Permanent Soldier Pile Wall Question

[mjalexan]

Permanent Soldier Pile Wall

Wall height (H) = 12 feet
Using 14x73 H piles with precast concrete lagging

Deflection is limited to H/100 => 1.44 inches

Soil:
Sand = 120 pcf, phi=28 from top of wall to 21 feet
Sand = 120 pcf, phi=32 from 21 feet to 40 feet

I have a traffic surcharge of an additional 2 feet of fill behind the wall and level back fill.

I have a 14x73 H pile in the center of a 30 inch predrilled hole which will be filled with 3,000 psi concrete. I saw a thread about this but my question was not answered.
I want to determine the composite stiffness to use below the dredge line to keep my deflection down. Everything I have found online is the reinforced concrete design example with a row of rebar in the tension side of a beam, no circular shafts or columns.
Using just concrete or just the h pile seems too conservative, especially with the very limited deflection.

 

[PEinc]

What is your pile spacing?

http://www.PeirceEngineering.com

 

[PEinc]

FYI, I assumed that you could use Coulomb earth pressure coefficients and wall friction for both active and passive coefficients. I assumed 10' maximum soldier pile spacing. I ignored the strength of the concrete in the analysis. I assumed a passive resistance width of 3b = 3 x 2.5' = 7.5'. I added a Boussinesq area surcharge of 240 psf (= 2' x 120 pcf) starting 1 foot off the wall and extending 25 feet back. Using an HP14x73, GR50. I get an deflection of 0.99 inches. In my opinion, your 1.44 inch maximum allowable deflection (H/100) is not very limiting. I would design a permanent wall for less deflection than that. I would probaby design for no more than an inch unless specs required less.

Also, if you are using precast lagging, I hope you are building a fill wall where you can stack the lagging from the bottom up. It is hard to install concrete lagging in lifts as the excavation is being made. If you are building a fill wall with drilled soldier beams and concrete lagging, you probably are building an uneconomical wall.

http://www.PeirceEngineering.com

 

[mjalexan]

Thank you very much for your help.

 

[dcarr82775]

The only way to reliably get composite action between the H14 and the concrete pier is to use Shear Studs, or some type of shear lug. My experience is that contractor's hate doing this so I assume no composite action and use a beam sized with that in mind.

 

[msquared48]

Considering the low strength of the concrete encasing the pile so it can be easily removed to install the lagging, I would not rely on any composite action of the W shape with the 30" concrete pile.

If you are placing a permanent concrete foundation wall next to the W shapes, then composite stud action will work to attach the p[ile to the concrete wall, but, since the W shape is already loaded laterally, the composite action will only affect lateral deflections if the wall is further loaded laterally.

Have you considered using soil arching action to decrease the lateral load to the pile. If not, ask your geotech.
The load reduction may give you the lateral deflections that were recommended.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[geoxh]

PEinc,

Can you give more detail how did you calculation the deflection? any source for the calculation?

thanks!

 

[PEinc]

Go to the web site for CivilTech Software. Open a file with their Shoring Suite Manual. It should discuss their deflection calculations.

http://www.PeirceEngineering.com

 

[geoxh]

PEinc, thanks for your response. I did some search online and found two related softwares: shoring suite and supportIT. Which one will you recommend?

 

[PEinc]

No experience with shoreIT. Have used Shoring Suite extensively for years.

As with any program, you first need to know how to do the calcs by hand. You also need to know how the program is calculating the results. If not, it's just a block box for GIGO.

http://www.PeirceEngineering.com

 

[FixedEarth]

I have been using SBWALL program from Soilstructure for the past year or so for soldier pile design. Used it for few projects in Northern CA and all went well.

 

[geoxh]

It seems that the function of SBwall is kind of simple. One layer of soil is considered and no water table can be input.

 

[PEinc]

IMHO, you are wasting your time if you use a free or cheap wall design program that does not handle water level and multiple soil layers and bracing levels.

http://www.PeirceEngineering.com