Heat and Water Transfer in Compacted and Layered Soils

Abstract

Clay material is frequently used to cover landfills or to line hazardous waste disposal landfills. The cover of a landfill is usually exposed to solar radiation, which can cause desiccation and shrinkage of the landfill cover. This study presents two nonisothermal conditions (small and large surface temperature amplitudes) to evaluate heat and water transfer in closed soil columns. The small surface temperature amplitude ranged from 1.0 to 11.0°C, and the large surface temperature amplitude ranged from 15.0 to 16.0°C. Both uniformly compacted and layered soil columns were exposed to small temperature amplitudes, but large temperature amplitudes were used only with uniformly compacted soil columns. Clarinda clay (fine, montmorillonitic, mesic Vertic Argiaquoll) and Fayette silty clay loam (fine‐silty, mixed, mesic Typic Hapludalf) soils were moistened to initial gravimetric water contents of 0.281 and 0.187 kg kg −1 , respectively. The moistened soil was packed into polyvinyl chloride columns (0.75 m in diameter and 0.30 m long). For uniform compacted soil columns, the bulk densities were 1.45 and 1.67 Mg m −3 for Clarinda and Fayette soils, respectively. In the layered soil columns, the bulk densities of the upper layers (0.05 m thick) were similar to the densities in uniform compacted soil. The bulk density of the lower layers (0.25 m thick) was 1.0 Mg m −3 . A numerical model of coupled heat and water transfer predicted soil temperature and water distributions well in comparison with the measured distributions for all of the conditions. Predicted net water transfer in layered soil revealed that thermal water transfer is significant in comparison with isothermal water transfer.