Applying vibration to those particles will tend to create a dense configuration. However, the amount of water in the voids of the granular soils will affect the cohesion between the particles. Dumping sand or gravel from the bed of a truck or from a scraper places the granular material in a relatively loose condition, particularly if the sand contains only a small amount of surface moisture. This material must be compacted so it can provide the required strength. If the material is not compacted, then it can lead to settlements in the future.
This type of equipment is designed to consolidate granular soils to a high density, compacting very efficiently to shallow depths. They come in different sizes and different tons capacity.
Flat Plate Vibrators
There are excellent flat plate vibrators, with a gasoline engine mounted to a unit that causes a flat skid plate to vibrate. These will do an excellent job on sands and small gravels, compacting to a depth or lift thickness of about 6 inches. Commonly used on small tranches and for small diameters pipe installation
The vertical vibration in the pile disturbs or ‘liquefies’ the soil and causes the soil particles to lose their frictional grip on the pile. The pile moves downward under its own weight, plus the weight of the vibratory hammer. Amplitude of at least one inch is usually required to cause enough soil disturbances to achieve pile driving. Vibratory compaction works well as the soil disturbance due to vibration, causes the soil particles to move into a denser configuration. Large amplitude results in a high soil strain level, a greater influence radius and higher degree of compaction.
This is another very effective device for compacting clean, free- draining sands and gravels. It resembles a standard internal concrete vibrator but is much larger and more powerful. The probe provides large capacity water jets, which act downward and sideways, flooding the soil and breaking the surface tension. This allows the sand particles more freedom to settle into a compact configuration as the granular particles are vibrated.