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The Technical Guidance section on this page provides
equations and calculations for compaction, excavation and earthwork problems.
Geotechnical Info .Com provides free downloads from the list of publications below that
relates to Compaction, Excavation and Earthwork. Please look at the information
and related sources for Compaction, Excavation and Earthwork in the
technical guidance section below. Or, post a question in
the Geotechnical Forum.
Compaction, Excavation and Earthwork Publications Available for Downloading
NAVFAC 7.02 -
Foundations and Earth Structures. Main topics includes excavations, compaction/
earthwork/ hydraulic fills, analysis of walls/ retaining structures, shallow foundations and
deep foundations. This manual includes guidelines for braced excavations, excavation
stabilization, embankment compaction, underwater fills, cofferdams, uplift resistance,
foundation waterproofing and lateral load capacity on deep foundations.
NAVFAC 7.03
- Soil Dynamics and Special Design Aspects. Main topics include soil dynamics,
earthquake engineering and special design aspects. Information pertaining to these topics
include machine foundations, impact loadings, dynamic soil properties, slope stability,
bearing capacity, settlement, vibratory compaction, pile driving analysis and field testing,
ground anchor systems, seismic design parameters, liquefaction, sheet pile walls and laboratory
testing.
USACE
TM 5-852-4 - Arctic and Subarctic Construction - Foundations for Structures.
The main topics are site investigations, foundation design, construction considerations and
monitoring for structures in cold weather. Includes material considerations, excavation,
backfill, inspection, slope stability, retaining walls, creep and bearing capacity.
USACE TM 5-818-4
- Backfill for Subsurface Structures
USACE EM 1110-2-2906 - Design of Pile
Foundations. Note: This publication does not have an appendix. For link to appendix,
click here.
USACE ETL 1110-1-185 - Guidelines on Ground Improvement for
Structures and Facilities
USACE TM 5-822-5 - Pavement Design for Roads,
Streets, Walks and Open Storage Areas
USACE EM 1110-2-2502
- Retaining and Flood Walls. Note: This publication does not have an appendix. For link to appendix,
click here.
USACE EM 1110-1-2908 - Rock
Foundations
USACE TM 5-822-14 -
Soil Stabilization for Pavements
USACE TM 5-818-1 - Soils and Geology Procedures
for Foundation Design of Buildings and Other Structures (Except Hydraulic Structures)
References to Compaction, Excavation and Earthwork in other Publications
Canadian Society for Civil Engineering, Cold Climate Utilities Manual, Canadian Society for Civil Engineering,
Montreal, 1986. An in-depth publication concerning water facilities. Also has excellent information
pertaining to foundations, roadways, runways, dams, earthwork and soil properties.
Teng, W.C., Foundation Design, Prentice Hall International,1962.
Johnson, S.M. and Kavanaugh, T.C., The Design of Foundations for Buildings,
McGraw Hill Book Company, 1968.
Peck, R.B., Hanson, W.E., and Thornburn, T.H., Foundation Engineering,
John Wiley and Sons, Inc., 1974.
Detailed specifications and guidance can be found at your local State
Department of Transportation Specifications for Roads and Bridges. Some of these principles
may apply to building structures, retaining walls and slope stability. Most State Departments have
a wealth of information on-line. See calculations for compaction, earthwork
and phase diagrams below:
COMPACTION
Example #1: A project requires fill to be
compacted to 95% relative density with relation to the standard Proctor
(ASTM D698). Laboratory results for the standard Proctor indicated that the
soil has a maximum dry density of 19.0 kN/m3 (121 lb/ft3),
and an optimum moisture content of 8.9%.
After compaction of the fill soils with a vibratory roller, field
testing with a sand cone, nuclear densiometer, or other appropriate method
indicated that the compacted fill soils have an in-place unit weight of
18.76 kN/m3 (124.4 lb/ft3), and a moisture content of
7.5%. Calculate the relative compaction, and does the compacted fill exceed
project requirements?
Given
gm = 19.0 kN/m3 (121 lbs/ft3)
maximum dry density
mo = 8.9%
optimum moisture content
g = 19.54 kN/m3 (124.4 lbs/ft3)
in-situ density
m = 7.5%
in-situ moisture content
Rd = 95%
required relative compaction per project specifications
Solution
Verify that compacted fill meets or exceeds compaction requirements,
Rd > 95%
Rd = gd
gm
gd =
g - g(m) dry density of
the in-situ soil
100
gd =19.54 kN/m3 -
19.54 kN/m3(7.5%) = 18.07 kN/m3
metric
100
gd =124.4 lb/ft3 -
124.4 lb/ft3(7.5%) = 115.1 lb/ft3
standard
100
Rd = 18.07 kN/m3 =
95.1% > 95% o.k.
metric
19.0 kN/m3
Rd = 115.1 lb/ft3 =
95.1% > 95% o.k.
standard
121 lb/ft3
Conclusion
The compacted fill exceeds project requirements of at least 95% relative
density.
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Example #2: A project requires fill to be
compacted to 100% relative density with relation to the standard Proctor
(ASTM D698). The fill has been vigorously compacted to a relative density of
96.9%. Subsequent compacting does not increase the relative density. What
could be the problem?
Solution
1) Check the moisture content of the compacted fill. Depending on the
soil type, an in-situ moisture content deviating 2% to 4% from the optimum
moisture content as determined from the Proctor test, may create impossible
conditions to achieve the required compaction. If this is the case, scarify
soil and add moisture (or let dry), and re-compact at the optimum moisture
content. Sometimes, complete removal and replacement of the soil is
necessary.
2) Verify the maximum dry density as determined from the Proctor test
still holds true for the 'un-compactible' soils.
Sometimes the maximum dry density changes as different soils are excavated
from the borrow pit. If this is the case, use the new maximum dry density
value when determining the relative density.
3) Check compaction methods. Type of equipment used for compaction and
the depth of compacted lifts make a difference in the relative compaction.
4) Check for inadequate compaction in underlying lifts. Sometimes
achieving adequate relative density is impossible when compacting soils on
top of loose or unconsolidated soils.
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EARTHWORK/ COMPACTION/ PHASE DIAGRAM
Example #3: This is in part, a
phase diagram
problem. A project requires fill to be compacted to 95% relative density
with relation to the standard Proctor (ASTM D698). Laboratory results for
the standard Proctor indicated that the soil has a maximum dry density of
19.49 kN/m3 (124 lb/ft3), and an optimum moisture
content of 9.5%. Borrow soil from another location that will be used as
compacted fill for this project has a moisture content of 12%, a void ratio
of 0.6, and a specific gravity of 2.65.
Assuming that no moisture is lost during transport, what is the volume
of borrow required that is needed for 28.32 m3 (1000 ft3)
of compacted fill?
Given
gm = 19.49 kN/m3 (124 lbs/ft3)
maximum dry density
mo = 8.9% optimum moisture content
e = 0.6
void ratio of borrow soil
Gs = 2.65
specific gravity of soil
m = 12.0% moisture content
of soil
Rd = 95%
required relative compaction per project specifications
VT = 28.32 m3 (1000 ft3) total
soil volume of required fill
gw = 9.81 kN/m3 (62.4 lbs/ft3)
unit weight of water (constant)
Solution
Find dry unit weight,
gd, of soil required for 95% compaction.
gd =
Rd
gm
100
= 0.95(19.49 kN/m3) = 18.52 kN/m3
metric
= 0.95(124.0 lb/ft3) = 117.8 lb/ft3
standard
Calculate the weight of the soil solids, Ws, required
for 95% compaction. The weight of the soil solids will be equal for both the
fill and borrow material because only volume changes via compaction.
Ws =
gd (VT)
*see notes within conclusion
= 18.52 kN/m3 (28.32 m3) = 524.5
kN
metric
= 117.8 lb/ft3 (1000 ft3) =
117,800 lb
standard
Determine the volume of soil solids, Vs, required for 95%
compaction.
Vs = Ws
Gs (gw)
= 524.5 kN
= 20.18 m3 metric
2.65(9.81 kN/m3)
= 117,800 lb
= 712.4 ft3 standard
2.65(62.4 lb/ft3)
Find the volume of voids, Vv, for the borrow material
Vv = e (Vs)
= 0.6(20.18 m3) = 12.11 m3
metric
= 0.6(712.4 ft3) = 427.4 ft3
standard
Calculate the total volume, VT, of the borrow soil
VT = Vv + Vs
= 12.11 m3 + 20.18 m3 =
32.3 m3
metric
= 427.4 ft3 + 712.4 ft3 = 1140
ft3
standard
Conclusion
The volume of soil required from the borrow pit is 32.3 m3
(1140 ft3). Equations used for this problem are standard phase
diagram relationships shown here. Other
phase diagram equations may be required depending on the situation.
COMPACTION
Below are a few powerpoint presentations that you can download. The original author of
these powerpoints is unknown. The original versions were slightly edited afterwards.
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