An Analysis of the Thermal Fixation of Pilings

Abstract

Pilings, fixed in place with frozen sand-water fill, are used as foundations in regions of the world where the ground is permanently frozen. The heat transfer processes in the piling-fill-ground-ambient air system have been studied using a finite difference formulation of the heat conduction equation. A composite ground with a time-varying snow layer and time-varying meteorological conditions, typical of the North Slope of Alaska, are considered. The method of analysis is verified by comparing the computed thermal history of the natural ground with temperature measurements in the ground. This study indicates that when a piling is first set in the ground (in the late winter) the fill freezes completely in two days, that the system reaches a condition of periodic steady state within two weeks, that seasonal thawing of the sand-water fill will extend no more than 0.3m deeper than the seasonal thawing of the natural ground, and that the temperature of the ground adjacent to the fill is within 1°C of the temperature of the unaffected ground.