Multiple stepped sheet pile walls

[craigmcg]

I've attached a file that details what I'm asking. The drawing isn't to scale so this is more for theoretical purposes. I hope that someone here can confirm or correct my reasoning...

As the image shows, I'm looking at two stepped retaining walls in very close proximity to one another. All are situated in a uniform medium dense sand with the water table fluctuating greatly. As you can see, the coulomb active and passive failure planes (AFP/PFP) intersect between the two walls. My thoughts on analysis are as follows (feel free to disagree):

1) Full active pressure on Wall 1 along AFP 1.

2) Reduced passive pressure on Wall 1 along PFP 1. All passive pressure above the PFP1/AFP2 intersection on Wall 1 is negligible. Soil above this intersection simply acts as a surcharge load.

3) Partial active pressure on Wall 2. Does anybody know how to calculate this?

4) Full passive pressure on Wall 2.

I'm not looking for conservative ways of analyzing, just the proper way. Any input is appreciated. Let me know if anything requires clarification.

Thanks.

 

[InDepth]

See attached - 2 documents (one from a computer software and one from a project that was built). This may help. This also applies to general stepped retaining walls.

What is not included is a downdrag load caused by friction on the steel sheet pile. You could probably model this as a sum of Boussinesqs in 1 ft increments.

 

[craigmcg]

Exactly what I was looking for, thanks a lot!