ACIP-D (Displacement ACIP Piles)

[humanengr]

I am considering the use of ACIP-D piles in lieu of "standard" ACIP to reduce the volume of spoils (excavated soil).
Would like to inquire if anyone has had some enlightening experience with ACIP-D.
In particular:

How much reduction in spoils can be expected?
What are the different types of ACIP-D piles / methods that should be considered?
Is any modification to the geotech. design required?
Is there a significant cost increase for ACIP-D?
Does the installation equipment for ACIP-D require greater vertical or horizontal clearances and access?

Thank you in advance for any experiences you can share.

 

[GeoPaveTraffic]

Saw them tried once. Refused at at about 20 feet when the design was for ~80 feet. Almost no spoil though.

Suggest you talk with your Geotech and then with a couple of specialty contractors.

Mike Lambert

 

[BigHarvey]

- How much reduction in spoils can be expected?
when you withdraw your tool line, a reverse auger will displace what has been falling during drilling in the annular space. Therefore you will have a very nominal amount of spoil after finishing a pile : roughly the volume of soil in the dispmacement tool.
- What are the different types of ACIP-D piles / methods that should be considered?
slight differences in the displacement Tools
- Is any modification to the geotech. design required?
there is certainly a possibility of taking advantage of the pros of this method. Some contractors like Berkel have developed adapted designs. Dépends also on applicable codes. In any case a load test would help.
- Is there a significant cost increase for ACIP-D?
Unfortunately for the contractors no
- Does the installation equipment for ACIP-D require greater vertical or horizontal clearances and access?
No but I haven't seen low headroom Equipment for this method

 

[ATSE]

1. How much reduction in spoils can be expected? -> for a typical 14" to 16" diameter barrel auger, about 1/4 to 1/8 of a cubic yard per pile

2. What are the different types of ACIP-D piles / methods that should be considered? -> Some methods are propriety (auger type and reverse flight pattern)

3. Is any modification to the geotech. design required? -> Displacement augers are not for very dense or stiff soils. Rule of thumb: Nspt >20 for more than 2ft, and the driller will start cooking the auger.

4. Is there a significant cost increase for ACIP-D? -> No

5. Does the installation equipment for ACIP-D require greater vertical or horizontal clearances and access? -> Different rigs completely.

You will likely see higher load carrying capacity from displacement vs. CFA (displacement / cavity expansion effects are large for granular soils).

Yes, talk to your geotech, but as with more construction fields, the contractors lead the way, and sometimes have more technical knowledge (particularly load test results) than your average jack-of-all-trades geotech engineer. So talk with a design-build contractor with engineers on staff.