We offer the following design variants:
Cased bored piles (kelly boring)
These bored piles are fabricated using a supporting casing, which is initially drilled into the soil. Soil material is then extracted from inside this tubing using an auger drill or drilling bucket. This method requires a kelly rotary drill and leader. When working in groundwater areas, a hydrostatic force of ≥1m is required to create excess pressure against the assumed water level. The drill cuttings generated during bored pile fabrication must be used or disposed of legally according to test results. Once drilling works are complete, a reinforcement cage is inserted. The tremie method is used to pump concrete into the borehole through tremie pipes from the bottom up. A pile protocol compliant with DIN EN 1536 is generated to record important data during the pile manufacturing process.
Gripper boring procedures with casing machines
Bored piles can also be fabricated in limited height conditions. Height restrictions can arise in works on existing buildings, under bridges or while working near power lines. Gripper boring procedures with casing machines can be used to fabricate bored piles in working height conditions from approx. 5m.
Bored piles with suspension support
As a general rule, the borehole is supported by casing until the concrete is introduced. Where piles are particularly long, however, there is a risk that casing may become stuck in the subsoil or may even break off.
In this scenario, boreholes may be supported with casing at the top, while deeper layers are instead supported by a pressurised liquid. This prevents the bore wall from breaking up or sagging. The soil is loosened and extracted using a kelly drill or, with particularly long bored piles, a cable dredger and gripper drill.
The supporting liquid, which will later be displaced by fresh concrete, generally consists of a suspension of bentonite clay. This clay can also be used to manufacture cast in situ concrete diaphragm walls. Where groundwater or supporting liquid is present, underwater concrete must be made and inserted.