Page 21 - Building Regulation and Design Guidelines - Structural (Grey Code)

SECTION: 1 GEOTECHNICAL GUIDELINES & REGULATIONS SECTION: 1 GEOTECHNICAL GUIDELINES & REGULATIONS

1.4.1.a Deep Compaction (Vibro Compaction)
The Vibro Compaction technique, Fig. (1.22), is most suitable
for medium to coarse grained Sand with less than 10 % material Penetration
finer than 63 m and clay content (particle size less than 0.002 The vibroprobe penetrates to the required
depth by vibration and jetting action of water
mm) of less than 2%. Cohesive soils consisting of silt and clay and/or air from bottom nozzle jets.
material do not respond to vibratory compaction. The range of
soils suitable for a vibratory technique is shown on, Fig. (1.19).

Compaction
The vibroprobe is retracted from the
maximum depth in approximately 0.5m
(V23) to 1m (V48) intervals. The in situ sand
Follow up
tube
Coupling
Electric Motor
The compaction is achieved either with
Bearing
Eccentric
Nose Cone Fig. (1.23): Deep Compaction (Vibro Compaction)
Method Statement
48 mm amplitude

Penetration Compaction 1.4.1.b Dynamic Compaction
Dynamic compaction, Fig. (1.24), involves lifting and dropping
Fig. (1.22): Deep Compaction (Vibro Compaction) Technique a heavy weight several times in one place. The process is
repeated on a grid pattern across the site. Trials indicate that
the masses in the range 5 to 10 tones and drops in the range 5
to 10m are effective for compacting loose sand.
• The Vibro Compaction can increase the in situ density.
Increase in soil density is achieved through compaction
by an applied static or dynamic stress. The advantage of
Vibro compaction is to mitigate liquefaction for depths
up to 20.00m.
• The compaction pattern shall be proposed on a triangular h
pattern with maximum grid dimensions of (3.00 – 5.00)
m or as recommended by the specialist. Smaller spacing m
may be tried in case of not reaching the specific test
result. The re-compaction may be required in case of
where compaction criteria have not achieved. Fig. (1.23)
shows the vibro- compaction method statement.
Fig. (1.24): Dynamic Compaction Technique

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