The soil physics defines soil as a mixture of air, water and solid particles held together by shear forces (internal friction) and cohesion. The less air and water, that is the less void it contains, the firmer it is. During the vibroflotation process, the vibro reduce the voids in the soil. It’s compacting.
The deep vibrator produces horizontal vibrations. The energy produced by these vibrations is absorbed by the soil creating compaction. Under the influence of these vibrations the intergranular friction is overcome for a time. During this period, under the influence of gravity and complete stress relief, the soil particles rearrange themselves into a more compact arrangement.
The most important machine for all of these methods is the deep vibrator. It is a steel pipe with an eccentric and an electric motor inside. It’s head, the isolator, is assembled with follow up tubes. The upper end of the Vibroflot is called the lifting head. This lifting head has a wire roll for the wire of the crane, to lift up the Vibroflot. The standard length of the Vibroflot is between 10 and 50 m, with our Vibroflots a length of 100 m is possible and efficient.
The deep vibrator is suspended from a crane; it is positioned above the points intended for compaction. Then, while adding jetting water at high pressure from its tip, it is lowered to the intended final depth – phase 1 in our diagram. Once it has reached its final depth, the jetting water is cut off. The compaction of the soil occurs during the extraction cycle of the vibrator while it is being raised. The redistribution of the sand grains can be improved by adding water at the top of the vibrator – phase 2. During the process of compaction a cone of depression forms on the surface. This is filled with additional material – either from the surface soil or by importing selected material – phase 3.
In this way a compacted, cylindrical body of soil is formed. By overlapping these compacted bodies, a layer of ground with a consistently high degree of firmness is produced.