frost heave 2

[dittowizard]

Is there a formula to calculate the Force generated, lifting capacity and expansion factor of frost heave or frozen water (ice)?

I have a project in upstate SC. The Architect has stated the frost heave is not relevant to his scope of work in regards to civil design of building approaches and walks and curb design.

I would be happy to agree with him, except I have been involved in a lawsuit in NC where on the northeast side of the building the frost heave raise the building approachs concrete and blocked several fire exits and accessible routes.

I have always wondered about the lifting capacity and expansion factor of freezing water and it resulting effects on a rigid structure. There is also a question about sealing expansion joints between the structure and sidewalks.

Thank you in advance.

 

[andycivil]

Dittowizard.....I am unfamiliar with "frost heave". Are you talking about expansion from freeze - thaw cycles?

 

[CarlB]

Ice formation can generate several hundred psi, easily enough to lift building foundations. The problem you cite (heaving at doorways blocking doors) is common in subarctic areas. Typical solutions are to put several feet of NFS (non frost susceptible) soil beneath pavements/sidewalks adjacent to doorways, and/or omit the insulation on the foundation wall under doorways and substitute horizontal insulation (1 to 2 feet deep) extending out from the building a few feet. Insulation is the rigid, extruded polystyrene type, typically 2" thick. This helps keep soils thawed outside doorways.

HTH,
Carl

 

[dicksewerrat]

You will need to put in the 1-2 feet of granular , compacted well at all bldg. enteries. Abd yes the sidewalks, etc have to be sealed from the rain and this year snow melt along the bldg.Frost heave can push the sidewalks 3-6 inches in no time at all.

 

[dittowizard]

Thanks for the information. Yes, AndyCivil, Frost Heave is the same as expansion from freeze - thaw cycles.

If anyone has a formula to calculate the Force generated, lifting capacity and expansion factor of frost heave it would ne greatly appreciated. Even a rule of thumb would help.

 

[CarlB]

A few sources you might try given below. In the first one I saw a reference to "over 10 tons per square foot", and there is a chart for maximum pressure vs. particle size/permeability.

http://www.usace.army.mil/publications/armytm/tm5-852-4/entire.pdf

http://www.usace.army.mil/publications/armytm/tm5-818-1/ch-18.pdf

http://www.crrel.usace.army.mil/techpub/CRREL_Reports/reports/TR00-16.pdf

http://www.crrel.usace.army.mil/techpub/CRREL_Reports/reports/CR95_12.pdf

http://www.bio.mie-u.ac.jp/~kunio/pdf/dthesis/chap2.pdf

http://www.usace.army.mil/publications/armytm/tm5-852-1/entire.pdf

 

[dittowizard]

thank you CarlB! This info hits the spot. makes for some "light" reading, but just what I am looking for.

 

[KRSServices]

Frost heave! The evil twin brother of Canadian winters. I did not realize that frost penetration was such that frost heaving was a problem N.C. The heaving occurred due to the behavior of different soil types (residual moisture, composition properties) to freezing. To heave to a level whereby accesses were blocked...thats a water problem, not "heaving" per se. The underlying soils must have been soaked. The best solution is to ensure that the areas are well graded and if necessary to utilize some granular material, but that is expensive. Sidewalks are typically constructed over 6" of 3/4" crush on a clay subgrade. The walkways drain to the road or away from the concrete. If you place concrete on top of say, organic material, it will heave, crack, spall and be replaced within 10 years because that soil is highly suseptible to moisture retention. Placing several feet of granular is a waste of money.

The best bet, ensure the areas are well graded. Use a sealant, such a sica-flex to seal any cracks that will allow water to accumulate. Most of all, if as a result of the lawsuit the approach is reconstructed, get rid of unsuitable materials (silts, organics) and replace with a clays, and top it off with a graded aggregate. KRS Services

http://www.krs-services.com

 

[boo1]

check:

http://irc.nrc-cnrc.gc.ca/cbd/cbd061e.html

 

[dittowizard]

Frost heave is not as bad in NC as in IN, but does happen. In the above case it was found the owner did not turn the sprinklers off in the planters between the building and the sidewalks. When a week long hard freeze hit the problem occurred and the Fire Marshall made them close the wing affected. The owner said it was due to poor construction, not the fact the water was on in freezing weather, and he wanted someone to pay for damages and lost money.

Damage was due to the raising of the concrete above the lower level of the stucco wall covering, causing the stucco to be broken and removed from the wall.

Thank you for the help with research materials.

 

[jheidt2543]

Back to your original question. You might do a search on "permafrost". There were lots of studys done years ago, in preparation for the Alaska pipeline, on the effects of permafrost on foundations etc.

Just a thought!

 

[BigH]

jheidt2543 - you're right although I would believe that most of them have to do with uplift of piles as most of the pipeline is elevated. Still, they would be of use with expected heave.

KRS: - while I have you here on this thread; I know you are in BC. Do you have a copy of the BC std drawing for superelevation section in fill??? Want to know if they "breakback" the shoulder on the uphill side. If you do, and you don't mind sending me a scan of it, I would certainly appreciate it. bohica@indiatimes.com

Many thanks and best to all watching these wonderful threads. Better - much much better - than watching Hindi movies.

BigH

 

[KRSServices]

BigH,

Actually I am a former BC resident. I now live in Alberta, but yes I do have the highways spec and some drawings for the superelevation. If I do, I'll scan and send to you. KRS Services

http://www.krs-services.com

 

[BigH]

KRS - Thanks; I worked in Fort McMurray for about a year during the initial box cuts at Syncrude; long time ago. Lived also in VCR for about 7 years. Alberta was okay other than Calgary rolling up the sidewalks at 1700h!!

 

[MartinWG]

For a comprehensive book of the subject of Cold Weather Building, try "Building Science for a Cold Climate" by Hutcheon and Handegord, published by the Institute for Research in Construction. This book comes from the National Research Council of Canada, and has a detailed study of water and heat related building problems. There is an excellent graph of heaving pressures for various types of soil particle diameters. All values are in SI.

It is book written from the "researcher's perspective", but could have great value to those confronted with cold weather building construction problems. It is a good foundation book for those interested in building science.

 

[bplech]

one writer offered the several hudred psi, and another writer quoted tne tons per square foot. Interestinly , the values are 200psi and 139 psi respectively. frost heave is a result of the water in the ground freezing. water expands when it freezes to a maximum volume at around degrees F. The frost heave is a result to the expansion of the water in the soil freezing. The change in volume is approximately 8% for the depth of ground frozen.

 

[BigH]

This assumes that "no water is added." In some formations, clays/mudstones, etc., water continues to be attracted to thin lenses that have started between beds and with the added water, the ice lenses increase in size. This can create pressures more than just the 8-9% expansion.

 

[bmike]

It is true that water swells on freezing, but imagine the amount of water, by volume, in the soil that has frozen, and imagine an eight percent volume change. I suspect the amount of surface movement will be much less than the heaving dittoposter observed. The amount of surface heaving due to the lower density of ice would be about 8% of the soil volumetric water content (identical to porosity in a saturated soil)times the thickness of frozen soil, not 8% of the frozen soil thickness.

But frost heaving will occur even in soils with pore fluids that contract upon freezing.

The real culprit is the migration of pore fluid to the freezing front, allowing the growth of segregated lenses of ice. As the water freezes, more water will move to the freezing surface to replace it. It flows for several reasons that I am aware of, there are probabaly others:

1. The heat is flowing from the earth to the atmosphere. The cool water near the freezing front has a lower vapour pressure than the warmer water below. The temperature gradient induces an upward hydraulic gradient.
2. Tension develops at the ice-water interface, drawing more water upward toward the freezing front.
3. The water near the ice becomes hypertonic, since the frozen ice is nearly pure. Low osmolarity water from further away flows to this region until the two zones become isotonic.

The water comes from below because this is usully the only (or nearest) unfrozen, available water in the area.

The small pore size in fine grained soils is also associated with capillarity, which allows water to rise above the level of atmospheric pressure, again due to a membrane tension at the water surface.

This is more likely what you have observed.

You need three components to have frost heaving. 1) Freezing temperatures in the soil, 2) frost susceptible soil (usually fine grained), and 3) a source of water. Eliminate one of the three elements, or slow down the cooling or water flow, and solve the problem (or eliminate two for a belt and suspenders approach). Good drainage design is usually the simplest.

Several good suggestions have been offered. Floor slab details for unheated buildings (like a warehouse or barn in freezing zones) would be a good starting point. Check with a Department of Agriculture extension service. Your outdoor building approaches are in a thermal regime similar to this.

Roads are usually not designed to eliminate heaving altogether, but will have details that, in theory, eliminate differences in heaving, and features to prevent the weakening that occurs when they begin to thaw from the top in spring, and become fully saturated if not drained. In some cases temporary reduced vehicle weights will be enforced during this period.