frost-thaw actions

[maxpack]

Living in Northern Maine, we experience deep penetrating frost action as much as 7-10 feet deep, depending on temperatures, soils, moisture content, snow cover, etc. I am looking for information showing different soil types with or without different moisture levels and the depth of frost penetration achieved under similar temperatures. In addition, I am looking for information showing the freeze thaw relationship over time, specifically does frost action still penetrate deeper when the thaw cycle begins, and under what conditions. My understanding is that frost is a suface down phenomenon and so is the thaw cycle, but it seems that municipal water systems continue to experience frozen pipes even when temperatures are rising and surface thawing has begun.

 

[BigH]

My position has been that freezing is from top down. However, thawing is from both ends - for the non-frozen soil below the maximum depth of frost penetration will start adding head on the underside as well - definitely at a lower rate, but still will do so. I saw ice lensing remnants in the NWT (Hay River)when there hadn't been enough time to completely thaw at depth. (My borings were put down in September - just as the temperature started to get ready to drop again.) There is a USArmy manual (EM) or (TM) on frost penetration, etc. that you might want to reference. If I can find the number I'll advise in later reply.

 

[VAD]

Hello maxpack:

There are several opinions that can be advanced based on experinces gained from other jurisdictions. Since soil type is one of the three important factors, I would suggest that you may be able to obtain this kind of information from the Department of Highways in Maine. Genearally, DOTs tend to have a lot of information on this subject as frost probes are used to understand depth of frost penetration during the winter and thaw seasons. Load bans are developed for some roadways based on this information. I would try the DOT as information from them would be pertinent to your environment.

Just as some info, it is found that a significant issue to frost problems is the speed at which the freezing plane penetrates the soil. If the speed is rapid as caused by a severe drop in temperature below freezing at the onset of winter then there is hardly much time for frost lens to develop and the effects are much less severe than if the winter is milder and causes a slow penetration of the freezing front.

The freezing of water pipes can result from a number of issues - depth of embedment with respect to frost penetration, nature of surrounding soil, bedding material etc., use or non use of insulation. It should be noted that gravel materials tend to allow a deeper penetration of the frost front. The design of water mains take these and more into consideration but sometimes it is not economical to design for the worst conditions.

I do not know if the above helps. The frost problem is always an interesting one requiring the evaluation of soil type, water and temperature. Silts are the most troublesome in this regard.

 

[maxpack]

Thank you BigH for the feedback,if you find that reference manual, let me know.

 

[maxpack]

Vad; I did find some DOT info on the internet from Minnesota, and it is helpful. Specifically I am hoping to find some table of data illustrating different frost penetrations for different conditions where I might compare to what we experience in this region. Thanks for the feedback.

 

[BigH]

try:

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

This should work.

 

[TAC]

Here's a link to a book I refer to occasionally:

http://www.pubs.asce.org/BOOKdisplay.cgi?8401470

Its "Frost Action and Its Control" a US Army and ASCE publication. There's some good discussion of freezing and thawing as well as designing in frost prone soils.