Chapter 20
Frost heave in freezing soils
Damage to roads and pavements in regions which experience prolonged
freezing is essentially due to the process whereby ice lenses
accumulate in the subsoil (the damage occurs in thawing, when melting
leads to ground collapse), and this accumulation is part of the
phenomenon called frost heave, as the suction of water towards the
freezing front to produce the lenses also causes the ground surface to
heave. Although studied since the 1930s, the mechanism of frost heave
is still controversial. This chapter considers one model, that due to
Miller, and shows how it can be reduced to a much simpler form,
essentially a quasi-static generalised Stefan problem with a
complicated interfacial (Stefan-type) condition. In one dimension, the
model can even be solved explicitly.
In his thesis, Chris Noon shows how these procedures can be applied to
more complicated models, including compressibility and saline soils,
and a similar reduction. He also shows that the model is susceptible
to a spatial instability, and this may explain the formation of earth
hummocks, which are prevalent in places such as Iceland (and there is
a nice photo of them by Bill Krantz opposite page 370). Some of this
latter work has been published (Fowler and Noon
1997a,b),
albeit succinctly.