The telescopic Kelly bar method is used for inserting piles in uncased, casing pipe or cement casing drill holes. The drill component that digs into the soil is attached to the telescopic Kelly bar.
Using fully or partially supported drill pile techniques the casing pipe is inserted and the soil gradually removed until the borehole reaches the required depth. When cement casing is used the cement is pumped into the borehole at the same time as the soil is removed.
Drill holes created using the telescopic Kelly bar method are usually equipped with reinforced shells before concreting the piles. If fully or partially supported drill pile techniques are used, then the casing pipe is gradually removed as the concreting process progresses.
Piles inserted in the given way have the advantage of reaching great depths in large diameters. AS YIT Eesti will use the above described technology for drilled piles with nominal diameters of 880, 1180 and 1500 mm.