Laserfiche WebLink
Box Canyon Mining Area -Maximum tilt, based on analyses of West Ells Mine subsidence <br />• measurements, is projected to range from 0.004 beneath West Flatiron to 0.035 above the <br />northernmost panel beneath Box Canyon. <br />Maximum Curvature <br />Curvature, i.e., subscript (Cm) which is the reciprocal of radius of curvature (and thus expressed in <br />radians/foot [rad/ft]), is calculated from differential tilt. Maxunum positive (convex upward) <br />curvature in the West Elk Mine monitoring network is as much; as 50 percent more over chain <br />pillazs than it is above longwall panel boundaries. Maximum positive curvature at the current West <br />Elk Mine ranges from 14.4 to 18 (Sm/dz) with a numeric range of 0.000060 to 0.000065 rad/ft above <br />longwall panel boundaries to an average of 24 (S,,,/dZ) with a numeric range of 0.000144 to 0.00022 <br />rad/ft above the chain pillars. <br />Maximum negative (concave upwazd) curvature averaged about the same when measured above the <br />chain pillazs as it did above the panel boundaries. Maximum negative curvature ranges from about <br />-20 to -25 (Sm/d2) (-0.000111 to -0.000066 rad/ft) above longwall panel boundaries and has an <br />average value of -24 (Sm/dz) (-0.00012 to -0.00025 rad/ft) in the panel centers between the chain <br />pillars. Maximum positive and negative curvature in four different areas of the Westem United <br />States ranges from 9 to 45 (Sm/dz). Maximum curvature ranges aze; given below for the eastern and <br />western panels of the Apache Rocks and the Box Canyon mining areas. <br />Apache Rocks Mining Area -Maximum positive curvature projected for B-Seam mining in the <br />eastem ~anels of the Apache Rocks mining area (using an average West Elk Mine value of <br />24 (Sm/d )), ranges from 0.000023 to 0.00025 rad/ft; maximum negative curvature (using a similar <br />average of -24 [Sm/dz]) ranges from -0.000033 to -0.00069 rad/ft. Maximum positive curvature <br />projected in the westem panels of the Apache Rocks mining azea; after E and B-Seam mining is <br />completed, is projected to range from 0.00026 to 0.00132 rad/ft.~ Maximum negative curvature <br />projected in the westem panels for E and B-Seam mining ranges from approximately -0.00026 to <br />-0.00132 rad/ft. <br />Box Canvon Mining Area -Maximum positive curvature for the two northern panels, Panels 1 and <br />2, is projected to be 0.000030 to 0.000410 rad/ft; for Panel 3, 0;.000024 to 0.000202 rad/ft; for <br />Panels 4 through 6, 0.000016 to 0.000239 rad/ft. Similarly, maximum negative curvature is <br />projected at -0.000022 to -0.000410 rad/ft for Panels 1 and 2; -0.000024 to -0.000202 rad/ft for <br />Pane13; -0.000016 to -0.000239 rad/ft for Panels 4 through 6. ' <br />Maximum Horizontal Strain <br />Maximum horizontal tensile strain (Em) measured in the West Elk Mine monitoring network ranges <br />from 1.12 to 1.4 (S,,,/d) (0.0058 to 0.0102). The range of horizontal tensile strain in four different <br />mine azeas of the Westem United States studied by Mr. Dunmd is 0.45 to 3 (Sm/d). Using an <br />average value of 1.3 (Sm/d) for maximum predicted horizontal tensile strain above the chain pillazs, <br />the gate road entries, and barriers between panels and an average of 2jSm/d) for 2 (S,,,/d) for <br />maximum predicted horizontal compressive strain, the following strain values are projected for the <br />Apache Rocks and the Box Canyon mining azeas. <br />~. <br />2.05.118 Mosch IOOSPRII / <br />~, ~~b <br />