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Mine #3 <br />Cohesion F. Angle Density Pore Press. Safety <br />Run # lb /sq.ft Degrees lb /cu.ft. Ratio Factor <br />#1 860 37 108 .50 1.79 <br />#2 860 37 108 .75 1.24 <br />, - ;> #3 860 32 108 .50 1.64 <br />#4 940 37 108 .50 1.88 <br />#5 860 32 108 .75 1.18 <br />#6 680 30 108 .50 1.39 <br />#7 600 38 108 .50 1.46 <br />Run #1 uses the residual cohesion and the peak angle of friction, <br />which is reasonable since the material above the #4 sieve cannot be <br />tested. Run #3 uses all residual values, which is conservative, and <br />results in a safety factor of 1.64. Runs #2 and #5 show that if the <br />pore pressure ratio reaches .75, the slope safety factor drops <br />below 1.3. These high pore pressure ratios are not expected in the <br />field. <br />Runs #6 and #7 show lower than reported cohesions with varying <br />friction angles. Both have acceptable safety factors. <br />The expected case for long term stability is Run #3, which is <br />included in Appendix B. <br />Inspection of the minimum factor of safety failure circles on the <br />maps shows that the circles are limited by the stiff ground of the <br />highwall and the bench itself. Since large pieces of concrete <br />rubble are to be placed in the bottom of the fill, this will <br />increase the safety factor of the fill. <br />