Static Ice Loading on Water Tank

[bigmig]

Does anyone have information on static Ice loads caused by ice expansion in a water tank that will be in winter conditions? I researched previous posts and found references to an Army Corps of Engineers cold weather research design manual for cold weather retention tanks, but couldn't find any thing like this at the ACOE site. Does anyone have this manual or a link to it? We will be sealing the tank and adding a waterproofing admixture to the concrete (it is a concrete tank) to help eliminate water seepage and freeze/thaw damage. The tank is remote, so we only have very limited solar power for inlet/outlet valve cylanoids, meaning we can't run pumps to ripple the water. Someone once suggested using a polystyrene foam liner. Doesn't this waterlog and deteriorate? The water will be used for human consumption. My past experience with trying to design structure to resist ice heave is don't. The ice wins.

 

[RHTPE]

Given that the volume change from liquid atate to ice is about a 10% increase, you could determine the change in diameter (assuming a round tank), and then determine the resulting strain in the tank wall.


Ralph
Structures Consulting
Northeast USA

 

[bigmig]

THE TANK IS RECTANGULAR.

 

[RHTPE]

Okay, so it's rectangular. Same principle though. The analysis gets more interesting as you would have tension in the wall from the outward movement of the perendicular walls plus a force pushing aginst the wall from the ice.

A common ploy in my area for swimming pools left full of water for the winter is to cover them with a tarp and support the middle of the tarp with a 3' inflatable ball. I assume that the ball provides a place for the ice to expand.

Perhaps providing sloped walls would permit the ice to ride up rather than be forced to push against the walls. OR, situate the tank so the water won't freeze (like underground below frost level).


Ralph
Structures Consulting
Northeast USA

 

[bigmig]

Ralph,

The beach ball is an interesting idea, but I'd bet the ice bridges the hole and binds up anyways (imagine a finite plate model with a hole in it). The sloped walls a good, albiet expensive idea, with the added concrete.

The tank is a retrofit. The existing tank walls are 8' tall, with the tank sitting on grade. New demands have led to a request for a larger tank. we are going in and using the existing walls as forms and extending up to an overall
height of 15', essentially casting a shell inside the old one. Do you know of any foam product that can be submerged for long periods without water logging? Your "beach ball idea" could be used by adding foam around the roof slab column supports (14" dia. conc cols at tank centerline spaced approx 11' o.c.). Any thoughts on this?

 

[RHTPE]

What do you know about the tank's history with ice build-up? Moving water generally does not freeze. Is this a constantly used water source, or is it storage for fire protection?

As far as the foam - you should be able to find an FDA approved closed-cell foam to suit the purpose.


Ralph
Structures Consulting
Northeast USA

 

[bigmig]

The tank is fed via inlet at the bottom. The same pipe that feeds also removes (i.e. there is only 1 pipe). The surface is not disturbed and is totally calm at all times (I'm assuming). The water elevation goes up and down. The owner reported ice during use of the past tank.

 

[msquared48]

With the foam idea, it sounds like a memory foam might be right up your alley.

I don't know about the water intrusion issue regardint the foam though, or another possible one of chemical contamination of the water from the foam leaching over time.

Mike McCann
MMC Engineering