Ensuring a safe geomechanical state of the rock mass surrounding the mine workings in the Karaganda coal basin, Kazakhstan

Abstract

Purpose. The research purpose is to determine the instability zones in the host rocks and the dynamics of propagation of active fracturing zones to ensure the stability of the rock mass surrounding the mine workings. Methods. The research uses a set of analytical and experimental studies to determine the dynamics of the deformation process development in the coal-rock mass surrounding the mine workings. Mathematical modeling of the stress-strain state of the rock mass surrounding the active extraction workings is performed using the numerical method of finite elements in modern AN-SYS, Mergel and KMS-III software products. Findings. The influence has been studied of the mine working section shape and the coal seam dip angle on the value of the maximum stresses that arise in the rock mass when the mine working is fastened with the roof-bolt support. The instability zones in the host rocks and the dynamics of propagation of active fracturing zones have been determined both ahead of the front of the conducted mine working and on its sides for rocks of different strength. Originality. For the conditions of the Karaganda coal basin, the dependence of a change in the development of conventional inelastic deformation zones (CIDZ) on the host rock strength has been revealed. The influence of the coal seam dip angle on the dynamics of stratifications around preparatory working has also been substantiated. In addition, new data have been obtained on the influence of the roof rock strength on the stratification of the rock mass surrounding the mine working. Practical implications. By determining instability zones in the host rocks and the dynamics of propagation of active fracturing zones, it is possible to control geomechanical processes in the border rock mass of a mine working and influence it in order to prevent the occurrence of negative rock pressure manifestations. The data obtained are the basis for the development of recommendations on the use of roof-bolting technology for fastening extraction workings to ensure their stability and reduce the cost of their operation.