Loess in China is thick

and groundwater levels are always very deep in loess area where is characterized by low precipitation

which makes loess always at unsaturated state. Soil-water characteristic curve is the foundation of researches on stress state

strength and permeability of unsaturated loess. This paper experiments on typical Malan loess in Longdong plateau

the soil-water characteristic curve of undisturbed sample is determined by tensionmeter

and the experimental data are then fitted with three theoretical models

of which Gardner model is the simplest with the least parameters

while Fredlund & Xing model has the best fitting effect. The relationship between permeability coefficient and matric suction or water content of unsaturated loess is built based on the measured soil-water characteristic curve by Childs & Collis-Geroge model which is commonly used to predict unsaturated permeability coefficient. The results show that the permeability coefficient decreases dramatically as saturated loess becoming unsaturated

the relationships between permeability coefficient and matric suction or volume water content of unsaturated loess can all be expressed in exponential form. Study of the soil-water characteristic curve and permeability coefficient prediction of typical loess provides loess engineering problems

such as the slope stability evaluation with the effects of rain infiltration and the computation of collapsible deformation of unsaturated foundation

with theoretical basis.