| Coal mine bumps occur in most countries where coal is mined by underground methods. Coal bumps can be characterized as unstable releases of strain energy associated with energy changes that take place with progressive mining. This research is conducted to study the strain energy effect on coal bump problems associated with underground coal mining. The roofs are modeled as elastic beams on continuous elastic foundations subject to exponentially distributed abutment stress. Elastic beam theory is applied to develop analytical solutions for deflection of single-layer roof models. Methods for analyzing double layer roof and double layer foundation models are also discussed. Formulae for assessing critical spans of the roof beds and strain energy storage in the roof and foundation are developed. Based on a data bank of rock mechanics properties for coal measure strata from the results of 2813, 1102 and 126 tests for compression, tension and shear tests, respectively, from 50 coal seams in 90 coal mines by 63 coal companies in all the coalfields of the United States, the factors affecting roof cavability and energy accumulation are identified and analyzed. A parametric analysis reveals that mechanical characteristics of roof beds, foundation properties, and roof configurations may interact to influence roof cavability and energy storage. |
