Unsaturated weathered soils are frequently encountered in most areas of Korea during construction works. Nevertheless, studies on unsaturated soils have been seldomly conducted. Especially, in Korea, rainfall infiltration mainly affects the behavior of unsaturated soils. Thus the coefficient of permeability is an important factor in analyzing unsaturated soil behavior. Generally the permeability decreases as the matric suction increases.
The permeability of unsaturated soils can be obtained by a triaxial permeameter which is able to apply matric suctions. The triaxial permeameter can easily control air pressures, maintaining constant water pressures. The difference in the air pressure and water pressure develops the matric suction. By applying Darcy’s law, the permeability of the soil can be calculated.
For the unsaturated soils sampled in Seochang, Asan and Okchun areas, Soil-Water Characteristic Curves(SWCC) and the permeability functions can be obtained by plotting the test results. The results can be compared with existing theoretical equations of SWCC and permeability functions.
Permaebility functions can be estimated using SWCC or curve-fitting the test results. Appropriate permeability functions which can be applicable for Korea weathered unsaturated soils are proposed. The permeability seems to be influenced by soil particle size distribution and especially fine particle contents.
