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Bench Geometry IVIo <br />Basic Hillside Geometry <br />T <br />1 <br />Approx. Nttmber of Benches = :B = V/f[ <br />Approx. Average Step Width = Wb = f:[B <br />(assumes right angle benches) <br />>e mined <br />Pre-mining Surface <br />a ~,~~~~~~~~~~~~~~~~~ <br />u :, <br />m- <br />'/6 0 L fp 'b. f9 ffi f9 ib' & ib $ #d ~ Fi $. £; tE ~ h 22 & CS ."i <br />Individual Bench Geometry <br />Next Hightt Beech <br />T <br />Wr <br />W <br />_ _T <br />b2 = baclcwall angle F ', <br />bl =inside bachwall angle ~, <br />a =opposite inside angle <br />W = backwall height <br />wb =average step width (assume right angles) <br />C = CDIreChOn distance. <br />Bw =true step width <br />F = backfill depth at backwall <br />Sp = slope of fill (e.g. far 2:1 Sp=2) <br />Wr = remaining backwall after bacl~dl <br />Ar =cross-sectional area of fill <br />Bench Backfill <br />Sp <br />Mined Brnch <br />~,~ C ~, .E Bw <br />wn <br />Y <br />.~ <br />!= <br />61180-b2) a=(9(}-bl) <br />c = w(tan a) = w(can(9o-bl)) = w(tan(bz-9o)) <br />Bw = wb-c=wb-(w(tan(9o-b 1)) = wn fi'v(tan(ba-9o))) <br />F=Bw/Sp <br />Wr=W-F <br />~w,.~ For radians when spreadsheet is used for modeling: <br />C = W(tan(0.0174533`a) = w(tan(0.0174533(90-b1))) = W(tan(0.0174533(62-90~))) <br />Bw = Wb-(W(tan(0.0174533(90-b1))) = wb-(W(tan(0.0174533(b2r90)))) <br />Remai"'"g Backwall <br />L/ <br />~~ <br />• <br />U <br />Page 12 <br />~-H <br />