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Progress Report on Tatum House Subsidence issues Page 4 <br />April 12, 1995 <br />The conclusion that the over burden appeared to subside in a relatively coherent <br />rockmass is consistent with m}• observations in the area, including the effects of <br />mining on Rancho Escondido and at Morley, Colorado south of Trinidad. This would <br />tend to contradict the conclusion that the influence of the mine would be drastic as <br />stated by OSMz or drastic and disruptive as stated by the State of Colorado, <br />Department of Natural Resources, Division of Minerals and Geology' . Attwooll <br />finds that the house damage is consistent with subsidence failuresi . <br />The raw data for this study is available in the Denver Office of the US Bureau of <br />Mines in a poorly organized file. <br />SDPS (Surface Deformation Prediction System 4.0) <br />A computer program has been developed by the Department of Mining and Minerals <br />Engineering, Virginia Polytechnic Institute and State University. This program is <br />used by the OSM in developing their subsidence models. The USBM has recently <br />acquired this program for testing. <br />I talked to Dean Michael Karnis, the Head of the Department at VPI & SU, and one <br />of the developers of the program. The conversation centered around where the <br />program had been used, how reliable it had been in duplicating case studies, and <br />whether it had been used in western applications. He noted that they had had a <br />good experience with the application, and that it had been used in the west. <br />He told me that empirical data could be inputted into the model, however it did not <br />take into consideration the effects of water in the mine, and he would tend co <br />increase the extraction to 90 %, in a room and pillar mining situation, to take this <br />into account. He also advised me not to confuse the "angle of draw" which tends to <br />maximize at 27°, and the "angle of influence" which can be much larger, 35° more or <br />less when measured the same way. He also gave me the name of the software <br />distributor that handles the program. Subsequently I obtained a copy of the <br />program from Carlson Software. <br />The program has several different methods that it uses to predict surface <br />deformation. A Profile Function Method which utilizes data generated by many <br />observations in the Eastern United States together with some site specific <br />parameters. It generates a subsidence curve that is along an axis that is orthogonal <br />to an infinitely long underground excavation. An Influence Function method is an <br />alternative. This method can calculate subsidence curves using default data <br />developed by experience in Eastern Coalfields, or can allow the input of empirical <br />data based on site specific information. It will calculate subsidence in either <br />t•ansverse (orthogonal) or longitudinal directions. <br />The OSM analysis did not use the right mode], the Tatum House is situated <br />longitudinally with respect to the underground mining at First North in the Golden <br />Eagle mine. <br />