deep compaction - cradle of technical excellence
TRANSCRIPT
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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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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