Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: Frozen soil = disturbed earth?

[Subject Prev][Subject Next][Thread Prev][Thread Next]
I'm no frost expert (although I once did design a major structure on permafrost), but does it make sense to build on once-frozen ground, since it could presumably freeze again -- not a Good Thing.

In other words, I'm suggesting building down below the frost depth.  Duh.

Ralph Hueston Kratz, S.E.
Richmond CA USA

In a message dated 3/20/09 3:05:09 PM, Tom.Hunt(--nospam--at) writes:

From perhaps a definition standpoint I would not consider frozen/unfrozen soil as disturbed soil as this would disqualify all soil north of Texas however this does not give you the green light in placing a foundation on known crappy soil.  You can freeze and thaw good well graded/compacted soil all you want and nothing much will happen but take soil with some glacial till in it and you are in big trouble.

Thomas Hunt, S.E.

Jim Wilson <wilsonengineers(--nospam--at)>
03/20/2009 06:25 AM
Please respond to seaint To

Frozen soil = disturbed earth?

Is previously frozen soil considered disturbed earth?  Perhaps there isn't a definitive answer to this question, but in general terms, if there is evidence that the soil has frozen and heaved, is it thereafter unusable for placement of a footing?
The easy CYA engineering answer is to require a soils engineer, do testing, compaction, etc.  But sometimes the easy answer is not the right answer.
For example, one numbskull called me this winter with cracks in his foundation wall.  Sure enough, he placed new concrete walls and footings in December, left them exposed and then we had sub-zero temps for about two months straight.  Come February, the walls had several cracks.  No wonder.  But after the frost subsided, the cracks closed and didn't look like much of anything.  Is there an argument that the foundation is okay (notwithstanding analysis of the cracks) because it returned to its original condition?  Soils in our area are typically sandy gravel with decent bearing capacity.
Jim Wilson, PE
Stroudsburg, PA

Feeling the pinch at the grocery store? Make meals for Under $10. (