Discussion:
Suppose the slope in the sketch is cable bolted. No surcharge is present. Bolt spacing is 50 ft (15.2 m) in the vertical direction and 25 ft (7.6 m) in the horizontal direction. Bolts assemblages are composed of 12 strands of Type 270 cable (495,600 lbf, ultimate strength or 2.22 MN) and are installed in down holes (5?). Design tension is 60% of the ultimate strength. Find the safety factor obtained by bolting and therefore the improvement in the safety factor obtained (difference between the bolted and unbolted slope safety factors).