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All About Frost Heaves
Thu Jan 29, 2004
Listen in RealAudio 
"I'm Karen Henry. I'm a research civil engineer with a geotechnical specialty. I study frost
effects and mitigation of frost effects in soils."
Hi, I'm Bryan Yeaton for The Weather Notebook. What Dr. Henry is talking about are frost
heaves. They are not just bumps in the road.
KH: What they are, are lenses of ice that have formed in the soil and they're much more than
a volume expansion of water upon freezing. When an ice lens starts to form, actually water is
drawn up to the bottom of the ice lens and freezes there. So, it can exert a lot of
pressure.
BY: So, it's not necessarily water that's seeping down through cracks. It's actually being
pulled up from lower soil?
KH: Right. I've seen telephone poles be heaved out of the ground and damaged dams, as well as
what we've seen on the roads. The volume of water that you end up with in a frozen state far
exceeds the capacity of the soil to hold that water. And, this is also what leads to the
damage during the spring when everything melts because you have highly saturated and
supersaturated water.
BY: Now, by "ice lens," what do you mean?
KH: It's a perfectly clear lens of ice in the soil. They're kind of fatter in the middle and
taper out toward the edges and the dimensions can be anywhere from something that you can't
see, to inches long and inches thick.
BY: I figured every place across the north had our - our wonderful frost heaves.
KH: The northern tier states do experience damage from frost. But, New Hampshire and Vermont
- and Maine too - experience some of the worst, because of the soils.
Tomorrow, Dr. Henry explains how she may be able to keep roads from heaving. Our show is
supported by Subaru of America and the National Scienc
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