= Hydraulic control of frost heave
{title2=$\dot h=\Pi[p_T-\rho gh]/(\mu d)$}
A porous sheet of thickness $d$ and <permeability of a porous medium> $\Pi$ supplies a thin <premelting> film. The <Darcy flow law> equates water supply to <ice> growth for equal densities. With equal film and <ice> conductivities, negligible latent heat relative to the through-going conductive flux, and $a\ll h$, phase equilibrium gives $p_T=(\rho L\Delta T/T_m)^{3/4}(A/(6\pi h^3))^{1/4}$. The increasing gravitational load limits growth. A quasi-steady <temperature> field alone does not imply the negligible-latent-heat approximation.
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