Abstract
Unsaturated water movement and volumetric expansion in clay can be analyzed according to the mathematical theory applying Darcy's law to both water and soil particles. This paper examines this problem by determining water diffusivity-water content and solid diffusivity-solid content relationships from infiltration experiments with the unsaturated bentonite. Both diffusivities exponentially increase during water movement in a liquid, when the water and solid content increase, respectively. However, they show a constant 0.55cm2/day for water diffusivity and 0.23cm2/day for solid diffusivity, during water movement in a vapor, that is, in the range of volumetric water content 0.05 to 0.45cm3/cm3.
When both diffusion equations of volumetric water and solid content are solved regarding infiltration in an unsaturated bentonite by the use of these diffusivities, the calculated water and solid profiles agree quite well with the measured data. The changes of cumulative infiltration and volumetric expansion with time computing from the surface flux of water and soil particles, also, appear to be agreed excellently with the measured data.
