Redistribution of rock pressure and deformation of the rock mass in the Karaganda coal basin

Abstract

The study examines the redistribution of rock pressure and associated deformation processes in the Karaganda Coal Basin. It focuses on the geometry and parameters of the abutment, unloading, and disintegration zones around underground workings, and on their influence on gas-dynamic phenomena. The methodological basis combines a critical review of current geomechanical models, calculation–graphic nomograms for estimating zone width as a function of mining depth and seam thickness, and schematic construction of high-stress regions from the boundaries of the goaf at limiting angles of 75–90°. It is shown that, with increasing depth up to about 500 m, the zone configuration becomes wedge-shaped with a tendency to narrow downward, while increasing seam thickness expands the affected areas. Lithology controls the localization of hazardous zones: weakly bedded argillites and siltstones accelerate loosening and loss of stiffness, whereas stronger sandstones form dome-like stress concentrations with elevated likelihood of sudden outbursts and rockbursts. As a verification case, an episode of a sudden coal-and-gas outburst was analyzed. The observed failure boundaries are consistent with the calculated wedge-shaped high-stress zone, supporting the validity of the chosen approach within the stated assumptions. The practical significance lies in refining threshold conditions that trigger mandatory comprehensive forecasting at depths exceeding ~400 m, justifying regular instrumental monitoring to validate calculations, and adjusting barrier-pillar parameters about seam thickness and depth. The findings can be applied to the planning and safe execution of longwall and development operations under outburst-prone conditions.