Current Theories and Concepts for the Determination of Roof Loading over the Hydraulic Supports in Longwall Faces

Underground mining of ores affects in-situ rock conditions, resulting in a sequence of strata motions. Roof rock pressure, which is the basis of all ground control issues, is caused by these instabilities. The hydraulic supports are subjected to excessive stress due to the roof rock pressure. The correct forecast of Rock Roof Loading (RRL) provides longwall face stability during ore exploitation, allowing the hydraulic supports to move more freely. This paper presents some of the current theories, approaches, and concepts for the determination of roof loading on longwall faces, with emphasis on the current gaps. This could improve the ability to manage the roof during mining workings, and govern the roof loading conditions and the supporting system. From this study, it can be seen that the periodic weighting of the main roof is an important aspect in the determination of loading requirements. Moreover, many loading calculation methods failed to take into consideration the swelling pressure of immediate roof rocks, and the tilting of the main roof blocks, which exert excessive loads on the supporting systems.