VIBROFLOTATION PDF

This vibrating poker is also known as depth vibrator or a vibroflot or simply flot. It is one of the most common ground improvement technique using vibration. Water flushing is done during the insertion process. Vibro-compaction in action Vibroflotation is most suitable for very loose sands submerged under water table. Efficiency of densification reduces with increase in silt and clay content and penetration rate reduces in case of dense sands with deep water tables. Principle The vibroflot imparts horizontal vibrations into the ground to breakdown the frictional contacts and effective stress between soil structures.

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This vibrating poker is also known as depth vibrator or a vibroflot or simply flot. It is one of the most common ground improvement technique using vibration. Water flushing is done during the insertion process. Vibro-compaction in action Vibroflotation is most suitable for very loose sands submerged under water table. Efficiency of densification reduces with increase in silt and clay content and penetration rate reduces in case of dense sands with deep water tables. Principle The vibroflot imparts horizontal vibrations into the ground to breakdown the frictional contacts and effective stress between soil structures.

Thus ground settles into a denser structure as shown in image. Soil structure is breakdown under dynamic stresses of around 0. When acceleration is increased to about Further increase to 3 g, will lead to dilation of the soil. The level of compaction is lesser near to the compaction point. For successful compaction, the ground should drain freely. With increasing silt content in ground, the shear stresses are not effectively transferred or are damped affecting the efficiency of compaction.

Similarly, higher fines reduces degree of improvement achieved. Vibro flotation Compaction points are usually at spacing of 1. Vibrating Poker Description The vibrating poker or vibroflot consists of Vibrating unit; Lifting head. Power developed: 35 kW to kW, even kW for some machines; Vibration frequencies: 30 Hz or 50 Hz; Amplitudes of mm, up to 23 mm.

Penetration of flot during initial boring is supported by compressed air or water jets. Compaction of the ground is done in vertical steps of about 0. Applications of Vibro-Compaction or Vibro-flotation Vibro-flotation was first used in saturated natural fine sands. Application of vibro compaction are as follows: It is applied to improve hydraulic fills Vibro-flotation reduces risk of liquefaction during seismic event.

Vibro-compaction is used over water. Depths of 30 m can be treated and it can be upto about 50 m. Multiple vibrators can be coupled together in groups.

Vibro compaction is used in conjunction with surcharging. Coarser grain size limit is applicable to vibro-compaction. Cannot be used in low permeable soils.

Vibro-Compaction or Vibro-flotation Facts Spacing of treatment points are determined by means of empirical graphs and influence coefficients. Vibro-flotation treatment must extend outside the planned area of loading. Cone penetration testing and SPTs are used to test density before and after process. Control of degree of compaction is governed by spacing, depth of compaction, vibration energy and duration of vibration.

Posted by Anand Paul November 3,

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Vibroflots

The vibroflotation will compact the soil making it suitable to support design loads. It involves the introduction of granular soil to form interlocking columns with surrounding soil. The technique is used to improve bearing capacity and reduce the possibility of differential settlements that might be allowed for the proposed loads. The compaction of soil can be obtained in soils as deep as feet. The risk of liquefaction in an earthquake prone area is also drastically reduced. Vibroflotataion Techniques Vibroflotation can be obtained by using three different techniques: Vibro Compaction method- This method allows granular soils to be compacted. This method is only used to compact sandy soils.

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Ground Improvement by Vibroflotation Method

Introduction Loose soils are a well documented problem, common in the construction industry. Immediate settlements of 1 inch per foot depth of loose sand can occur in worst-case scenarios. The term vibroflotation is often used interchangeably with vibrocompaction in the literature. However vibrocompaction is a broader term that encompasses two different techniques. The first is vibroflotation, which uses a vibroflot that vibrates horizontally. The second utilizes a vibrating probe which vibrates vertically. It should be noted that vibroflotation is used as a mechanism for implementing vibro-replacement, a method which combines the technique of vibroflotation with gravel backfilling in order to create stone columns.

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Vibroflotation

Home Technology Vibroflots Vibroflots Deep vibratory techniques using Vibroflots are generally known as vibro compaction and vibro replacement. A vibroflot is a slim, hydraulically driven vibratory needle. A Vibroflot can be extended with so-called followers to be able to work to the desired depth. Of course a Vibroflot is used in soft or granular soil, usually sand.

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