Sheet Pile Drop Structure - Tie the Channel Lining to it? 1

[JoelTXCive]

We have two drainage channels that are intersecting, and one channel's flowline is 2ft below the other channels.

The land engineer's are proposing a sheet pile drop structure on the higher channel. This sheet pile structure will have concrete channel lining all around it. See below photos for the concept.

My job will be do design the sheet piles and channel lining.

The land engineers (and me) are concerned about water getting under the channel lining and eroding the entire structure from below.

The Question:

Does anybody know if any textbooks have construction details on a structure like this? Maybe an old Army Corp document or US Dept of Agriculture, or NRCS?

Should there be a bond break between the piles and the concrete? Or, do I go the opposite direction and cast concrete right up against the sheet piles (looks like that's what they did in this photo). Another idea is to weld studs on the side of the sheet piles and connect the channel lining to it. I'm not sure if I should be trying to lock everything together, or loosen everything up.


Thank you in advance.

 

[GC_Hopi]

The Bureau of Reclamation or USACE are good resources. You should be able to google their technical publications or engineering manuals. I can not think of one that would cover this exact layout but the design guides would cover hydraulic structures. My advice on this structure is to continue the concrete over the top of the sheet piles and maybe down the face then provide joints with waterstop. Or continue the concrete over the top of the sheet piles to cap them, no concrete at the face of the sheet piles, then expansion waterstop at the interface from concrete to the face of the sheet piles.

 

[r13]

Is the new pile on upstream, or down stream of the existing sheet pile wall? I suggest to look for the design and construction of cofferdam. Seepage might not be a big concern as finding good support. I don't quite get the idea of sheet pile with concrete channel lining, or facing. Are the concrete channels be precast or CIP?

 

[JoelTXCive]

Retired13 -

Currently, there are zero piles. We have an existing drainage ditch owned by the local county government. We are going to dig a new channel and cross the existing channel. Our channel is going to be 2ft deeper than the existing county channel. I don't understand all the hydraulics, but in a low-flow situation, our channel will take the county's flow. At higher flows, some of the county's water will go into our new channel, and some will pass right by the intersection. (that's what the hydrologists say anyway)

I believe using the sheet piles is significantly cheaper than a fully cast in place concrete structure.

In Houston, you see sheet piles in drainage ditches used as flow control weirs all over the place. I believe they just drive the piles and then cast 5" or 6" thick channel lining around them. I have not seen one for a drop structure though.

For a small 2ft drop, I am not worried about the sheet piles. I will get geotech data, but we'll probably drive them at least 10ft below the flowline.

I worry about the interface between the concrete and the sheet piles. I don't know if I should be attempting to seal it up as tight as humanly possible, or allow some small amount of movement of the piles by installing a bituminous bond break (or other material).

 

[r13]

I worry about the interface between the concrete and the sheet piles.

Why break the bond? Use reinforced concrete, and design the wall as composite, using studs to tie the sheet pile and concrete panel.

 

[cvg]

I would expect a significant amount of water will go through and under the sheet piles unless you drive them quite deep, you may have uplift pressure on your concrete channel lining. an underdrain system could work to reduce that pressure as could weepholes through channel/sheets

U.S. Army Corps of Engineers
No. 1110-2-2007
Engineering and Design
STRUCTURAL DESIGN OF CONCRETE LINED FLOOD CONTROL CHANNELS

 

[r13]

The problem is more on scour/erosion at the base. Protection by riprap should be considered.