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Mine #3 <br /> Cohesion F . Angle Density Pore Press . Safety <br /> Run # lb sg. 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 /> resu i is i n a saf ety f actor of 1 . 64 . Runs #2 and #5 show that i f 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 or; 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 />