Laserfiche WebLink
<br />TABLE A -III <br />C -SEAM AUGER SPACING AND EXTRACTION RATIOS <br />(Auger C or D seam, not both) <br /> <br /> TYPE AND SIZE OF AUGE R <br />Analysis Seam Factor of Sate ,Penetration and Overburden Condtions Circular 5 -Foot Diameter Circular 6 -Foot Diameter Rectan ular 13 -Foot Width <br />Location Thickness Type Auger Bedrock Depth Spoil Depth W W/D Extraction W W/D Extraction W W/D Extraction <br /> tt Peneration tt max f[ max ft in % in % in <br />North Wall Variable <br />7 6 2.0 0 to 300 175 0 35 0.58 41.3 42 0.49 49.6 81 1 .22 60.4 <br /> 6 1.5 500 175 170 52 0.67 35.1 62 0.86 42.2 135 2.05 49.1 <br />West Wall Variable <br />6 6 2.0 0 l0 300 175 0 35 0.58 41 .3 42 0.49 49.6 85 1.23 60.3 <br /> 6 1.5 500 355 0 65 1.08 31.4 78 1.08 37.7 169 2.56 44.0 <br />East Wall Variable <br />B 6 2.0 0 to 300 365 0 146 2.24 18.9 176 2.47 22.2 386 5.85 14.4 <br /> 6 1.5 500 415 0 146 2.24 16.9 178 2.47 22.2 386 5.85 14.4 <br />NOTES: <br />1 . Analysis Location, refer to Fig. A-2 <br />2. Factor of Safety conditions (average web stress). <br />Variable -Indicates overburden depth increases with depth of auger penetration (Fig. A-3). <br />- Factor of Safety is a minimum of 2.0 at face, and 1.5 at maximum auger penetration. <br />Uniform -Indicates uniform, maximum overburden depths were used, FS minimum of 2. <br />3. W -minimum web width recommended (in.). Minimum 42 in. for 6 tt. dia.; 48 in. for 7 tt. dia.; and W/D > 1.0 for rectangular. <br />4. W/D indicates approximate width to height ration of web. Minimum Of 0.57 for circular and 1.0 for rectangular. <br />5. Circular extraction ratios were calculated based upon full seam thickness and exact auger diameter. <br />6. Rectangular extractlon ratios were based upon an auger height equal to seam thickness minus 6 inches. <br />7. Between 300 and 500 foot auger penetration, Interpolation can be used to detemine web width (NI). _ _ _ <br />