Stress transfer between multi-seam longwall mines

Abstract

The future of most underground coal mining in the USA will entail the extraction of coal under multi-seam mining conditions. Mine design in such an environment will require the accurate prediction of stress transfer between adjacent seams. The available knowledge on criteria controlling stress transfer has been exhaustively reviewed and critical factors affecting multi-seam mining investigated. Young's Moduli of rock layers, thickness of rock layers, number of these layers and the coefficient of friction between these layers were identified as important parameters which affect stress transfer from mining of one seam to another. These parameters were studied using photoelastic methods and results analyzed both qualitatively and quantitatively. Finite element studies were also performed using UTAH2PC. Data obtained from field studies was used to correlate laboratory findings with prototype observations. Excellent correlation was obtained between laboratory and field data. Validity of the research is demonstrated using case studies.