation of the through damage zone between the ground surface and the channel was interpreted as potential transition of static deformation of the undermined rock mass into dynamic process with sinkhole generation. It is found that conditions for sinkhole at the site of fresh water breakthrough into mine are: formation of water conducting channel with a radius of 5–10 m in salt strata, deformation and the resultant decrease in strength and deformation properties in the overlying strata by factor 6 or more. In this case, the time of sinkhole formation is estimates in the range of 250–500 days.

1. Mustel I. P., Shlendova T. K. Changing of hydrogeological conditions under emergency deformation of the undermined rock mass (with an example of Berezniki-1 mine). Gornyi Zhurnal. 2016. No. 4. pp. 32–39. DOI: 10.17580/gzh.2016.04.06
2. Baryakh A. A., Samodelkina N. A. Geomechanical estimation of deformation intensity above the flooded potash mine. Journal of Mining Sciences. 2017. Vol. 53, No. 4. pp. 630–642.
3. Ponomarenko T. Ecological, economic and social consequences of emergencies on potash mines. Management Systems in Production Engineering. 2012. No. 2(6). pp. 28–31.
4. Owoseni J. O., Tamarautobou E. U., Asiwaju-Bello Y. A. Application of Sequential Analysis and Geographic Information Systems for Hydrochemical Evolution Survey, Shagari Environ, Southwestern Nigeria. American International Journal of Contemporary Research. 2013. Vol. 3, No. 3. pp. 38–48.
5. Courtney M. G. R. Determining the number of factors to retain in EFA: Using the SPSS R-Menu v2.0 to make more judicious estimations. Practical Assessment, Research and Evaluation. 2013. Vol. 18(8).
6. Hisafumi Asaue, Naoyuki Tadakumsa, Katsuaki Koike. Application of GIS to Hydrogeological Structure Modeling Aimed at Conservation of Groundwater Resources. Geoinformatics. 2014. Vol. 25, Iss. 3. pp. 159–168.
7. Belkhiri L., Narany T. S. Using multivariate statistical analysis, geostatistical techniques and structural equation modeling to identify spatial variability of groundwater quality. Water Resources Management. 2015. Vol. 29, Iss. 6. pp. 2073–2089.
8. Kologrivko A. A. Decrease in geoecological consequences by underground mining of potash fields. Herald of Polotsk State University. Series F: Civil Engineering. Аpplied. 2014. No. 16. pp. 101–110.
9. Zubov V. P., Smychnik A. D. The concept of reducing the risks of potash mines flooding caused by groundwater inrush into excavations. Journal of Mining Institute. 2015. Vol. 215. pp. 29–37.
10. Samodelkina N. A. Prediction of negative consequences of Berezniki Mine-1 flooding. Strategies and Processes of Georesources Development : Collection of Scientific Papers. Perm : GI UrO RAN. 2014. Iss. 12. pp. 84–87.
11. Devyatkov S. Yu. Determining conditions of sinkholes on ground surface. Strategies and Processes of Georesources Development : Collection of Scientific Papers. Perm : GI UrO RAN. 2014. Iss. 12. pp. 96–98.
12. Baryakh A. A., Devyatkov S. Yu., Samodelkina N. A. Theoretical explanation of conditions for sinkholes after emergency flooding of potash mines. Journal of Mining Science. 2016. Vol. 52, No. 1. pp. 36–45.
13. Baryakh A. A., Samodelkina N. A. Rheological analysis of geomechanical processes. Journal of Mining Science. 2005. Vol. 41, No. 6. pp. 522–530.
14. Amusin B. Z., Linkov A. M. Applying variable modules in solving a class of problems of linearly hereditary creep. Izvestiya Akademii Nauk SSSR. Mekhanika tverdogo tela. 1974. No. 6. pp. 162–166.
15. Konosavsky P. K., Potapov A. A., Makashov S. E. Predictive estimate of carnallite dissolution in pillars in Berezniki Mine-1 after emergency flooding (Upper Kama Potash Deposit). Modeling in solution of geoecological problems: Sergeev’s Lectures. Moscow : GEOS. 2009, Iss. 11. pp. 357–361.
16. Khodkov A. E. Test data on in situ leaching of carnallite. Transactions of the All-Union Research Institute of Mineral-Salt Production. 1953. Iss. 28. pp. 38–49.