Page 198 - Geotechnical Engineering Soil and Foundation Principles and Practice

Soil Density and Unit Weight
Soil Density and Unit Weight 193

9.7. (a) Explain how a moisture content can exceed 100%. (b) What soil minerals
are indicated by moisture contents in excess of 100%? (c) Why is it
advantageous to define moisture content on the basis of dry weight rather
than total weight?
3
3
9.8. A proposed earth dam will contain 4,098,000 m (5,360,000 yd ) of soil.
It will be compacted to a void ratio of 0.80. There are three available borrow
pits, which are designated as A, B, and C. The void ratio of the soil in each
pit and the estimated cost of moving the soil to the dam is as shown in the
tabulation.

What will be the least earth-moving cost, and which pit will it be most
economical to use?
Cost of moving
Pit Void ratio per m 3 per yd 3

A 0.9 $1.67 $1.28
B 2.0 1.19 0.91
C 1.6 1.56 1.19

9.9. Prepare a bar graph with vertical bar heights representing dry and
submerged unit weights of (a) uniform quartz spheres in rhombic packing,
(b) uniform quartz spheres in cubic packing, (c) solid quartz, (d) Portland
cement concrete.

Further Reading

American Society for Testing and Materials, Annual Book of ASTM Standards, Vol. 4.08:
Soil and Rock.
Mitchell, J. K. (1993) Fundamentals of Soil Behavior, 2nd ed. John Wiley & Sons,
New York.

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