The paper considers the problem of refining the critical depth of rock burst hazard for the Nyorkpakhk apatite-nepheline ore deposit in the context of transition to underground mining. The relevance of the study results from the discrepancy between the value of 400 m (according to regulatory documentation) and the actual mining and geological conditions, especially considering the significant impact of the existing open pit on the stress-strain state of the rock mass and other natural factors of the region. The aim of the study is the development and testing of a comprehensive methodology for assessing the critical depth of rock burst hazard, including core discing analysis, seismicity monitoring, spatial numerical modeling of the stress-strain state using the CAE Simulia Abaqus software, assessment of the rock burst hazard potential of rocks based on the Kaiser criterion, and comparison with a geomechanically similar analogue Oleniy Ruchey deposit. Core discing analysis revealed only local stress zones associated with tectonic faults, without characteristics pointing to rock burst hazard down to the +100 m level. The results of numerical modeling confirmed the absence of stress concentrations down to the +35 m level both before the start and after the completion of open pit mining. Comparison using the similarity method showed expected manifestation of rock burst hazard below the +50 m level. The studies, according to the described methodology, enabled scientific justification of increasing the critical depth of rock burst hazard relative to the regulatory value, down to the +100 m level. It has also been determined that for the Khibiny deposits there is no direct correlation between the brittleness criterion and the propensity for rock burst hazard. The proposed methodology is recommended for testing at rock burst hazardous deposits with complex mining and geological conditions.

The technology of construction of the mine shaft in urban areas. The technology of construction of permanent roof supports. The main characteristics of the objects and supporting construction. The advantages of each technology, as well as its shortcomings.

The volumetric model taking into consideration the driving of the mine through zone of weakening. The results of mathematical modeling on the basis of the method of finite elements of a non-linear deformed ore body with the working out of a vaulted contour are represented. The carrying out of the working is implemented step-by-step transversely to the weakness zone.

The volumetric model taking and performed mathematical modeling the process of construction of the pit under the enclosing wall of secant piles. The results of mathematical modeling on the horizontal displacements of the pit wall. Set out conditions for the construction of the pit and the main technological solutions.

According to geological data which was received at the Yakovlevsky deposit, the volumetric model was developed. This model taking into consideration the driving of the mine through zone of weakening. During the analysis of the stress-strain condition near the mine the character of distribution and numerical results of tangential and longitudinal stresses have been revealed. The zone of weakening affects to the distribution of stresses and displacements around the mine. To select the parameters of the lining support it is necessary to take into consideration weakenings and contacts in the ore massive and the distance for these zones.