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expectations. The maximum amount of daily ballast <br />adjustment rarely exceeded four inches at any station <br />although up to eight inches would have been <br />required to maintain a differential gradient of ±2 <br />percent. <br />5 CONCLUSIONS AND RECOMMENDATIONS <br />A computerized version of the graphical method first <br />described in the Subsidence Engineers Handbook <br />has been successfully and efficiently used to predict <br />subsidence and related deformations at the <br />Twentymile Coal Mine. The system lends itself to <br />accurately predicting three - dimensional and time - <br />phased displacements associated with multi -panel <br />undermining. <br />6 REFERENCES <br />Breeds, C.D., 1976. A study of Mining Subsidence <br />Effects on Surface Structures with Special Reference <br />to Geological Factors. PhD Thesis, Univ, <br />Nottingham, England, 1976, 250 pp. <br />Karmis, M.., and Haycocks, C. 1983. Computer <br />Simulation of Mining Subsidence Using the Zone <br />Area Method. Final Report to the Mineral Institutes, <br />Bureau of Mines prepared by Virginia polytechnic <br />Institute and State University, Mining Department, <br />March, 1983. <br />Karmis, M.., Haycocks, C., and Agioutantis, Z., <br />1992. The Prediction of Ground Movement Caused <br />by Mining. Proc. 3rd Subsidence Workshop Due to <br />Underground Mining, Morgantown, West Virginia, <br />June, 1992. <br />Mark, C., 1990. Pillar Design Methods for longwall <br />Mining. US Bureau of Mines Information Circular <br />9247, 1990. <br />NCB, 1975, Subsidence Engineers Handbook. <br />Published by the National Coal Board, Production <br />Department, 1975, ] H pp. <br />Shadbolt, C.H., 1977. Mining Subsidence, <br />Historical review and State of the Art. Proc. Large <br />Ground Movements and Structures, University of <br />Wales Institute of Science and Technology, Cardiff, <br />Wales. Published by John Wiley and Sons, NY. <br />Singh, M.M., 1992. Mine subsidence. Chapter 10.6 <br />SME Mining Engineering Handbook. Published by <br />Society of Mining, Metallurgy, and Exploration, <br />Inc., 2260 pp. <br />Stewart, C., and Shoemaker, J.E., 1992. Subsidence <br />Monitoring Program at Cyprus Coal's Colorado <br />Operations. Proc. 3rd Subsidence Workshop Due to <br />Underground Mining, Morgantown, West Virginia, <br />June, 1992. <br />Su, D.W.H., 1992. Finite Element Modeling of <br />Surface Subsidence Induced by Underground Coal <br />mining. Proc. 3rd Subsidence Workshop Due to <br />Underground Mining, Morgantown, West Virginia, <br />June, 1992. <br />VPI, 1987. Prediction of Ground Movements Due to <br />Underground Mining in the Eastern United States <br />Coalfields, Volume 1, Development of Prediction <br />Methods. Department of Mining and Mineral <br />Engineering, Virginia polytechnic Institute and State <br />University, Blacksburg, Virginia. <br />