Drillmaster New Product – Full Displacement Pile(FDP) Tools

Full displacement pile is very popular all over the world. Let see what is it and why it’s popular in this article.

What is full displacement pile?

Soil full displacement piles are bored piles that use the torque and pressure of a rotary drilling rig to drive the displacement drill into the ground. The prerequisite for the success of this process is a rotary drilling rig with relatively large torque, large pressure and pull-out force, and a set of drilling tools with strong torsion resistance.

This technology is very suitable for a wide range of soil conditions, from sandy gravel, sand, silt and clay to soft organic soil, as long as the soil is displaceable.

However, in some special cases, such as abundant groundwater, loose soil or poor geological conditions, the construction of full displacement piles may meet certain challenges and difficulties.

Advantages of full displacement pile

1) High bearing capacity The soil in the center of the pile hole is squeezed to the surrounding of the pile hole, thereby producing high-density soil, which can effectively increase the friction and bearing capacity of the pile.

2) Reduce waste When drilling underground, the extrusion and expansion drill is drilled into the ground, and the drilled soil will be completely squeezed around the pile hole without being discharged to the ground outside the hole. The transportation cost of the slag is reduced. In addition, there is less waste on the construction site, and the construction is more convenient.

3) Reduce concrete consumption Compared with other bored piles, the concrete over-cubic ratio is significantly reduced. Save concrete.

4) Small vibration during construction During construction, the extrusion and expansion drill is drilled into the ground by a rotary drilling rig, and the vibration is very small, which will not cause vibration of nearby buildings, thereby avoiding cracking and collapse of buildings.

5) High construction efficiency Since there is no need to take the slag out of the hole, the construction efficiency is much higher than that of ordinary rotary piles.

However, full displacement pile will also have certain negative effects on the surrounding soil, such as causing soil deformation, settlement and ground uplift, etc. Therefore, when designing and constructing spoil piles, it is necessary to fully consider their impact on the surrounding soil and take corresponding measures to control and prevent them.

Structure of full displacement pile tools — Full displacement drill rod and Full displacement drill bit

- Full displacement drill rod: The full displacement drill rod is a double-wall drill rod, with a pressurized drill rod at the upper end and an extrusion drill bit at the lower end. The two ends are connected by hexagonal male and female joints, and the center hole is used to pour concrete. The diameter of the drill rod and the size of the hexagonal joint should be designed according to the torque of the drilling rig. The length of the drill rod is designed according to actual needs.

- The full displacement drill bit is a conical spiral drill bit with a male or female joint at the top, a cutting tooth at the bottom, and a concrete outlet. According to the function during drilling, it is divided into loosening section, extrusion section, stabilization section, and reinforcement section from bottom to top.

1) Loosening section - The drill teeth loosen the soil and transport it upward through the blades

2) Extrusion section - The conical drill rod squeezes the soil upward into the pile hole

3) Stabilization section - The cylindrical drill rod further squeezes the squeezed soil to form a stable pile hole wall

4) Reinforcement section - When lifting the drill, the drill rotates to squeeze the fallen soil back into the pile hole.

Construction process of full displacement pile

1) Determine the pile position, start the drill and place the drill tool in the center of the pile hole. Check whether the drill teeth and concrete outlet are working properly.

2) The rotary drilling rig drives the drill bit to drill into the ground. After the soil is loosened by the drill bit, it is squeezed around the pile hole.

3) After drilling to the final set depth, start to reverse and pull the drill tool out of the pile hole. During the process of lifting the drill, the concrete is transported to the bottom of the hole through the drill bit and the concrete outlet. When lifting the drill, the drill tool rotates slowly to squeeze and reinforce the soil dropped from above.

4) If the pile hole does not need to put a steel cage, then the construction is completed. If the pile hole needs to put a steel cage, then insert the steel cage into the hole and vibrate it all underground with a vibrator, and the construction is completed.

Precautions — When using full displacement pile tools for foundation treatment, the following points should be noted:

1) Fully understand the geological conditions and engineering requirements, and select appropriate pile types and construction methods.

2) Strictly control the compaction or extrusion during construction to avoid excessive impact on the surrounding soil.

3) Take appropriate measures to control and prevent possible soil deformation, settlement, and ground uplift.

4) Strengthen monitoring and testing during construction to ensure the quality and effect of soil-displacement piles.