Auger Cast Piles

Auger cast piles, also known as continuous flight auger (CFA) is essentially very similar to drilled shafts; the only difference is that auger cast piles are typically done in one continuous process. Instead of pushing an auger down to earth, the mast of an auger cast drill rig, a hollowed-stem flight auger supported by a pile lead that can be customized and manufactured to the length and size of the holes, are pushed down into the hole in a continuous process. As the auger is drilling, the flight of the auger is filled with drill cuts. These drill cuts provide lateral support to the holes and stabilize the hole. Once it has reached the desired depth, concrete grout is pumped in through the stem as the auger is being removed. After that, rebar will be placed in. In a wide hollowed-stem auger, rebar can be inserted through it before grouting is done. Here is a picture by Liebherr showing how the process of installing an auger cast piles.

1 – drill rigs are set up at the location of the hole.

2 – the hollowed-stem auger is drilling through the earth in one continuous motion until desired depth.

3 – As the auger is being extracted, concrete or grout is being pumped to fill up the space left behind.

4 – After concrete placement, rebars are inserted into the hole.

5 – A completed auger cast pile.

Here is a video by Liebherr as well to see a real-life auger cast pile installation.

The picture below is of an Italian brand drill rig, Soilmec SF-50 that is designed to perform continuous flight auger installation.

For more details about the drill rigs, please go to https://www.soilmec.com/en/products/cfa_piling_rigs/sf50.

Helical Pier/Piers

This foundation type is somewhat new compared to the other two that was mentioned so far. However, it is growing to be more and more preferred in the industry due to its quick installation and cheap cost. Helical piles are essentially long metal screws that is screwed into the earth to provide the same vertical support as drill piers or auger casts. One of the advantages that this has over the two is the easy setup of the drill rigs. The drive head that is used to install the helical piles are made to be compatible with most machines such as drill rigs, tractors, and it can even go on skid steers. The ability to use skid steer to install the foundation allows lower cost .With a production rate of around at least 8-10 piles a day, helical piles are proving to be a cheap alternative. Furthermore, it is effective in small spaces, as long as a skid steer can fit in it.

Here is a video by FoundationSystem that will provide more insight to a helical pile installation.

Another video by American Piledriving Equipment shows how well helical pile drill rigs can be used to install in a low headroom site condition, i.e. inside an existing building.

As we can see from these two videos, the drive head for the helical piles can be attached to different types of equipment depending on the work site, transforming any regular track machine into a capable drill rig. Here is a link to Pier Tech systems where they rent out all equipment and parts that will be needed to assemble a helical pier drill rig.