HÜDIG - Practical tips for wellpoint dewatering
The permeability "k" or k-value is used in dewatering to quantify the permeability of soils for liquids (e.g. groundwater). In order to ensure that air infiltration does not endanger the vacuum system when the groundwater level is lowered or that the excavation pit is successfully drained, it is necessary to ensure proper filter coverage, In this context, the correct distance from the bottom of the excavation pit to the top edge of the filter must be determined. Should this prove to be too low in relation to the k-value, the excavation pit may also be flooded unter certain circumstances.
Rule of thumb and tips:
If, for example, the k-value has not been determined and a groundwater lowering has been successfully carried out in the local environment using the vacuum method, the following rule of thumb applies:
Filter distance: 1 - 2 m
Filter overlap: 0.5 - 1 m
At the end of the suction line, the negative pressure must be 1 - 2 m higher than the geodetic suction height from the filter tip to the installation level of the vacuum unit.
Adjusting the vacuum:
The average atmospheric pressure (atmospheric pressure) at sea level is about 1 bar, which corresponds to a water head of 10 m. Depending on the type of vacuum pump, Hüdig units can generate a vacuum of -0.92 bar (dry-running) and up to -0.99 bar (oil-lubricated). Not every construction project requires such a high vacuum. Therefore the vacuum in Hüdig vacuum systems can be regulated and adapted to the corresponding depth of the construction project. Thus energy and money can be saved in the long run.
filter overlap - sufficient
filter overlap - small