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Compaction, Excavation and Earthwork

Compaction Excavation Earthwork

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Compaction, Excavation and Earthwork

Please look at the following information relating to Compaction, Excavations and Earthwork. These resources include Publications and Technical Guidance


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:



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?



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



Verify that compacted fill meets or exceeds compaction requirements,

Rd > 95%

Rd =    gd   

gd = g -  g(m)      dry density of the in-situ soil
gd =19.54 kN/m3 -  19.54 kN/m3(7.5%)  = 18.07 kN/m3                  metric
gd =124.4 lb/ft3 -  124.4 lb/ft3(7.5%)  = 115.1 lb/ft3                           standard

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



The compacted fill exceeds project requirements of at least 95% relative density.



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?



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.




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?



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)



Find dry unit weight, gd, of soil required for 95% compaction.

gd =   Rd   gm

    = 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



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.     




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.

  • Review of Compaction Principles powerpoint
  • Relative Density powerpoint


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