Laserfiche WebLink
"D" Seam Longwall Subsidence Page 56 August 17, 1998 <br />PREDICTED LANDSLIDE SUBSIDENCE EFFECTS <br />Plate 1 (Panels #1 - #3) and Plate 2 (Panels #4 - #6) indicate <br />the portion of the outline of the potential landslide overlying <br />portions of Panel #3 and Panel #9 (JUnge, 1978). The northernmost <br />part of the potential landslide overlies the extreme southwest <br />corner of Panel #3 and the extreme southeast corner of Panel #4. <br />The portion of the potential landslide, which overly Panel #3 and <br />Panel #4, will be subjected to vertical subsidence and horizontal <br />strain. <br />The vertical subsidence accompanying longwall mining of Panel <br />#3 and Panel #4 should lower the upper northern end of the <br />landslide by as much as 10 feet. Lowering the upper part of a <br />landslide should increase the stability of the landslide mass by <br />tilting the crest of the landslide back into the slope. The <br />predicted worst-case vertical subsidence will decrease the <br />downslope thrust of the landslide mass. The overall slope of the <br />sliding surface under the landslide will be flattened by <br />approximately 0.3° (10-ft vertical over an approximate 2000-ft <br />horizontal distance). <br />The overall effect should be an increase in overall stability <br />of the potential landslide. This is also true for the south facing <br />and sloping hillsides that will be undermined by the planned <br />longwall "D" Seam longwall mining because of the planned north to <br />south direction of mining. As the longwall panels advance toward <br />the south they will initially tilt the ground surface toward the <br />north. All the longwall panels stop at barrier pillars separating <br />the equipment recovery rooms from the "D" Seam Main Entry. <br />Therefore, the tilt toward the north will be a permanent result of <br />stopping the longwall panel advance. <br /> <br />56 <br />