Water Saturation on Retaining Wall 2

[Althalus]

I just got onto a project with a team with very different backgrounds than I'm used to. Different countries and different codes all seem to be clashing. So, I need some consensus on a particular issue.

We have a large, rectangular concrete tunnel. Don't ask why they didn't make it round.

The other engineers are postulating that when it rains the soil will become completely saturated to the point where the water will subject the soil particles to buoyancy. Thus, the EFP will change because of the fluid pressure. It will then be EFP + FP.from_water.

I could see that if it were pure sand that is completely pervious. But it is road base with about 10% to 15% fines. I just don't see that happening.

I tend to believe that the water will moisten the soil and it simply will not be "fluid". But it could add to the overall density of the soil. Thus, we'd still have the same (K.0)* new_gamma (with water).

Am I off on this? Could the water behave in a completely fluid manner through such soil?

 

[Althalus]

Thanks for all the comments. I'm afraid I'm not allowed to share a lot of details of this project. But you've given me food for thought. And there may be some considerations that the other engineers conservatively made, even if the probability is very low.

I checked rainfall data in the area. And it would take a 1000 year storm to fill up the void spaces for the depth of the buried box. But for some reason, that is enough for them to be worried about it.

I would have ignored it. But I'm the new guy on the team.