Rock pressure management during deep deposit development

Abstract

Relevance. The intensification of underground mining at the Gaisky underground mine is caused by the ever-increasing demand for raw materials and leads to mining depth growth. It therefore drives the need to formulate the problem of mining system structural elements stability. Data on the size and degree of fracturing of the rock mass disturbed layer on the outcrop (sheath) formed from natural cracks opening and drilling and blasting operations, made it possible to correct the stress distribution patterns on the contour and around the goaf. Research results established the dependence between the stress concentration and the structural weakening coefficient with distance from the outcrop. Research objective is to geomechanically substantiate rock pressure control methods and options for backfill mining method, improve safety and reduce geodynamic phenomena manifestation in the course of mining. Methods of research include full-scale experimental measurements of rock mass and ore stress state at accessible depths and horizons of the deposit. An integrated scientific research method was used which includes the analysis and theoretical generalization of the patterns of stress distribution in masses of extracted chamber reserves, mathematical modeling of the research results, and theoretical results comparison with the instrumental observations results. Results analysis. The paper presents the results of stress state formation in the ore in place, obtained through modern methods for mine structures stress-strain state calculation. Regularities in the rock mass stress state distribution were revealed. A set of active rock pressure control methods was formed on the example of the Gaisky underground mine. Findings. As compared to existing methods, rock pressure control is most effective through creating protective zones, artificial planes, using two panels in the lying and hanging sides tunneled along the strike of the ore body and forming sharp corners in the roof and bottoms, which will make it possible to move the maximum compressive stresses from technologically critical to less critical and more stable sections of the rock mass and concentrate the maximum compressive stresses on themselves, thereby unloading the workings of the bottom and the roof of future chambers in the protective zone. It is more rational to work out mining units with the I–II stage chambers according to existing schemes, and release the III stage chamber rock mass with double chambers and form diamond-shaped asymmetric interfloor pillars.