资源环境科技发展态势分析平台

Water transport in large‐specific surface soil is controlled by soil microstructure and soil‐water interaction. In this paper, soil‐water interaction and confined water dynamics as well as soil microstructure are studied by combining the nuclear magnetic resonance technique and the mercury intrusion porosimetry. It is revealed that during a drying process pore water drainage occurs sequentially from larger pores to smaller pores and surface interaction parameter ρ₁ appears to be a well‐defined quantity at a water content above one water layer, below which ρ₁ shows a different trend. With the two‐dimensional T₁‐T₂ correlation measurements, surface dynamical parameters, including residence time and surface affinity coefficient, are determined, showing that the mobility of pore water decreases gradually with the decrease in water potential. The effect of temperature on the soil‐water interaction is discussed via the variation of relaxation time with temperature. The increase in residence time and surface affinity coefficient as well as effective activation energy ΔE indicates that the mobility of pore water decreases with the decrease in water potential. In addition, the positiveness of ΔE indicates that unsaturated hydraulic conductivity of clay increases with temperature, and a larger ΔE implies that the unsaturated hydraulic conductivity for the sample equilibrated at smaller potential is more sensitive to the temperature. The average pore sizes of the saturated samples are also determined by the mercury intrusion porosimetry, showing clear consistency between the MIP and NMR measurements.