CFA Pile wall design 3

[SuperSandman]

I have recently graduated (2009) and currently working for geotechnical consultants. I was given the task to work alongside a very experienced geotechnical engineer in the design of a CFA pile wall. I do not have any books or papers that can assist me in the design of the wall, all I have at the moment is the knowledge from university. I was hoping that somebody could give me a list of good design aids (books or papers) that I can use to read up on before I meet with the engineer to go over his prelim design.

 

[Jalthi]

I think you are designing a secant or tangent pile wall with CFA piles. Google secant pile wall/ tangent pilw wall/ drilled shaft wall; you will find enough information.

 

[FixedEarth]

Try

http://www.GeotechLinks.com

Good luck.

Congratulations on picking up books (versus Software) in learning the fundamentals.

 

[InDepth]

Take a look at the CFA publication by FHWA. If you are in britain you can look at the ICE publications.

http://www.fhwa.dot.gov/engineering/geotech/foundations/auger.cfm

For Geotech Circular 8
Geotechnical Engineering Circular No. 8 - Design and Construction of Continuous Flight Auger Piles

http://www.fhwa.dot.gov/engineering/geotech/library_sub.cfm?keyword=022

If you are looking for secant and tangent piles, there are other resources.

 

[wmta]

you need to review these references

http://www.fhwa.dot.gov/engineering/geotech/library_arc.cfm?pub_number=55

 

[SuperSandman]

Thanks for the help guys!!!

I have used the aids to much success, unfortunately i cannot find information on design of the pile diameter and the steel schedules. I believe that once the bending moment is obtained then the pile is designed as a concrete member in bending, is this assumption correct?

Some engineers use data tables to pull of the diameter and the percentage of steel for each individual pile, i find this method easier but i wish to determine the pile size and steel schedules by first principles before trusting the data from data sheet.

any help on this matter would be appreciated, Thanks guys!!!

 

[dirtydude]

Correct, the problem becomes a simple concrete member in bending.

To resist the bending you could design a tied reinforcing steel cage or size a steel beam to be placed within the pile. The cage can be designed using the latest CRSI Design Handbook in the circular column tables. Or use the latest AISC design methods to select a steel beam.

FWIW, the steel beam may be more expensive to purchase, but it is much easier to install into a pile while the concrete/grout is still plastic.

 

[csd72]

I have used a simple formula to estimate pile capacity for initial sizing.It is called the charles whitney method from 1942.

2 layers of half the reinforcement 0.67Ds apart, and a concrete section 0.8D deep by (As/0.8D) wide. Where D is the actual diameter of the section, and Ds is the diameter of the steel cage.

This is an approximation, and as such you should always ensure that you have at least 10% or so up your sleeve for any inaccuracies. I would also note that I imagine it would be very inacurate if there were any significant axial loads.

Try an 18" pile with minimum steel and move on from there.