Cantilever Soldier Pile Wall Design

Cantilevered Solider Pile Retaining Wall Design

I have attached a pdf showing the basics of designing a cantilevered solider pile retaining wall. It is largely based on the California Trenching and Shoring manual. The California trenching and shoring manual is a great design reference for earth retention. However I found some parts to be slightly confusing so I tried to make it easier to understand.

PDF: Soldier Pile and Lagging Caltan 1990

Also a TEDDS calc example: Soldier Pile and Lagging Caltan 1990 Tedds Calc Note that I need to update the nomenclature and I haven’t incorporated the surcharge how I show in the hand calc, but it should be conservative.

For an Anchored wall see Anchored Soldier Pile Design

Design Concept

The design method is very similar to sheet pile design. Instead of multiplying the soil pressure that is above the excavation line and acting on the pile by the spacing of the piles a reduction factor ‘f’ is used. This factor reduces the passive pressure resistance. This factor also considers that the passive pressure will act over a greater width than just the pile width. Therefore and effective pile width is used (based on the soil friction angle with a maximum value of 3). Therefore you must remember that after you determine the maximum moment on the pile you should multiply it by the pile spacing to get the total moment. Also you can see that if you set ‘f’ = 1.0 you can use this design methodology for sheet pile design as well.

A general ‘net’ earth pressure diagram is assumed. Essentially the portion of the soldier pile that is above the excavation line (bottom grade) is subject to active pressure. Then below the excavation line passive pressure is exerted on the pile until a point of no translation or a pivot point per se. This is the point where the pile is assumed to pivot about. Because of this rotation there is now passive pressure on the back (high) side of the pile. More than one soil stratum may be used however the active and passive pressure diagrams would need to be adjusted accordingly. From there it is simple statics. The pile must be in equilibrium, so sum your forces and moments to find the distance of these inflection points. It should be noted that the embedment depth of the pile should be increased 20-40 percent after ‘D’ (the depth below the excavation line) is found in the design example. Alternatively a factor of safety may be applied to the passive pressure. Any type of lateral pressure resulting from a surcharge may be superimposed on the soil pressure diagram and an example can be found in the California Trenching and Shoring Manual.

 

2 comments for “Cantilever Soldier Pile Wall Design

  1. Pete
    April 24, 2013 at 9:37 pm

    few questions:

    1) You used Za = .35; why not Za = (1-sin(phi))/(1+sin(phi))?
    2) Shouldn’t Sum of Moments & Sum of forces equal Zero?
    3) What happened to the surcharge load in your sum of forces & moments equations?

    • Ryan
      April 28, 2013 at 7:51 am

      Pete sorry for the delay. We are moving and i should be able to respond this week.

Thoughts? Comments? Questions?