Forecasting stability of Irokinda deposit underground mine workings based on comparison of rock mass state prediction estimate methods

The purpose of the study is to compare and adjust the results of stability forecast for Irokinda gold deposit underground mine workings using various estimation methods of rock mass state based on the analysis of structural parameters only, multiparameter classification of structural parameters and engineering-geological indicators according to Z. Bieniawski as well as mass fracturing distribution. Engineering and geological conditions of deposit deep horizons have been estimated using the data obtained under geomechanical description of the core when drilling exploratory and hydrogeological boreholes and description of the walls of underground mine workings. All these made it possible to estimate the rock mass fragmentation degree, which affects the stability of underground mine workings. A full range of physical, mechanical and deformation property definition was performed using rock samples taken from the core of exploratory boreholes and mine workings. A total of 184 samples have been taken and analyzed during the field season with distinguishing of 10 rock varieties characterized by different strength and stability degree. The comparative analysis conducted on the example of the Irokinda field implies the need of the integrated use of these methods, which will enable increasing of result reliability and most accurate determination of the stability class of the rock mass for its further mining. The results obtained by various methods should be considered as a set of signals for making design decisions on strengthening mine workings.