M. S.

Most research on surface subsidence pertains to domestic as well as foreign experiences with longwall mining. Investigations into room-and-pillar subsidence have often been neglected, despite the fact that this is the predominant mining system in this country. However, the recent economic incentives which have caused the need for higher secondary extractions in room-and-pillar mines and the severe subsidence occurrences over certain abandoned mines have placed added emphasis into the subsidence phenomenon above such panels. In this research, a comprehensive subsidence data bank for cases of partial extraction was compiled through both literature sources and unpublished data. Emphasis on Appalachian data was sought in order to minimize geologic variation. The data was then used to validate various published empirical models for subsidence prediction within the U.S. From this analysis, and from the longwall information used in previous research, a more comprehensive prediction method for partial subsidence was obtained. The modeling represents a relationship between various geometric and characteristics. geologic parameters with subsidence profile In addition to the empirical methods, the zone area technique was investigated for a predictive computer model of room-and-pillar subsidence. Alteration of a previous VPI & SU, longwall subsidence, zone area program allowed the formulation of the room-and-pillar model. The resulting zone area program for predicting room-and-pillar subsidence is not only more applicable to partial mining techniques, but also more flexible, allowing for more complex mine geometries and variable mine parameters. / M.S.