Effect of structural disturbance on stability of pillars in geological conditions of apatite–nepheline deposits

The apatite-nepheline deposits of the Khibiny massif are the main base for the extraction of apatite-nepheline ores in the Russian Federation and are characterized by high intensity of work, increasing depth of development and more complex mining and geological conditions. The rock mass at the field is strong, fragile and structurally damaged, which predetermines various forms of loss of stability of the structural elements of the development, in particular pillars. At the same time, in regulatory documents when assessing the stability of mine workings, the parameters of structural damage that have a direct impact on the mechanical behavior of the rock mass are taken into account indirectly, i.e. indirect method. The article studies the influence of the structural discontinuities of the massif on the stress state of the pillars using the methods of numerical modeling and physical modeling on equivalent materials. The results obtained demonstrate the significant influence of the block structure of the massif on the results of forecast its stress-strain state in comparison with models of the behavior of the massif that implements the principles of continuum mechanics. In which the presence of structural damage and their quantitative characteristics are taken into account by an indirect method, i.e. through an artificial reduction in the deformation properties of the massif, based on the results of geotechnical mapping and determination of the Bieniawski RMR rating. The mechanism of loss of stability of the block array differs due to the presence of weakening planes. Qualitative convergence of the results of numerical and physical modeling is achieved. The quantitative discrepancy between the results between the two modeling methods does not exceed 25 percent. Research shows the need to take into account structural discontinuities explicitly and develop additions to the methodology for assessing the stability of pillars located in structurally damaged block massif.

Bagautdinov I. I., Streshnev D. A. Effect of structural disturbance on stability of pillars in geological conditions of apatite–nepheline deposits. MIAB. Mining Inf. Anal. Bull. 2024;(12-1):129-144. [In Russ]. DOI: 10.25018/0236_1493_2024_121_0_129.

I.I. Bagautdinov, Cand. Sci. (Eng.), Leading Researcher, Empress Catherine II Saint-Petersburg Mining University, 199106, Saint-Petersburg, Russia, e-mail: bagautdinov_ii@pers.spmi.ru, Scopus Author ID: 57204217965,
D.A. Streshnev, Head of Department of Forecast and Warning of Rockburst, Kirovsk branch of JSC Apatit, PJSC PhosAgro, 184250, Kirovsk, Russia, e-mail: info@apatit.com.

I.I. Bagautdinov, e-mail: bagautdinov_ii@pers.spmi.ru.

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