Investigation of Heat and Moisture Migration in Unsaturated Soil Under Natural Boundary Conditions

摘要

Theoretical and experimental investigations were conducted to determine the heat and moisture migration in unsaturated soil under natural surface boundary conditions. Theoretically, a new model of heat and moisture migration in unsaturated porous media was developed, in which the gradients of volume water content, temperature, and partiaI vapor pressure were considered as the main driving forces which influence the process of heat and moisture migration in unsaturated soil. A set of coupled, nonlinear, partial differential equations were developed, which are related dynamically to the surface boundary conditions. Heat and moisture migration in sandy soil under solar radiation and air convection were studied experimentally. Tempera- ture, volume water content, and water table evaporation were measured under unsteady conditions. The predictions are in good agreement with experimental data from a fairly sandy soil.