Thereare several special types of compaction techniques have been developed for deepcompaction of in-place soils. These techniques are used in the field forlarge-scale compaction works. The methods of deep compaction that have beendeveloped are vibroflotation, dynamic compaction, and blasting. Among these methods, we are going todiscuss about vibroflotation. Vibroflotation is a deep compaction groundtreatment technique for granular soils in-situ become denser by means of avibrating probe, or “vibroflot”.
Vibroflotation also known as vibrocompaction. Vibrocompactioncomprise of two different techniques. Vibroflotation is the first principalwhich uses a vibroflot that vibrate horizontally and the second principalutilizes a vibrating probe that vibrates vertically. The interparticle between thesoil can be reduced through vibroflotation as vibroflotation utilizeshorizontal vibration in conjunction with fluid. The soil will become denser andthe strength is increased besides reduce in compressibility. The relativedensity of soil is increased through vibroflotation.
When the relative densityof soil increases, the settlement is reduced and the resistance to liquefactioncan be improved. Vibroflotation was developed in Germany in the 1930s. Aprocess called vibroflot unit also called the vibrating unit is involves whichis about 2.1m long. This vibrating unit has an eccentric weight inside it andcan develop a centrifugal force, which allows the vibrating unit to vibratehorizontally. There are openings at the bottom and top of the vibrating unitfor water jets and is attached to a follow-up pipe.
Thevibroflotation 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 penetrateinto the ground.Stage2: A quick reaction is created by the water jet and it allows the vibratingunit to sink into the ground.Stage3: Pour granular materials from the top of the hole. The water from the lowerjet is transferred to the jet at the top of the vibrating unit. Granularmaterials are carried by water down the hole.
Stage4: The vibrating unit is gradually raised lift and held vibrating for about 30seconds at each lift. This process compacts the soil to a denser state.