Q. Principle of airlifting for cleaning pile bores?
Airlifting is generally carried out before concreting to remove debris and clean the base of pile bores. It basically acts as an airlift pump by using compressed air. The setup of a typical airlifting operation is as follows: a hollow tube is placed centrally inside pile bore and a side tube is connected to the end of tube near pile bottom for the passage of compressed air inside the tube. Upper end of the tube is linked to a discharge tank for the circulation of pumped fluid from pile base.
Efficiency of airlifting operation is dependent on the performance of air compressor. At the time of airlifting, compressed air is piped down the tube and it returns up to discharge tank carrying it with the fluid. It functions by imparting energy to fluid and forces the fluid to move vertically upwards. Injected air mixes with the fluid, which leads to the formation of lower unit weight of combined mixture when compared with surrounding fluid. This hydrostatic pressure forces the air/fluid mixture up to the discharge tanks.