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

Abstract

Longwall mining is one of the most productive methods for
extracting underground coal seams. Although the understanding of longwall
mining-associated geotechnical mechanisms has been significantly
improved that contributes to better ground control, roof rock/top coal fall
ahead of support (roof fall) has not been fully understood that causes severe
damage to equipment and casualty at face. Empirical, theoretical and
modelling methods were successfully used in past studies to understand the
mechanisms driving roof fall; however, key mechanisms and their
interactions during the fall were not satisfactorily investigated due to
limitation of each method. This study aims to gain a systematic
understanding of roof fall mechanisms in longwall operation. A review of
past studies on roof fall is implemented with emphasis on the principles of
applied research methods. The study confirms that the interaction between
roof strata, coal seam and face support largely controls roof fall while
numerical modelling shows great potential in studying roof fall complex
mechanisms. The paper’s findings provide mining engineers/scientists with
a systematic understanding on roof fall from which more effective roof
control strategies can be further developed.