Seepage and water retention characteristics of fill in a construction site in Yan'an

With the urbanization in China, there are more and more projects involved with miscellaneous fill. In order to study the seepage and water retention characteristics of unsaturated soils, two kinds of tests are made. One is the horizontal soil column infiltration test with different dry densities, and the other is the triaxial shrinkage test with controlled net mean stress at 0. Both of them include 3 dry densities, 1.40, 1.50 and 1.60 g/cm³. The test results show that when the saturation is about 0.65, the semi-logarithmic relationship between the saturation and the diffusivity is approximated to be two straight lines. Besides, when the saturation is less than 0.65, the difference of dry density has little effect on the diffusivity. When the saturation is higher than 0.65, there is a large difference in the diffusivity. The semi-logarithmic relationship between the permeability coefficient and the saturation of unsaturated miscellaneous fill is approximately linear, and with the increasing saturation, the density has less effect on the permeability.