Concept and characteristics
Extraction piles, bore-cast and concreted «in situ», constitute one of the classic foundation systems for problems arising from the soil´s bearing capacity or from the need to carry the heavy loads transmitted by the structure.
The pile diameters that can be achieved have no limitation, but generally vary progressively between 400 and 2500 mm. The depths that can be reached exceed 60 m.
There are basically three phases in the procedure for a pile bored and concreted «in situ»:
a) The bore
b) Reinforcement placing
The characteristics of the ground (stratigraphy, water level, etc.) condition the bore type and system: dry rotation, rotation with recoverable casing, rotation with muds or polymeric mixtures and, finally, with a recoverable casing chisel and grab.
Bored piling is popular in construction in foundations, especially for bridges and tall buildings. Usually bored piles are used for those tall buildings or massive industrial complexes, which require foundations that can bear the load of thousands of tons, most probably in unstable or difficult soil conditions.
Piles are also used to protect digging by supporting the soil. Depending on the characteristics of the soil to be retained they are set as tangent or even secant piles.