Justification of the parameters of support for maintenance of workings in front of the longwall face in coal mines

Abstract

Purpose. To develop an effective rock-bolting technology for deep mine workings in the Karaganda Coal Basin. The proposed solutions aim to improve roadway stability and safety while reducing repair and maintenance costs. Methods. The study employed theoretical and experimental research, patent searches, analysis of national and international practices, and numerical modelling of the rock mass stress–strain state. The calculated results were compared with field observations from the Kazakhstan Mine. Findings. Roof displacement before installing reinforcing support should not exceed 50 mm; displacements of 50–200 mm reduce the load-bearing capacity of the reinforced rock mass by 15–65%. A two-level support system using 2.4 m and at least 5 m long bolts reduces the need for additional hydraulic props by up to 85%, while roof displacement ceases 150–200 m behind the longwall face. Originality. A two-level rock-bolting system was proposed, with parameters accounting for rock strength, mining depth, roadway span, and rock failure zones. Quantitative relationships between rock displacement and the reduction in the load-bearing capacity of the reinforced rock mass were established. Practical implications. The recommendations can be applied when designing and supporting deep mine workings in the Karaganda Coal Basin, including areas of increased rock pressure. Their implementation allows mine workings to be preserved for reuse, reduces maintenance requirements, and improves mining safety and productivity.