Compaction of Soil By Vibroflotation

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2. PRESENTERS
SULEMAN SHAHID
2012-MS-CEG-17
MUHAMMAD SAIFULLAH
2012-MS-CEG-25
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3. COMPACTION OF SOIL
BY
VIBROFLOTATION
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4. Compaction
 It is type of mechanical stabilization where
the soil mass is densified with the
application of mechanical energy also
known as compacting effort. The
mechanical energy may be produced by
dynamic load, static load, vibration or by
tamping.
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5. Why we do Compaction?
 To improve the density of the soil thus improving
its shear strength and its bearing capacity.
 Compaction decreases the tendency of the soil
mass to settle under repeated load.
 Improving the shear strength of soil by
compaction, the stability of slopes and excavations
increases.
 To reduce the permeability of soil.
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6. Factor Affecting Soil Compaction:
 1- Soil Type
 2- Water Content (wc)
 3- Compaction Effort Required (Energy)
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7. Compaction methods
 Static - a large stress is slowly applied to the soil and
then released.
 Impact - the stress is applied by dropping a large mass
onto the surface of the soil.
 Vibrating - a stress is applied repeatedly and rapidly
via a mechanically driven plate or hammer. Often
combined with rolling compaction.
 Rolling - a heavy cylinder is rolled over the surface of
the soil. Commonly used on sports pitches. Roller-
compactors are often fitted with vibratory devices to
enhance their ability.
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8. Soil Compaction in the Field:
1- Rammers
2- Vibratory Plates
3- Smooth Rollers
4- Rubber-Tire
5- Sheep foot Roller
6- Dynamic Compaction

9. In-situ Densification
In-situ
Densification
Dynamic
Compaction
Rapid Impact
Compaction
Vibroflotation
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10. VIBROFLOTATION
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11. VIBROFLOTATION
Compaction of granular soils by depth
vibrators is known as“Vibro
Compaction” or “Vibroflotation”
Natural deposits as well as artificially
reclaimed sands can be compacted to a
depth of up to 70 m
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12. MECHANISM
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13. Vibroflotation Methodology
Densify the soil by down hole vibratory
Probe.
Probe is lowered to required depth by
Crane.
Soil gets densified by the vibratory energy.
Densification causes depression at surface.
Depression is filled by granular backfill.
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14. TYPICAL VIBROFLOTATOR
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15. PROCEDURE
 The device sinks at the rate of 1 to 2 m/min into
the ground and sets the partical to float due to
excess of water coming out of the lower jet and
vibration .
 when the the instrument reaches the desire depth
after a few minutes of operation the top jet is
turned on and vibrofloat is withdrawn at the rate
of 0.3 m / min.
 sand is added to the crater formed at the top which
is typically 10 % of the compacted volume.
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16. Working of Vibroflotation
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17. Working of Vibroflotation
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18. Vibroflotation
Probe includes the vibrator mechanism
and water jets
Probe is lowered into the ground using
a crane
Vibratory eccentric force induces
densification and water jets assist in
insertion and extraction
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19. Procedure
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20. Palm Jumeirah, Dubai, UAE
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21. VIBROFLOTATION EQUIPMENT
 Vibroflotation utilizes a cylindrical penetrator 432
mm in diameter, 1.83 m long, and weighing
about 17.8 kN.
 An eccentric mass rotates inside the cylinder at
about 1800 rpm to develope a horizontal
centrifugal vibration force of about 90 kN.
 The device has water jets top & bottom with a flow
rate of 300 L/min at a pressure of 430-580 kPa
 The device sinks at the rate of 1-2 m/min into the
ground
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22. VIBROFLOTATION EQUIPMENT
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http://www.imeco.at

24. Vibroflotation
Ground Type Effectiveness
Sands Excellent
Silty Sands Good
Silts Poor
Clays Not Applicable
Mine spoils Good (if Granular)
Dumped Fill Depends on nature of fill
Garbage Not Applicable
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25. FILL MATERIAL
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26. Vibroflotation limitation
The method most commonly
used to densify cohesion-less
deposits of sand and gravel,
with less than 20% silt & 10%
clay.
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27. Effective Range
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28. Probe Spacing
 The spacing of the probe should be such that the zone
of influence of each probe should overlap in manner as
shown below.
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29. Beware of transmission of vibrations
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30. Case Study
1. Port Botany Expansion Project:
 The project involved the extension of port with 60
hectares of land.
 Vibro compaction was done in 2 ways
a) Marine Vibro Compaction:
Bottom level of compaction was -13m and volume of
material treated was 800,000 m3
b) Land Vibro Compaction:
Ground was compacted up to -22m and volume of
material treated was 1.37M m3
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31. PORT BOTANY EXPANSION PROJECT
SYDNEY, AUSTRALIA
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33. CASE STUDY
 LOCATION: BEACHLAND ESTATE, APAPA,
LAGOS, NIGERIA
 PERIOD: JUNE 2002 – OCTOBER 2002
 SAMPLE POST- COMPACTION TEST
RESULTS:
With a maximum load of 150kN/m2 the
maximum total settlement was 32mm. The
improved soil exhibited an allowable bearing
capacity of 250kN/m2.
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34. CHEK LAP KOK HONG KONG INTL AIRPORT
 The world’s
largest
vibrocompaction
project is in
Hong Kong –
Penny’s Bay.
 Vibrocompaction
was done upto
the depth of 40
m. 34

35. REFERENCES
 Joseph E. Bowles, Foundation Analysis and Design, 5th Ed.
 Braja M. Das , Fundamentals of Geotechnical Engineering ,
3rd Ed.
 M. S. Qureshi & Aziz Akbar , Fundamentals of Soil
Mechanics
 www.nptel.iitm.ac.in
 www.archiexpo.com
 www.bauer.ro
 www.foundaquiq.com
 www.ptc.fayat.com
 www.imeco.at
 www.menardbachy.com.au
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