Design Methodology of Navy Style Bulkhead

[sublim21]

Hey All,

I'm a first time poster and beginning engineer. I was hoping to find someone with expertise in bulkhead design to review my methodology and to answer some questions on my design of a navy style bulkhead.

I've been tasked with design of a navy style bulkhead (8" dia piles spaced 4' O.C.). The design calls for a tieback at 4' from the top, active water height of 4.65' and a passive water height of 7.55' (roughly 2' of water surcharge) and passive soil height of 15'. All measurements are from top of the wall.

My design methodology so far is done by the free earth support method.

I found the necessary depth of sheet piling by finding the necessary theoretical depth by finding the depth necessary to generate zero moment about the tie rod.

With the depth calculated - tie rod force was found.

Max moment in sheeting was found by finding the point of zero shear and summing moments at that point.

Up until this point, I am confident in my design - my question arises in design from this point. How do the piles effect moment strength of the sheeting? Should i use rowe-reduction? I'm just confused where to move forward from this point. I'm guessing the piles restrict flex of the sheeting - in which case rowe-reduction shouldn't be used at all. But then again, wouldn't the piles also increase flexural capacity of the sheeting?

If any one has an design examples of a navy style bulkhead - aka anchored soldier pile with sheeting running vertical (in direction of retained soil height) I'd greatly appreciate it.

Looking forward to my time in this community.

-Pete

 

[PEinc]

I never heard of a "Navy style" bulkhead. Please explain. What are the 8" piles for if you have steel sheeting?

http://www.PeirceEngineering.com

 

[PEinc]

From the web site of Pile Buck International: "Many wood sheet pile walls follow the “Navy Wall” design concept, where loads are transferred to round timber master piles and standard dimensional lumber is used for the sheeting."

http://www.PeirceEngineering.com

 

[sublim21]

We're not sure what type of material to use for the sheeting currently. We're looking at corogated vinyl or reinforced polymer depending upon loads.

The design is for the replacement of a currently failing bulkhead. The 8" dia piles are 8' o.c. with wales tied in that are 5' from the top.

I'm not sure if this is standard design. The piles are on the passive (exposed) side of the sheeting. I was told that this type of design is called 'navy style' but maybe there is a more generally used term for this type of style.

 

[PEinc]

The vinyl and polymer sheets may have a large section modulus, but their allowable bending stress is usually low compared to steel sheets. Therefore, these sheets need to be tiedback if they are not low cantilevers.
Why do you need the 8" piles? Are the tie rods level or angled downward? Are the piles just to support the wales? If so, can the wales be bolted to the sheets in order to eliminate the wales?

http://www.PeirceEngineering.com

 

[sublim21]

I'm not sure why the piles are needed, beyond the fact its what the boss wants.

I'm assuming it would be safe to design the bulkhead as a tiebacked system ignoring rowe-reduction because of the added stiffness of the piles. My theory is, if it works for without the reduction the piles will have no negative effect.

Any objections?

 

[PEinc]

If the 8" piles are not touching the sheet piling (touching only the wales), they should have no effect on the flexibility of the sheets.

http://www.PeirceEngineering.com