Evaluation of high rock pressure zone parameters under conditions of an active mining panel

Purpose. The aim of this study is to quantitatively assess the spatial and stress characteristics of the high rock pressure zone under the conditions of an active mining panel, taking into account the temporal evolution of the stress state and the sequence of extraction of adjacent seams. Particular attention is paid to identifying the nature of the rock pressure gradient variation within the rock mass in the vicinity of the active longwall face. Methodology. The finite element method was employed for three-dimensional modeling of the stress–strain state of the rock mass. The numerical model incorporates the geometric and physical-mechanical properties of the seams and surrounding rocks, processes of plastic deformation, fracturing, and irreversible displacement, step-by-step extraction of adjacent longwalls, boundary loading conditions, and contact interaction between the rock mass and mined-out areas. A series of simulations was conducted for various stages of the mining process, followed by analysis of the resulting stress gradients. Results. Numerical modeling revealed that the parameters of the HRPZ vary both spatially and temporally, depending on the extraction sequence of adjacent reserves. Maximum values of the rock pressure gradient were recorded near the edges of the active longwall, reaching up to 25 MPa/m. In the central part of the longwall, the gradient decreases to 18–20 MPa/m, and along extended boundaries it does not exceed 14 MPa/m. The gradient of stresses decays exponentially with increasing distance toward the roof and floor of the seam. At a depth of 30 m below the mined seam, the maximum gradient values do not exceed 1.5 MPa/m. Scientific novelty. For the first time, a quantitative assessment of the rock pressure gradient in the HRPZ was performed considering stepwise development and irreversible deformation processes. A regularity of exponential decay of the stress gradient toward the roof and floor of the seam was established. It was substantiated that traditional methods based on the superposition principle of HRPZs without considering the extraction history may result in significant errors when assessing the actual stress state. Practical significance. The findings of this study can be applied to improve the methods for predicting HRPZs under complex mining and geological conditions, to optimize the layout of development workings and the selection of safe parameters for the mining front, and to enhance the safety level of underground mining operations by enabling a more accurate consideration of the actual stress distribution within the rock mass. Keywords: high rock pressure zone, rock pressure, mining panel, numerical modeling, stress–strain state