With reference to the generic wedge in the sketch and the specific data in Table 2.8 if the safety factor with respect to sliding down the line of intersection is greater than 1.10, then safety is assured. The water table is at the crest of the slope (but may be lowered to meet the safety criterion), vertical distance between a and g is 85 ft (25.9 m), point e is 48 ft (14.6 m) from point a, rock specific weight is 158pcf (25.0kN/m3) and active wedge volume is 3,735 yd3 (2,856 m3). What range of face orientations (dip directions) is of concern in an open pit mine where benches 95 ft (28.96 m) high areplanned?

Dip Cohesion psf Friction angle Direction angles Area ft? Parameter Dip dir. (m2) i (kPa) of nomals a.B.y ) plane Joint A Joint B Face Upland Tension crack 3,318 (308) 338 (31.4) 1,800 (86.2) 26 45 90 180 135 45 1,080 (S1.7) 75 32 7,144 (664) 148 68 48 | |