Find the minimum required operating room for parallel cuts. The required values are given below; Bench height=40 ft. The minimum clearance b/w the outer truck tire & safety berm=5 ft. Bench face angle=70◦ Truck capacity=85 tons Truck Width=16 ft. Tire rolling radius=4 ft. Working bench=102 ft. Cut width=60 ft. Swell factor=0.90 Holes Diameter=12 (1/4) inches

1. GhulamMehdi (23101)
Q#
Find the minimum required operating room for parallel cuts.
The required values are given below;
Bench height=40 ft.
The minimum clearance b/w the outer truck tire & safety berm=5 ft.
Bench face angle=70◦
Truck capacity=85 tons
Truck Width=16 ft.
Tire rolling radius=4 ft.
Working bench=102 ft.
Cut width=60 ft.
Swell factor=0.90
Holes Diameter=12 (1/4) inches
Shovel Specifications:
Shovel capacity=9 yd3
Dumping radius at maximum height (B) =45.5 ft
Maximum dumping height (A) =28 ft.
Radius of floor radius (G) =32.25 ft.
Maximum cutting radius of the shovel (E) =54.5 ft
Maximum cutting height of the shovel (D) =43.5 ft
Illustrate by using 8-Steps to solve this problem.
Ans#
Step 1:
We required the safety berm.
For this we know that the tire rolling radius is equal to 4 ft. Assumed to the angle of repose 45◦,
the width of the safety berm will be 8 ft.
Step 2:
The centerline of the truck to the crest distance is find in such a way that the clearance distance
b/w the safety berm and the wheel of the truck is 5 ft plus the safety berm width (8 ft) and half of
the truck width (16/2=8 ft).
Truck centerline to the crest distance (Tc) =21 ft
Step 3:
Shovel specifications are essential to considered.
Shovel Specifications:
Shovel capacity=9 yd3
Dumping radius at maximum height (B) =45.5 ft

2. GhulamMehdi (23101)
Maximum dumping height (A) =28 ft.
Radius of floor radius (G) =32.25 ft.
Maximum cutting radius of the shovel (E) =54.5 ft
Maximum cutting height of the shovel (D) =43.5 ft
Step 4:
The shovel dimensions are given above. With the help of these dimensions and the truck
centerline to the crest distance (Tc), we find the desired working bench.
WB= Tc + B +G
WB = 21 + 45.5 +35.5
WB =102 ft
Step 5:
Now find the cut width. For this purpose we know that;
Wc=(Swell factor) 2*G
Wc= (0.90) 2*35.25
Wc= 63.5 ft
In design cut width we should be kept the cut width less than this value.
Hence 60 ft has been assumed.
Step 6:
Now find the Safety bench. We know that;
WB = SB +Wc
Putting values, we have;
SB =102-60
SB =42 ft
Step 7:
The slope of the bench can find by this formula:
Slope = Tan-1 (Bench Height)/(E-G)
Putting values;
We have;
Slope = Tan-1 (40)/(54.50-35.25)
Slope = 64.3◦
Thus the shovel can easily scale the 70◦ bench face.
Step 8:
For drilling and blasting pattern,
Using a common thumb rule, the burden (B) is given by;
B =25(De/12)
B =25(12(1/4)/12)
B =25 ft
The spacing is equal to the burden.

3. GhulamMehdi (23101)
S =25 ft.