Cantilever Sheet Pile Wall Design - Granular Soils 8

[ChiEngr]

Hi Everybody,

I have a general question with regards to cantilevered sheet pile wall analysis with Granular soils. I am able to easily perform the pressure analysis due to active and passive pressures on the wall when there is no surcharge. However, when surcharge is introduced I am a bit confused. Do I include the surcharge only as an active pressure on the wall? Or should I be multiplying the surcharge pressure by (Kp - Ka) if I am trying to determine the passive pressure acting on the wall? I guess my question is, in the attached image, how do I incorporate the surcharge in calculating P_J. It does not make sense to me to multiply that pressure by (Kp-Ka). I have looked endlessly through textbooks and online for examples of this situation, and I am shocked I have not found anything of the sort. Thanks in advance for your help!

 

[PEinc]

About the 28' SSP length, for cantilevered walls, it is prudent to have at least as much embedment as the height of the wall. A 14' wall should have at least a 14' embedment, unless the soil (or rock) below subgrade is very much stronger than the retained soils. This is a good rule of thumb for keeping you out of trouble. Compare this to the (Teng's?) design graphs for embedment that are in Winterkorn & Fang and, I think, in Teng's book.

http://www.PeirceEngineering.com

 

[PEinc]

Here is another way for estimating the embedment depth of the cantilevered SSP wall that I used in my above example. As expected, the graph (which does not consider soil properties other than Ka and Kp) gives a more conservative embedment depth than either the USS conventional method or the CivilTech simplified method. The calculated embedment depth with the added 20% is 13.44' which is very close to the 14' wall height. FYI, if you use Rankine earth pressure coefficients (0.27 & 3.69) instead of USS's Coulomb coefficients (0.27 & 6.56), the embedment depth per the chart will increase from 13.44' to about 19.0'.

www.PeirceEngineering.com

 

[jayrod12]

This is all great info PEinc.

Member dik started a similar thread for fine grained soils with cohesion but it never gained any traction. Any chance you could pop into that one with some guidance you have on that front?

 

[PEinc]

Maybe. Where is it?

http://www.PeirceEngineering.com

 

[jayrod12]

thread507-489873

 

[dik]

Thanks for the interest... just trying to further my understanding. This thread has been great.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Settingsun]

OK, that's the final piece of the puzzle AFAIC and the picture looks as expected. Satisfying.

 

[ChiEngr]

I want to thank everybody who contributed in answering my initial question. I greatly appreciate it and this has been a very beneficial thread to learn through.

 

[dik]

ChiEngr... thanks for the topic. I've picked up a bunch of added info and reinforced stuff I was aware of. It's been a great topic.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik