Laserfiche WebLink
Investigation into Continued Damage at the Solitario Ranch Page 8 <br /> <br /> <br />western subsidence parameters were different The Influence Function Method <br />would work, however, by changing program parameters until a subsidence <br />calculation duplicated the actual field measurements. The Bureau was <br />permanently closed in the summer of 1995, and all of the employees were laid <br />off. <br />Dr Kohli provided help and references concerning coal mine flooding and related <br />pillar failures, especially concerning the punching of pillars into soft mud <br />floors.' <br />Dr Able, in addition to general observations concerning western coal mine <br />subsidence, provided additional details of the phenomenon of the raising of <br />survey monuments, observed during the study of the York Mine. In the report <br />this action was attributed to landslides along the edges of the subsidence basins, <br />where the clay-like soils flowed back into the subsidence depressions. The <br />discussion confirmed his opinion. <br />Much additional time was spent at the Arthur Lakes Library at the Colorado <br />School of Mines to review and obtain the pertinent literature on coal mine <br />subsidence. Many documents were obtained through the library document <br />exchange program with other libraries. <br />Computer Investigation <br />Measured rp ofiles <br />The first step in a computer analysis of this problem was to draw subsidence <br />curves based on the measured subsidence at the Allen Mine and the Golden <br />Eagle Mine and then to duplicate these curves by adjusting the subsidence <br />parameters in the program until the actual subsidence curves were duplicated. <br />The program allows a computed curve to be shown on the same screen as the <br />measured curve for comparison. <br />The survey information obtained from the public files indicated that there was <br />substantial subsidence over the NW#1 Section and some subsidence over the 3N <br />entry, of the Golden Eagle mine <br />The next step was to construct a computer model that would duplicate the <br />measured subsidence along the railroad tracks, using the same subsidence <br />parameters that were developed for the profiles that were based on measured <br />subsidence. <br />To do this, an assumption was made that some pillars had punched into the soft <br />mud floor in northeast corner of 1N. Approximately 50 trial computations were <br />made. The solution that most closely matched the measured subsidence assumed <br />that the two pillars in the northwest corner of the entry 7 had failed and that <br />neighboring pillars had partially failed. This is the zone where reentry for <br />surveying was blocked after flooding. <br />The program provides for an unlimited number of prediction points and this <br />prediction point grid was extended in a direction and a distance that would be in <br />the proximity of the Tatum house and beyond. Using the model it was clear that <br />the influence of the assumed subsidence extended to the house. <br />~ Characterization of Subsidence over Pillar Extr¢ction Panels, R.W. Bruhn, R.C. Speck, July 22, <br />1986, Contract # Jo233920, GAI Consultants, Inc, USDI USBM. Available through NTIS at Norlin <br />Library, University of Colorado. <br />