Geotechnical mechanisms of roof fall ahead of face support in longwall mining

Longwall mining is one of the most productive methods forextracting underground coal seams. Although the understanding of longwallmining-associated geotechnical mechanisms has been significantlyimproved that contributes to better ground control, roof rock/top coal fallahead of support (roof fall) has not been fully understood that causes severedamage to equipment and casualty at face. Empirical, theoretical andmodelling methods were successfully used in past studies to understand themechanisms driving roof fall; however, key mechanisms and theirinteractions during the fall were not satisfactorily investigated due tolimitation of each method. This study aims to gain a systematicunderstanding of roof fall mechanisms in longwall operation. A review ofpast studies on roof fall is implemented with emphasis on the principles ofapplied research methods. The study confirms that the interaction betweenroof strata, coal seam and face support largely controls roof fall whilenumerical modelling shows great potential in studying roof fall complexmechanisms. The paper’s findings provide mining engineers/scientists witha systematic understanding on roof fall from which more effective roofcontrol strategies can be further developed.