Device for fabrication of in-situ concrete piles has endless drilling screw with additional separately vibration-charged inner tube in core tube

The device has an endless drilling screw with helix arrangement (W). The screw has a core tube (S) and an inner tube (I) positioned centered and axially within the core tube. Drilling screw and inner tube can be moved independently of each other in longitudinal direction. The inner tube is longer than the screw and projects over its end, so that vibration energy can be supplied via a vibrator (R). The diameters of core tube and inner tube are adjusted relative to each other dependent upon ground conditions and concrete to be fed in.