Department of Civil

Engineering,

NIT, Jamshedpur

DEEP COMPACTION

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Outlines

1. Definition of Soil Compaction

2. Aims Of Compaction.

3. Methods of Deep compaction. Vibro-Compaction.

Dynamic Compaction.

Blasting.

4. References.

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Soil Compaction

Definition:

The method of mechanically increasing

the density of soil by expulsion of airvoids

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Aims Of Compaction:

1. Increases load-bearing capacity.

2. Prevents frost damage.

3. Providesstability.

4. Reduces water seepage, swelling and contraction.

5. Reduces settling of soil.

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Methods of

Deep compaction

Vibro-Compaction.

Dynamic Compaction.

Blasting.

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Vibro-Compaction

Known as “VibroFlotation“.

Is used to densifiy clean, cohesion less soils.

action of the vibrator, usually accompanied by waterjetting.

Allowing them to move into a denser configuration, typically achieving a relative density of 70 to 85 percent.

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Expected Vibro-Compaction Results:

Ground TypeRelative

Effectiveness

Sands Excellent

Silty Sands Marginal to Good

Silts Poor

Clays Not applicable

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Dynamic Compaction

- pounding the ground by a heavy weight

Suitable for granular soils, land fills

and karst terrain with sink holes.

Pounder (Tamper)

solution cavities in

limestone

Crater created by the impact

(to be backfilled)

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Dynamic Compaction

Dynamic Compaction is the dropping of heavy

weights on the ground surface to densify soils

at depth.

Pounder (Tamper)

Mass = 10-30 tons

Drop = 50-100 ft3/28/2020 9

Vibro-compaction Acceptance Testing:

Standard Penetration Test (SPT).

Cone Penetrometer Test(CPT).

Pressuremeter Test (PMT).

Dilatometer Test(DMT).

Load test.

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Typical Dynamic Compaction ProgramInvolves:

Weights of 10 to 30 tons.

Drop heights of 50 to 100 ft.

Impact grids of 7 x 7 ft to 20 x 20ft.

Important Dynamic Compaction Geotechnical Parameters:

Soil conditions.

Groundwater level.

Relative density.

Degree of saturation.

Permeability.

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Important Dynamic Compaction Construction Conditions:

Minimum 100-150 ft clearance from any structure.

Review site for vibration sensitivity.

Dynamic Compaction Acceptance Testing:

Large-Scale Load Test . Standard Penetration Test (SPT). Cone Penetrometer Test(CPT). Pressuremeter Test (PMT). Dilatometer Test (DMT). Shear-Wave Velocity Profile.

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Blasting

Blasting is the process of detonating small charges within loose cohesion less soils for the purpose of densification.

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Expected Soil Behavior with Blasting:

Immediate and long-term surface settlement.

Settlement can be 2-10 percent of treated

strata thickness.

Penetration resistance will increase slowly with

time for several weeks.

Dense zones may be loosened during blasting.

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DesignConsiderations:

1. Charges should be placed at approximately 1/2-3/4 of desired depth of compaction.

2. Spacing of detonation holes should be between 5-15 m.

3. Successive coverage's are separated by hours or days.

4. Individual charge 1-12 kg, the amount of total explosive is 89-150 g/m̂ 3 of treatedsoil.

5. Soil closest to the surface will be poorly compacted and may need compaction by another method or removal.

6. The compaction resulting from blasting is a function of the initial relative density.

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References

• http://www.concrete-catalog.com/soil_compaction.html

• http://tc17.poly.edu/vc.html

• http://www.haywardbaker.com/services/dynamic_compa ction.html

• http://www.keller-ge.co.uk

• http://www.sbe.napier.ac.uk/projects/compaction/chapter 3a.htm

• http://www.haywardbaker.com/services/dynamic_compa ction.htm

• www.geoengineer.org/files/Compaction-Sivakugan.ppt

• http://externalweb.nmt.edu/mining/labs.htm

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