Probabilistic analysis application to substantiate support parameters in seismically active and fractured rock masses

Purpose. The research aims to substantiate support parameters for underground mine workings in the conditions of fractured and seismically active masses using probabilistic stability analysis. Methods. The research is based on the integration of field engineering-geological observations, geological-structural ana-lysis, numerical modeling and probabilistic stability assessment methods. Based on the geotechnical description of oriented cores, the mass fracturing parameters (RQD, Jn, Jr, Ja) were determined, stereographic analysis using Dips software was performed and the mass quality index Q′ was calculated. Probabilistic stability analysis of wedges was conducted in the Unwedge software package, taking into account dynamic effects and seismicity coefficients up to 0.4. Scenarios without support, with roof-bolt and combined supports are discussed. Findings. It has been found that at unfavorable mine working orientation and high seismic loads, the factor of safety (FS) does not reach the design values (FS ≥ 1.5) without the use of support, which necessitates the use of combined support schemes. Originality. The novelty is in the complex application of probabilistic stability analysis taking into account real geometric and mechanical characteristics of fracturing, seismic impact and spatial anisotropy of the mass. For the first time, field data, Q′ index and Unwedge modeling have been combined for specific engineering-geological conditions to substantiate the parameters of a combined support adapted to seismically active fractured masses. Practical implications. The developed methodology can be adapted to various mining-technical conditions and helps to increase the reliability of design solutions for construction and operation of underground structures in difficult geological and seismically active areas.