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<br />lnAUt Data• <br />Pillar Stability: <br />Average unit weight of overburden ... 160.00 (pcf) <br />Average overburden depth ............ 420.00 (ft) <br />Pillar width ....................... 80.00 (ft) <br />Pillar length ....................... 80.00 (ft) <br />Pillar height ....................... 7.00 (ft) <br />Opening width .... ............. 18.00 (ft) <br />Average extraction ratio .......... 33.00 ($) <br />Calculated extraction ratio ......... 33.36 (~) <br />In-situ uniaxial compressive strength of coal: 866.03 (psi) <br />- 258 effect of flooded mine =....675.00 (psi) <br />Calculated Parameters: <br />Safety Factor <br />1. Bieniawski 4.6 <br />2. Holland 3.3 <br />3. Holland - Gaddy 2.1 <br />4. Obert - Duvall 3.2 <br />Depth for Safety Factor = 1 <br />1. Bieniawski 1935 (ft) <br />2. Holland 1376 (ft) <br />3. Holland - Gaddy 901 (ft) <br />4. Obert - Duvall 1349 (ft) <br />Table I. Pillar stability Calculation for Golden Eagle Kine <br />No. 1 North <br />12 <br />