Buoyancy question

[MikePP]

This may be a stupid question but here goes..

I have a number of large diameter tanks located in a bunded area. The tanks are bolted down to a concrete ring beam with gravel pad infill. In the event that one tank ruptures the spillage will be contained within the bund and the fluid level will be above the floor level of the other tanks. Given that the floor of the bund is concrete (i.e. effectively impermeable) and the joints between the tank baseplates and the top of the ring walls are sealed, I do not see that flotation can occur, since there is no way that any fluid can find it's way to the underside of the tank.

I think I am right but I would appreciate a second opinion - thanks.

 

[Focht3]

You need to consider buoyant forces. The site soils and gravel infill may permit the fluid to get underneath the tank, creating an "uplifting" force.



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora. See faq158-922 for recommendations regarding the question, "How Do You Evaluate Fill Settlement Beneath Structures?"

 

[CarlB]

If there is no way for fluid to get below the floor of the tank (as there shouldn't be, that is the reason for liners/seals/concrete containment floor/ etc.) then there will be no buoyant(uplift) force on the tank. There will just be the lateral fluid pressure on the outside of the ringwall and tank.

 

[Focht3]

Hmmm,

Liners, seals and concrete can develop cracks and leaks. Ignore hydrostatic pressures only if you get your client to buy off on the decision; remember that you won't be around to be sure that the tanks are properly maintained.



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora. See faq158-922 for recommendations regarding the question, "How Do You Evaluate Fill Settlement Beneath Structures?"