A Model for Coupled Moisture and Heat Flow in Unsaturated Soil

S. Kim

Manager, Ph.D., Dept. of Project Development,
Korea Land Corporation, 217 Jeongja-Dong Pundang-Gu Sungnam Kyunggi 463-755, Korea


A. G. Heydinger

Professor, Department of Civil Engineering, University of Toledo, Toledo, OH 43606-3390


Soils within and below pavement systems are designed to be in an unsaturated state. Therefore, moisture and temperature distributions in unsaturated soils are affected by climatic factors. Hydraulic gradients due to rainfall cause moisture flow and sensible heat transport, and thermal gradients due to temperature changes induce not only heat flow but also moisture flow. Freezing temperatures significantly reduce the permeability of soil but increase moisture flow caused by hydraulic gradients due to ice lens formation in the frozen soil that act as sinks.

Heat flow and moisture flow have been recognized as coupled processes with complex interactions between them. This paper presents an analysis model by the finite element method for the coupled heat flow and moisture flow in unsaturated soils. The model is applicable to both one-dimensional and two-dimensional problems. The model can be used to predict not only the change of temperature and water content, but also frost heave with time. The model is tested through comparisons with results by other computational models and by experimental results.

Keywords: coupled flow analysis, finite element method, permeability function, soil-water characteristic function, unsaturated soil, strength testing, temperature, vitrification, wave velocity

The entire paper is available (zip)