Regularities of Rock Pressure Changes During Pillarless Mining in the Zone of Regional Pressure Relief

Purpose. The purpose of this study is to examine the mechanisms of rock pressure redistribution in previously relieved zones during the extraction of adjacent reserves under mine conditions, as well as to analyze the influence of the rheological properties of surrounding rocks on the stability of the rock mass and to develop recommendations for the placement of development workings. Methodology. The study was conducted using numerical modeling of longwall mining development, taking into account the actual sequence of longwall operations. Two scenarios of rock mass behavior were considered: without rheological properties (elastic rock mass) and with rheological properties (including creep and stress relaxation). The analysis was based on the distribution of stresses within the rock mass at various stages of development. Results. In elastic rock masses, after complete extraction of adjacent reserves, the stress increment diagram in the area of the primary relieved longwall was symmetrical, with peaks of 0.65 near the boundaries. In masses with rheological properties, a pronounced asymmetry in pressure distribution was observed: the stress increment reached 0.46 on the side of the first longwall and 0.88 on the side of the second. The zone of minimal pressure increment in the rheological mass was narrower (75 m compared to 100 m in the elastic mass). Originality. For the first time, regularities of asymmetric rock pressure redistribution in previously relieved zones within rheological rock masses were established, depending on the sequence of longwall operations. The influence of creep and stress relaxation on the loading behavior around old workings was demonstrated. Practical value. The obtained results make it possible to reasonably recommend the optimal placement of development workings in the regional pressure relief zone, depending on the properties of the rock mass. This contributes to improved stability of mine workings, reduced risk of accidents, and increased economic efficiency of mining operations. The proposed scientifically based approaches to assessing changes in rock pressure help to minimize technogenic risks, ensure personnel safety, and enhance the overall reliability of mine infrastructure operations.