References for design of lagging/wall for soldier pile retaining wall

[Shanman_]

Hello, I am looking for any up-to-date references on the design of lagging or more specifically, a horizontally spanning member for a soldier pile retaining wall. This would hopefully include the effects of passive arching with a known EFP, internal friction angle, & cohesion.

I was given a list of equations with no explanation that called for friction angle and cohesion but I'm not understanding why EFP is not considered.

 

[r13]

What is EFP, elastic force procedure/protocol?

 

[Shanman_]

Equivalent fluid pressure - active pressure exerted by the soil on the wall.. expressed as a triangular load similar to fluids (psf/ft depth)

 

[r13]

If unit weight of the soil is provided, with c and ∅ are known, then you don't need EFP, as you shall derive the load from the given parameters, rather than EFP, which is an approximation/simplification in most cases.

 

[Shanman_]

Indeed. I understand that active pressure can be obtained using Rankine theory. I'm wondering how this relates to the design of the wall, say, 20 ft tall, spanning horizontally from pier to pier. If I calculate active pressure at the bottom of the wall it will be 20x that of the active pressure 1ft down from the top of wall. My understanding is that due to the passive arching of the soil, the distribution of active pressures is parabolic by nature and as such gives doesn't give a simple distributed loading diagram. If this were a small wall I would design the entire wall based on the active pressure at the bottom of the wall and be done with it. This extra work is being done to create a cost-effective design. It doesn't seem wise to design the entire wall for an active pressure of 65 psf/ft based on a 20 ft retained height (1300 psf).

 

[jayrod12]

If you've got 20 ft excavation, I assume this is not a cantilevered wall system as that would be an extreme cantilevered scenario. Not sure how you would get that to work out from a plug design standpoint.

So if braced, take a look for Peck's research. He has some test results that confirm his stress envelope. Might be a good place to start.

 

[JAE]

A few links for references that I found:

https://www.wsdot.wa.gov/eesc/bridge/designmemos/07-2007.htm

https://www.pilebuck.com/foundation/soldier-pile-lagging-walls-uses-advantages-materials-used/

Also attached is a pdf that might be of help (note other references listed at the end).

 

[r13]

Okay, I understand that you want to include arching effect in the design of the wall between two piles. While the arching will reduce the pressure on the lagging, the full load will still have to be resisted by the piles, because without rigid supports, arching will not occur. I don't remember the specific, but I'll let you know if I find something on it.

 

[r13]

This one could be interesting in understanding and further research. Link

 

[r13]

By the way, it seems you are using at rest pressure instead of active pressure in the calculation. Note that the soldier pile with lagging wall is a temporary setup, that large deflection is anticipated and can be tolerated/corrected, thus it is not justified to design for the at rest pressure, which is a long term phenomenon, unless you want it to be permanent setups. Also, if the soil has cohesion, then it is a clayey soil, the friction angle should be quite low then.

 

[JAE]

retired, that link is for vertical piled embankments. Not really applicable to flexible lagging and soldier piles.

 

[r13]

The cause of loads are different, but the concept is the same - relieved pressure between supports, full/adjusted load on support. One can learn by parallel thinking.

 

[JAE]

The OP already understands the concept of passive arching...see first post. Not sure why you needed to post that.

 

[r13]

Hurting anybody, or intentional miss leading? Stop this (picking) behavior, young man.

 

[JAE]

Your not hurting anyone. Just being redundant.

 

[r13]

Shanman,

This one should resolve your concern. Link Use previous one for further study in depth, I think it may worth the purchase cost.

 

[JAE]

Much better

 

[r13]

Keep my words in mind - there maybe bones inside, but the egg is still nutritious, but tasty.

 

[Shanman_]

Thanks for the input, both of you. I took the time to read through most of the article you both linked. It is proving to be exactly what I need to justify our approach and maybe even refine our numbers/gain some confidence in what we have. Very interesting topic, although it is not easy to find more two sources that are in agreement on the approach.

 

[r13]

Not even in the research world. Engineering judgement, with good understanding, is required ultimately.