Mining Institute, Kola Science Center, Russian Academy of Sciences, Apatity, Russia

I. E. Semenova, Head of Geomechanics Department, Candidate of Engineering Sciences, i.semenova@ksc.ru
S. V. Dmitriev, Researcher
N. N. Kuznetsov, Senior Researcher, Candidate of Engineering Sciences

The subject of research is a site of the Oleniy Ruchey deposit. The Oleniy Ruchey apatite–nepheline deposit occurs on the southeastern side of the ijolite–urtite arc of the Khibiny Massif and is operated by North-Western Phosphorus Company. The geological features of the selected site are: the absence of ore bodies with uniform content of useful component; the presence of different-scale and different-dip structural discontinuities that form blocks; different parameters of the stress–strain behavior of blocks, which differ both in orientation and in absolute magnitudes. The implemented numerical stress–strain analysis of the test site in rock mass at the Oleniy Ruchey deposit using contact elements revealed variations in actual gravitational tectonic stress state nearby a structural discontinuity. It is shown that the stress pattern assessment in the roof of a mine opening agrees with the geodynamic characteristics obtained from the visual inspection of rock mass. The normal and tangential stiffness values of structural discontinuities in rock mass in the test site are determined experimentally. The stress–strain modeling with the contact elements demonstrated their efficiency in case of structural discontinuities without fill and proved the conformity of the model stress field with the actual geomechanical conditions.
The study was supported by the Russian Science Foundation, Grant No. 22-17-00248, http://rsf.ru/project/22-17-00248.
The authors express their gratitude to North-Western Phosphorous Company for the help in the research process and to the Leading Engineer of the Mining Institute, KSC RAS A. K. Pak for the laboratory experimentation and testing.

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