The purpose built rigs of Woltman are able to operate in many drilling configurations, such as:
- Semi displacement drilling
- CFA drilling
- Full displacement drilling
- Double rotary drilling
Semi displacement piles
With semi displacement piles a combination of CFA and displacement is used. The center of the auger is much wider which creates a larger displacement movement then a normal auger would do. Still it has the spirals on the side which create the upward movement of the soil. This pile is mostly used when the soil is too weak for a normal CFA pile.
Woltman 55DR in Semi displacement operation
Continuous Flight Auger (CFA) piles are installed by screwing an auger into the ground. During this process soil is moved upwards by the spirals of the auger. After reaching the desired depth, concrete is pumped through the center pipe while the auger is being extracted. The same auger can be used to install multiple piles. When the auger is extracted from the hole the ground crew will put the reinforcement in. This method is very fast but pile loads are limited due to the fact that the piles are not reinforced over the full length. Woltman offers multiple machines for CFA operation.
Woltman 35DR in CFA operation
This method is used in the weaker soil conditions. The piles made according this drilling system have a higher bearing capacity compared to the CFA piles because no soil is moved upwards but the soil is pushed to the side and so will be compacted. Because of the compaction of the soil a bigger and stronger machine is required compared to CFA drilling. In some cases the contractor simply prefers not to take soil out of the ground. A perfect example could be soil which used to belong to a chemical factory or oil refineries. The displacement drilling piles are becoming more and more popular in Western Europe and the USA. Thanks to the soil in Holland we have already more than 15 years’ experience with soil displacement drilling. Therefore the rigs that Woltman has to offer for this type of drilling are well developed over the years.
Woltman 90DR in soil displacement operation
Double rotary drilling
Double rotary drilling is a method in which a casing and auger are drilled into the ground simultaneously with help of a double- or two rotary head(s). In most cases this is performed to install a pile wall for example as a wall in an underground parking garage or a wall towards a tunnel.
Woltman 45DR in Double rotary configuration