are several special types of compaction techniques have been developed for deep
compaction of in-place soils. These techniques are used in the field for
large-scale compaction works. The methods of deep compaction that have been
developed are vibroflotation, dynamic compaction, and blasting.
Among these methods, we are going to
discuss about vibroflotation. Vibroflotation is a deep compaction ground
treatment technique for granular soils in-situ become denser by means of a
vibrating probe, or “vibroflot”. Vibroflotation also known as vibrocompaction. Vibrocompaction
comprise of two different techniques. Vibroflotation is the first principal
which uses a vibroflot that vibrate horizontally and the second principal
utilizes a vibrating probe that vibrates vertically. The interparticle between the
soil can be reduced through vibroflotation as vibroflotation utilizes
horizontal vibration in conjunction with fluid. The soil will become denser and
the strength is increased besides reduce in compressibility. The relative
density of soil is increased through vibroflotation. When the relative density
of soil increases, the settlement is reduced and the resistance to liquefaction
can be improved.
Vibroflotation was developed in Germany in the 1930s. A
process called vibroflot unit also called the vibrating unit is involves which
is about 2.1m long. This vibrating unit has an eccentric weight inside it and
can develop a centrifugal force, which allows the vibrating unit to vibrate
horizontally. There are openings at the bottom and top of the vibrating unit
for water jets and is attached to a follow-up pipe.The
vibroflotation compaction process can be divided into four stages (Figure 2)Stage1:
The jet at the bottom of the Vibroflot is turned on and allowed to penetrate
into the ground.Stage
2: A quick reaction is created by the water jet and it allows the vibrating
unit to sink into the ground.Stage
3: Pour granular materials from the top of the hole. The water from the lower
jet is transferred to the jet at the top of the vibrating unit. Granular
materials are carried by water down the hole.
4: The vibrating unit is gradually raised lift and held vibrating for about 30
seconds at each lift. This process compacts the soil to a denser state.