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at a certain value. If the full area of the influence were mined out, the point in question <br />would undergo 100% of maximum possible subsidence. If some portion within the zone <br />of influence were unmined, subsidence would be correspondingly reduced. <br />5.2 Model Calibration <br />Subsidence predictions were made using a numerical model calibrated with baseline <br />subsidence data from the Upper D Seam. BRL monitored the long-term surface response <br />to longwall mining over the D1 to D9 panels. The results of this monitoring were used to <br />establish modeling parameters for the Upper B Seam while considering similarities in <br />lithologic conditions in the Upper D and Upper B seams and available regional data <br />within the Somerset basin. <br />Panels D5 through D9 were selected for model calibration considering closer spacing <br />of monuments and frequency of monitoring. Initially, we focused on the western portion <br />of the longwall block because of closer spacing of monuments and lack of past mining <br />activities in the B and C seams. As illustrated in figures 1 and 2, U.S. Steel and the <br />operator of the King Mine practiced irregular mining in the B and C seams to the east <br />side of the longwall block, creating some uncertainty due to reactivation of movement in <br />the old workings. Because of the rather uniform overburden thickness over the western <br />portion of the panels, we used a fixed cover for initial modeling while comparing <br />measured and calculated deformation for the D7, D8, and D9 panels. <br />Figure 11 compares measured and calculated results for select monuments located <br />toward the center of the longwall area about an approximate north-south cross section. <br />Good agreement is shown. The model appears to underestimate subsidence at station <br />22D and overestimate it at 14C. The difference is probably caused by the changes in <br />topographic conditions at these monument locations (the pile-up effect). <br />Additional modeling included digitizing the overburden contours and thus <br />• incorporating the variability in topographic conditions to improve goodness of fit. Slight <br />Maleki Technologies, Inc. Page 30