TECHNOLOGY OF MAKING SDP PILES WITH A DIAMETER OF 410 AND 520 mm (PRESSING DRILLED PILES).
Soil Displacement Piles(SDP) are a fast, quiet, vibration- and shake-free replacement for driven piles suitable for use in cities. As with driven piles, this manufacturing technology results in no excess material that needs to be removed after the pile is made.
This technology is ideal for use in light to medium compacted granular material, soft clays and sludge, which is similar to CFA piles. By using tools with an extended initial part, it is possible to go through thinner layers of harder materials.
The main features of SDP technology are:
- Higher load-bearing capacity compared to bored piles
- High production dynamics (as with CFA piles)
- There is no excavated material to be removed
The main features of SDP technology are:
By pressing the drilled material into the surrounding soil, a layer of compacted soil is formed around the pile. This leads to an increase in load-bearing capacity per sheath as well as the base of the pile in relation to the drilled pile of the same diameter. The load-bearing capacity of the pile made with this technology is ~ 50% higher than the load-bearing capacity of the CFA pile of the same diameter.
Minimum amount of excavated material
During drilling and pressing with a special drilling tool, the disturbed material is pressed into the surrounding soil with the extended body of the drilling tool. The drill bit is pulled out by rotation, as a result of which the collapsed material is pressed into the ground again.
Technology and workflow:
The main features of SDP technology are:
- Drilling by combining the force of rotation and stress of the tool connected to the rotating head by means of a drill.
- Pulling out the tool and at the same time concreting it to ground level, unobstructed, through the hollow stem of the drilling tool.
- Installation of a reinforcing cage over fresh concrete.
In order to ensure fast positioning of the reinforcement cage in fresh concrete, the concrete should have the following characteristics: aggregates with a maximum diameter of 16 mm (three-fraction) and concrete class S5 and SCC are used.
When using S5 concrete with a diameter of more than 220 mm, the maximum installation depth of the cage is usually 12-15 m, while when using SCC concrete it is possible to lay the cage on piles up to 30 m long, in favorable conditions.
Concreting of piles is done using a concrete pump whose output is in the range from 80 to 120 m3 / h.
The reinforcement cage, must be assembled respecting several principles: the lower part must be conical in shape to facilitate the insertion and centering of holes. The minimum protective layer of concrete must be about 7.5 cm.