Polar Division, Norilsk Nickel Mining and Metallurgical Company, Norilsk, Russia:

V. V. Balandin, Director of the Oktyabrsky Mine, rudokt@nornik.ru
V. L. Leonov, Deputy Director of Mining Practice

Saint-Petersburg State Mining University, Saint-Petersburg, Russia:
A. D. Kuranov, Head of Laboratory, Candidate of Engineering Sciences
I. I. Bagautdinov, Senior Researcher, Candidate of Engineering Sciences

Selection and design of safe and efficient support systems for mines is a critical problem at the Oktyabrsky copper–nickel deposit. The deposit is composed of strong and hard rocks. The uniaxial compression strength of high-grade and disseminated ore is 70–120 and 95–150 MPa, respectively. The stress state is mostly gravitational. As per Russian regulatory documents (SP 91.13330.2012), parameters of horizontal and inclined underground excavations are calculated based on the estimated anticipated displacements in rock mass. This approach is inefficient in the geological conditions of the Oktyabrsky deposit. There are two approaches to the support system design. The conventional approach considers the support system as an engineering structure subjected to external loads. The other approach is based on the concept on interaction of the support and rock mass as a single deformable system. The Saint-Petersburg Mining University assumed the research object to be development headings and permanent openings with estimated span of 6 m and area not more than 25 m², at the depth to 900 m. First, the rock mass quality was assessed using the Q-index by Barton. The support system design was determined by the Q support chart from Grimstad and Barton. The analysis shows that the Grimstad–Barton recommendations on the support system design can be restrictedly applied in the geological conditions of the Oktyabrsky deposit and need refinement. For this reason, additional calculations were performed for the specific conditions. The numerical modeling determined the possible fall zone parameters using the generalized Hoek–Brown criterion. It is assumed that the possible failure zone dimensions are not higher than the sizes of inelastic strain zones in sidewalls and roof of the mine workings. The determined dimension of the possible roof fall zone and the value of loads applied to support are the required parameters for any support system design for underground mines. Thus, in the article, the support system design is implemented for rock mass areas with the known rock quality by the Q-index. The scope of the support system design embraces the reinforced c concrete and reinforced polymer rock bolting, composite support composed of rock bolts and mesh reinforcement, shotcrete and arch-wise yielding support systems.
The authors appreciate participation of V. P. Marysyuk, Yu. N. Nagovitsyn and M. P. Sergunin in the study.

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