National University of Science and Technology–MISIS, Moscow, Russia¹ ; Don State Technical University, Rostov-on-Don, Russia²:

Pleshko M. S.^1,2, Professor, Doctor of Engineering Sciences, mixail-stepan@mail.ru

National University of Science and Technology–MISIS, Moscow, Russia

Pankratenko A. N., Head of Department, Professor, Doctor of Engineering Sciences
Pleshko M. V., Associate Professor, Candidate of Engineering Sciences

Platov South-Russian State Polytechnic University (NPI), Novocherkassk, Russia

Nasonov A. A., Associate Professor, Candidate of Engineering Sciences

With an increase in the depth of shafting and subsequent risk growth, it becomes necessary to make a maximum accurate estimate of the actual stress–strain behavior of the shaft lining. Real-time monitoring and numerical simulation of the bottomhole zone of a shaft in the process of sinking is proposed as an effective approach to the solution of this problem. The results of an experimental check in three sites of shafts in similar engineering–geological conditions are presented. The real-time monitoring provided control of tensile forces in rock bolts before installation of the main support. Rock bolts 1.8 m long were used with full- and partiallength grouting in the hole. In each test area, 18 strain gauged rock bolts were installed with tensometric sensors glued along the rock bolts. As a result of the research, an array of data on 486 values of tensile forces is obtained. The graphs of the force variation along the rock bolts are plotted at different sizes of its grouting in the borehole. In all experimental sites, the minimum tensional forces in the rock bolts were observed when the bolts were fully grouted in the borehole. When the bolts were partially grouted, the forces were 1.4–1.7 times greater. At the second stage of the research, the 3D finite element models were built for the bottomhole area of vertical shafts in three experimental areas. The calculation took into account the deformation nonlinearity by using stepwise iterative procedures. The comparison of the experimental and numerical simulation results shows the similar qualitative distribution of forces along the rock bolts. According to the quantitative analysis, the maximum deviation of the force values never exceeds 19%. The higher calculated values can be explained by the fact that numerical modeling neglects structural yielding of the rock bolts. The obtained comparative data confirm the correctness of the numerical models. Based on that, the numerical models were then used to find the maximal stresses in the shaft lining, and the structure strength was estimated. As the main method for increasing the bearing capacity of the lining, it is recommended to use concrete of higher strength at depths greater than 700 m.

1. Pleshko M. S., Stradanchenko S. G., Maslennikov S. A., Pashkov O. V. Study of technical solutions to strengthen the lining of the barrel in the zone of influence of construction near-wellbore production. ARPN Journal of Engineering and Applied Sciences. 2015. Vol. 10(1). pp. 14–19.
2. Walton G., Kim E., Sinha S., Sturgis G., Berberick D. Investigation of shaft stability and anisotropic deformation in a deep shaft in Idaho, United States. International Journal of Rock Mechanics and Mining Sciences. 2018. Vol. 105. pp. 160–171.
3. Kaledin O. S. Innovative technologies for the construction of superdeep mine shafts. Mining Journal. 2014. No. 4. pp. 77–81.
4. Tarasov V. V., Koshev G. Ya., Zagvozdkin I. V. Solution of security problems in the construction of vertical shafts at potash deposits. Industry labour safety. 2015. Vol. 8. pp. 64–67.
5. Tarasov V. V., Pestrikova V. S. Overview of emerg encies that occurred at the Verkhnekamsk potassium salt deposit during the mining of shafts. GIAB. 2015. No. 5. pp. 23–29.
6. Xiaowei Feng, Nong Zhang, Fei Xue, Zhengzheng Xie. Practices, experience, and lessons learned based on field observations of support failures in some Chinese coal mines. International Journal of Rock Mechanics and Mining Sciences. 2019. Vol. 123. 104097. DOI: 10.1016/j.ijrmms.2019.104097
7. Corkum A. G., Damjanac B., Lam T. Variation of horizontal in situ stress with depth for long-term performance evaluation of the Deep Geological Repository project access shaft. International Journal of Rock Mechanics and Mining Sciences. 2018. Vol. 107. pp. 75–85.
8. Strickland B., Board M., Sturgis G., Berberick D. Elliptical shaft excavation in response to depth induced ground pressure. SME Annual Conference and Expo: The Future for Mining in a Data-Driven World. 2016. pp. 407–412.
9. Kharisov T. F. Mine shaft rock walls convergence investigations in the conditions of the out-of-limit state of the borehole massif. Izvestiya vuzov. Gornyi zhurnal. 2017. No. 5, pp. 46–51.
10. Sousa L. R., Sousa R. L., Vargas Jr. E., Velloso R., Karam K. Risk assessment on CO₂ injection processes and storage. Rock Mechanics and Rock Engineering. 2017. Vol. 3(12). pp. 359–397.
11. Pleshko M. S., Silchenko Yu. A., Pankratenko A. N., Nasonov A. A Improvement of the analysis and calculation methods of mine shaft design. GIAB. 2019. No. 12. pp. 55–66.
12. Pleshko M. S., Pashkova O. V., Nasonov A. A. Analysis of geometrical nonuniformityf lining in operating shafts and its influence on shaft stability. Gornyi Zhirnal. 2015. No. 3. pp. 33–37. DOI: 10.17580/gzh.2015.03.05
13. He M., Li. C., Gong W., Sousa L. R., Li S. Dynamic tests for a constant-resistance-large-deformation bolt using a modified SHTB system. Journal of Tunneling and Underground Space Technology. 2017. Vol. 64. pp. 103–116.
14. Shuxue D., Hongwen J., Kunfu C., Guo’an X. Bo, M. Stress evolution and support mechanism of a bolt anchored in a rock mass with a weak interlayer. International Journal of Mining Science and Technology. 2017. Vol. 27. pp. 573–580.