Gravel screeding for Immersed tube tunnel

[sykimm]

Hi,
I'm looking for some information to get the appropriate gravel foundation for immersed tube tunnel.
Factually, immersed tube will be designed for seawater intake and we are now considering direct gravel foundation under the sea of depth 20m.

If you have any information and experience, please share your experience with me.

- To get the appropriate leveling within tolerance
- screeding method
- rock and/or gravel size
- etc.

 

[BigInch]

What kind of pipe, concrete coated steel, concrete and what is the diameter?

At 20 meters depth, perhaps it should be burried in a trench to eliminate wave and current loads and provide mechanical protection from anchors, trawl drags etc. It is possible that it could be laid on the bottom with a rock mat or rock placed (dumped) on top.

Bedding you should use depends on the surrounding material and if some type of beddings might be washed out. For some pipe in some natural soils/sands/gravels, you may not need special bedding and trench backwashin will suffice.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com