Soldier pile wall with ties to a pile anchorage

[oleary194]

I designed a soldier pile wall with ties back to a short anchor pile located 40'-0" behind the main wall. The main soldier pile wall retains a cut of 19.50', and the soldier pile embeds a min. of 12' below dredge line. I had the tie at 6' below top of wall, and the short anchor pile extended 9'-0" below tie. I used the Pile Buck manual in my design, adapting their example for a continous sheet pile wall with a continuous sheet pile wall anchor.

Now, the contractor would like to cut the top of the anchor pile off at 1.0' above the tie, to allow a drainage pipe to be installed above. Also, they decided that if 9'-0" of embedment is good, then 35' of embedment is better (and it's already driven). I am trying to figure out if there is a problem with this. My main hesitation is the concern of the overlapping failure wedges, and the global stability of the wall system. If I subtract the passive capacity in the overlapped failure wedge area from the overall passive capacity of the 36' anchor pile, then I still have a factor of safety of 4.0. However, I'm worried that the tie is no longer anywhere near the resultants of the passive and active pressures on the anchor pile. How much of that 36' anchor pile is actually getting mobilized when you pull on the top 1'-0" of it?

Also, I'm worried that all that extra embedment is now applying an additional horizontal load to the main soldier pile wall. Do I recalc that wall with an added surcharge equal to the active pressure on the anchor pile?

Does anyone have a good reference that I can access quickly (ie, on the internet) that helps with pile anchorages? NAVFAC DM 7.02 briefly mentions pile anchorages as a way to carry tieback loads, but then devotes the remainder of the section to the analysis of buried deadman anchorages.

Thanks for the help

 

[SlideRuleEra]

Look in the "USS Steel Sheet Piling Design Manual" that I recently posted on my website. See thread256-150901 for the link.

http://www.SlideRuleEra.net

 

[PEinc]

Isn't the Pile Buck (RIP!) manual a reprint of the US Steel Manual but with additional information?

 

[SlideRuleEra]

I'm have not seen the Pile Buck Manual, but it must be true - see thread158-43132

Maybe more helpful information can be found in:
"Simplified Procedures for Design of Tall, Flexible Anchored Tieback Walls"

http://itl.erdc.usace.army.mil/pdf/ITL-TR-02-9.pdf

or
"Simplified Procedures for Design of Tall, Stiff Tieback Walls"

http://itl.erdc.usace.army.mil/pdf/ITL-TR-02-10.pdf

or
"Methods Used in Tieback Wall Design and Construction to Prevent Local Anchor Failure, Progressive Anchorage Failure, and Ground Stability Failure"

http://itl.erdc.usace.army.mil/pdf/ITL-TR-02-11.pdf

or
"The Seismic Design of Waterfront Retaining Structures"

http://itl.erdc.usace.army.mil/pdf/itl9211.pdf

or maybe even
"How To Determine Lateral Load Capacity of Piles", Article #9 on this page of my website

http://www.slideruleera.net/AWPI-Page.html

http://www.SlideRuleEra.net