PTC Vibrodriver Technology
The Vibrodriver vibrates profiles, sheet piles or casings to drive or extract in vertical vibrations. This in turn causes the adjacent ground to shift. The ground is loosened, which leads to the pile being driven into the ground by its own and the vibrator's weight. It can be extracted by the same principle via the pulling force of the carrier (crane) in use.
The vibrodriver is shifted in unidirectional vertical vibrations through the eccentrics mounted in the gearbox. The eccentrics, ordered in pairs, turn with the same angular velocity in opposite directions.
Both eccentrics generate centrifugal forces fc. The horizontal components fh are offset at the same time that the vertical components fv are added resulting in a centrifugal force Fc.
The element to be driven or extracted is clamped under the gearbox via a hydraulic clamp.
A yoke is located above the gearbox and prevents the transmission of vibrations through elastomer blocks. The heavy yoke causes an additional downward force through its own weight, which can be increased by adding additional weights.
The selection of a vibrodriver is based on:
- Cross section of pile
- Ram profile weight
- Soil layer consistency
- Soil porosity
The diagram, which has been derived from experience, can be used to preselect the vibrodriver.
Moreover, driving efficiency can be improved by air or water jetting.
Eccentric Moment: Mt (Nm)
is the product of the mass (m) of the eccentric and the distance (r) between its centre of gravity and its rotational axis. The eccentric moment of the vibrodriver is equal to the sum of the moments of the eccentrics:
Centrifugal Force: Fc (kN)
Each eccentric generates a centrifugal force:
Amplitude: A (mm)
is the total vertical displacement of the vibrating elements during one complete revolution of the eccentrics. The maximum amplitude is achieved using the formula:
Dynamic Weight: mv (t)
This is the sum of the weights of the vibrating gearbox, the clamping head and the element to be driver or extracted.