Page 100 - Moving the Earth_ The Workbook of Excavation

SURVEYS AND MEASUREMENTS

2.50 THE WORK

which he or she may be getting paid. The swell factor is found by dividing the bulk of a bank yard
by the bulk of a loose yard, per the formula

1
Swell factor
1 decimal of swell
If the swell is 25 percent,
1 1
Swell factor .8 or 80%
1 0.25 1.25
The percentage of voids is found by subtracting the swell factor from 1.00.
The tables provided in Fig. 2.44 show average swell, swell factor, and voids for various classes
of soil. It also shows the shrinkage factor, which is the reduction in bulk to compacted yards in a fill.
Shrinkage. When soil placed in a fill is thoroughly compacted by rolling, it will shrink, the
amount of shrinkage depending on its character, its structure in the bank, the thickness of fill layers,
and the weight and type of roller. Blasted rock may retain some swell, while ordinary loam may

TABLE I
Swell Voids
Clean sand or gravel 5 to 15% 4.75 to 13%
Top soil 10 to 25% 9 to 20%
Sandy, clayey loam 10 to 35% 9 to 26%
Good common earth 20 to 45% 17.7 to 31%
Clay with sand or gravel 25 to 55% 20 to 35.5%
Clay—friable and light 30 to 60% 23 to 37.5%
Clay—dry, lumpy and tough, with rock 35 to 70% 26 to 41%
Shale and soft rock 40 to 85% 28.5 to 46%
Hard rock—well to poorly blasted 50 to 100% 33.3 to 50%
The loose or aerated part of the load uses space as a percentage of the full heaped pile and
is shown above in the second column as “voids.”
TABLE II
As a means of simplifying the consideration of these factors, they have been reduced to a
representative four as follows:
Sand 10% Voids
Common earth 20% Voids
Clay 30% Voids
Shot rock 40% Voids
TABLE III
Excavation, or place yards may be judged then to represent:
In sand 90% of the heaped maximum capacity
In common earth 80% of the heaped maximum capacity
In clay 70% of the heaped maximum capacity
In rock 60% of the heaped maximum capacity
TABLE IV
Loose yards will represent:
In sand 111% of bank yards
In common earth 125% of bank yards
In clay 143% of bank yards
In rock 167% of bank yards
FIGURE 2.44 Soil swell and shrinkage.